you need to bring this to the pro section, you can get real answers there
we are not allowed to discuss this sort of thing in this forum!
.
We are a commercial contractor who ran into a siuation that maybe the residential guys can help me on. We called Trane residential factory and they didn't have a diffinative answer for this:
we have a 90% 100,000 BTU airhandler with Natural gas backup and 5 ton heatpump outside. The unit came with a TAYPLUS heatpump relay kit for the fossil fuel protection.
There is a total of 5 unit sets that serve a light commercial office building.
Here is the issue. These units do not come with a factory loss of charge switch. Another company advised the client to put these on to save compressor damage, as Trane uses the thermal overloads as there safety on these units. They add a manual resettable low pressure switch set at 5lbs and installed it on the common suction line of the compressor. Back in thy summer, we had a no cooling call and I went out and the unit was tripped. I put my gauges on it and re-set the switch and the unit took off with all pressures reading ok. The owner's rep stated that every week or so they had to go out and push the button to reset the unit but progressively got worse. None of the other 4 units were tripping at the time so I replaced the low pressure swith with a true 7psi loss of charge cube switch, automatic re-set. The unit has ran fine since. I went back last week to do the heating season checkouts and two more units were tripped. Again, I re-set them and they started and all refrigeration readings are fine. Mechanically the indoor and outdoor units appear to be running fine. I went back yesterday and these same two units were tripped again and in aux heat.
Not knowing how these units are sequenced, when there is a call for the heat pump the unit starts in cooling mode, the compressor starts the condensor fans on a delay then (assuming) as the head pressure builds up the fan kicks on then I hear the reversing valve switch over into heating mode. I had assumed earlier that the reversing valve started in heating and never energized until a call for cooling. Kind of like a hot water heating valve that failsafe's into heating mode with no power.
I am going to replace the manual reset switches but I kind of want to know what would cause that suction pressure to drop that low and recover or am I masking some other problem???
If you need more info, post and I will reply.
Thanks
you need to bring this to the pro section, you can get real answers there
we are not allowed to discuss this sort of thing in this forum!
.