Thermaflow TH-750 Series User manual

TH-750-IMI-REV-5
I
Since 1986
Manufacturers Of Steam Fired Specialty Equipment
ncorporated
E
ngineering
r
TH-750 SERIES
STEAM FIRED WATER HEATER
OPERATION & MAINTENANCE
MANUAL
READ THIS MANUAL COMPLETELY BEFORE ATTEMPTING START UP
P.O. Box 473639 • Charlotte, NC 28247
12249 Nations Ford Road • Pineville, North Carolina 28134
Phone [phone] • Fax [phone] • www.thermafloengineering.com

316LStainless Steel ASME
Code Stamped Shell
and fitting Removable Vinyl Jacket Standard.
Electronic RTD Sensor
Intra-Tank Circulator
Cold Water Inlet
Tube Bundle
Steam Trap
Condensate Outlet
Predrilled Floor Mounting Holes
ASME Pressure and
Temperature Relief Valve
High Temp Dump
Solenoid Valve
EC800 Control Panel
Electronic Steam
Control Valve
Powder Coated Base
Support Stands
Electronic Version Shown
MADE IN USA PRODUCTS Manufacturing Facilities: 12249 Nations Ford Road, Pineville, NC 28134 www.thermafloengineering.com
TH-750 Steam Fired Water Heater
Hot Water Outlet
Outlet Thermometer
Circulator on/off
switch
Expanding Crossflow UTube
Bundle to remove scale and build-up
Shell Drain
(in rear not shown)
Steam Inlet
Steam Pressure
Gauge
Vacuum Breaker
I
Since 1986
Manufacturers Of Steam Fired Specialty Equipment
ncorporated
E
ngineering
r

2
TH-750-IMI-REV-5
Section 1 – Hookup and Installation
1.The TH-750 should be located in an area so that it will be easily accessible for any inspection
and repairs. Secure to the floor using the four mounting holes in the base floor stand.
2.Pipe clean water or fluid to be heated to the inlet on the lower side making provision for the
loop recirculation. Install a check valve and suitable “Y” strainer on the inlet.
3.Pipe the heater outlet from the top of the TH-750 to the users. A recirculation loop for the
hot circuit is recommended.
4.Service (isolation) valves should be located at all inlets and outlets.
5.Always open the cold side first and check for any leaks.
6.Pipe steam (125 psig Max) to the control inlet valve. If a “Y” strainer and drip steam trap were
not supplied with the TH-750 heater, they should be installed with the isolation valve.
7.If a “Y” strainer and drip trap are not installed, dirt and condensate will build up on zero or low
load conditions. Failure to install a “Y” strainer and drip trap on the steam supply line
voids the warranty.
8.Be sure the steam supply is sized correctly – consult Thermaflo Engineering if you are unsure
of the size.
9. Always open the cold (WATER) side first before opening the hot (STEAM) side and always
introduce steam to the unit slowly.
10. For gravity return systems, the TH-750 will be supplied with a factory sized Float &
Thermostatic steam trap. Never substitute with another manufacturer’s steam trap or a
different trap other than that supplied with the TH-750V unit as this could effect
operation and will void the warranty. If the steam trap cannot be located at the time of
installation, contact your local Thermaflo Engineering representative.
11. For TH-750 units installed where the condensate drains into a gravity return system,
the condensate piping must not be elevated or lifted as this will cause water hammer,
erratic control, flooding of the tube steam space, premature tube failure and will void
the warranty.
12.
For pressurized condensate return systems or where a lift is required, the TH-750 should
be supplied and fitted with a Thermaflo Engineering pump trap on pressure powered
pump in place of the F & T trap.
13. Pipe the high temperature dump valve shell drain valve P&T Valve to suitable drain.
This valve will discharge a considerable amount of water when it opens. Never allow this valve to
be piped to drain that will not carry full flow discharge. Installer is responsible for selecting
adequate drain size. See drawing for details.
1
4. Always leave the vacuum breaker, located below the inlet steam pressure gauge, open to
atmosphere.

