Warmth Pump Reversing Valves and Their Management Designation

O/B TERMINALS

As Gary talked about in a current podcast, reversing valves are utilized in warmth pumps to direct the circulation of refrigerant relying on the demand for heating or cooling. Additionally talked about was the truth that reversing valves have a default place when they don’t seem to be energized. Most producers at this level default to warmth (O terminal is energized for cooling), although there are some that nonetheless default to cooling (B terminal is energized for heating). Under is a listing of producers that use B as a result of it’s much less widespread:

• Rheem
• Ruud
• Weathermaker
• Ameristar
• Bosch air supply (WSHP makes use of O)

One other consideration with warmth pumps is gentle industrial methods. Many producers will nonetheless use conventional warmth pump management wiring for his or her methods, however a handful truly use standard wiring, very like you’d see with a fuel furnace with AC. Essentially the most notable examples that I’ve encountered are Service and York. These methods, no matter cooling phases, use W1 to energise all compressors for heating and W2 to energise auxiliary warmth. It’s because on a name for Y1, the management sign goes by way of the economizer management first (in a RTU software) earlier than probably energizing the stage one compressor contactor.

W1 then is used to convey on all compressors for heating for a pair causes: it bypasses this economizer management, guaranteeing no pointless exterior air enters the airstream, it brings on all of the compressors as a result of we aren’t involved about latent warmth removing, and it permits the logic board to find out the suitable reversing valve place. With Service particularly, these logic boards are utilized in tandem with both a defrost board of their warmth pumps or an ignition management board for his or her fuel furnace RTUs.

I WOULD ALSO LIKE TO ADD A NOTE THIS

Again within the day, I’ve work on packaged water cooled warmth pumps in ceiling areas the place they used mercury thermostats to regulate them.  These warmth pumps failed in heating, so a name for W1 would run the warmth pump in heating mode.  To run within the cooling mode, they took an fascinating method.  A name for Y1 would energize the reversing valve and a name for Y2 would pull within the contactor for the compressor.  The constructing had many warmth pumps by way of out many flooring that have been wired this manner.  Gary McCreadie

RTFM

As with every system, crucial factor that anybody can do is to RTFM: learn the incredible guide. This ensures that the system you’re engaged on is wired and arrange correctly on the thermostat.