Armstrong Flo-Rite-Temp FRT8120R User manual

Flo-Rite-Temp®
Installation and Operation Manual
IOM-780-N

2
Table of Contents
Introduction.............................................................................................................................................3
Steam Piping Installation......................................................................................................................10
Water Piping Installation.......................................................................................................................11
Pressure Relief (Pop-Off Value) Installation ........................................................................................12
Optional Thermostatic Controllers and Safety Equipment ...................................................................13
Start up and Adjusting Procedure Flo-Rite-Temp ................................................................................15
Recirculation System Piping and Operation.........................................................................................17
AMOT Piping (Thermostatic Diverting Valve)
RADA Piping (Thermostatic Mixing Valve)
Accumulation System Piping................................................................................................................18
Tempered Water Systems for Safety Shower/Eye Wash Station........................................................19
Flo-Rite-Temp Pre-Packaged Systems................................................................................................20
Single Temperature (Non-Recirculated)
Single Temperature (Recirculated)
Multi Temperature Packages
Troubleshooting Guide .........................................................................................................................21
Disassembly .........................................................................................................................................22
Clean In Place Operation .....................................................................................................................23
Control Valve Parts Listing...................................................................................................................24

3
Flo-Rite-Temp®Feed-Forward Instantaneous
Steam/Water Heaters
Flo-Rite-Temp feed-forward instantaneous steam/water heaters offer a simple yet time-proven alternative to traditional feedback
instantaneous, semi-instantaneous and tank-type steam-heating methods.
By eliminating the temperatures sensing feedback element and relying upon the actual hot water
system demand requirement within the system or application, feed-forward systems respond rapidly and are extremely accurate.
Flo-Rite-Temp Feed-Forward Instantaneous Steam/Water Heater is a more attractive option because:
• The constant, non-modulating steam pressure within the shell eliminates cycling damage.
• The system demand or flow feed-forward activation eliminates the requirement for either steamn control valve or thermostatic
control device.
• It delivers a consistent outlet temperature (+/-4°F of set-point) with no thermal lag and resulting temperature swing.
• It is extremely safe because the mixing unit will position to cold water flow upon failure of the primary operating component.
The Armstrong Flo-Rite-Temp can easily do the work of a storage tank unit many times its size - at lower installed cost and with minimum maintenance. Even the largest
capacity Flo-Rite-Temp requires only 7 square feet (0.63 m2) of floor space.
The Armstrong feed-forward design eliminates the troublesome temperature regulator and uses a differential pressure diaphragm valve
to regulate flow and control temperature. The valve teams up with a shell and tube heat exchanger to complete the system.
The idea is simple: Overheat water in the heat exchanger and then blend it (as needed) with proportional amounts of cold water to
achieve the correct outlet temperature for a wide range of flows. There’s no storage tank or potential health hazard posed by standing
water.
Gives you a jump on peak demand periods. The differential pressure diaphragm acts immediately upon a change of demand so there’s
no lag time. You get all the hot water you need - up to the unit’s capacity - instantly. What’s more, if the diaphragm fails, a spring
returns the valve to a closed position (cold), so there’s no danger of scalding by accident.
Makes maintenance a straight, easy shot. Virtually everything about the design and operation of the Flo-Rite-Temp reduces mainte-
nance. (See below.) For starters, the tubes inside the carbon steel shell are straight for easy mechanical cleaning. And steam pressure
in the heat exchanger is not modulated but constant, which ensures condensate drainage and nixes potential water hammer and corro-
sion.
Pushes you out front in savings. When it comes to replacing a bulky storage tank system, the choice is clear. The Flo-Rite-Temp
consumes dramatically less floor space, and you don’t have to tear out walls to install it. In fact, it slips through a standard doorway.
Payoff? Lower installed cost. Another advantage: An energy-efficient Armstrong Flo-Rite-Temp instantaneous water heater won’t waste
energy by constantly reheating stored water. You can even insulate the heat exchanger shell for greater savings.

4
Heat it as you need it. Match your capacity needs with one of the four models of Armstrong’s Flo-Rite-Temp instantaneous water
heaters. For an application overview or technical assistance in selecting and installing, contact your Armstrong Representative today.
Table 4-1. How Flo-RIte-Temp Scores on Key Benefits
Flo-Rite-Temp Feed Forward Storage Tank Feedback Tankless Instantaneous Feedback
Saves space Yes No Yes
Saves energy Yes No Yes
Eliminates temp. swings Yes Yes No
Eliminates thermal lag Yes Yes No
Ensures accurate control Yes Yes No
Designed with straight tubes for easy
cleaning Yes No No
Eliminates potentional health hazard for
standing water Yes No Yes
Fails cold for safety Yes No No
Eliminates thermostatic control Yes No No

5
Flo-Rite-Temp®Single Wall Instantaneous
Water Heater
Model 665 and
8120 Valve
Figure 5-1.
Note: Double wall units
available.
Heater Installation
NOTE: Flo-Rite-Temp is provided with one
Armstrong Steam Trap and Thermostatic Air Vent
(shaded). All other items shown
not included. Removable/reusable insulation
covers for the heat exchangers are available.
Contact Armstrong or your local
representative for more information.
Table 5-1. Dimensions
Model
A B C D E F G H J K L M
in mm in mm in mm in mm in mm in mm in mm in mm in mm in mm in mm in mm
415 54 1372 4-1/2 114 7-1/2 190 7 178 4-1/2 114 3-5/16 84 3 76 7 178 6 152 6-1/4 159 50 1270 7-1/2 190
535 67-1/2 1715 5-1/4 133 8-5/8 219 9 229 5-9/16 141 4 102 3-11/16 94 7-7/8 200 7 178 7-1/2 191 62 1575 9 229
665 82 2083 5-3/4 146 10-3/8 264 10-3/8 264 6-5/8 168 4-5/8 117 4-9/16 116 9-1/4 235 8 203 8-3/4 222 74 1880 11 280
8120 85 2159 5-3/4 146 11-3/4 299 12 305 8-5/8 219 6 152 8-7/8 225 9-1/2 241 8 203 9-1/2 241 74 1880 12-3/8 314
Table 5-2. Connections and Weights
Model
Connections Weight
123
in (mm) in (mm) in (mm) lb kg
415 1” (25) NPT 3/4” (20) NPT 2” (50) NPT 133 60
535 1-1/2” (40) NPT 1” (25) NPT 2-1/2” (65) NPT 235 107
665 2” (50) NPT* 1-1/4” (32) NPT 3” (80) NPT 358 162
8120 3” (80) NPT* 2” (50) NPT 4” (100) 150#ANSI 585 265
*665 and 8120 connections for water inlet and outlet are on opposite sides of the valve body.
Table 5-3. Specifications
Application Steam Supply Pressure Water Supply Pressure Maximum Water Pressure Drop
Steam to Water 2 - 15 psig (0.14 to 1.0 bar) 20 - 150 psig (1.4 - 10.3 bar) 10 psig (0.7 bar)
NOTE: Reusable insulation wraps available.
Table 5-4. Materials
Model Valve Valve Seats Diaphragm Heat Exchanger
Shell
Heat Exchanger
Tubes Tube Sheets Tube Bundle End Cap
Bronze
(415) 303 Stainless Steel
w/ Teflon Inserts
(415/535)
303 Stainless Steel Viton® GF
Reinforced
w/Nomex®Fiber
Carbon Steel
ASTM “U”
Stamped
5/8” 16 BWG
Admiralty Brass Brass Brass
(535/665/8120) Brass (665/8120) Brass

