Mestek BT26-H General instructions

BT2-0218
45W30-WG0848
IN UNITED STATES: 260 NORTH ELM ST. WESTFIELD, MA 01085 800-465-8558 / FAX [phone]
IN CANADA: 7555 TRANMERE DRIVE, MISSISSAUGA, ONTARIO, L5S 1L4 [phone] / FAX [phone]
SECTION 1: INTRODUCTION
Model BT Overview ..................................................................... 2
SECTION 2: SPECIFICATIONS & DIMENSIONS ................ 3
SECTION 3: LOCATION & MOUNTING
Prepare the Unit ......................................................................... 3
Location....................................................................................... 3
Handling/Hoisting ........................................................................ 3
SECTION 4: ELECTRICAL CONNECTIONS
Overcurrent Protection & Wire Sizing ......................................... 4
SECTION 5: REPLACEMENT PARTS .................................. 4
SECTION 6: PIPING DIAGRAMS........................................... 5 & 6
SECTION 7: LIMITED WARRANTY....................................... 7
MODEL BT26-H,
BT40-H & BT80-H
INSTALLATION,
OPERATION &
MAINTENANCE
MANUAL
Buffer Tanks
Hydronic Thermal Storage Tanks
Qualified installer only –
This product must be installed only by a qualified service
technician. The installation must be done using recognized
industry practices, and in compliance with this manual and all
applicable codes. Failure to comply could result in death, serious
injury or substantial property damage.
For information not included in this manual, see the following:
This manual includes only basic information for installation,
operation and maintenance of thermal storage tanks and
supplemental back-up heaters. For more advanced applications
and information not shown in this manual, contact Technical
Support for assistance and supplemental instructions. Call 413-
564-5530 in Westfield, MA or visit our website at www.mestek.
com to send an e-mail or review technical literature.