3
TH-750-IMI-REV-5
15. The EC800 control panel requires a single-phase 120 V/60Hz power supply. Supply wiring
connections are furnished so that only one simple connection is required. Supply circuit
should be fitted with a minimum 10 amp breaker with fused disconnect and should
comply with local codes.
16. VERY IMPORTANT - Prior to connecting power to the unit, ensure that the re-
circulation pump ON-OFF switch (black in color and located on the right side of the
EC800 control panel) is in the OFF position to prevent the pump from running dry and
damaging the seals which will consequently fail on start up. Evidence of the pump
being run dry will void the warranty.
17. The EC800 panel powers the re-circulation pump and all of the controls on the TH-750 unit.
No additional wiring is required. Each TH-750 Digital Temperature Controller is “Factory
Set-up and Tested” for the stated operating conditions. NO ADJUSTMENTS should be made
unless the operating conditions have changed from conditions stated on the purchase order.
18.
For TH-750 units supplied with a pneumatic steam control valve, connect a clean 40-psig Min
(120 Max) air supply to the bottom supply port tubing connection. The outlet tubing to the
control valve is supplied with the unit but is disconnected for shipping and will have to be
reconnected during the installation process. Simple slide fittings allow easy connection of the
poly air tubing. Units with electric or self acting actuation of the steam control valve require
no outside air source.
19. Prior to startup, all head flange bolts should be retightened as these may have loosened
during shipping or due to piping stress during installation. Bolts should be torqued
incrementally and in the sequential order shown in the tables and drawings in Appendix A.
20. Retightening of head flange bolts is important and failure to complete this procedure can lead
to head gasket leaks. The bolts should also be checked and adjusted as necessary after
startup.
21. Included in Appendix B of this manual are drawings showing typical hookups for various
applications. It is recommended that the drawing outlining the relevant application is carefully
reviewed before startup is attempted. If you are uncertain about correct hookup contact your
local Thermaflo Engineering representative or the factory.
22. As water expands when heat is applied, installation of a properly sized thermal expansion
tank is recommended if the TH-750 does not have continuous usage. Failure to install an
expansion tank may cause excessive popping of the relief valve and or high pressure which
could cause damage to the tube bundle or shell.
23. SAFETY NOTE: The TH-750 is supplied as standard with a double safety shutdown system.
However it is strongly recommended that when the TH-750 heater supplies hot water for
domestic use, a secondary blending valve system be installed to prevent any chance of a
scalding situation. Consult your engineering consultant or local Thermaflo Engineering
representative if this is not in place.
YOU ARE NOW READY FOR STARTUP

4
TH-750-IMI-REV-5
Section 2 – Startup Procedure and Operation
1.Verify that all manual valves are closed on the water and heat (steam) sources.
2.Locate the black circulation pump On-Off switch (on side of EC800 panel) and make sure
that it is in the OFF position. Failure to turn the recirculation pump off will run the pump
dry causing failure.
3. Power up the panel. This will close the high temp drain solenoid valve and activate the
temperature controller. This valve is a normally closed valve.
4.Slowly open the water supply valve to the shell of the TH-750 and allow the shell to fill with
water (checking for leaks). Repair any leaks before proceeding with startup.
5.Open valves on the recirculation loop and when shell is full of water turn the recirculation
pump ON.
6.With a small user turned on and calling for hot water (sink hot water faucet or shower), slowly
open the hot water outlet valve. This will allow the shell to completely fill with water and
remove any air from the shell. Never use the Pressure & Temperature relief valve to
remove air.
7.The digital controller will sequence for a few minutes following initial power up and then
return to its operation mode. The controller has been preset at the factory before shipment
and should not require adjustment.
8.Two numbers will appear on the front of the controller. The lower number is the outlet water
temperature set point. The upper number is the actual water temperature in the shell.
9.For TH-750 units with pneumatic control, ensure that the instrument air supply is
connected and open to the panel.
10. The EC800 panel for pneumatic control includes a pressure gauge. This gauge indicates the
air pressure to modulate the control valve.
11. When the system is first turned on, the water in the shell will be cold and controller will be
sending out its maximum air signal to the control valve which will register 15 to 30 psig on the
gauge.
12. As the system nears set point, the pressure will begin to drop until the gauge finally reads
zero when set point temperature has been achieved.
13. As the system functions normally, the pressure reading on the gauge will rise and fall,
modulating the steam valve.