6
Flo-Rite-Temp®Double Wall Instantaneous
Water Heater
The DW (double wall) version of the Armstrong Flo-Rite-Temp instantaneous water heater uses a double-walled tube to provide positive separation of
the steam and water in the heat exchanger. The area between the walls of the tubes vents to atmosphere so you can detect tube failure without cross-
contaminating either the steam or water. The Flo-Rite-Temp DW is well suited for all hot water applications where steam is available and plumbing
codes or safety requirements prevent the heating medium and the potable water supply from being cross-contaminated.
Model 415DW and 535DW profile shown
below. 665DW and 8120DW profile
would show that connections for water
inlet and outlet are on opposite sides of
the valve body.
NOTE: For capacities, see sizing table on
page HWS-10.
Model 665DW and
8120 DW Valve
Model 415DW and 535DW Profile
Table 6-1. Dimensions
Model
A B C D E F G H J K L M
in mm in mm in mm in mm in mm in mm in mm in mm in mm in mm in mm in mm
415DW 76-1/8 1934 4-1/2 114 7-1/2 190 7 178 4-1/2 114 3-3/8 86 3-3/4 95 10-1/2 267 6 152 6-7/8 175 75 1270 7-1/2 190
535DW 77-3/8 1965 5-1/4 133 8-5/8 219 9 229 5-9/16 141 4 102 4-1/4 108 11-1/2 292 7 178 8-1/8 206 75 1575 9 229
665DW 90-5/8 2302 5-3/4 146 10-3/8 264 10-3/8 264 6-5/8 168 4-3/4 121 5 127 11-3/4 298 8 203 9-3/4 248 87 1880 11 280
8120DW 79-7/8 2029 5-3/4 146 11-3/4 299 12 305 8-5/8 219 6 152 8-3/4 222 12-5/8 321 8 203 11-5/8 295 76 1880 12-3/8 314
Table 6-2. Connections and Weights
Model
Connections Tube Bundle
Removable
in (mm)
Weight
123
in (mm) in (mm) in (mm) lb kg
415DW 1” (25) NPT 3/4” (20) NPT 2” (50) NPT 75” (1905) 199 90
535DW 1-1/2” (40) NPT 1” (25) NPT 2-1/2” (65) NPT 75” (1905) 270 122
665DW 2” (50) NPT* 1-1/4” (32) NPT 3” (80) NPT 87” (2210) 444 201
8120DW 3” (80) NPT* 2” (50) NPT 4” (100) 150#ANSI 75” (1905) 665 302
*665 and 8120 connections for water inlet and outlet are on opposite sides of the valve body.
Table 6-3. Specifications
Application Steam Supply Pressure Water Supply Pressure Maximum Water Pressure Drop
Steam to Water 2 - 15 psig (0.14 to 1.0 bar) 20 - 150 psig (1.4 - 10.3 bar) 10 psig (0.7 bar)
Table 6-4. Materials
Model Valve Valve Seats Diaphragm Heat Exchanger
Shell
Heat Exchanger
Tubes Tube Sheets Tube Bundle End Cap
Bronze
(415DW) 303 Stainless Steel
w/ Teflon Inserts
(415DW/535DW)
303 Stainless Steel Viton® GF
Reinforced
w/Nomex®Fiber
Carbon Steel
ASTM “U”
Stamped
5/8” 16 BWG
Admiralty Brass Brass Brass
(535DW/665DW/8120DW)
Brass
(665DW/8120DW)
Brass
*Units are ASME “UM” stamped - ASME “U” stamped available on request.
**There is an open vent to atmosphere between the tube sheets to detect tube failure.