2
Section 1: Introduction
Hazard Definitions
The following terms are used throughout this manual to bring
attention to the presence of potential hazards or to important
information concerning the product.
Indicates an imminently hazardous situation which,
if not avoided, WILL result in death, serious injury or
substantial property damage.
Indicates an imminently hazardous situation which,
if not avoided, COULD result in death, serious injury
or substantial property damage.
Indicates an imminently hazardous situation which,
if not avoided, MAY result in minor injury or property
damage.
Used to notify of special instructions on installation,
operation or maintenance which are important to
equipment, but not related to personal injury hazards.
To reduce the risk of excessive pressures and temperatures in
this water heater, install temperature and pressure protective
equipment required by local codes and no less than a
combination temperature and pressure relief valve certified by a
nationally recognized testing laboratory that maintains periodic
inspection of production of listed equipment or materials, as
meeting the requirements for Relief Valves and Automatic Gas
Shutoff Devices for Hot Water Supply Systems, ANSI Z21.22.
This valve must be marked with a maximum set pressure not
to exceed the marked maximum working pressure of the water
heater. Install the valve into an opening provided and marked for
this purpose in the water heater, and orient it or provide tubing
so that any discharge from the valve exits only within 6 inches
above, or at any distance below, the structural oor, and does
not contact any live electrical part.
The discharge opening must not be blocked or reduced in size
under any circumstances. Hydrogen gas is produced in a hot
water system served by this heater that has not been used for a
long period of time (2 weeks or more). Hydrogen gas is extremely
ammable. When hydrogen is present, there will probably be
an unusual sound such as air escaping through the pipe as the
water begins to ow.
There should be no smoking or open ame near the faucet at
the time it is open. When a water heater is installed in a closed
water-supply system, such as one having a back-ow preventer
in the cold-water supply, means shall be provided to control
thermal expansion. Contact the water supplier or local plumbing
inspector for information regarding the control of this situation.
Model BT26-H, BT40-H & BT80-H
Overview
The Model BT-Series are water tanks suitable for storage of
water and water/glycol mixtures for use in all hydronic systems
for heating, cooling, or a combination of both heating and cooling.
The wide operating range of 32-194°F (0-90°C) allows its use with
chiller/heat-pump, geothermal, fossil fuel or solar systems, or any
combination thereof. The tanks are designed for space conditioning
only. They are not approved for potable or domestic water.
The tank's volume provides thermal storage to retain energy
during period of off cycle or defrosting, and buffering, to extend
boiler or heat pump cycle times, increasing overall system
efficiency and allowing tighter control of supply temperature.
Additionally, each tank is equipped with four circulation ports;
when piped in a primary/secondary arrangement, this ensures
hydraulic separation of the system.
When energized, the two heaters provide 6 kW, or approximately
20,500 BTU/hr of heat to the contents of the buffer tank.
This can be used to achieve three distinct purposes, as controlled
by the Solstice Heat Pump, and configurable through the Carel
μC2 control interface.
1. Standby Freeze Protection. When the chiller is in Standby
(inactive)and the water within the chiller drops below a
predetermined temperature, defined by Parameter A04, the
chiller will engage the circulator immediately, and energize the
electric heaters after an adjustable time delay (0-10 minutes,
adjustable via timer relay, KT, inside the heat pump). The pump
and heaters will continue to operate until the temperature
reaches A04 + A05. The default settings are, A04=36, A05=5
degrees F.
2. Heat Pump Heat Boost. If the water temperature in the circuit
starts below, or falls below, a predetermined temperature,
defined by parameter A08 the chiller will engage the electric
heaters after the adjustable KT time delay. The heaters will
continue to operate until the temperature reaches A08 + A09.
The default settings are, A08=90, A09=5 degrees F.
3. Defrost Operation. If parameter d11 =1 the chiller will engage
the heater during defrost operation after the adjustable KT
time delay,, in order to provide a an additional heat source
to offset heat lost from the system. Setting the parameter to
d11=0 disables this feature. For use with SCM-036, SCM-
060 and LAHP48 heat pumps only.
As with any hydronic heating system, it is HIGHLY recommended
that an oxygen barrier tubing is used throughout the system.
Buffer tanks are to be used in hydronic heating and/or
cooling systems only. All local plumbing codes must
be adhered to. Do not operate beyond specifications
on the rating plate. Failure to comply can result in
property damage, personal injury, or death.
The major components of the BT Series are:
• The BT26-H and BT40-H contain a welded, 18-gauge (.047")
grade 304 stainless steel inner tank with ports for circulation,
air separation & pressure relief, and drain. BT80-H contains a
16-gauge (.059") SSC innner tank.
• 50mm (2") expanded polyurethane insulation for R11 insulating
value.
• Outer shell of .020” powder coated carbon steel.
• ¼" ID temperature sensor well, isolated from the tank interior.
• ½" NPT aquastat well, open to the tank interior.
• Two each 3 kW resistive electric heating elements.
• Electrical junction box for connecting electrical power and
safety circuit wiring for the electric heaters.
DO NOT use for potable water heating. The storage tank and
components are not suitable for the application.
Additional Components Required
• Air Separator and Pressure/Temperature relief valve, to be
located directly in the top of the tank.
• Expansion tank sized for the entire system volume, including
the BT tank, and intended operation mode; heating, cooling, or
combination.

