Rheem RTHW25 Manual

Air Source Heat Pump Installation,
Maintenance and Service Manual
This booklet is to be carefully read and instructions followed for
efficient and trouble free operation of the
Rheem Thermal Hot Water Heat Pump
Rheem Manufacturing Company (Singapore) Pte Ltd
8 Pandan Crescent
#02-02 Singapore 128464
Tel : [phone] / Fax : [phone]
Email : [e-mail]
Website : www.rheemasia.com
REV: OCTOBER 2019

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TABLE OF CONTENTS
INTRODUCTION ……………………………………………………………………………..….. 3
SECTION 1: INSTALLATION ………………………………………………………………….. 4
1.1 Installation Guidelines ……………………………………………………………… 4
1.2 Plumbing …………………………………………………………………………….. 5
1.3 Electrical …………………………………………………….….…………………… 7
1.4 Control Design ……………………………………………………………………… 7
SECTION 2: COMMISSIONING ……………………………………………………….………. 9
SECTION 3: OPERATION …………………………………………………….……..……….. 10
3.1 Thermostat Model (Carel PJEZ Controller) …………………..…………..…..... 10
3.2 Rheem IQTM Model (Intelligent Controller) ……………………………………… 10
3.3 De-Icing …………………………………………………………………………….. 11
SECTION 4: MAINTENANCE ………………………………………………………………… 11
SECTION 5: TROUBLESHOOTING ………………………………………………………… 12
5.1 Thermostat Model ………………………………………………………………… 12
5.2 Rheem IQTM Model ……………………………………………………………….. 13
SECTION 6: INSTALLATION SCHEMATIC DRAWING ………………………………….. 14
SECTION 7: WARRANTY …………………………………………………………………….. 14
The End

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INTRODUCTION
Rheem Thermal Hot Water Heat Pumps are available in sizes from 20kW to 135kW* nominal
output and are suitable for Mechanical, Process and Hydronic heating applications. The unit is
most commonly manufactured as air-to-water design, in which it extracts heat from ambient air
and transfers this to water, providing a highly energy efficient method of water heating. The units
are also manufactured as water-to-water and ground-coupled design.
Each is a fully packaged unit, requiring only electrical and water connections to be made on
installation. A water circulation pump is not supplied with the unit and must be fitted and sized
accordingly to suit the required water flow rate.
Each is factory charged, with refrigerant R407c being ideally suited for commercial or industrial
situations requiring hot water up to 65°C. Refrigerant R134a may also be used for special hot
water applications.
As the performance of the Rheem Thermal Heat Pump varies with ambient operating conditions,
water flow, water temperature and also due to the wide diversity of commercial and industrial
applications, selection of the unit should be done in conjunction with an experienced heat pump
dealer or the manufacturer.
In hot water application, vessels and reticulation containing the heated water should all be
suitably insulated to obtain the optimum performance from the system.
Each Rheem Thermal unit is custom-manufactured to meet specific task/site requirements.
Warm coastal climates may never accumulate ice on the coil. In cooler and/or more volatile
climates removal of any ice buildup is essential and various de-ice mechanism options are
provided.
This manual includes important information in regard to installation, operation, maintenance and
servicing and should be retained for the life of the heater. Correct installation and familiarity with
the operational guidelines given will ensure that the heater gives optimal efficiency and trouble-
free operation over many years.
Caution should be taken if soldering to avoid damage to the thermostat sensor. The sensor
should be removed prior to soldering and refitted once the pipe has cooled. The sensor is located
in a well on the return water pipe.
*Higher heating capacity models are available upon request.

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SECTION 1: INSTALLATION
For validity of warranty, installation must be carried out by registered trade person.
1.1 Installation Guidelines
• Heating efficiency and output increases with the rise in entering air temperature, as
such full advantage should be taken for direct sunlight, typically with evaporator coil
facing north-west or facing a heat source like boiler room, etc.
• Locating the unit close to other system equipment like the pump, tank, etc. will minimize
friction and heat losses.
• Free circulation of air across the coil, requires no obstructions on the intake or fan
discharge of Heat Pumps. Do not position the unit with any intake side closer than
1,000mm to adjacent wall, fences, hedges, etc. Ensure that walls, eaves, etc. do not
obstruct the release of discharge air such that this may recirculate in the incoming air
stream of the unit.
• Service access is required at both ends of the heater. Allow a minimum 850 mm service
access at the compressor end if possible for units up to 80 kW. For units 100 kW and
above 1000 mm access at the compressor end is required.
• Where multiple heat pumps are to be installed, follow the required minimum clearance
indicated in the heat pump catalogue.
• The Heat Pump requires a concrete slab. Rubber mounts shall be installed between
the unit and slab.
• Local building authorities should be consulted for regulations concerning minimum
installation distance from pool or other amenities.
• Units to be used in areas having highly corrosive atmosphere, must be specified at time
of ordering.
• Consideration should be given to the operating noise, wherever possible the exhaust
should be directed away from the occupied areas.
• To ensure proper drainage of the Heat Pump, make sure that the unit is located at a
slightly tilted angle with the drain on the downhill side of the unit. This can be done by
making the concrete slab slightly higher at one end or lifting one end of the unit by
rubber mounts.

