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.
