Hubbell BWP Series User manual

INSTALLATION, OPERATION AND
MAINTENANCE MANUAL FOR
INDIRECT FIRED WATER HEATER
ELECTRIC HEATER COMPANY
BASE MODEL “BWP”
Edition 2019

2
HUBBELL
ELECTRIC HEATER COMPANY
P.O. BOX 288
STRATFORD, CT 06615
PHONE: [phone]
FAX: [phone]
INTERNET: http://www.hubbellheaters.com/
-- IMPORTANT --
Always reference the full model number and serial number when calling the factory.
WARNING / CAUTION
1. FLUIDS UNDER PRESSURE MAY CAUSE INJURY WHEN RELEASED.
Always shut off all incoming and outgoing valves and carefully decrease all trapped
pressures to zero before opening any covers, piping or gauge connections, etc.
2. HOT WATER OR HOT SURFACES CAN CAUSE SEVERE BURNS.
Wear safety goggles and protective gloves when carrying out maintenance procedures
involving the heater and/or when removing and accessories from the heater. Shield
your eyes and body to protect from spray when opening a relief valve.
3. Tank is to be completely filled with water and all air is to be vented before energizing.
4. Due to the rigors of transportation, all connections should be checked for tightness before
heater is placed in operation.
5. Safety relief valve must be installed in tapping provided.
6. KEEP AWAY FROM LIVE ELECTRICAL CIRCUITS.
Do not perform any maintenance, make any adjustments, or replace any components
inside the control panel with the high voltage power supply turned on. Under certain
circumstances, dangerous potentials may exist even when the power supply is off. To
avoid casualties, always turn the power supply safety switch to off, or ground the circuit
before performing any maintenance or adjustment procedure.
7. Generalized instructions and procedures cannot anticipate all situations. For this reason,
only qualified installers should perform the installations. A qualified installer is a person
who has licensed training and a working knowledge of the applicable codes and
regulations, tools, equipment, and methods necessary for safe installation of an indirect
fired water heater. If questions regarding installation arise, check with your local
plumbing and electrical inspectors for proper procedures and codes. If you cannot obtain
the required information, contact the company.

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SECTION
TITLE
PAGE No.
I
GENERAL DESCRIPTION AND CONSTRUCTION
5
General Description
General Operation
Construction
II
INSTALLATION
9
Codes and Regulations
Water Heater Placement
Piping Installation
Electrical Installation
Filling the Heater
III
OPERATION
15
Startup
Shutdown
IV
SCHEDULED MAINTENANCE AND SERVICING
16
Recommended Maintenance
General Maintenance
V
TROUBLESHOOTING
18
VI
MISCELANEOUS CHARTS AND FORMULAS
19

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MODEL BWP -
OUTLINE DIMENSIONS

5
SECTION I
GENERAL DESCRIPTION AND CONSTRUCTION
GENERAL DESCRIPTION
This manual provides a complete description, as well as installation, operation, troubleshooting,
maintenance, and servicing procedures for a fully packaged indirect fired water heater. This
heater provides potable hot water for various functions. It is a permanently installed, stationary,
self-contained unit with automatic operating controls.
The complete assembly on a standard unit consists of the storage tank, a brazed plate heat
exchanger (piped to the storage tank), a circulator pump, and an ASME rated combination
temperature and pressure safety relief valve. Optional equipment may be supplied with your
unit. Please consult the product drawing for details specific to your assembly. The unit is
factory assembled, insulated, jacketed, piped, tested, and ready for service connections.
GENERAL OPERATION
The BWP model operates using boiler water as its energy source for heating potable hot water.
The BWP series can provide potable hot water up to 180°F. Therefore, the supplied boiler
water must be within the range of 150°F to a maximum of 220°F and must be at least 5° above
the potable water temperature desired from the water heater storage tank outlet.
Boiler water and potable water enter the plate heat exchanger, in a counter flow pattern, where
heat transfer takes place from the boiler water to the potable water. The heated potable water
exits the heat exchanger and enters the storage tank. An integrally mounted control panel
provides a central location for electrical power connections.
How it Works
1. When there is a demand for hot water consumption, hot water exits from the top of the
storage tank and is replaced by cold water entering the bottom of the tank. When enough
cold water enters the storage tank to lower the stored hot water temperature below the
desired value, the control circuit closes creating a call-for-heat, which energizes the
circulating pump and boiler water control valve.
2. When the circulating pump and control valve are energized, the pump circulates domestic
water from the storage tank through the potable side of the heat exchanger plates. Boiler
water flowing through the opposing side of the heat exchanger plates heats the potable
water before it returns to the storage tank.
3. When the stored water temperature increases above the desired value, the control circuit
opens and the circulating pump and boiler water control valve are de-energized. With
the pump no longer running, no more potable water flows from the heat exchanger into
the storage tank.
CONSTRUCTION
The water heater components and operating controls are factory selected, sized, piped, and
tested to ensure reliable operation. See applicable drawing supplied with water heater for
specific details.
TANK CONNECTIONS
The storage tank is constructed of all welded carbon steel, and internally lined with specially
formulated Hydrastone cement to a ½-inch minimum thickness for superior protection and tank
longevity. The tank is designed for a maximum allowable working pressure of 150 psi (225 psi
TP).