7
Sizing and Single and Double Wall
Flo-Rite-Temp®
Table 6-2. Connections and Weights
Model
Connections Tube Bundle
Removable
in (mm)
Weight
123
in (mm) in (mm) in (mm) lb kg
415DW 1” (25) NPT 3/4” (20) NPT 2” (50) NPT 75” (1905) 199 90
535DW 1-1/2” (40) NPT 1” (25) NPT 2-1/2” (65) NPT 75” (1905) 270 122
665DW 2” (50) NPT* 1-1/4” (32) NPT 3” (80) NPT 87” (2210) 444 201
8120DW 3” (80) NPT* 2” (50) NPT 4” (100) 150#ANSI 75” (1905) 665 302
Table 6-3. Specifications
Application Steam Supply Pressure Water Supply Pressure Maximum Water Pressure Drop
Steam to Water 2 - 15 psig (0.14 to 1.0 bar) 20 - 150 psig (1.4 - 10.3 bar) 10 psig (0.7 bar)
*Units
may be piped in parallel when desired capacities exceed that of a single unit.
NOTES:
Minimum water temperature increase is 60°F (33°C). Consult factory if less than 60°F (33°C) increase is required or a set temperature below 120°F (49°C) is
required. See page PTC-37 for proper pressure reducing valve selection.
psig psig psig psig psig psig psig psig barbar barbar barbar barbar
2510 15 2510 15 0.14 0.35 0.710.14 0.35 0.71
gpm gpm gpm gpm lbs/hr lbs/hr lbs/hr lbs/hr m3/h m3/h m3/h m3/h kg/h kg/h kg/h kg/h
17 18 20 20 714 767 839 901 3.8 4.1 4.5 4.5 323347 379407 415
37 40 43 45 1,543 1,657 1,814 1,946 8.49.1 9.810.2697 749820 880535
69 74 80 80 2,855 3,067 3,356 3,601 15.7 16.8 18.2 18.2 1,2901,386 1,5171,628 665
142 145 145 145 5,680 6,160 6,760 7,160 32.2 32.9 32.9 32.9 2,5762,794 3,0663,248 8120
15 16 17 18 681 734 807 868 3.4 3.6 3.8 4.1 308332 365392 415
32 34 37 39 1,472 1,587 1,743 1,876 7.37.7 8.4 8.8 665717 788848 535
58 63 68 73 2,723 2,936 3,226 3,472 13.2 14.3 15.4 16.6 1,2301,327 1,4581,569 665
112 122 136 145 5,040 5,490 6,120 6,705 25.4 27.7 30.9 32.9 2,2862,490 2,7763,041 8120
12 13 15 16 646 700 773 835 2.7 3.0 3.4 3.6 292316 349377 415
27 29 32 34 1,397 1,513 1,671 1,804 6.16.6 7.3 7.7 631684 755815 535
50 54 59 63 2,585 2,799 3,091 3,338 11.3 12.2 13.3 14.3 1,1681,265 1,3971,509 665
88 97 109 120 4,400 4,850 5,450 6,000 20.0 22.0 24.7 27.2 1,9962,200 2,4722,722 8120
9101112572 627 702 765 2.0 2.3 2.5 2.7 259283 317346 415
20 22 24 26 1,235 1,355 1,517 1,652 4.55.0 5.5 5.9 558612 686747 535
37 40 45 48 2,286 2,508 2,806 3,057 8.49.1 10.2 10.9 1,033 1,1341,268 1,382665
69 83 89 95 4,140 4,980 5,340 5,700 15.6 18.8 20.2 21.6 1,8782,259 2,4222,585 8120
5567344 386441 4871.1 1.11.4 1.6156 175200 221415
12 13 15 16 861 966 1,104 1,219 2.7 3.0 3.4 3.6 390438 501553 535
23 26 39 32 1,663 1,866 2,134 2,355 5.2 5.9 6.67.3 754846 9681,068 665
43 47 52 59 3,010 3,290 3,640 4,130 9.710.711.813.41,365 1,4921,651 1,8738120
19 20 20 20 692 745 816 877 4.3 4.5 4.54.5 313337 369396 415
41 44 45 45 1,495 1,609 1,764 1,896 9.310.010.210.2676 727797 857535
76 80 80 80 2,767 2,977 3,264 3,508 17.3 18.2 18.2 18.2 1,2511,346 1,4751,586 665
145 145 145 145 5,740 6,090 6,580 7,035 32.2 32.2 32.2 32.2 2,6032,762 2,9853,191 8120
16 17 19 20 660 712 785 846 3.6 3.8 4.34.5 298322 355382 415
34 37 40 45 1,425 1,539 1,695 1,827 7.7 8.4 9.1 9.8 644696 766826 535
64 68 75 80 2,637 2,848 3,137 3,381 14.5 15.4 17.0 18.2 1,1921,287 1,4181,528 665
127 138 145 145 5,080 5,520 6,120 6,760 28.8 31.3 32.2 32.2 2,3042,504 2,7763,066 8120
13 14 16 17 626 679 752 813 2.9 3.2 3.63.8 283307 340367 415
29 31 34 37 1,352 1,467 1,624 1,756 6.6 7.0 7.7 8.4 611663 734794 535
54 58 64 68 2,502 2,715 3,005 3,250 12.2 13.2 14.5 15.4 1,1311,227 1,3581,474 665
99 108 121 134 4,455 4,860 5,445 6,030 22.5 24.5 27.5 30.4 2,0212,204 2,4702,735 8120
10 11 12 13 553 608 682 744 2.3 2.5 2.73.0 250275 308336 415
21 23 25 28 1,194 1,313 1,473 1,607 4.7 5.2 5.76.4 540593 665726 535
39 42 47 51 2,210 2,429 2,725 2,974 8.99.5 10.7 11.6 9991,098 1,2321,344 665
76 90 95 102 4,180 4,950 5,225 5,610 17.2 20.4 21.6 23.1 1,8962,245 2,3702,545 8120
5667332 3734
28 4731.1 1.41.4 1.6151 169194 214415
12 14 16 17 831 934 1,071 1,185 2.7 3.2 3.6 3.9 377424 486537 535
24 27 30 33 1,605 1,805 2,069 2,289 5.4 6.1 6.8 7.5 728819 9381,037 665
49 55 63 72 3,185 3,575 4,095 4,680 11.1 12.5 14.3 16.3 1,4451,622 1,8572,123 8120
18 19 20 20 638 690 762 822 4.1 4.3 4.54.5 288312 344372 415
38 41 45 45 1,378 1,491 1,646 1,777 8.7 9.3 10.2 10.2 623674 744803 535
70 76 80 80 2,550 2,760 3,046 3,288 15.9 17.3 18.2 18.2 1,1521,247 1,3771,486 665
145 145 145 145 5,110 5,565 6,090 6,510 32.2 32.2 32.2 32.2 2,3182,524 2,7622,953 8120
15 16 17 19 605 658 729 790 3.43.6 3.84.3 273297 330357 415
32 34 38 40 1,307 1,421 1,576 1,708 7.3 7.7 8.69.1 591642 712772 535
58 63 69 75 2,418 2,629 2,917 3,160 13.2 14.3 15.7 17.0 1,0931,188 1,3181,428 665
111 123 137 145 4,440 4,920 5,480 6,080 25.2 27.9 31.1 32.2 2,0142,232 2,4862,758 8120
10 11 13 14 533 588 661 723 2.3 2.5 2.93.2 241266 299327 415
22 24 27 30 1,152 1,270 1,428 1,561 5.0 5.5 6.1 6.8 521574 645706 535
41 45 50 55 2,132 2,349 2,642 2,889 9.310.211.312.5964 1,0621,194 1,306665
85 99 104 115 4,250 4,950 5,200 5,750 19.3 22.5 23.6 26.1 1,9282,245 2,3592,608 8120
5677320 360414 4591.1 1.41.6 1.6145 163188 208415
13 14 16 18 800 902 1,037 1,150 3.0 3.2 3.6 4.1 363409 470522 535
25 28 32 35 1,546 1,743 2,004 2,221 5.7 6.4 7.37.9 701791 9091,007 665
59 67 80 90 3
,
540 4
,
020 4
,
800 5
,
400 13.4 15.2 18.1 20.4 1
,
6061
,
8232
,
1772
,
4498120
Water and Steam Capacities (Note: Capacities for single-wall and double-wall units are identical.)
Metric
Hot Water Capacities* Steam Capacities Hot Water Capacities* Steam Capacities
Steam Pressure
Inlet
Temp.
Set
Temp.
Standard
40
°F °F
Steam Pressure
120
130
140
160
180
120
130
140
160
180
60
50
160
180
130
140
°C °C
Inlet
Temp.
Set
Temp.
4
49
54
60
71
82
71
82
Steam Pressure Steam Pressure Model
16
54
60
71
82
10
49
54
60
Table 7-1. Water and Steam Capacities (Note: Capacities for single-wall and double-wall units are identical.)

