PrecisionTemp TwinTemp Junior User manual

TwinTemp Installation Manual
Please read these instructions thoroughly before starting your installation
Note: These instructions apply to both models. The TwinTemp-2 is a dual zone heating unit whereas the Junior is a
single zone. Both also provide continuous hot water. Installation is identical except for the additional zone.
The TwinTemp is designed to be installed in a ventilated compartment of the vehicle such as a lower luggage
compartment
or “basement” and vented through the bottom of that compartment to the outside. The heater must not be mounted
in the living area of the vehicle or in a way that receives its combustion air from the living area or flues into the
living area of the vehicle. Doing so will void the warranty and cause the heater to malfunction and could cause
damage, injury or death.
Please read these instructions before making any modification to the construction of your RV.
Installation Overview
The installation of the TwinTemp is done in three steps:
•Installation of main heating unit and exhaust system
•Installation of blower heating units and thermostats
•Routing wiring and high temperature tubing from main heating unit to blowers
Installation of main heating unit and expansion tank
When selecting an installation location, please note the following installation requirements:
•Surface should be able to support at least 100 pounds
•The front panel of the heater should be accessible for inspections or servicing
•The vent must be able to be installed through the floor without interference with frame members or
other equipment.
•The compartment where the heater is installed must not be air tight from the outside. There should
be at least 12 square inches of fresh air available from the outside, NOT FROM THE LIVING
AREA OF THE VEHICLE OR TINY HOUSE.
Caution: the combustion air cannot be supplied from any compartment which may contain
combustible gases (i.e. battery gases, gasoline fumes, propane fumes, etc.)
•Water, gas and electric line should be able to run to the installation.
•Installation must be done to allow at least 10” access to the front and at least 8” access above the
•unit. There must be access to all plumbing connections on the right side of the heater if they are not
•made prior to securing the installation into place.
•There should be at least 1” clearance in the back and at least 8” of top clearance is recommended to
•facilitate startup.
It is recommended to install the heater as close to the gas supply as practical to minimize the length
of the gas line.

Note the locations of the flue cut-out and mounting holes. Be sure they will not interfere with any framing
members, wiring or equipment under the coach. Be sure to observe proper clearances around the unit. Drill
the four 3/8
th
” mounting holes. Next cut the 2.25 minimum hole for the flue and the 4: minimum hole for the
combustion air. Be sure they are located where they cannot be covered or blocked.
NOTE: If the TwinTemp cannot be mounted with sufficient access to the connection side of the unit to make
connections after installation, the connections must be made prior to mounting the unit. See sections regarding
Plumbing Hook-ups, Wiring Hook-ups and Gas Line Hook-up.
Use the ¼ 20 bolts supplied to attach the hold down strips onto the bottom front and rear of the TwinTemp. The
hold down strips are used to secure the TwinTemp to a floor using wood screws or nuts, bolts and washers
depending on type of surface. If the installation is located in a position which allows access to all hookups after
installation, the TwinTemp can now be installed and secured. Lift the TwinTemp into position taking care not to
damage the flue transition pipe, protruding from the bottom. Align the flue transition pipe with the flue cutout and
hold down strips. Drop the unit into place and secure . Following the instructions on the package, install the
expansion tank in the same compartment. Attach and clamp the tube to the bottom barb on the expansion tank and
attach the other end to the barb fitting under the radiator cap.
Exhaust Pipe Installation
The exhaust pipe assembly is supplied in two parts. They are a 2” X 17” aluminized steel elbow and a 2” X 4.5”
aluminized steel pipe. After the TwinTemp unit is secured into place the exhaust is installed as follows:
•Fit the 17” long elbow pipe into the 2 X 4.5” transition pipe” and push the flare side of the elbow up
•onto the flue tailpiece of the TwinTemp.
•Locate the pipe out from under the coach while positioning it so that it point about 30˚ to the rear of
•the coach.
•Allowing for about 2” to protrude from under the coach, mark the length, remove and cut to size.
•Screw the cut pipe to the elbow, re-position and install to the TwinTemp flue tailpiece.
•Screw assembly into place and use a proper exhaust bracket to support the bottom o the coach.
NOTE: The above procedure is a typical exhaust installation. If the coach floor is more than 1” inch thick or the
tail pipe needs to be longer than 17”, contact PrecisionTemp for additional components and information.