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Temperature and Pressure Relief Valve
A combination safety temperature and pressure relief valve is installed at the top of every
storage tank. An overflow line (either 1-inch or ¾-inch connection) should be utilized from the
relief valve outlet to a suitable floor drain. Refer to Section II, Piping Installation, Figure I,
Temperature and Pressure Relief Valves section of this manual for additional information.
Outer Shell, Insulation, and Supports
The tank is encapsulated in 2-inch thick polyurethane foam insulation. The insulation is
protected by a high impact non-corroding colorized composite protective jacket. The entire
vessel is supported on heavy-duty integrally welded steel supports for sturdy floor mounting.
BRAZED PLATE HEAT EXCHANGER
The water heater is supplied with an
efficient high quality Brazed Plate
Heat Exchanger. The heat
exchanger consists of individual
embossed plates contained between
end plates. The serially arranged
plates are brazed together forming a
sealed pack with flow gaps between
each plate. The boiler water and
potable water flow through every
other flow gap in opposite
directions for efficient heat transfer.
The number and arrangement of the
heat exchanger plates depends on
the specific requirements of each water heater application. Refer to the separate component
O&M manual for a complete functional description as well as detailed information on the
construction and maintenance of the brazed plate heat exchanger.
BOILER WATER COMPONENTS
Boiler Water Control Valves
The standard BWP model includes a 2-way Modulating Control Valve. Refer to the
technical drawings provided with the heater to determine which valve type is utilized.
Control Valve, 2-Way
A high quality electrically operated control valve is installed in the
boiler water line upstream of the heat exchanger. This
sophisticated electronic device controls the flow of boiler water to
the heat exchanger providing the precise amount of boiler water to
produce the desired potable water output temperature. This valve
receives an electrical position signal from the panel mounted
temperature controller to maintain the pre-set water temperature.
The control valve is installed in such a way that in the event of
reaching the potable water high limit temperature, power is
removed from the control valve allowing it to automatically close.
The closed valve blocks the flow of boiler water to the heat
exchanger, thereby preventing excessively high temperatures of the potable water. Refer to
the separate component O&M manual for a complete functional description as well as
detailed information of the 2-way valve.

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POTABLE WATER COMPONENTS
Thermocouple
A thermocouple is mounted in the storage tank. That element is wired to the panel mounted
temperature controller for monitoring and control of the desired water temperature. See
Control Panel components for additional detail.
Temperature and Pressure Safety Relief Valve
A temperature and pressure Safety Relief valve is
provided for installation in the potable water line
downstream of the heat exchanger.
Circulator Pump
A recirculation loop is used to maintain the
necessary flow of potable water from the storage tank through the heat exchanger. This loop
recirculates the potable water via a circulator installed between the heat exchanger inlet and
the storage tank. The circulator runs any time the system initiates a “call-for-heat.” For
more information regarding the circulator pump see included supplemental material from the
pump manufacturer.
Strainer
A cast bronze ‘Y’ strainer with 20 mesh stainless steel screen protects the potable water
controls and the passages within the plate heat exchanger from dirt and debris in the water
supply.
CONTROL PANEL COMPONENTS
Control Panel Enclosure
A painted steel NEMA 1 enclosure houses the main electrical control elements.
On/Off Switch
A lighted toggle switch is mounted through the enclosure door and is utilized to turn on
power to the unit.
Temperature Controller
A temperature and process controller is configured to control the
boiler water control valve with input from a thermocouple mounted
in the storage tank. The controller is mounted through the enclosure
door to allow full access to the user interface. Refer to the separate
component O&M manual for a complete functional description as
well as detailed information.
High Limit Thermostat
The water heater is supplied with an immersion thermostatic switch that is installed and
wired at the factory. The immersion thermostat can be adjusted through a range of 100°-
190°F and is typically set 10°F above the panel mounted high limit set point. The thermostat
is adjustable with a flat tip screwdriver.
Fused Low Voltage Transformer
A fused low voltage transformer is supplied prewired within the control panel. This is used
to step down higher voltages to 24-volts for the control circuit.