8
Flo-Rite-Temp®SS - 316 Stainless Steel
Steam Instantaneous Water Heater
The Flo-Rite-Temp®SS is a compact, steam to water, instantaneous water heater with all wetted metal parts of type 316 stainless steel.
Because of its construction materials, this heater is well-suited for heating most corrosive liquids, such as demineralized, deionized or
reverse osmosis water commonly used by manufacturers of electric equipment, pharmaceuticals and food.
Features
• Feed-forward control provides accurate temperature control on demand even when demand fluctuates abruptly.
• Feed-forward operation ensures that the heater will fail safely in the closed (cold) position to prevent overheating.
• Straight, non-U-bend tube bundle with removable end cover provides for easy tube cleaning along with the capability to visually
inspect all tubes.
• Constant steam pressure on heat exchanger at all times means positive condensate evacuation, avoiding damage to the exchanger
due to water hammer.
• Heavy duty 5/8” tubes of 16 gauge 316L stainless steel ensure long life and maintainability backed up by a 10-year tube bundle
warranty against workmanship and material defects.
• Control valve is mounted integral to the heat exchanger, thus eliminating intermediate piping leaks
Note: Heavy duty 5/8” tubes of 16 gauge
316L stainless steel ensure long life and
maintainability backed up by a 10-year tube
bundle warranty against workmanship and
material defects.
Control valve is mounted integral to the
heat exchanger, thus eliminating
intermediate piping leaks.
Model 665 SS and 8120 SS Valve
Table 8-1. Dimensions
Model Dimensions Connections Weights
A B C D E F G H J K L 1 2 3
665 SS in 82-3/4 5-3/4 10-3/8 10-3/8 6-5/8 4-3/4 5-1/2 9-1/4 8 8-3/4 74 2 NPT 1-1/4 NPT 3 NPT lb 335
mm 2102 146 264 264 168 121 140 235 191 222 1880 50 32 80 kg 152
8120 SS in 90 5-3/4 10-3/8 10-3/8 8-5/8 6-1/8 8-7/8 9-1/2 8 14-1/2 74 2 NPT 2 NPT 4 150# ANSI lb 670
mm 2286 146 264 264 219 156 225 241 203 368 1880 50 50 100 kg 298
Table 8-2. Materials
Body Valve Valve Seats Diaphragm Heat Exchanger Shell Heat Exchanger Tubes Heat Exchanger Tube Sheets
T-316 Stainless Steel Viton® GF Reinforced
w/Nomex®Fiber
Carbon Steel (Stand.)
T-316 Stainlee Steel (Opt.)
T-316L
Stainless Steel
T-316L
Stainless Steel
Table 8-3. Specifications
Application Steam Supply Pressure Water Supply Pressure Maximum Water Pressure Drop
Steam to Water 2 - 15 psig (0.14 to 1.0 bar) 20 - 150 psig (1.4 - 10.3 bar) 10 psig (0.7 bar)

9
Flo-Rite-Temp®SS Sizing
*Units
may be piped in parallel when desired capacities exceed that of a single unit.
NOTES:
Minimum water temperature increase is 60°F (33°F). Consult factory if less than 60°F (33°F) increase is required or a set temperature of below
120°F (49°C) is required.
2510 15 2510 15 0.14 0.35 0.710.14 0.35 0.71
41 44 47 51 1,695 1,821 1,993 2,138 9.3 10.0 10.7 11.6 769 826 904 970 665 SS
84 89 97 103 3,351 3,720 4,100 4,368 19.1 20.2 22.0 23.4 1,520 1,687 1,860 1,981 8120 SS
35 37 41 43 1,617 1,743 1,915 2,061 7.9 8.4 9.3 9.8 733 791 869 935 665 SS
66 72 80 86 2,974 3,239 3,611 3,956 15.0 16.4 18.2 19.5 1,349 1,469 1,638 1,974 8120 SS
30 32 35 37 1,535 1,662 1,836 1,982 6.8 7.6 7.9 8.4 696 754 833 899 665 SS
52 57 64 71 2,596 2,862 3,216 3,540 11.8 12.9 14.5 16.1 1,178 1,298 1,459 1,606 8120 SS
17 18 19 21 1,011 1,110 1,242 1,353 3.9 4.1 4.3 4.0 459 503 563 614 665 SS
44 48 53 57 2,726 2,990 3,346 3,646 10.0 10.9 12.0 12.9 1,237 1,356 1,518 1,654 8120 SS
12 13 15 17 860 964 1,103 1,217 2.7 3.0 3.4 3.9 390 437 500 552 665 SS
32 35 40 44 2,316 2,598 2,971 3,280 7.3 7.9 9.110.01,051 1,178 1,348 1,488 8120 SS
45 48 53 56 1,643 1,768 1,938 2,083 10.2 10.9 12.0 12.7 745 802 879 945 665 SS
91 97 105 113 3,300 3,550 3,892 4,183 20.7 22.0 23.8 25.7 1,497 1,610 1,765 1,897 8120 SS
38 41 44 47 1,566 1,691 1,862 2,007 8.6 9.3 10.0 10.7 710 767 845 910 665 SS
75 81 89 95 2,997 3,257 3,740 4,031 17.0 18.4 20.2 21.6 1,359 1,477 1,696 1,828 8120 SS
32 34 38 41 1,486 1,612 1,784 1,930 7.3 7.7 8.6 9.3 674 731 809 875 665 SS
58 64 71 79 2,628 2,867 3,212 3,558 13.2 14.5 16.1 17.9 1,192 1,300 1,457 1,614 8120 SS
17 19 21 23 978 1,075 1,206 1,316 3.9 4.3 4.8 5.2 444 488 547 597 665 SS
46 51 56 61 2,635 2,896 3,249 3,545 10.4 11.6 12.7 13.9 1,195 1,314 1,474 1,608 8120 SS
12 14 16 18 830 933 1,070 1,183 2.7 3.2 3.6 4.1 376 423 485 537 665 SS
33 37 42 47 2,235 2,513 2,882 3,188 7.5 8.4 9.510.71,014 1,1401,307 1,446 8120 SS
51 55 60 64 1,590 1,713 1,883 2,027 11.6 12.5 13.6 14.5 721 777 854 919 665 SS
71 104 122 130 3,247 3,500 3,846 4,139 16.1 23.6 27.7 29.5 1,473 1,588 1,745 1,877 8120 SS
42 45 49 53 1,514 1,639 1,808 1,952 9.5 10.2 11.1 12.0 687 743 820 885 665 SS
86 92 100 108 3,093 3,347 3,694 3,988 19.5 20.9 22.7 24.5 1,403 1,518 1,676 1,809 8120 SS
35 37 41 44 1,436 1,561 1,732 1,876 7.9 8.4 9.3 10.0 651 708 786 851 665 SS
66 73 81 87 2,620 2,903 3,233 3,703 15.0 16.6 18.4 19.8 1,188 1,317 1,466 1,680 8120 SS
18 20 22 24 943 1,040 1,170 1,279 4.1 4.5 5.0 5.5 428 472 531 580 665 SS
49 54 60 65 2,543 2,801 3,151 3,445 11.1 12.3 13.6 14.8 1,154 1,271 1,429 1,563 8120 SS
13 14 17 19 799 901 1,035 1,148 3.0 3.2 3.9 4.3 362 409 469 521 665 SS
35 39 44 49 2
,
152 2
,
427 2
,
791 3
,
093 7.98.9 10.0 11.1 976 4
,
401 1
,
266 1
,
403 8120 SS
Water and Steam Capacities (Note: Capacities for single-wall and double-wall units are identical.)
82
Inlet
Temp.
°C
Set
Temp.
°C
m3/h
bar
60
71
82
10
49
54
60
71
82
40
50
60
4
16
120
130
140
160
Model
gpm lbs/hr
psig psig
kg/h
bar
Steam Pressure Steam Pressure
Metric
49
54
60
71
49
54
180
120
130
140
160
180
120
130
140
160
180
Hot Water Capacities* Steam Capacities
Set
Temp.
°F
Inlet
Temp.
°F
Steam Pressure Steam Pressure
Standard
Hot Water Steam Capacities
Table 9-1. Water and Steam Capacities (Note: Capacities for single-wall and double-wall units are identical.)