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• For the plant-room installation, make sure that sufficient fresh air is available via
provision of inlet grills in building design, etc. Exhaust air from the unit must be
discharged by a duct away from the fresh air supply. Proposed ductwork should be
submitted to the manufacturer for approval. The unit should never be installed in a fully
enclosed area.
1.2 Plumbing
• It is essential that the water recirculating pump and pipe sizes be engineered to suit the
particular application, giving correct water flow through the heat pump. Inadequate or
excessive water flow detracts from heating efficiency and can lead to damage to the
unit. Selection of the recirculating pump must be made in accordance with the design
flow rate and pressure drop as per the manufacturer’s specification.
• Consult Rheem ASEAN specialists and/or your local distributor for recommendations
for optimum flow rate. Assistance will be provided in relation to optimum plumbing
design and pump selection.
• Water connections on the unit are clearly marked as water inlet and water outlet. The
water lines should be as short as conditions will permit. The size of these lines is not
necessarily the same as unit connections.
• Breakable unions should be installed on both inlet and outlet pipes to facilitate
maintenance and water drainage of the system. If the unit is situated below the level
an open holding tank l, shut off valves should be fitted on the water side of both unions
so that removal of the machine is possible without draining the system.
• Caution should be taken if soldering to avoid damage to the thermostat sensor. The
sensor should be removed prior to soldering and refitted once the pipe has cooled. The
sensor is located in a well on the return water pipe
• Diagram 1 shows a typical plumbing schematic.
• Where multiple units are installed, the heaters must be installed in parallel to equalize
pressure drops and balance flow through the heaters. Systems of three or more heat
pumps require a plumbing loop.
• All Plumbing should be carried out by qualified tradesman.

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RECOMMENDED CIRCULATING PUMP FLOWRATE
UNIT
FLOWRATE L/S
RTHW25
1.01
RTHW30
1.16
RTHW40
1.57
RTHW50
2.09
RTHW65
2.17
RTHW80
3.13
RTHW105
4.19
RTHW135
5.41
1.2.1 Water Quality
The heat pump must be installed in accordance with this advice to be covered by the
Rheem Thermal Warranty.
This heat pump is manufactured to suit the water conditions of most public reticulated
water supplies. However there are some known water chemistries which can have a
detrimental effects on the heat pump and its operation and / or life expectancy. If you
are unsure of your water chemistry, you may be able to obtain information from your
local water supply authority. This heat pump should only be connected to a water supply
which complies with these guidelines for the Rheem Thermal warranty to apply.
1.2.2 Change of Water Supply
The changing or alternating from one water supply to another, e.g. a rain water supply,
bore water supply, desalinated water supply, public reticulated water supply or water
bought in from another supply, then water chemistry should be tested to ensure the
water supply meets the requirements given in these guidelines for the Rheem Thermal
warranty to apply.
1.2.3 Saturation Index
The saturation index (SI) is used as a measure of the waters corrosive
or scaling properties. Where the saturation index is less than -1.0, the water is very
corrosive and the Rheem Thermal warranty does not apply to the heat pump. In a
corrosive water supply, the water can attack copper parts and cause them to fail. Water
which is scaling may be treated with a water softening device to reduce the saturation
index of the water.