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MISCELLANEOUS COMPONENTS
Dial Temperature and Pressure Gauge
A combination temperature (70°-250°F) and pressure (0-200 psi)
gauge with a 2½-inch dial may be installed within the potable and
boiler water inlet and outlet piping for local indication.
OPTIONS
The following optional features may be included in your water heater. Reference included
drawing specific to your heater for further details.
Single Solenoid Safety System
A single solenoid safety system closes the water supply to the control valve should the
temperature in the tank reach the high limit set point.
Control Valve, 3-Way
The control valve is a motorized 3-way characterized control valve that regulates the flow of
boiler water to the heat exchanger, providing the precise amount of boiler water to produce
the desired potable water output temperature. This valve receives an electrical position
signal from the panel mounted temperature controller, directing excess boiler water flow
around the heat exchanger and directly to the boiler water outlet piping.
Isolation Valves for Clean-in-Place Heat Exchanger Maintenance
Depending on the water quality and operating temperature, scale can form during operation
and will continue to accumulate inside the heat exchanger. If non-damaging water
conditions are particularly poor, it may be necessary to outfit the heat exchanger piping with
isolation valves to utilize Clean-in-Place practices for heat exchanger maintenance.
Double Wall Brazed Plate Heat Exchanger
Depending on the application a Double Wall Brazed Plate Heat Exchanger may be required.
Ultimately a double wall configuration differs from a single wall configuration by utilizing a
gap of air between the plates to prevent cross contamination of fluid streams in the event of an
internal leak within unit.

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SECTION II
INSTALLATION
WARNING/CAUTION
CODES AND REGULATIONS
This equipment must be installed in accordance with all appliance markings, the instructions
included in this manual, and any supplemental instructions provided. This equipment must
also be in compliance with any installation regulations enforced in the local area where the
installation is to be made. These must be carefully followed in all cases. Authorities having
jurisdiction must be consulted before installation. In the absence of such regulations, the
installation must be in accordance with the latest edition of the applicable state and local
mechanical and plumbing codes. The storage tank conforms to the current edition of the
ASME Boiler and Pressure Vessel Code Section IV, and the plate heat exchangers conforms
to the current edition of the ASME Boiler and Pressure Vessel Code Section VIII.
For protection against excessive pressures and temperatures, local codes may require the
installation of a temperature-and-pressure (T&P) relief valve certified by a nationally
recognized laboratory that maintains periodic inspection of production of listed equipment of
materials, as meeting the requirements for Relief Valves and Automatic Gas Shutoff for Hot
Water Supply Systems. ANSI Z21.22-1971. THE CUSTOMER IS RESPONSIBLE TO
PROTECT PROPERTY AND PERSONNEL FROM HARM WHEN THE VALVE
FUNCTIONS.
All water heaters have a risk of leakage at some unpredictable time. IT IS THE
CUSTOMER'S RESPONSIBILITY TO PROVIDE A CATCH PAN OR OTHER
ADEQUATE MEANS, SO THAT THE RESULTANT FLOW OF WATER WILL NOT
DAMAGE PROPERTY.
Never operate unit in excess of design conditions.
The tank should be fully drained in the event the incoming boiler water is shut off and if there is
danger of freezing.
WATER HEATER PLACEMENT
Checking Equipment Before Installation
Inspect the unit completely upon receipt from the freight carrier before signing the bill of
lading. Inspect the heater and all accompanying parts for signs of impact or mishandling.
Verify the total number of pieces shown on packaging slips with those actually received.
Contact the freight carrier immediately if any damage or shortage is detected.
Handling and Locating the Water Heater
WARNING: Use industry standard safe rigging methods when attempting to lift or move
this product. Failure to follow industry standard safe rigging methods (such as the use of
straps and spreaders bars when lifting the water heater skid assembly) can cause
uncontrolled tipping or even dropping of the water heater, resulting in property damage,
personal injury, or even death.
1. Place the heater on a solid foundation in a clean and dry location. This location
should be as close as possible to the point of most frequent hot water. Additionally,
the location chosen should be near to boiler water and/or electrical power as practical.
2. If the heater is to be raised off the floor, the entire bottom of the heater should be
supported by a solid surface.
3. Verify that the system utilities are adequate to meet the water heater requirements as