10
Steam Piping Installation of a Single Unit
NOTICE:
No water heater will work satisfactorily if improperly installed and operated. These instructions contain important information for the
installation and adjustment of the Flo-Rite-Temp®Water Heaters. Read these instructions carefully before installing this unit. FAILURE
TO ADHERE TO THESE INSTRUCTIONS COULD RESULT IN SERIOUS BODILY INJURY OR PROPERTY DAMAGE.
Single and Double Wall
The unit includes the mixing valve mounted to the heat exchanger, channel iron and U-bolts mounted, thermostatic air vent installed on
the heat exchanger, a water pressure pop off valve integral to the unit control valve and a separate Armstrong Inverted Bucket Steam
Trap.
NOTE: FLO-RITE-TEMP is provided with (1)
one Armstrong Steam Trap and Thermostatic
Air Vent (shaded). All other items shown
not included.
NOTE: Units may be piped in parallel for
larger capacity requirements. See Fig. 17-1
for an example of parallel unit installation.

11
Steam Piping Installation
Refer to Figure 2-1.
1. Install the Flo-Rite-Temp®with adequate room to allow for tube bundle removal when cleaning is required. See Table 12-1 for
specific dimensions.
2. If 2-15 psig of steam is available a pressure reducing valve is NOT required. If a pressure reducing valve is required, an Armstrong
Inverted Bucket Steam Trap is recommended to drain condensate at the inlet of the pressure reducing valve.
3. An Armstrong Y-strainer should be installed before the pressure reducing valve to reduce the chance of dirt fouling.
4. If an externally piloted pressure reducing valve is used, the control pipe should be pitched away from the PRV and installed at the
pressure gauge on the shell of the heat exchanger.
5. A steam safety relief valve should be used prior to the heat exchanger if either or both of the following conditions exist. (1) If the
maximum steam pressure could exceed the minimum water pressure in the tubes, or (2) The maximum steam pressure could
exceed 150 psig (the maximum steam pressure rating of the shell).
IMPORTANT -Steam supply pipe size coming to the heat exchanger should NOT be smaller than the steam connection supplied on
the heater, otherwise steam flow could be restricted. If a pressure reducing valve is used, installation should be as close as pos-
sible to the Flo-Rite-Temp. Downstream piping from the Pressure Reducing Valve should be expanded immediately after the PRV
to accommodate the expanded volume of steam.
6. To vent start-up air, an Armstrong Thermostatic Air Vent is included and installed on the top connection, opposite the trap drain
connection of the heat exchanger. This discharge can be piped to drain or the floor if preferred.
7. Install a vacuum breaker in the piping between the heat exchanger drain connection and the steam trap. This will prevent improper
draining of the heat exchanger caused by a possible vacuum forming when the steam is shut off.
8. Install a suitable steam pressure gauge in the 1/4” coupler located in the top mid section of the heat exchanger shell. This gauge
will help diagnose pressure problems should they occur. This port may also be used for a PRV external control pipe if a PRV is
required.

