[Airman 307]

I have inherited a job that is a Rheem Hp with a Rheem Furnace that is two years old an has had problems every since start up. The problem is that it continuously trips the high pressure switch in both modes but more frequently in the heat mode. It is 12 SEER and the duct work is ok, I have adjusted charge according to the factory chart on the door. The coil is matched correctly. Has anyone had any problems with a Rheem dual fuel system if so what did you do?

 

[BaldLoonie]

What are you using for a dual fuel kit?

Mine consists of a DPDT relay! When 2nd stage calls, it shuts off Y and energizes the gas!

In 11 years, I've had one unexplained trip of the HP switch. I have gas coming on during defrost too.

 

[lra]

Hey Loonie, I've used them too, with success...but... with gas coming in on defrost, didn't you install a tempering kit as well ? The reason I ask is Lennox requires them or they void the warranty, saying it causes excessive indoor coil temps. Just curious. I too have had very few nuisance trips of the pressure switch (Rheem) and they usually occur when the HO forgets the filter in heat mode.

 

[Airman 307]

The installer used the Bill Porter board with no outdoor tstat. In my area most people use the Porter board and it to should control the heat pump the same way. This is the first time that I have seen this happen and I have used this same controls to operate dual fuel systems that I have installed. I have removed all r-22 and blew through the system and replaced the drier as well. What I did not mention earlier was that it may not trip right away but it may run a day or so without tripping and then it may trip everytime the HO resets it. I have set and monitored the unit while it ran in the heat mode and the cooling mode and the head pressure looks fine. I was told by Rheem that it was a charge issue so I removed all of the r-22 and wieght it back in according to the specs. on the unit and I did not allow for the line set so if anything it is underchared. I also replaced the pressure switch at Rheems request but still have the same problem.

 

[BaldLoonie]

I do have a discharge stat under the furnace, I think it opens around 100° but backup is a 2 stage 80 so by the time the inducer fires, ignitor gets on and low fires, the air never gets that hot.

What evap you using 307?

 

[Airman 307]

The matched Rheem evaporator coil with the txv.

 

[protk1]

What's the model number of the heat pump condensor? All Rheem condensors(heatpump and straight cooling) 2-1/2 tons and down require 1/4" liquid line. If this happens to be 3/8" you will have problems. good luck.....