10
specified in this manual and/or other applicable appliance markings.
4. Unit should be level to permit proper drainage should any water connections leak. A
suitable drain would be capable of accepting hot water discharge (at least 210°F) from
the water heater temperature and pressure relief valve.
5. This water heater is suitable for indoor installation only and must not be subject to
freezing.
6. When the water heater has been placed in its final location, remove all shipping
supports and bracing.
Service Clearances
A minimum service clearance of 18” is recommended on all sides and above the water heater
to facilitate easy access for inspection and service of installed components. Optional
equipment may increase the clearance requirements.
Also allow sufficient space for installing and servicing connections such as building water,
electrical, pump, boiler water, heat exchanger, and any other auxiliary/optional equipment.
PIPING INSTALLATION
IMPORTANT: The most effective means for preventing deterioration from accelerated
corrosion due to galvanic and stray current is the installation of dielectric fittings/unions.
The installation of these fittings is the responsibility of the installing contractor.
IMPORTANT: If two or more water heaters are piped in parallel, it is critical that the
piping systems are balanced to assure that the combined capacity is realized. It is
recommended that reverse return piping is utilized in multiple-unit installations.
CAUTION: DO NOT use galvanized pipe or fittings or steel pipe or fittings when making
waterside connections. Use only non-ferrous waterside materials.

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Figure 1: Installation Diagram of an Integrally Mounted Single Pass Heat Exchanger.
(Not all components shown are supplied by Hubbell)
Figure 2: Installation Diagram displaying a multiple 2-Pass Heat Exchanger Assembly.
(Not all components shown are supplied by Hubbell)

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Potable Inlet and Outlet Piping
1. All domestic and boiler water pipes should be flushed before assembly and
installation. Failure to flush lines could cause components to clog or malfunction.
2. All integral components have been properly sized to meet design conditions. Piping to
the unit should not be smaller than the size of pipe connections furnished by Hubbell.
Additionally, piping and components connected to the water heater must be rated for
potable water, the water temperatures they will experience, and for their application.
3. It may be necessary to ship some piping assemblies disconnected and separately
secured to the shipping container to avoid damage to the water heater components. In
this case, these assemblies need to be reconnected. Reconnect the heat exchanger
potable water lines to the storage tank as indicated in the installation diagrams.
Contact factory if the storage tank and/or heat exchanger need to be relocated using
field-supplied piping. Relocating the heat exchanger may require a larger field-
supplied pump to overcome the distance between the exchanger and storage tank.
4. When tightening unions, valves, flanges, and/or fittings on the storage tank and heat
exchanger it is recommended to use a backup wrench. Using a different tool may
cause damage due to over-tightening which can void the warranty on supplied
components.
5. It is considered common practice to install shut-off valves and unions in the potable
water and boiler water inlet and outlet piping to aid in servicing. Use caution when
threading pipe nipples into storage tank and heat exchanger connections to prevent
over-tightening or cross-threading.
6. If the water heater is installed in a closed water supply system (requiring a back-flow
preventer or a check valve in the cold-water line) it may be necessary to provide
thermal expansion control via a thermal expansion tank.
7. Pipe the Y-Strainer valve and the storage tank drain valve to a suitable drain capable
of accepting hot water discharge when opening the water heater drain valves.
8. After plumbing, verify that all fittings, connections, and components are leak free.
9. After confirming the system is leak free, all boiler water and hot potable water piping
(including the heat exchanger) should be insulated to the minimum pipe insulation
thickness: specified in ASHRAE 90.1 “Energy Standard for Buildings Except Low-
Rise Residential Buildings.” If cold water supply lines are subject to freezing during
operation or shutdown periods, insulate or otherwise protect them.
WARNING: Failure to insulate or guard all surfaces containing hot water can result in
property damage, personal injury, or even death. Uninsulated or unguarded surfaces
containing hot water can be hot enough to cause severe burns instantaneously.
Boiler Water Piping
WARNING: All system piping to the heat exchanger plumbing must be adequately
supported. Failure to provide adequate support will result in excessive loads on the heat
exchanger connections that can cause hot water discharge resulting in property damage,
personal injury, and even death.
1. All boiler water pipes should be flushed before assembly and installation. Failure to
flush lines could cause components to clog or malfunction.
2. The unit will perform in accordance with the boiler and domestic water temperatures
and flows to which it is connected. It must be installed to operate with the
temperature and flow conditions specified when selecting the heater. Therefore, the
boiler water piping must be sized to deliver sufficient hot water to the heat exchanger
without excessive pressure drop.
3. When tightening unions, valves, flanges, and/or fittings on the storage tank and heat
exchanger it is recommended to use a backup wrench. Using a different tool may