Interior Heat Exchanger (Blower) and Room Thermostat Mounting Locations
Up to four blowers per zone, or a total of eight blowers, can be installed in the TwinTemp-2 system. Up to six
blowers can be installed in the TwinTemp Junior system. In a two zone system, the living and kitchen areas are
general put on one zone and the bedroom and bath area on the other zone. Each zone is controlled by its own room
thermostat. The mounting locations for the thermostats should be selected carefully to ensure even heat
distribution throughout each heating zone. Do not mount the thermostat where it can be affected by drafts, dead
spots behind doors, radiant heat from the sun, appliances or unheated areas such as an outside wall behind
thermostat.
Locate the heat exchangers so that even heat distribution will be felt throughout the interior. For slideouts, it is
recommended to place blower(s) on the opposite side of the coach, pointing towards the slideout. Sufficient return
air must be supplied to each interior blower. (See Illustration 2) Mounting blowers without sufficient ventilation
will severely reduce their overall heating performance. In order to provide sufficient ventilation, the return air
registers must be the same size or larger that the outlet registers. Return air must be supplied from the interior
heating zones. Allow for access to all heat exchangers for tubing hook-up and for potential servicing and cleaning.
To mount the blowers once all permanent mounting
locations have been selected, cut out the opening for
each outlet air and return air register and screw down
each heat exchanger permanently into place.
•Cut an opening for each heat exchanger and
cold air return.
•Mount each heat exchanger permanently into
place.
•Install the hot air outlet and cold air returns.
•There must be complete access to the heat
exchangers until the plumbing and electrical
hook-ups have been made.
Illustration 2
Mounting locations for the water, gray and
black tank heat exchanger
A tank blower should be strategically placed in the domestic water plumbing area to prevent freezing of the
plumbing lines and storage tanks. Position the tank heater in the storage tank/ plumbing bay area so even heat
distribution will be achieved. NOTE: The optional heat exchanger with the built-in thermostat should be used.
This blower should be installed in zone one loop. For best heating results, place the exchanger as close to the floor
of the plumbing bay as possible (heat will naturally rise). Sufficient ventilation (cold air return) must be supplied.
Return air should be supplied from the same compartment.

Connecting Gas Supply
The gas line should be of approved
type and size with a 3/8” female flare
nut. If the gas line is very long or has
numerous bends, it should not be less
than 3/8” ID or performance of the
TwinTemp will suffer. The maximum
inlet gas pressure must not exceed 13
water column inches and no less than
10 WCI. This gas line should be one
uninterrupted line from the LPG tank
regulator with no tees or connections
within the coach. Some standards
may require a manual gas shut of
valve in the gas line external to the
TwinTemp. The TwinTemp must be
isolated from the gas supply system
during any pressure testing of that
system at test pressures equal to it or
in excess of ½ PSIG. The flare nut on
the gas line should be hand connected to the flare Illustration 3
should be hand connected to the flare
connection on the TwinTemp to assure it’s not cross-threaded.
No pipe dope should be used on this flare connection. Tighten with a wrench. This connection should be tested
for leaks prior to start up, using soapy water or liquid leak test solution. Do not use a flame to test for leaks.
Wiring
The TwinTemp is pre-wired internally with a 12
pin connector for all of the 12 VDC hookups
(see Illustration 4). A mating pig tail is supplied
to make all field connections. Observe the
illustration color codes, the wring sizes and
procedure described below. The 12 VDC
TwinTemp power switch should remain OFF
during installation.
Note: Illustration 4 shows the TwinTemp-2
connector. The Zone 2 terminals are not used for
the Junior. All connections should be secure
and not in a wet location.
Illustration 4