5
TH-750-IMI-REV-5
EC800 Panel with Electronic Control
14. Fully open the condensate isolation valve to allow condensate to drain from the steam trap.
15. As the system nears set point, the pressure will begin to drop until the gauge finally reads
zero when set point temperature has been achieved.
16. Very slowly open the inlet steam isolation valve to about 10% and allow steam to flow into
the heater. The steam control valve will be 100% open at this point as the water in the shell
is
cold. Steam must be slowly introduced through the inlet valve at a controlled rate manually
for warm up. The upper number on the controller will begin to increase as the steam is being
introduced to the heating coil.
17.
After about 10 minutes of warm up, slowly open fully the inletsteam isolation valve and allow
the TH-750 to come up to fulloperating (setpoint) temperature. This may take several
minutes. During this time the control valve will begin to take over and fully control.
18.
Gradually close the hot water users (sink hot water faucetor shower) used for setup and
allow the TH-750 to function in the automatic normal mode. It will take several minutes for a
new system to settle down into a normal operating mode.
19. Often a new system will have no users on line demanding hot water. If this is the case, after
the system reaches operating set point it will enter a hold mode. It is advisable for the owner
Circulation Pump
Switch located here.

6TH-750-IMI-REV-5
to open several users and let the system operate for 30-60 minutes before shutting down all
hot water users.
20. Recheck the head bolt torque levels and repair any system leaks as required.
21.
For TH-750 units with electric control, no instrument air supply is required. Otherwise the
startup procedure is the same as for pneumatic control
22. The electric actuated valve is a “spring to close”electronic ball type valve with a soft Teflon
seat that closes tight on shutdown.
EC800 Panel with Electric Control
23.
The self acting (SA) version of the TH-750 will utilize the Thermaflo Engineering type 25
series valve.
A manual corresponding with the valve type supplied is included in the documentation
package that accompanies the TH-750 heater.
24. The controller illustration below is a quick reference for startup use. A dedicated controller
manual containing more detailed information is also included in the documentation package.
25. Note that all controllers, prior to shipment, are factory set for the operating parameters
provided by the end user at time of order. Each controller is configured so that only the outlet
temperature set point can be changed. All other critical control settings are locked out
(password protected) to prevent inadvertent change or tampering by unauthorized personnel.
The default pass code is 0125.

7
TH-750-IMI-REV-5
THIS CONTROLLER HAS BEEN SET UP SO THAT ONLY THE SETPOINT CAN BE
CHANGED WITHOUT PASS CODE
SEE ELECTRICAL SCHEMATICS ON PAGES 19 - 26 OF THIS MANUAL
Process Value Set Point Value
Constant light
equals process
is running a
flashing light equals
a pause in
the process
Arrow keys adjust
settings such as set point
Advances through parameter prompts
Infinity key goes
back to previous
level
Zone Display
1-9
10 = A
11 = B
12 = C
13 = D
14 = E
15 =

8
TH-750-IMI-REV-5
Section 3 – Shutdown Procedure
1.Turn off all power to the circulating pump and / or electric controls, if so equipped.
2.Close all valves in the water inlet line (or boiler water / high temperature water line).
3.Relieve the pressure from the energy source line (water, boiler water, or high temperature
water), where possible.
4.Close all remaining valves in the system in this order:
a) Hot water outlet line
b) Cold water inlet line
c) Condensate return line (or boiler / high temperature water return line).
5.After the system has cooled, drain the unit by opening the tank drain valve and holding the
pressure relief valve in the open position. This will prevent the formation of a vacuum and
increase the drainage flow. Consider any freezing situation.
6.Proceed with required maintenance or repairs. For correct maintenance procedures see
pages 9 – 12.
7.After performing the required maintenance or repairs, return the unit to operation by following
the start up procedures detailed on pages 4 - 7.