13
cause damage due to over-tightening which can void the warranty on supplied
components.
4. It is considered common practice to install shut-off valves and unions in the potable
water and boiler water inlet and outlet piping to aid in servicing. Use caution when
threading pipe nipples into storage tank and heat exchanger connections to prevent
over-tightening or cross-threading.
5. Pipe the Y-strainer in the boiler supply piping near the heat exchanger inlet to a
suitable drain capable of accepting hot water discharge.
6. Confirm that an air separator is installed in the boiler water supply piping to the heat
exchanger.
7. Concerning the boiler water control valve, use standard design practices to avoid
“deadheading.”
Temperature and Pressure Relief Valve Piping
The BWP water heater storage tank is supplied with a temperature and pressure relief
valve(s) sized in accordance with the ANSI/ASME Boiler and Pressure Vessel Code, Section
IV. The brazed plate heat exchanger included with the BWP water heater is supplied with a
pressure relief valve sized in accordance with the ANSI/ASME Boiler and Pressure Vessel
Code, Section VIII.
The relief valve(s) must be threaded directly into the dedicated fitting(s) located near the top
of the storage tank/heat exchanger and each relief valve discharge must be separately
plumbed to a suitable floor drain.
The discharge line must not be smaller than the relief valve opening, must allow complete
drainage of the valve and line and it must be positioned in the floor drain (in the event that
any water or steam forcefully exiting the drain line does not openly splash).
The water heater must not be operated without a correctly installed, properly sized and
properly operating relief valve. It is industry standard that the relief valve(s) be manually
operated at least once a year. If water does not freely flow from the manually operated relief
valve(s) or if it does not fully reseat when released, then a new relief valve(s) is required.
The new valve(s) must be of the same type, temperature and pressure rating, and relieving
capacity as the original relief valve supplied with the water heater.
Do not plug or restrict the relief valve or the relief valve drain line.
Outlet to floor drain
Install into provided tapping
Manual Release
Lever
Temperature Probe
WARNING: Do not install a reducing coupling, valve or other restriction between the relief
valve discharge and a suitable floor drain. Such a restriction could prevent the valve from
fully relieving if the pressure settings are exceeded, which could result in property damage,
personal injury, or even death.

14
IMPORTANT: A relief valve that periodically discharges may result from thermal
expansion. As stated in the “Potable Inlet and Outlet Piping” section of this manual: if the
water heater is installed in a closed water supply system (requiring a back-flow preventer or
a check valve in the cold-water line) the system will require a means to control expansion.
Contact Hubbell, a water heater, and/or a plumbing professional to resolve this situation.
ELECTRICAL INSTALLATION
IMPORTANT: This heater is wired for 120VAC, 1ph, 60Hz service (unless specified
otherwise). The heater must be electrically grounded in accordance with the latest edition of
the National Electrical Code ANSI/NFPA No. 70. When the unit is installed in Canada, it
must conform to the CSA C22.1, Canadian Electrical Code and/or Local Electrical Codes.
CAUTION: Do not use the water heater or any attached piping as an electrical ground of
any kind.
1. Refer to Hubbell drawing for any electrical requirements.
2. Enter electric enclosure with properly sized feeder leads. Install these power leads
into the box lugs on the terminal block or magnetic contactor.
3. All other electrical connections are made at the factory; therefore, no other electrical
connections are necessary.
4. Due to the rigors of transportation, check factory wiring connections for tightness.F
FILLING THE HEATER
1. Fill the entire system with water. To be sure that the unit is not inoperative because of
air in a space normally filled with water (air-bound), open the relief valve. Leave the
valve open until a steady flow of water is observed. Then close the valve and
complete filling the system.
2. Check the unit again to make sure there are no system leaks. Avoid using petroleum
based products to stop any leaks that may be discovered. All system leaks must be
repaired.