12 Volt DC Power Hook-up
This is the main power harness that should be switched at a panel inside the coach on a 15 amp circuit. The wire
must not be smaller than 12 gauge. Red is positive (+) and black (or green) is negative (-). Under-sizing this wire
will result in the TwinTemp malfunctioning.
Zone 1 Thermostat and Blower Harness
Run 18 gauge wires to the Zone 1 room thermostat, observing the wire colors in the illustration to assure
continuity of operation. 18 gauge minimum wires should be wired parallel to each blower in the Zone 1 circuit.
The black wire is negative (-) and should be connected to the black wire on the blowers and the colored wire is
positive and connected to the red wire on the blowers. Again, observe all wire colors in the illustration.
Zone 2 Thermostat and Blower Harness (TwinTemp-2 only)
As in Zone 1, run 18 gauge wires, observing wiring colors of the illustration and be sure both thermostats are
turned to their lowest setting during installation. Observe polarity of thermostat.
110 Volt AC Electric Elements Cords (Single Element/ Circuit on Junior)
These wires are provided with a 15 amp “SJT” plug that is to be plugged into a switched outlet “handy box”.
These should be dedicated 15 amp circuits that are switched at a panel inside the coach. Keep Power off to this
circuit at this time. If this circuit in energized prior to filling the system with antifreeze, severe damage will occur.
Illustration 5

Plumbing
The plumbing installation involves two systems:
•Zone heating system blowers
•Domestic hot water system
It is recommended to use 5/8” OD PEX high temperature tubing and push fitting, Otherwise, an adapter will
be required to make the connections.
Zone Heating System Blowers Piping
The Twintemp 2 heating system consists of two separately controlled zones with up to four blowers in each zone.
The Twintemp Junior has one heating zone and can service up to six blowers.
The TwinTemp has a supply line and a return line connection for each zone. It is suggested to use the red PEX
line for Zone 1 and the blue PEX pipe for Zone 2 to avoid confusion during hookups.
Prior to running the PEX pipe, it is advisable to connect all PEX push fittings to the blowers and the TwinTemp
water/ anti-freeze connections. Use a high quality Teflon tape on these fittings when making the connections. Take
care not to let the Teflon tape get into the system.
The Zone 1 loop should be used for the longest loop with the most blowers in it, generally the living room/ kitchen
loop. Install all PEX pipe and mark with labels at both ends. Arrows should indicate the supply and return lines.
Minimize extreme bends and any extreme rises in height should be avoided. Where possible use “flow bender”
clamp rather than elbow fittings the reduce restriction. PrecisionTemp can supply the flow benders. Be sure the
secure all PEX where necessary and apply protective shielding in areas where chafing may occur.
As shown in Illustration 8, the 3 way by-pass valve and tee fitting has been installed between the supply and return
fittings in Zone 1. This is to prevent the heated anti-freeze from circulating to the blower units in warm weather,
when space heat is not required.
Connect to the Zone 1 supply line from the TwinTemp to the by-pass tee and then continue it to the closest blower
unit. Be sure the end of the PEX is cut perfectly square and push it into the push fitting until it bottoms out. Then
pull gently on the PEX tube to assure it is tight into the fitting to avoid leaks. Continue this process until all
blowers in the Zone 1 loop have been plumbed (up to four blowers). From the top outlet fitting of the final blower
in the Zone 1 loop, return the red PEX line to the 3 way by-pass valve and continue back to the TwinTemp “Zone 1
in” (return) fitting of the TwinTemp. As above, all PEX tubing should be tightly secured to all of the push fitting
on the blowers and TwinTemp. (The junior can accommodate up to six blowers on its single zone.)
Repeat the above process for the Zone 2 loop using blue PEX piping.
Domestic Hot Water Piping
Although the TwinTemp is capable of delivering continuous hot water on demand, the plumbing system for the
domestic hot water is plumbed exactly as it would be with basic recreational vehicle hot water systems. (see
Illustration 6). The pressure cold water supply is connected to the “cold” fitting on the TwinTemp and the hot
water line to the fixtures is connected to the “hot” fitting. As when running the heating system tubing, be sure to
secure the push fitting to the TwinTemp and cut the PEX tubing square and bottom it out into the push fittings.
If the coach is equipped with water pipes other than 5/8” OD PEX tubing, adapters should be used to make the
connections to the ½” NPT connections on the TwinTemp. See Illustration 7 “Winterizing” drawing to incorporate
the winterizing valve set into fresh water system this will assure a convenient way to drain the fresh water system
and prevent freezing of the TwinTemp potable water circuit during freezing conditions. Severe damage can occur if
this procedure if not followed.