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1.2.4 Chloride and PH
Where the chloride level exceeds 250 mg / l the Rheem Thermal warranty does not
apply to the heat pump. In a high chloride water supply, the water can corrode stainless
steel parts and cause them to fail.
Where the PH is less than 6.0 the Rheem Thermal warranty does not apply to the heat
pump. PH is a measure of whether the water is alkaline or acid. In an acidic water
supply, the water can attack stainless parts and cause them to fail.
Water with a PH less than 6.0 may be treated to raise the PH. The water supply from a
rainwater tank in a metropolitan area is likely to be corrosive due to the dissolution of
atmospheric contaminants.
1.3 Electrical
•All electrical work must be carried out by licensed electricians and all the wiring should
be carried out to AS3000 latest edition wiring standards.
•Refer to the internal electrical wiring diagram supplied with the units before proceeding
with electrical work. Cable and fuse sizing must be correct relative to unit specified
Volts/Hz/Phase.
•An isolating switch must be fitted adjacent to the unit up to 80 kW, units above 100 kW
have a factory installed isolation switch.
•To install the unit, remove the electrical service panel. No conduit entry points are
provided, the installer has to drill an appropriate hole in the desired location. Earth and
Neutral wires need to be connected to the appropriate terminal. Line voltage to
terminals L1 and L2 and L3 if unit is three phase.
•Water must be running through the unit before the unit is switched on.
1.4 Control Design
Standard Rheem Thermal heat pumps intended for individual installation are
manufactured with in-built thermostat control and refrigeration pressure safety
switches
•Typically, the thermostat is mounted on the outside panel and displays entering water
temperature, with the sensor being located in a well to the inlet water pipe inside the
unit.

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For systems comprised of multiple heat pump units, the thermostat sensor and well
may be provided as follows depending on client requirement:
Provided loose to allow installation of thermostat controller display in heat pump control
panel (located separately to the heat pumps) with probe installed in the hot water
storage tank.
Provided in the nominated lead-unit (i.e. the control heat pump) with relays fitted to the
slave units to allow control wiring to be run to these units.
The thermostat sensor is the controlling device in the heating system. This determines
whether the heat pump unit should run and is activated in response to the parameters
set for temperature control. That is, the heat pump will run when the entering water
temperature (EWT) or tank temperature is less than the desired set point (normally with
a 2°K split) and stop running when the EWT is a set point. The heat pump will likewise
not run without water flow so there is a very direct link between the heat pump, hot
water recirculating pump and thermostat controller.
The thermostat sensor can be located in the hot water tank with control wiring back to
the water recirculating pump. The operation of the recirculating pump will be controlled
by tank temperature, with water flow to the heat pump activating its operation. This
approach reduces recirculating pump and heat pump run-hours and duty. Contact
manufacturer at time of ordered to discuss wiring requirements.
•Rheem IQTM Intelligent controller is provided as an option. It is an advanced control
system to perform BMS monitoring, error/fault diagnostics, etc. There are two types of
installation of Rheem IQTM, 1) mounted on the external panel of the heat pump, 2) wired
to a separate control panel (optional). Refer to the Owners Guide and Installation
Instructions supplied with the heat pump for information regarding system installation
and product application.

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SECTION 2: COMMISSIONING
The Rheem Thermal heat pump is fully charged with refrigerant. The following checks
should be carried out:
a) Installation and operation instructions should be read prior to commissioning.
b) The unit should have unrestricted supply of fresh air to the coil and exhaust air
removed from closed in areas.
c) The unit should stand on a firm base with fall to take condensate or rain water away
from the compressor compartment and to the unit’s drainage at the plumbing end.
d) Noise should be directed away from living areas.
e) Water connected correctly as indicated.
f) Condensate drain runs to waste.
g) Unit is wired correctly and has full amperage,
h) Unit is not to be started without flow of water.
i) The thermostat, reset button and/or Rheem IQTM controller are set.

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SECTION 3: OPERATION
•The Heat Pump has an internal thermostat located in the return water pipe which maintains
storage tank water temperature at the nominated set point. The normal operating range
for entering water is between 55°C and 57°C.
•As water usage occurs, mains water will enter the storage tank, lowering the overall stored
water temperature, which in turn, activates the Heat Pump. The Heat Pump will run until
the water temperature (at the sensing point) reaches set point.
3.1 Thermostat Model (Carel PJEZ Controller)
To check set point, push and hold the “Set” button for 1 second, current set point will be
displayed, push the “up” or “down” arrows to adjust the value. Press “set” to confirm the
value.
a) Adjusting the differential or Hysteresis “All parameters” screen must be accessed.
b) Press and hold “Set” for approx. 5 seconds, PS will be displayed.
c) Press “Set” then “Arrow up” till the password value “22” is displayed “PS” will be
displayed
d) Press “Arrow up” unit parameter “rd” is displayed.
e) Press “Set” Value will be displayed.
f) Press “Arrow up” or “Down” to set the desired value.
g) Press “Set”
h) Press and hold “Set” for approx. 5 seconds, until temperature is displayed to save
values.
3.2 Rheem IQTM Model (Intelligent Controller)
Refer to “ Rheem IQ Owner’s Guide and Installation Instructions ”Manual and/or the
provided Operations and Maintenance Manual for the respective project.
The manufacturer’s detailed full Instructions on the operation of the controller will be supplied
with the unit and reference may also be made to these instructions.