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SECTION III
OPERATION
STARTUP
CAUTION: To avoid pump damage, do not energize the heater or circulating pump until the
tank is full of water.
CAUTION: To avoid damage to the heat exchanger, gradually introduce boiler water to the
heat exchanger.
1. When placing the unit into operation, open the relief valve to purge air from the top of
the tank and begin to fill the tank with cold water (checking for leaks). Be sure the
tank is completely filled before closing the relief valve.
2. Locate the ON/OFF switch in the control box. Activate the pump and thermostats by
pushing the control switch to the “ON” position.
3. Verify the desired set-point temperature. The operating thermostat is set at the factory
at approximately 140°F, and the hi-limit device is factory set at approximately 200°F.
If changes to the desired temperatures are required please reference the provided
supplemental instructions from the controller manufacturer.
4. Push the operating switch to “OFF” before opening the main boiler water supply
valve. To prevent thermal shock, do not allow boiler water to the heat exchanger
suddenly when the heat exchanger is empty or cold.
5. Gradually open valve to allow water to enter the heat exchanger until all passages of
the heat exchanger are filled and slowly bring the heat exchanger up to temperature.
6. Push the operating switch to “ON” to energize the pump and control valve. This will
begin to heat the water in the storage tank. Allow the water temperature in the storage
tank to rise above the set-point entered into the temperature controller and to de-
energize the circulating pump and control valve.
7. Confirm the pump cycles on when the stored water temperature drops enough to cause
the temperature controller to re-energize the circulating pump by opening a nearby hot
water tap to consume hot water from the storage tank. Check operation of all safety
and operating controls (Repeat as necessary).
8. Confirm there is no pulsation or water hammer, since this can cause vibration and
strain which can result in damage or leaks. Contact a water heater or plumbing
professional to resolve this situation.
9. Gaskets may require tightening after the heat exchanger has reached the set-point
temperature. Follow the supplemental instructions provided by the heat exchanger
manufacturer to retighten the gasket joints.
10.Never operate unit in excess of design conditions.
11.Never break any joint, (gasketed or screwed), until the pressure in the unit has been
reduced to zero and the unit drained.
SHUTDOWN
1. Remove all power from the system.
2. Close all boiler water supply valves to the unit.
3. Close all cold-water supply valves to the unit.
4. If the water is to be removed from service for an extended period of time: the storage
tank, heat exchanger, and piping can now be drained completely. (1) Lift lever on
relief valve to vent tank. (2) Open drain valve.

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SECTION IV
SCHEDULED MAINTENANCE AND SERVICING
WARNING / CAUTION
WARNING: Turn off all electrical service to the heater before accessing electrical
components or terminals located inside the control cabinet or at any other point of wiring
access. Close and fasten the control cabinet cover or any other point of wiring access before
restoring electrical service to the heater. If the electrical service is not turned off and these
components are touched, a shock can occur, which can result in property damage, personal
injury, or even death.
IMPORTANT: Hubbell cannot control the use of the product provided, the water conditions
in which it is used, or the adherence to a regular maintenance schedule, therefore, the
warranty on the BWP unit does not cover poor performance, structural failure, or leaking
due to an excessive accumulation of scale.
RECOMMENDED MAINTENANCE SCHEDULE
Monthly Maintenance
1. Test low-water cutoff device.
2. Check gauges, monitors, and indicators.
3. Check instrument and equipment settings.
Annual Maintenance
1. Check all joints, pipe connections and the heat exchanger for tightness, corrosion, or
deterioration.
2. Check all pumps, valves, controls, and devices including thermostats for proper
operation.
3. Check relief valves for proper operation.
4. Test hi-limit and operating temperature controls.
As Required Maintenance
1. Tank flush and cleanout.
2. Clean heat exchanger.
3. Clean potable water Y-Strainer.
4. Clean (or blow down) boiler water Y-Strainer.
GENERAL MAINTENANCE
Tank
Depending on the water quality and operating temperature, scale can form during operation
and will continue to accumulate on the bottom of the tank. Therefore, it is recommended to
inspect the tank every six months (more frequent inspections may be required if higher
scaling conditions are present). To help prevent the accumulation of scale, flush the tank at
regular intervals.
To flush:
1. Remove power to the unit by turning off the electrical disconnect switch.
2. Open the drain valve and allow water to flow through the tank until it runs clear.
3. Close the drain valve and restore power to the unit by turning on the electrical
disconnect switch. Refer to Section III –Operation section of this manual for further
instructions.
NOTE: When the heater is returned to service, conduct a thorough inspection of all
connections, fittings, and wiring.