TwinTemp Start-up / Testing Procedure
Filling system with antifreeze
Power, propane and water should be turned off. Turn Thermostats to highest setting.
•Remove radiator cap from TwinTemp tank.
•Turn Summer/Winter valve to winter position.
•Using a funnel fill tank with appro imately 2.5 gallons of 50/50 propylene glycol/distilled
water mi .
•Turn on 12 volt power switch located on TwinTemp, Do not turn on propane, turn on
both zone one and two thermostat to call for heat.
•As antifreeze level drops top off tank with antifreeze mi until level stops dropping. If there
is difficulty in priming the pump disconnect the zone one pipe connection and cycle the
on/off switch multiple times until fluid starts moving then reconnect zone one pipe.
•After fluid level stops dropping run the TwinTemp an additional 15 minutes to purge all air
from hydronic system plumbing.
•Top off tank, reinstall radiator cap and fill e pansion tank to the cold line.
•Turn off power and turn on propane, check propane connections for leaks.
•Turn on 12volt power. Cycle power on/off every 15-20 seconds to purge air from propane
lines.
•NOTE: If pump sounds as if it is cavitating or you hear a knocking or banging noise turn off
propane and allow pump to run an additional 10-15 minutes to purge air from hydronic
system plumbing. Ne er remo e radiator cap when fluid is hot. As unit heats up the anti-
freeze will e pand into the e pansion tank. After all e pansion has taken place, be sure
e pansion tank is filled to full line. When the unit is shut off and cools down the fluid level
in the e pansion tank will lower. When cold, be sure to fill above the “Add” line. If
e pansion tank is ever empty, check the fluid level in the TwinTemp tank and top off if
necessary.
Start-up and Testing Space Heating
•Turn summer / winter valve in winter position.
•Turn on 12volt power
•Observe that the flame is on and remains on. It should take 8-10 minutes to completely
bring the system up to temperature (185 degrees) and burner goes out.
•Turn room thermostats to highest setting and verify all interior heat register blowers come
on and deliver heat. NOTE: Tank fluid temperature must reach 160 degrees before heat
register blowers will come on
•Turn off thermostats and let system run until burner goes off.

Testing Water Heating System
•Put Summer/Winter valve in summer position.
•Turn on power and allow the system to heat up until burner shuts off.
•Open hot water tap and purge all air from hot water line
•Water should be hot (appro imately 120 degrees) within 30 seconds. Allow hot water to
run for 3-5 minutes and verify burner activates to maintain water temperature.
•Turn off water tap and check for water leaks and correct if needed.
Testing Electric Heating Element water heating
•Be sure the system is filled with antifreeze then turn on 110vAC electric element(s)
•From a cold start it could take up to 20 minutes to completely heat the tank.
•Check hot water operation.
•Note: The 115vAC element is used for minimal hot water needs since it has only 20% the
capacity as the propane operation.
Sequence of Operation
Before using the TwinTemp for the first time, it is important to know the proper sequence of operation to ensure
understand of its operation. Sequence of Operation is as follows:
•The 12 VDC power switch on the TwinTemp is turned on.
•Tank thermostat inside turns on Pump 1 and the burner ignites automatically.
•Anti-freeze circulates from burner to Zone 1 blowers and back to the tank as it heats.
•Burner remains in high fire until set temperature is approached and gas is modulated to a low burn until set
temperature is attained.
•Burner and pump shut down when set temperature is attained. This takes about 5-15 minutes depending on
ambient temperature.
•TwinTemp is now in standby mode until a room thermostat is activated or hot water is called for.
If Room Heat is Needed
Set Zone 1 or Zone 2 (TwinTemp only) thermostat to desired temperature. The corresponding pump and blowers
will activate and within seconds heat is delivered from blowers. When tank temperature is below set point the
burner will re-light and maintain proper tank temperature. When room reaches set temperature, the pump and
blowers for that zone will go off. If tank temperature is below set temperature, pump 1 and the burner will stay on
until tank reaches set temperature.
NOTE: the heat register blowers will not activate if the antifreeze tank temperature is below 160˚ F. This assures
that the how water function takes priority under heavy usage conditions. Blowers will resume operation when tank
temperature goes over 160˚ F.