12
Water Piping Installation
1. The hot and cold pipe should drop a minimum of 18” immediately out of water heater (See Fig. 3-1A). These loops will act as a
thermal check valve or heat trap to prevent the conduction of heat through the water from the unit during inactive times.
2. Isolation valves and hose connections added to both the inlet and outlet water supplies will allow for Clean-In-Place equipment to
be utilized.
3. Use pipe unions on both the water inlet and outlet to allow ease of water heater mixing valve removal for maintenance and removal
of the tube bundle for cleaning (See Fig. 3-1A).
4. For adjusting the unit, an isolation valve and hot water by-pass to drain should be installed close to the unit down stream from the
thermal loops and prior to the recirculation loop (if one is used), See Fig. 3-1B. This allows for quick and easy setting of the Flo-
Rite-Temp® by one person. By isolating the unit from the hot water system, flow can be controlled to drain through the globe valve
while monitoring outlet water temperature during low and high flow adjustments on the water heaters mixing valve.
Minimum line sizes to drain should be as follows: model 415 = 3/4”, model 535 = 1”, model 665 = 1-1/4”, model 8120 = 2”. Line
sizes smaller than these will not allow sufficient flow for making high flow settings on the mixing valve.
6. A water temperature gauge should be installed directly after the by-pass drain valve. This thermometer is only used for initial
temperature adjustments of the Flo-Rite-Temp®or troubleshooting the unit.
NOTE: Expansion tanks should be used in on/off demand applications where there is a short duration of time from high flow to no flow
of water, i.e., a shut off time of 10 seconds or less.
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13
Pop-Off Valve Installation
1. Thread relief valve into the 1/4” NPT port located on the lower diaphragm half near the spring chamber. See drawing 4-1.
2. Tighten with a 3/4” wrench. Warning: Do Not Over Tighten. Distortion can result causing the relief valve not to seat.
Note: The discharge of the relief valve is 1/4” FPT and can be piped over to a drain to prevent the relief valve discharge from going onto
the floor underneath the Flo-Rite-Temp®.
Note: The function of this pressure relief valve is to relieve any excess pressure on the water side of the Flo-Rite-Temp®resulting from
system water hammer or water expansion pressure due to water heating. If the problem is severe, water hammer arrestors should be
placed on all equipment with fast closing water valves. Expansion tanks should be used for all expansion pressure problems. The relief
set point of this valve is 165 psig.
Note: For hard water applications, pipe pop-off valve
into dirt leg.
Figure 13-1

14
Optional Thermostatic Controllers and
Safety Equipment
See Fig. 3-1E for location of each option within the system. All options would be installed downstream of the water heater in the outgo-
ing recirculation loop, if one is present, or downstream of the hot water thermal loop if recirculation is not used but always before the
first hot water take off from the system.
Option #1 A temperature relief valve set at roughly 15-30 degrees above that of the
Flo-Rite-Temp® will help prevent any chance of overheated water reaching the faucets.
(NOTE: Normally unit will fail closed and either no water or only cold water will flow
from the unit.)
Option #2 A 3-way blending valve with a set point 10-30 degrees above that of the
Flo-Rite-Temp®will help prevent the chance of overheated water reaching the faucets
in the event of unit failure. Under normal operating conditions the hot water flows
straight through the blending valve from Port B to Port A. But in the event of an
overheated situation, the blending valve will open Port C to add sufficient cold water
to maintain a constant temperature. (NOTE: The blending valve should be sized to
handle the maximum flow of the system).
Note: The Armstrong Flo-Rite-Temp®comes supplied with a 1/4” NPT water pressure
relief valve. The standard valve has a cracking pressure of 165 psig. Installation
instructions (See AY-700) are supplied with each heater. The valve is a self relieving
and self seating valve which will open due to thermal expansion or hydrolic shock
continuous or intermittent discharge of this valve while heater is in service could
indicate a system pressure problem. See note for (Fig. 31F) on previous page for
possible solution.
Option #3 A temperature switch installed well downstream of the Flo-Rite-Temp®
outlet on a non-recirculated system or just into the outgoing recirculated system loop
on a recirculated system, with a set point 15-30 degrees above that of the
Flo-Rite-Temp®will help prevent the chance of overheated water reaching the faucets
in the event of system problems. This switch can be used to turn off the steam
supply to the heater in the event of overheating. The most economical way to
accomplish this is with a solenoid on the PRV. A full ported motorized valve on the
steam supply line may also be used. Option 3B. Along these same lines, a pressure
switch installed in the inlet water line would shut down the supply steam on the heat
exchanger in the event of water pressure loss, preventing thermal shock and water
hammer to the unit.
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Option 1
Option 3
Option 2

15
Start-Up and Adjusting Procedure
IMPORTANT: UNIT START-UP AND SHUTDOWN PROCEDURES
Its important to remember that water pressure must ALWAYS be greater than steam pressure on the unit to avoid boiling the water
in the tubes of the heat exchanger. When starting up a Flo-Rite-Temp®it is very important that the water supply is turned on to the
unit before any steam is turned on. Once the unit is up and running, the inlet water valve should never be closed unless the steam
is turned off first. When shutting down a unit you should always first shut off the steam and then allow water to run through the
unit until it has cooled and completely condensed all remaining steam in the heat exchanger before closing off the supply water to
the unit.
Adjusting Procedures
All models of Flo-Rite-Temp®’s have two settings which need to be made on initial start-up. One setting must be made at low flow while
the other is made at high flows.
IMPORTANT: Once the low and high flow adjustments have been made, the unit generally need not be adjusted again unless your
operating conditions change or a different set point is desired. A significant drop in temperature output or capacity is an indication
of a bad diaphragm or that the tube bundle needs to be cleaned. Do not readjust the valve unless isolation of the unit from the
system and running water to drain produces poor temperature control. If capacity is minimal, check the diaphragm or clean the
bundle but do not readjust the control valve.
Start-Up and Adjusting Procedure for Model 415
1. Before turning on the steam to the Flo-Rite-Temp®, begin by opening the water supply valve to the unit and checking for water
leaks at the unit or any of the associated piping.
2. If the unit is connected to a system which has a recirculation loop and pump, be sure the pump is turned off and the isolation
valve on the leg of piping going from the diverting valve back to the inlet of the Flo-Rite-Temp®is closed (this is the isolation valve
downstream of port “B” of the thermostatic diverting valve).
3. Close the isolation valve on the hot water outlet of the unit and open full and close several times the throttling bypass valve to
drain to purge all the air from the Flo-Rite-Temp®. (See Fig. 3-1B). This process also primes the units lower diaphragm area with
water. Failure to do this prior to initial adjustment can result in inaccurate settings and poor results.
4. Throttle the bypass valve to drain so that a constant 3 gpm of flow may pass to drain.
5. Slowly open steam valve or adjust the pressure reducing valve to allow 2 - 15 psig of steam pressure on the unit.
(CAUTION: always make sure there is water pressure on the unit before adding steam. Failure to do this will cause severe
hammering of the unit and possible damage).
6. Make sure that the steam trap draining the unit is functioning properly and allow the entire unit to come up to temperature for at
least three to five minutes while passing the 3 gpm of water flow to drain before beginning the adjustment of the unit.
7. Locate the low and high flow adjustments on top of the mixing valve hidden under the hex bonnet (see Fig. 7-1). Before beginning
adjustments, check to make sure the high flow adjustment is fully open. To do this start by pressing down on the high flow
adjustment when water pressure is present on the unit and there is no water flow through the unit. This should only depress about
1/8”. If it pushes in further, turn the adjustment stem counter clockwise to open. Check every turn until there is only 1/8” travel to
the high flow stem when pushed down.
Note: with water pressure on the unit the stem should pop back up after depressing it. If the high flow adjustment stem will not depress at all the valve is opened too far and you must turn the
adjustment clockwise until there is 1/8” travel downward to the stem.
8. With the unit now isolated from the hot water system and all flow of water being directed to drain at 3 gpm, let the temperature
stabilize.