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TH-750-IMI-REV-5
Section 4 – Maintenance
1. Gasket creep is inherent to most gasketed joints, and retorquing is required. The greater the
operating temperature and pressure, the greater the problem can become. It is imperative
that the head bolts be torqued after installation, after initial setup, and inspected several
times a year to be sure that the bolts are torqued correctly and there are no leaks. See
section 1 paragraph 19 for correct torque procedure.
2.Located at the lower rear of the unit, the TH-750 has a manual, shell blow down valve that
should be piped to a suitable drain. On a monthly to quarterly frequency, this valve should be
quickly opened for 2 seconds to remove scale buildup and any normal sediment that may
collect in the shell.
3.The intra-tank circulation pump is critical for the accurate operation of the TH-750. This pump
circulates the water in the shell across the temperature sensor and back into the shell through
the cold water supply inlet. This action allows the system to not only detect changes in flow
demand, but also temperature changes as well. The recirculation pump is fitted with
permanently lubricated bearings and therefore does not require any additional lubrication. If
however the TH-750 suddenly becomes unable to maintain accurate control, the pump should
be checked for operation.
4.On a yearly basis, the operation of the recirculation pump should be verified, and isolation
valves have been fitted on each side of the pump for this service. If the pump is not running,
make sure the pump ON-OFF switch (black in color and located on the right side of the
EC800 control panel) is in the ON position.
5.If the recirculation pump requires replacement, turn the pump ON-OFF switch to the OFF
position, isolate pump and remove.
6. Install new pump, open isolation valves and turn pump ON-Off switch to the ON position.
This can be done while the TH-750 heater remains in service so that hot water flow to end
users is not interrupted.
7.All TH-750 units must be fitted with a steam drip trap station (trap and strainer) at the steam
inlet before the control valve. The satisfactory operation of this trap is critical. On at least a
quarterly basis, this trap should be checked for condition and operation and the strainer
should be blown down to clean.
8.On a yearly basis it is good practice to operate each valve on the TH-750 unit to ensure all
valves operate and shut off as required.
9.Each TH-750 heater is fitted with a pressure gauge and steam siphon. At least once a year
the operation of this gauge should be verified by closing off the steam inlet valve and making
sure the gauge registers zero. If it does not, the accuracy may be off and it should be
replaced.
10. Each TH-750 heater is fitted with a pressure and temperature relief valve. Scale from hard
water can build up on the element and cause the valve to malfunction. We recommend that
this valve be replaced every two years to make sure operation is verified. A record of the

10
TH-750-IMI-REV-5
replacement schedule should be kept and adhered to by the operator/owner. THIS IS VERY
IMPORTANT.
11. TH-750 heaters are engineered and constructed to last for many years when the supply
steam is of good quality, the feedwater has been softened and the condensate is removed
correctly
12. The internal U type heating coil commonly referred to as the heating bundle is very important
to the overall operation of the TH-750. Every 2 years of operation, this bundle should be
removed and cleaned so that effective heat transfer can continue to take place.
13. Tube bundle removal procedure is as follows:
14. When removing tube bundle there are two gaskets that will need to be replaced with new.
These gaskets are located: one between the tube face of the coil and the flange welded to
the tank, and one with a divider to fit between the head and the tube sheet.
15. SAFETY NOTE: Water, boiler water, or high temperature water present situations that can
be very dangerous because of the high temperatures and pressures. To avoid possible injury
or death, use common sense and follow all accepted and recommended procedures when
performing installation, operation, and maintenance procedures. Caution! The combination
of electricity and water can pose a very dangerous situation. Turn off and disconnect all
power before attempting any maintenance procedures.
16. Follow Steps 1 through 7 of the shutdown procedures (page 8) to take the unit offline before
attempting to remove and inspect the heat exchanger coil.
17. Assure that the energy source, condensate / water return line, cold water inlet, and hot water
outlet have been shut off; that the tank has been completely drained; that the pressure has
been bled from both the water and energy source system; and that the water, all
components, and surfaces have cooled.
18. Carefully break the joint between the heat exchanger coil head and the small line leading to
the energy source pressure gauge.
19. Carefully break the connections between the heat exchanger coil head and the energy
source inlet and outlet lines. Note: It may be necessary to break the lines at a second
location, and for the lines to be rotated to allow clearance for the heat exchanger coil
to be removed from the tank. If it is necessary, care should be taken to insure that in-
line components are not damaged.
20. Break the bolts loose that secure the heat exchanger coil head to the tank. After all bolts
have been broken loose, remove them from the unit.
21. Carefully separate the heat exchanger coil head from the mounting flange and remove the
coil assembly from the tank. Caution! There may still be residual water condensate (or
boiler/high temperature water) in the coil that can run out during removal of the coil from the
tank. If sufficient time has not been allowed for cooling, this residual condensate/water could
present a danger of injury.