If Hot Water is Needed
Once the tank reaches set temperature (5-15 minutes after system is turned on), continuous hot water is delivered
when any tap is opened. Delivery temperature is determined by the setting of tempering valve (Adjustable 100˚ -
145˚ F).
Warning: this valve is factory set at approximately 120˚ F, adjusting temperature any higher could result in
severe injury due to scalding.
Tank thermostat turns pump 1 and burner on automatically when tank temperature starts to drop. Anti-freeze
circulates from burner and back to tank as it heats. Burner remains in high fire and gas modulates burner to low
burn until set temperature is attained. When set temperature is reached, burner and pump shut down and system
returns to stand-by mode.
Operating Instructions
To Operate the TwinTemp:
Hot Water
•Pressurize the water system by turning on pump or city water pressure.
•Purge all air from system by turning on taps until there is a steady stream of water. Turn off taps. Check for
leaks.
•Turn on the propane supply at tank and the manual gas valve if installed in system.
•Turn on the 12 VDC power supply and switch on TwinTemp. If this is the first time the system has been
used, power may have to cycle several times in 5-10 second intervals until air is purged from the gas line.
Using sight hole, verify that burner is on.
•It will take about 5-15 minutes for the system to heat up.
Turn on any hot water tap. Continuous hot water will be delivered in the time it takes to get from the
TwinTemp to the tap.
Space Heating
•Follow procedure 3-5 of “Hot Water” section above.
•Set the appropriate zone room thermostat to the desired temperature.
•Once the system is up to operating temperature blowers in that zone will provide heat within seconds of
being activated.
•When set temperature is attained, blowers will shut down.
NOTE: the blowers will not activate if the tank temperature is below 160˚ F. This assures that the hot water
function takes priority under heavy usage conditions.
WARNING: Always turn off the 12-volt power supply to the heater during any fueling operations.
Operating the TwinTemp or any other ignition source during fueling could cause a fire or explosion, which
could result in serious injury or death.
NOTE: Should overheating occur or the gas supply fails to shut off, turn off gas valve at the supply tank.
Immediately call a qualified service technician.
Do not use this appliance if any part has been under water. Immediately contact a qualified service
technician to inspect the appliance and replace any part of the control system and any gas control which has
been under water.

NOTE: When using an “on/off” button on a shower head or and outside was down box, always turn off the
hot and cold water valves when finished. Not doing so will result in cold water bleeding into the hot water
system and cold water or alternating warm and cold water will result.
The TwinTemp is designed to give a continuous flow of hot water as long as required and maintain the set
temperature through all flow rates within the capacity of the heater (op to 88˚ F temperature rise per GPM).
110 Volt Heating Element
The TwinTemp-2 is equipped with two 110 VAC electric heating elements and the Twintemp junior has one
element. These provide limited amounts of hot water or space heating, such as washing hands or dishes. The
electric element can be used with or without the propane burner, but for continuous hot water or space heat, the
propane burner must be used. To operate, turn the 110 volt switch(es) on in the coach and be sure the power wire
is plugged into the handy box(es) in the TwinTemp compartment.
For small amounts of hot water only, there is no need to turn the 12 volt power on to the TwinTemp. However, if
space heat is required in very cold weather, the 12 volt switch should be turned on. If there is a higher demand for
heat that the 110 volt element(s) can provide, the propane burner will activate automatically. For best operation,
turn the 110 volt elements on about 30 minutes before turning 12 volt switch on. This allows the tank to come up
to temperature utilizing the electric element before the burner can activate. This will help conserve propane.
Changing Hot Water Temperature Setting
The temperature on you TwinTemp has been factory set to approximately 120˚ F. it is not recommended that you
set the temperature any higher.
WARNING: Changing this setting could result in dangerously hot temperatures that could result in severe
injury.
If it is necessary to change the setting it can be done as follows: Open access door on the front of the heater.
Locate the tempering valve . Back out the screw in the center of the adjustment knob and turn counterclockwise
to increase temperature or clockwise to decrease temperature. The setting range is between 100˚ F to 145˚F.
Summer Operation
When the space heating function of the TwinTemp is not needed, the heated anti-freeze should not be circulated to
the blowers. To prevent this circulation, the Summer/Winter by-pass valve (see figure 8) should be turned to the
Summer position. When heating is again needed, this lever should best turned to the Winter position.