17
Temperature and Pressure Relief Valve
Test the temperature and pressure relief valve(s) on the storage tank and the heat exchanger
at least once a year. Do this by manually lifting the relief valve lever briefly. If a relief
valve does not open and close properly then it must be replaced with a new relief valve of
the same type. Refer to Section II –Piping Installation section of this manual for further
instructions.
Thermostats and Temperature Limiting Devices
The temperature sensors that regulate the process control of the unit extend into the water
inside the storage tank. Depending on the water conditions in your area, scale may coat
these sensors, affecting the accuracy of the sensors. This can allow water temperature to
exceed the desired limits. Therefore, it is recommended to remove and inspect these sensors
at regular intervals and remove scale if present.
Boiler Water Control Valve
The boiler water control valve is sealed and factory installed and therefore should require no
maintenance. However, durability of the valve stems and packing is dependent upon
maintaining non-damaging water conditions. Inadequate water filtration/treatment can result
in corrosion, scale, and abrasive particle formation. It is important then, to make sure the Y-
Strainers are regularly cleaned.
Additional preventative maintenance includes protecting the actuator from dropping water,
condensation, and other moisture and making sure the actuator is not covered with thermal
insulating material. Water or moisture could result in an electrical short, and high ambient
temperatures may damage the actuator.
Cleaning the Y-Strainer
Perform annually or more often, if required.
1. Remove blowoff bushing (E) or cap (F), as required.
2. Remove gasket (B), if required.
3. Remove, clean, and re-install screen (A).
4. Replace gasket (B).
5. Re-install blowoff bushing (E) or cap (F), as required.
Heat Exchanger
Depending on the water quality and operating temperature, scale can form during operation
and will continue to accumulate inside the heat exchanger. For instructions on regular
maintenance procedure consult the supplemental information from the heat exchanger
manufacturer.

18
SECTION V
TROUBLESHOOTING
Symptom
Probable Cause
Corrective Action / Remedy
Gradual loss of
heating capacity.
HX is fouled.
Clean HX per separate O&M.
Excess silt in bottom of
tank.
Drain and flush tank per Section IV,
annual scheduled maintenance.
Strainers clogged.
Clean strainers per Section IV,
annual scheduled maintenance.
Pump impellor deteriorated.
Repair or replace per separate O&M.
Operating conditions are
outside of design
parameters.
Check if the set-point is higher than
specified. Confirm the measured
flow rate by volume and rate, make
sure there are not additional loads on
the heater.
Overheating.
Malfunctioning or
misadjusted thermostat.
Reconfigure per separate O&M. If
the thermostat is properly adjusted
and is not de-energizing the
circulator pump, verify the wiring is
correct and replace the thermostatic
control if necessary.
Circulator not operating.
Repair or replace per separate O&M.
Circulator not de-energizing.
Repair or replace per separate O&M.
Outlet water
temperature is not
constant.
Insufficient recovery.
Check to make sure the heater
design rating is not being exceeded.
Malfunctioning or
misadjusted thermostat.
Repair or replace per separate O&M.
Excessive vibration.
High rate of flow beyond
design conditions.
Consult factory.
Under sized piping to the
unit.
Re-pipe lines to unit using proper
sized lines.
No hot water, even at
low flow.
Boiler water control valve
not opening.
Check that the electrical coils are
energized. If not, it is a wiring
problem. If so, repair or replace per
separate O&M.
Malfunction or misadjusted
thermostat.
Reconfigure per separate O&M. If
the thermostat is properly adjusted
and is not energizing the circulator
pump, verify the wiring is correct
and replace the thermostatic control
if necessary.
Circulator not operating.
Repair or replace per separate O&M.
* Red symptom indicates that equipment should be shut down immediately and cause of
malfunction corrected before unit is re-started or serious damage may result.

19
SECTION VI
MISCELLANEOUS CHARTS AND FORMULAS
METRIC CONVERSIONS

20
P.O. BOX 288
STRATFORD, CT 06615-0288
PHONE: [phone]
FAX: [phone]
INTERNET: http://www.hubbellheaters.com/