TH-750-IMI-REV-5
11
22. Examine the heat exchanger coil for scale buildup and signs of leakage. If no leakage is
detected, carefully clean any excess scale from the coils and prepare the heat exchanger coil
for installation. If leakage is detected between the coils and water in the tank, either repair
the leaking coil(s) or replace the heat exchanger coil.
23. Remove the old gaskets and completely clean the mating surfaces. Install the two (2) new
gaskets: one (1) between the tube face of the coil and the flange welded to the tank, and one
(1) gasket with a divider to fit between the heat and the tube sheet.
24. Carefully insert the heat exchanger coil into the tank. The coil should be installed so that the
divider in the head lines up with the coil, and that the divider is parallel to the horizon.
25. After assuring that the heat exchanger unit is correctly aligned, clamp the flanges together
and proceed with the torque procedures detailed below.
Note: Bolts used to secure the heat exchanger unit in the TH-750V Heaters are rated
as B7. Grade B7 bolts are designated by B7 on the head.
a. Lubricate the bolt threads and the nut faces with a suitable lubricant.
b. Insert the bolts through the flanges, and then start and finger tighten the nuts.
c. Number all bolts so that torque requirements can be followed.
d. Apply torque in three steps of 60%, 80% then 100% of required final torque, loading all bolts at
each step before proceeding to the next step.
Note: Appendix A contains tables listing ANSI approved target torques for Grade B7
bolts. The correct target torque can be determined by the nominal pipe
size, number and grade of bolts used to secure the flange, and the size of the bolt
used. Be sure of the bolt grade used in the unit.
When replacing bolts, be sure to use the same type of bolt and corresponding nuts. Grade
B7 bolts can be used in all cases.
e. Tighten bolts in the applicable sequential order (0º- 180°, 90°- 270°, 45°- 225°, 135°-315°
etc.) at each step until final target torque is reached (see applicable diagram contained in
Appendix A).
f. Use rotational tightening until all bolts are stable at final torque level. Two (2) complete
times around is usually required.
Note: Appendix A contains drawings depicting the typical flange configurations
(number of bolts, location, tightening sequence, etc.) for the TH-750 Heater. Reference
the applicable drawing for the unit being serviced.
26. Reconnect the energy source inlet and outlet lines to the heat exchanger coil. If these lines
were broken at an additional location to allow for removal of the coil, be sure to also tighten
those connections. Follow recommendations contained in the manufacturer’s documentation,

12
TH-750-IMI-REV-5
local codes, or accepted contractor practices as to the use and/or type of joint compound or
sealer at the connections.
27. Reconnect the small line leading to the energy source pressure gauge.
28. If the unit is equipped with a circulating pump, the pump relay must be interlocked with the
temperature control valve so that the energy source will shut off if the pump is not
operational. Failure to do so could create a very dangerous situation if the pump were to
fail.
29. Follow the startup procedures (page 5) to put the unit back online. Carefully check all
connections for any sign of leakage.