TWINTEMP WATER SYSTEM DRAINING/WINTERIZING INSTRUCTIONS
Note: Even though the heating system of the Twintemp is filled with antifreeze the water
heating exchanger inside the tank is filled with water and must not be allowed to freeze.
Freezing can cause severe damage not covered by the Twintemp warranty. When
traveling in freezing temperatures or in storage or not being used the plumbing system
containing water must be drained.
Turn off water pump or city water pressure. Turn the black hot and cold valve handles
to the opposite position as pictured below. Open all hot and cold water faucets to permit
the water system to drain from both valves. After water has drained close all faucets.
Apply air pressure to the hot winterizing drain valve to force water from the Twintemp
heat exchanger until air is heard from the cold drain valve. Leave valves in this position
until you are ready to refill the system with water. When you’re ready to use the system
again turn the valves to the position shown in the picture below.
Winterizing water valves (Illustration 7)

TwinTemp Hydronic Heating & Water Heating Operating Instructions
For maximum heat and hot water output, it is recommended to use the LPG mode of operation in addition to the
120 volt electric element. Electric element operation should be used for minimal hot water demand such as
washing hands or dishes. It is not necessary to have the water system filled to use the space heating system, but the
heating system must be filled with anti-freeze.
To Start Up System:
•Turn on the propane supply.
•Turn on 12 volt power switch on the right side of the TwinTemp cabinet.
•Turn on 12 volt power switch on coach, if applicable.
•Burner will start-up and system will be up to operating temperature in approximately 10-15 minutes
depending on position of Summer/winter valve.
Summer Operation
Position Summer/Winter valve in Summer position.
When the space heating function for Zone one of the TwinTemp is not needed, the heated anti-freeze should not be
circulated to the blowers. To prevent this circulation, the Summer/Winter by-pass valve should be turned ¼ turn.
When heating is again needed, this valve handle should be turned ¼ quarter turn from the Summer position to the
Winter position. This adjustment should only be needed twice a year for summer/ winter operation.
Illustration 8
Summer Winter
For Space Heating:
Position Summer/Winter valve in WINTER position.
Turn on main coach thermostat for Zone one or two and set to desired temperature.
When the system reaches set temperature the blowers will turn on and heat is delivered.
When room reaches set temperature, the pump and blowers for that zone will go off. If tank temperature is below
set temperature the burner will stay on until tank reaches set temperature.
NOTE: the heat register blowers will not activate if the tank temperature is below 160˚ F. This assures that the hot
water function takes priority under heavy usage conditions. Blowers will resume operation when tank returns to
operating temperature.
For Hot Water
TwinTemp unit and water system pump must be turned on or connect to city water system.
Turn on hot water tap.
Note: During heavy heat and hot water demand, the hot water system takes priority and the heat register
blowers may shut off briefly to maintain hot water supply. Hot water temperature is factory set at
approximately 120 degrees. To change temperature, consult the operating manual.