16
9. Monitor the outlet temperature on the gauge located in the bypass to drain (see Fig. 3-1B). Place an adjustable wrench on the
flats of the low flow adjustment (see Fig. 7-1). Turning clockwise raises the discharge temperature and counter-clockwise lowers
the discharge temperature. Make the appropriate adjustment to achieve the desired set point. For example if a set point of 140°F
is desired and the temperature reading is 155°F, you must turn the low flow adjustment counter-clockwise to lower the set point
temperature from 155°F down to 140°F.
IMPORTANT - When making the low flow adjustment the high flow adjustment shaft SHOULD rotate with the low flow
adjustment. If it does not do so, you will have to turn it by hand while making the low flow adjustment. Allow the unit
to stabilize to be sure that the unit will remain at the desired set point. The low flow is now adjusted and should not be
readjusted.
10. To make the high flow adjustment, SLOWLY increase the flow of water through the unit to drain while monitoring the outlet
thermometer. When the outlet temperature has dropped by approximately 10 °F below set point for a Model 415E, make your high
flow adjustment while maintaining that flow.
11. Place a small screw driver or center punch through the hole in the high flow adjustment stem (see Fig. 7-1) and turn it in a
clockwise direction. This will start to close the valve restricting the cooling water and cause the outlet water temperature of the
unit to rise. Continue until the outlet temperature is back up to your required set point.
IMPORTANT - When making the high flow adjustment the low flow adjustment SHOULD NOT rotate with the high flow
adjustment. If it does, you will have to hold it stationary while making your high flow adjustment.
12. The unit is now adjusted.
IMPORTANT - If for any reason you must readjust the unit, you will first have to return the high flow adjustment back to its full
up position as stated in point # 7.

17
Start-Up and Adjusting Procedure for Model
535EP, 665SEP, and 812Pop-Off Valve
Follow all the steps 1-6 as stated in the adjustment procedures of the model 415.
7. Locate the low flow temperature adjustment (LFT) and the high flow temperature adjustment
(HFT)on top of the mixing valve hidden under the hex bonnet (See Fig. 7-1). Before beginning
adjustments, check to make sure the LFT is fully closed. To do this, turn the LFT clockwise until it
stops. Also make sure the HFT is fully open. To do this start by pressing down on the HFT when
water pressure is present on the unit and there is no water flow through the unit. The HFT should
only depress about 1/8”. If it pushes in further, turn the HFT stem counter clockwise to open.
Check every turn until there is only 1/8” travel to the HFT when pushed down (Note: with water
pressure on the unit the stem should pop back up after depressing it). If the HFT stem will not
depress at all the valve is opened too far and you must turn the adjustment clockwise until there
is 1/8” travel downward to the stem.
8. With the unit now isolated from the hot water system and all flow of water being directed to drain, slowly increase the water
demand to approximately 3/4 of the maximum capacity according to the capacity chart on page 13. When starting a cold system,
you should take at least 2 to 3 minutes to slowly increase to this demand. This will allow time for the steam piping feeding the unit
to come up to temperature, pressure and purge itself of excess condensate.
9. Place a small screwdriver or center punch through the hole in the HFT adjustment and slowly turn the HFT to change the
temperature to the desired set point. Close (clockwise) the HFT to raise the outlet water temperature. Allow adequate time for the
water temperature to stabilize. This could take several minutes if the piping is cold and the measurement point is far from the unit.
IMPORTANT: When making the HFT adjustment, the LFT adjustment SHOULD NOT rotate with the HFT adjustment. If it does,
you will have to hold it stationary while making your HFT adjustment.
10. Lower the water flow rate to 3 gpm. The LFT adjustment is currently fully closed (see step 8). Slowly open (counterclockwise) the
LFT to lower the outlet water temperature to the desired set point. Allow adequate time for the temperature to stabilize.This will
take longer since the flow rate is so small.
IMPORTANT: When making the LFT adjustment, the HFT adjustment shaft SHOULD rotate with the LFT adjustment. If it does not
do so, you will have to turn it by hand while making the LFT adjustment.
11. Recheck the outlet water temperature at 3/4 of the maximum demand it will see. Adjust if necessary. Opening the HFT
(counterclockwise) will lower the temperature and closing the HFT (clockwise) will raise the temperature. Note: You may want
to fine tune the HFT adjustments during normal operation of the unit at heavy demand. If outlet temperature is slightly low, turn
HFT clockwise to raise it. This should only be done during the initial service of the unit or when the unit has been cleaned. Never
attempt to re-adjust the unit with a dirty tube bundle - always clean tube bundle first. The unit is now adjusted.
IMPORTANT: If, for any reason, you must readjust the unit, you will first have to return the LFT adjustment to the fully closed
position as stated in step 8).
CAUTION: When putting a heavy load on the heat exchanger, watch the steam pressure gauge. This pressure should not be
permitted to fall below 2 psig. If it does and severe water hammer develops, reduce the load by closing some of the faucets or
shut the system down. When steam pressure drops under heavy load and hammering occurs, not enough steam is getting to
the unit. This can be a result of an undersized reducing valve, lack of boiler capacity or restrictive steam lines. Hammering
can also be caused by a loss of water pressure where the water pressure in the unit falls below the pressure of steam. This
condition is usually caused by improper shutdown of the unit or someone closing the inlet water valve with the steam pressure
still on the unit.
Figure 17-1.