Cleaning Procedure:
On an annual basis when using extremely hard water the inner bundle
will need cleaning to remove lime and scale deposits. This is simply
done by draining the unit and following these steps:
1. Close the outlet isolation valve to the domestic system and turn off
recirculation pump.
2. Close the inlet isolation vales to the heater domestic supply and loop
recirculation. This will totally isolate the shell.
3. Remove the top thermometer from the shell. The connection will be a
¾” and is located at the very top of the shell.
4. Than using a small flexible funnel completely fill the shell with
“DD518”biodegradable descaling fluid (approx. 4 gallons) for a 10”
unit, and install the thermometer. Wear protective eye wear and gloves.
5. With the unit full turn on the recirculation pump for 2 hours. Do not
operate over 2 hours. Open lower drain valve and drain the shell of the
fluid as the fluid is biodegradable and can be sent to the drain.
6. After the shell is drained fill with cold domestic water twice and flush.
The system is now ready for use.

13

14
TH-750-IMI-REV-5
SEQUENCIAL ORDER
1 - 2
ROTATIONAL ORDER
1
3-4
5
5-6
3
7-8
7
2
6
4
8
1 - 2
1
3-4
5
5-6
9
7- 8
3
9 - 10
7
11 - 12
11
2
6
10
4
8
12
APPENDIX A
Bolt Torque Procedure
•
8-BOLTS
SEQUENCIAL ORDER ROTATIONAL ORDER
2
12-BOLTS

TH-750-IMI-REV-5
15
1 - 2
1
3-4
13
5 - 6
5
7 - 8
17
9 - 10
9
11 - 12
3
13- 14
15
15- 16
7
17- 18
19
19- 20
11
2
14
6
18
10
4
16
8
20
12
APPENDIX A
Bolt Torque Procedure
16-BOLTS
20-BOLTS
SEQUENCIAL ORDER
1 - 2
3-4
5-6
7- 8
9 - 10
11 - 12
13- 14
15- 16
SEQUENCIAL ORDER
ROTATIONAL ORDER
1
9
5
13
3
11
7
15
2
10
6
14
4
12
8
16
ROTATIONAL ORDER

16
TH-750-IMI-REV-5
Notes:
1. Suggested piping design. Designer should consult local codes to verify compliance.
2.
3. Always pipe supply steam from the top of the header as shown and install a main drip before
the control valve inlet.
4. When using the TH-750 for domestic hot water supply, it is highly recommended to install a
master blend valve to prevent any chance of scalding
Hookup shown with Float & Thermostatic steam trap piped to gravity atmospheric
condensate return line. For pressurized condensate return systems or where a lift is required,
the TH-750 must be fitted with a Thermaflo Engineering pump trap on pressure powered
pump in place of the F & T Trap.
APPENDIX B
TH-750 Steam Fired Single Unit Piping Hookup

TH-750-IMI-REV-5
17
APPENDIX B
TH-750 Steam Fired Single Unit Piping Hookup
With Storage Tank For Peak Use
Notes:
1.Suggested piping design. Designer should consult local codes to verify compliance.
2.Hookup shown with Float & Thermostatic steam trap piped to gravity atmospheric
condensate return line. For pressurized condensate return systems or where a lift is required,
the TH-750 must be fitted with a Thermaflo Engineering pump trap in place of the F & T trap.
3.Always pipe supply steam from the top of the header as shown and install a main drip before
the control valve inlet.
4.When using the TH-750 for domestic hot water supply, it is highly recommended to install a
master blend valve to prevent any chance of scalding.

18
TH-750-IMI-REV-5
APPENDIX B
TH-750 Steam Fired Single Unit Piping Hookup
With Blend Valve & Thermal Loop Diverter
Notes:
1.Suggested piping design. Designer should consult local codes to verify compliance.
2.Hookup shown with Float & Thermostatic steam trap piped to gravity atmospheric
condensate return line. For pressurized condensate return systems or where a lift is required,
the TH-750 must be fitted with a Thermaflo Engineering pump trap in place of the F & T trap.
3.Always pipe supply steam from the top of the header as shown and install a main drip before
the control valve inlet.
4.When using the TH-750 for domestic hot water supply, it is highly recommended to install a
master blend valve to prevent any chance of scalding.