Once the tank reaches set temperature (5-15 minutes after system is turned on), continuous hot water is delivered
when any tap is opened. Delivery temperature is determined by the setting of tempering valve Warning: this
valve is factory set at about 120˚ F. adjusting temperature any higher could result in severe injury due to
scalding.
Tank thermostat turns pump 1 and burner on automatically when tank temperature starts to drop. Anti-freeze
circulates from burner and back to tank as it heats. Burner remains in high fire and gas modulates burner to low
burn until set temperature is attained. When set temperature is reached, burner and pump shut down and system
returns to stand-by mode.
Winter Mode Hot Water Production
During winter operation if the system has been dormant for more than 20 minutes turn on interior thermostat to
call for heat. When the heat register blowers come on turn off thermostat and turn on hot water tap. Preheating the
system is required in winter mode for hot water production due to 3 gallons of cold fluid in the hydronic loop
suddenly being returned to the TwinTemp tank lowering the fluid (boiler antifreeze) temperature required for hot
water production. Once fluid temperature reaches set temperature the system will make continuous hot water.
To Use With 110 Volt Heating Element
Turn on 110 volt element switch located inside coach.
Let the unit heat up for a minimum of 30-60 minutes.
Note: In the 110 volt mode of operation the electric element supplies the heat until demand exceeds its
capacity at which time gas burner automatically ignites.
The TwinTemp Jr. is equipped with one 110 VAC electric heating element. The element provides limited amounts
of hot water or space heating, such as washing hands or dishes. The electric element can be used with or without
the propane burner, but for continuous hot water or space heat, the propane burner must be used. To operate, turn
the 110 volt switch on in the coach.
For small amounts of hot water only, there is no need to turn the 12 volt power on to the
TwinTemp. However, if space heat is required in very cold weather, the 12 volt switch should be
turned on. If there is a higher demand for heat than the 110 volt element(s) can provide, the
propane burner will activate automatically. For best operation, turn the 110 volt element on
about 30 minutes before turning 12 volt switch on. This allows the tank to come up to
temperature utilizing the electric element before the burner can activate. This will help conserve
propane
Routine Maintenance
All faucet aerators and showerhead screens in the coach should be cleaned regularly. It is recommended that the
TwinTemp be inspected by a qualified service technician at least once a year. Particular attention should be paid to
the following:
•Be sure that the air inlet openings and flue area are clear of any debris or obstructions (leaves, bugs, nests,
spider webs etc.). Be sure nothing is stored against the unit that would block air or access.
•Inspect boiler anti-freeze level in reservoir tank. Top off if necessary with a 50/50 mix of specified boiler
anti-freeze and distilled water.
•Check that heater mounting is still secure to the coach. Tighten if necessary.
•Visually inspect wiring and hoses. Be sure there is no chafing of the insulation.
•Drain boiler antifreeze every 24-36 months for units with stainless steel tanks and install new boiler
antifreeze. (system holds approximately 4-6 gallons of a 50/50 boiler antifreeze/distilled water mix)
•Inspect for evidence of antifreeze leaks at internal and external plumbing connections and correct if
needed. Test radiator cap and inspect the overflow reservoir hose connections.
•Rotate mixing valve temperature adjustment knob several times clockwise and counter clockwise direction
to end stops twice each year.

IMPORTANT
COLD WEATHER PROTECTION INFORMATION
WARNING: Do not disconnect or turn off the electrical
supply to include 12vDC and 120vAC electric element. Do not
turn off the propane supply when temperatures are near or
below freezing. The TwinTemp hot water heating system
will freeze if the electrical power source or propane is
disconnected.
WINTERIZING _____________
1. Turn off the power and gas supply to the TwinTemp.
2. Turn off main water supply.
3. Open all hot water taps. (Bathroom, kitchen, laundry,
etc.)
4. Drain water from plumbing lines.
5. Follow the fresh water winterizing instructions
attached to the TwinTemp winter drain valves on the
plumbing manifold side of the cabinet.

TwinTemp Preventive Maintenance Schedule
1. Clean interior of TwinTemp cabinet including
combustion air intake grill. *
2. Inspect all wiring connectors for corrosion and
tighten or repair if needed. *
3. Performance test heating and hot water functions
and rotate mixing valve temperature adjustment
knob several times clockwise and counter
clockwise direction. *
4. Check for fluid leaks at interior and exterior
plumbing connections, radiator cap and overflow
reservoir. **
5. Check propane connections for leaks. **
6. Check boiler antifreeze level in overflow tank.****
7. Drain and refill boiler antifreeze. ***
(Use a boiler antifreeze made for multiple metals with
our Stainless Steel tank)
* Annual inspection
** Bi-Annual inspection
*** Every 24-36 months
**** Bi-Monthly

3428 Hauck Rd.
Cincinnati, OH 45241
800-934-9690
www.precisiontemp.com
1/2020