18
Flo-Rite-Temp®Recirculation System Piping
and Operation
Because of its relatively small size and compactness, the Flo-Rite-Temp®can easily be installed close to the point of water use
eliminating the need for a recirculation system.
In applications where water heaters are located in basements or utility rooms and feed an entire building or wing a recirculation system
or loop must be utilized to assure instantaneous hot water to all usage points.
The recirculation system is made up of several different components designed to work together to maintain the temperature of the
water in the loop at times of low or no flow.
Recirculation pump - This is a constant GPM pump that runs continuously regardless of the hot water demand from the loop. Its
function is to continually recirculate the water in the loop in order to maintain the temperature during low or no flow conditions. As a
rule of thumb, the capacity of the pump should be approximately 10 to 15 percent of the maximum capacity of the Flo-Rite-Temp®and
be able to overcome any head found in the loop. The recirculation pump however, may be larger than 15 percent. But when a larger
pump is used, a full line size bypass with a globe valve must be piped to divert most of the flow around the thermostatic capsule.
Three-way Thermostatic Capsule - This device has a set point roughly 20 degrees below the set point of the Flo-Rite-Temp®and will
maintain the temperature in the loop between the set point of the capsule and the set point of the Flo-Rite-Temp®. The capsule senses
the temperature of the recirculated water and compares it with its pre-set temperature. If the temperature in the loop drops below the
capsule’s set point because of radiation loss from the piping and no hot water demand from the loop, then the capsule begins to divert
some of the loop’s flow to the inlet of the Flo-Rite-Temp®(ports A to B) for reheating. This diversion will bring the temperature of the
loop back up to its required temperature. Once the temperature in the loop is over the capsule’s set point all flow from the
recirculation pump now goes straight through the capsule (ports A to C) and the return water is fed back to the hot water supply line.
To regulate flow to the capsule, a balancing/bypass line with globe valve is required.
This diverting recirculating system eliminates the need for aquastats and any electrical wiring. It is a self contained, self regulating
system that controls the temperature of the water in the loop during low or no hot water demand situations. When there is a demand
for hot water the temperature of the water introduced into the system is instantly controlled by the Flo-Rite-Temp®feed forward mode
of operation.
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Figure 18-1.

19
Flo-Rite-Temp®Accumulation System
For peak load conditions or to avoid large intermittent steam demands
The Flo-Rite-Temp®water heater accumulation system is designed to provide a specified volume of accumulated hot water for short
duration peak loads or when steam is in short supply and a recovery time can be tolerated. During periods of low or no demand, the
water in the accumulator tank is heated to the set point temperature by the Flo-Rite-Temp®water heater.
An accumulator or large storage tank is installed in series with the Flo-Rite-Temp®water heater. Cold water is piped to the inlet of the
water heater and into the bottom of the accumulator tank. Hot water flows from the Flo-Rite-Temp®directly to the accumulator tank
through a pump that is controlled by an aquastat. When the pump is off the flow goes to the accumulator via a bypass around the
pump. This would occur when there is hot water demand and the temperature in the tank is at set point.
When the system is started the water in the accumulator tank is cold which causes the aquastat to turn the pump on. Water flows
out of the bottom of the tank to the inlet of the Flo-Rite-Temp®. The water continues this cycle until the aquastat in the tank senses
the appropriate temperature. At that time the pump shuts off and the water is ready for use. The globe valve on the bottom of the
accumulator tank should be adjusted at full system demand so that a pressure differential of approximately 8 psi is read across the Flo-
Rite-Temp®.
In operation, hot water is drawn off the top of the tank at the same time as cold water enters from the bottom and hot water from the
Flo-Rite-Temp®enters the tank from the side. When the peak load stops and the aquastat senses the cooler water in the tank, the
pump starts and the heating process begins another cycle.
A bypass line from the heater to the hot water demand is shown and is normally kept closed. When the accumulator tank requires
maintenance this bypass allows the tank to be isolated, with hot water being supplied by the Flo-Rite-Temp®only.
Advantages of the accumulation system are:
• Accumulation tank temperatures are restored over a period of time avoiding large intermittent steam demands.
• Providing the Flo-Rite-Temp®’s safety features to the entire system.
• Providing accurate hot water temperature control.
• Providing a back up alternative during tank maintenance.
• To allow accumulator tanks to be relatively small in size because hot water demand is supplemented by the Flo-Rite-Temp®.
Figure 19-1. Note: Position of system
thermometer. Thermometers
should not be placed between
Flo-Rite-Temp and “T” fitting
where3-Way valve ties back into
hot water outlet.

20
Flo-Rite-Temp®Tempered Water Systems
For Safety Shower/Eye Wash Stations
The problem which faces many companies today is how to safely warm water to be used effectively in a drench shower or safety
shower situation.
Storage tank units can run out of warm water causing people to go into possible shock due to cold water exposure or to end the
shower before proper flushing has taken place. Also, because the water in the tank is only heated to a temperature range of 65 to 95
degrees F. there is the potential and risk of legionella bacteria forming inside of the tank. Lastly, tank systems are feedback systems
which can cause severe overheating of the water when thermostatic elements fail causing personal injury.
The solution is to use the Armstrong Flo-Rite-Temp tankless instantaneous feedforward water heater in series with a self-contained fail
safe thermostatic mixing valve.
How the System Works
The system, when piped as shown in the drawing, will provide a safe, continuous and dependable source of accurately controlled warm
water.
Incoming cold water is heated between 120 to 130 degrees F by the Flo-Rite-Temp. (The unit is set to provide a constant supply of hot
water at an adjusted set point within this temperature range,usually the lowest set point of 120O degrees is used). The 120°F water
can be piped to the Rada Z358 thermostatic mixing valve which will blend cold water with the 120°F water to make the tepid water for
the safety shower/eye wash station. The Rada Z358 valve is equipped to allow cold water to the showerhead in the event of hot water
failure.
The Rada Z358 Mixing Valve (see Bulletin ALIB-Z358-20) properly proportions the hot and cold incoming water to obtain a preset
delivery temperature to the drench shower head. Demand induced changes are sensed and automatically compensated for by the valve
so that shower output temperature remains constant. A recirculation system may also be incorporated in this system and is especially
recommended in applications where shower lines are exposed to the cold air or shower heads are a
distance from the heater.
Feedforward control in the water heater eliminates the danger of thermostatic element failure and overheating typical in storage tank
feedback systems. Because there is no storage tank, there is no danger of legionella forming in the stored warm water. All water is
heated instantaneously on the spot, there is no shortage of heated water or shower time limits.
Option 1: Water recirculation when heater is servicing a long run to the shower head, more than one shower head, or piping is exposed to cold ambient temperatures.
Figure 20-1.