3
Section 2: Specications & Dimensions
Figure 2 BT26-H, BT40-H and BT80-H (ALL DIMENSIONS IN INCHES)
Section 3: Location & Mounting
Failure to comply with all of the guidelines IN THE FOLLOWING
could result in death, serious injury or substantial property damage.
The installation must comply with all applicable local codes.
Prepare the Unit
Step 1 Inspect the unit for shipping damage. DO NOT use if
there is a risk that the damage could affect unit operation.
Step 2 Make sure all required components are available.
Location
Step 1 Locate the buffer tank only indoors, protected from weather.
Step 2 Place the buffer tank on a stable surface that will not
shift, and is, or can be made level.
Step 3 If the buffer tank is in a location that may be subject to
seasonal ooding, it must beput upon a raised structure to
ensure that no portion of the buffer tank can be submerged.
Figure 3 Hoisting
Handling/Hoisting
Never attempt to move the buffer tank with any water in it.
The empty buffer tank may be moved safely by two individuals
over at, level ground or oor.
For moving the empty buffer tank over uneven ground, stairs,
onto or off of a vehicle; a lifting point may be fabricated by
assembling a ¾ NPT, steel or brass, pipe nipple into the branch
of a ¾ NPT tee and engaging the nipple into the ¾ NPT port in
the top of the tank. A lifting cable can then be threaded through
the run of the tee and attached to a hoist of crane.
Ensure the tank is level and stable, with no wobbling or rocking,
by installing inorganic (metal, plastic or composite) shims under
the feet.
When using Pex tubing, an oxygen barrier tubing
must be used.
Refer to Solstice Heat Pump (Extreme or SE) installation
manuals for information on system Glycol/Water concentrations.
DIM -D-
DIAMETER
VENT PORT 3/4 NPT
11-3/4
DIM -B-
-E-
-E-
2-5/8
DIM -C-
3/4 NPT DRAIN
AQUASTAT PORT
1/2 NPT
DIM -A-
TEMPERATURE
SENSOR
WELL .250 ID
-E-
-E-
SPL-WG1042_A
Specifications
Model BT26-H BT40-H BT80-H
Dimensions
Diameter 18-1/2" 18-1/2" 23-5/8"
-A- 45" 60" 64-1/8"
-B- 37-3/4" 52-3/4" 55-1/2"
-C- 25-1/8" 34-1/8" 34-5/8"
-D- 20-1/2" 26-5/8" 32-1/2"
Port Diameter NPT -E- 1-1/2" 1-1/2" 2"
Capacity US Gal. 26 40 80
Max Water Flow GPM 36 36 48
Ship Weight lbs. 84 104 130
Empty Weight lbs. 77 97 125
Full Weight lbs. 304 446 805
Min Circuit Ampacity Amps 30 30 30
Standard Buffer Tank

4
Section 4: Electrical Connection
Overcurrent Protection
Provide a separate power source and overcurrent protection for
the immersion heater. Refer to the Figure 4 for detailed wiring.
Figure 4 Field Connections
The figure below shows the electrical circuit for connecting the
buffer tanks to Solstice LAHP or SCM Heat Pumps.
Section 5: Replacement Parts
SPL-WG0141_A
SEAL, TAPERED
45R20000-260007
GASKET, FLAT
45R20000-260015
HEATER ELEMENT, 3kW
45R20000-00025
FLANGE, NO P/N, SHOWN TO
ILLUSTRATE ORIENTATION
AND ASSEMBLY SEQUENCE
THERMAL FUSE, 201F
45R2001-3631
SHEATH, WIRE

5
Section 6: Piping Diagrams
1"
1"
THERMAL STORAGE
BUFFERTANK
(INSULATED)
AIR VENT
72 72
KEY
PUMP W/ISO-FLANGES AIRELIMINATORS BLADDER EXPANSION TANK
BALLVALVE BOILER DRAIN VALVE PRESSURE RELIEF VALVE TWO-WAY MOTORVALVE SPRINGCHECK VALVE BACKFLOWPREVENTER ANTI-SCALD MIXING VALVE PRESSURE TEMP. GUAGE 24V.DIGITALTHERMOSTATS
ON
OFF
230V
HP-1
SUPPLY&RETURN LINES
TO ADDITIONAL HYDRONIC
TERMINAL UNITS (NOT SHOWN)
NOTE:ALL HYDRONICPIPING
IS REVERSE RETURN OR
FIRST IN LAST OUT RULE
ON
OFF
230V
72
FC-1
BT-40
`
4-PIPE BUFFERTANK CONNECTION
DRAIN
AQUASTAT
BLR-1
NOTE:THISISAREPRESENTATIVESCHEMATIC ONLY!YOURCONNECTIONS ANDOTHER DETAILSMAY VARY. ALWAYS FOLLOW INSTRUCTIONSWHENINSTALLING ANY HYDRONICHEATINGAND COOLING SYSTEM.
MAKE -UP
WATER
NOTE: FOR SYSTEMS USINGGLYCOLIT
IS RECOMMENDED TO USEAGLYCOL
MANAGEMENTSYSTEM RATHER THAN EMPLOYAMAKE-UPWATER FEED.