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3.3 De-Icing
All units include hot gas bypass de-ice. This will occur when to evaporator temperature
reaches -4°C, after a period of 30 minutes unit will go into de-ice mode and will terminate
when the coil temperature reaches 10°C of when 10 minutes have passed.
__________________________________________________________________
SECTION 4: MAINTENANCE
a) In locations where ambient temperature are very low, if unit is not used for a long period,
it is essential to drain all water from unit to prevent ice build-up in water pipe-work.
b) Leak test refrigerant system once every 6 months.
c) Check pressure switches, de-ice control and solenoid valves.
d) Check thermostat or Rheem IQTM controller.
e) Check fan motor support and fan blades.
f) Check condensate drain for blockages.
g) Check water inlet and outlet connections for any leaks.
h) Check current draw with and without load.
i) Check operating voltage at compressor terminal with load, without load and at start-up.
j) A minimum program of servicing every four months is recommended and should be
undertaken by a specialist refrigeration mechanic.
k) The unit casing is designed for outdoor installation and no specific maintenance should
be necessary. If the case is cleaned, ensure that power to the unit is switched off.
l) Clean evaporator coils. If coils are becoming clogged with leaves or debris, remove
any surrounding source of leaf or other litter.

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SECTION 5: TROUBLESHOOTING
5.1 Thermostat Model
5.1.1 Machine Will Not Start
As a safety feature, the Heat Pump has a programmed time delay between provision
of power and unit start, usually a few minutes. Wait for this time delay before making
the following checks:
•Check electrical supply to the unit is ON.
•Check water flow
•Check electrical for loose connections and wiring.
•Check supply fuse.
•Check thermostat is correctly set.
5.1.2 Storage Tank Will Not Heat
•Check that the ejected air temperature is colder than incoming air. If so, this means
the unit is extracting heat from the air and transferring this to water.
•Check that the evaporator and internal pipes sweating. This is evidence of heat
removal from the air, suggesting that the heater is working.
•Check inlet louvres, outlet grill and condenser coil has satisfactory airflow and is not
clogged.
•Check that thermostat is correctly set
•Check that water pump is running
•Check that inlet valves are not closed
•Check ambient air temperature suits design standards
The temperature rise for a heat pump heating may seem slow but the unit is probably
working. Typically, heat pumps have a much lower KW per hour heat output capacity
than gas and will need to operate for more time to deliver the same heat transfer.

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5.1.3 Compressor Will Not Run
Possible Cause
Possible Solution
Overload switch cut-
out (if fitted)
Find cause of overload and reset overload
switch.
System stopped on
safety lockout
A disturbance in water flow may have
triggered the safety lockout. Reset unit by
switching OFF, then back to ON.
If unit does not respond, fit gauges and
check refrigerant charge and HP/LP
operation.
Possible condenser water flow failure.
Check condenser pump water entering
temperature and flow rate.
Motor windings
faulty
Contact manufacturer for replacement.
5.1.4 Compressor Motor Hums But Will Not Start
Possible Cause
Possible Solution
Low voltage
Provide adequate voltage.
Wrong motor connections
Check with name plate or wiring diagram.
Tight or seized compressor
Replace.
No power on one phase
Check circuit breakers, main switch and
wiring for fault.
5.2 Rheem IQTM Model
Refer to “ Rheem IQ Owner’s Guide and Installation Instructions ” Manual and/or the
provided Operations and Maintenance Manual for the respective project.

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SECTION 6: TYPICAL INSTALLATION SCHEMATIC DRAWING
Diagram 1: Typical Schematic for Hot Water Heat Pump
___________________________________________________________________________________
SECTION 7: WARRANTY
Rheem Manufacturing Company Singapore Pte Ltd undertakes to provide twelve (12) months
warranty for Rheem Thermal Heat Pumps only against manufacturing defects during the Defects and
Liabilities Period (DLP) effective upon delivery date –subject to be confirmed by your local Rheem
distributor.
“In keeping with its policy of continuous progress and product development,
Rheem reserves the right to make changes without notice.”
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