6
Section 6: Piping Diagrams
1"
1"
THERMAL STORAGE
BUFFERTANK
(INSULATED)
AIR VENT
BT-40
72 72
KEY
PUMP W/ISO-FLANGES AIRELIMINATORS BLADDER EXPANSION TANK
BALLVALVE BOILER DRAIN VALVE PRESSURE RELIEF VALVE TWO-WAY MOTORVALVE SPRINGCHECK VALVE BACKFLOWPREVENTER ANTI-SCALD MIXING VALVE PRESSURE TEMP. GUAGE 24V.DIGITALTHERMOSTATS
ON
OFF
230V
HP-1
SUPPLY&RETURN LINES
TO ADDITIONAL HYDRONIC
TERMINAL UNITS (NOT SHOWN)
NOTE:ALL HYDRONICPIPING
IS REVERSE RETURN OR
FIRST IN LAST OUT RULE
ON
OFF
230V
72
FC-1
`
2-PIPE BUFFERTANK CONNECTION
DRAIN
AQUASTAT
BLR-1
NOTE:THISISAREPRESENTATIVESCHEMATIC ONLY!YOURCONNECTIONS ANDOTHER DETAILSMAY VARY. ALWAYS FOLLOW INSTRUCTIONSWHENINSTALLING ANY HYDRONICHEATINGAND COOLING SYSTEM.
MAKE -UP
WATER
NOTE: FOR SYSTEMS USING GLYCOL IT
IS RECOMMENDEDTOUSEAGLYCOL
MANAGEMENTSYSTEMRATHER THAN EMPLOY A MAKE-UPWATER FEED.

7
Section 7: Limited Warranty
The “Manufacturer” warrants to the original owner at the original installation site that the Buffer Tank Product (the “Product”) will be
free from defects in material or workmanship for a period not to exceed 10 years from startup. If upon examination by the Manufacturer
the Product is shown to have a defect in material or workmanship during the warranty period, the Manufacturer will repair or replace,
at its option, that part of the Product which is shown to be defective.
This limited warranty does not apply:
a) if the Product has been subjected to misuse or neglect, has been accidentally or intentionally damaged, has not been installed,
maintained or operated in accordance with the furnished written instructions, or has been altered or modified in any way.
b) to any expenses, including labor or material, incurred during removal or reinstallation of the defective Product or parts thereof.
c) to any workmanship of the installer of the Product.
This limited warranty is conditional upon:
a) shipment, to the Manufacturer, of that part of the Product thought to be defective. Goods can only be returned with prior
written approval from the Manufacturer. All returns must be freight prepaid.
b) determination, in the reasonable opinion of the Manufacturer, that there exists a defect in material or workmanship.
Repair or replacement of any part under this Limited Warranty shall not extend the duration of the warranty with respect to such
repaired or replaced part beyond the stated warranty period.
THIS LIMITED WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EITHER EXPRESS OR IMPLIED, AND ALL SUCH
OTHER WARRANTIES, INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR
A PARTICULAR PURPOSE, ARE HEREBY DISCLAIMED AND EXCLUDED FROM THIS LIMITED WARRANTY. IN NO EVENT
SHALL THE MANUFACTURER BE LIABLE IN ANY WAY FOR ANY CONSEQUENTIAL, SPECIAL, OR INCIDENTAL DAMAGES
OF ANY NATURE WHATSOEVER, OR FOR ANY AMOUNTS IN EXCESS OF THE SELLING PRICE OF THE PRODUCT OR ANY
PARTS THEREOF FOUND TO BE DEFECTIVE. THIS LIMITED WARRANTY GIVES THE ORIGINAL OWNER OF THE PRODUCT
SPECIFIC LEGAL RIGHTS. YOU MAY ALSO HAVE OTHER RIGHTS WHICH MAY VARY BY EACH JURISDICTION.

IN UNITED STATES: 260 NORTH ELM ST. WESTFIELD, MA 01085 800-465-8558 / FAX [phone]
IN CANADA: 7555 TRANMERE DRIVE, MISSISSAUGA, ONTARIO, L5S 1L4 [phone] / FAX [phone]