A solution to defrosting with an Oil furnace

[millertime77]

so when it finishes defrost and switches back to condenser inside the left over heat in heat exchanger could cause a high pressure trip. Am I understanding that correctly?

[millertime77]

I would also like to add that if possible I think the indoor coil should be on the return side of furnace.

[millertime77]

Read back down through the thread and saw where been there said not to put coil in the return, what is the reasoning behind that?

[beenthere]

if the heat exchanger is too hot when it comes out of defrost, it can trip the HPS and lock out the heat pump.

An evap coil in the return will cause condensation in the oil furnaces heat exchanger in the summer, and rot it out from the inside out. You also lose some of your heat pumps heat capacity to heating the chimney.

[millertime77]

if the heat exchanger is too hot when it comes out of defrost, it can trip the HPS and lock out the heat pump.

An evap coil in the return will cause condensation in the oil furnaces heat exchanger in the summer, and rot it out from the inside out. You also lose some of your heat pumps heat capacity to heating the chimney.

Thanks been there. As an inexperienced tech I appreciate the fact that you take the time to answer my questions. I feel blessed to be able to come here and ask questions and get answers from guys who are probably some of the best inn the trade, definitely a fortunate thing for younger technicians.

[mlstark]

Beenthere is not that great, he's just old and seen it all.

Sent from my PC36100 using Tapatalk 2

[beenthere]

if you get to work on any gas/electric RTUs. look at how rusted out the heat exchangers get with the evap coil before the gas heat exchanger. It can be real eye opener as to how quickly a HE can rust out from condensate forming in the HE from the A/C.

[beenthere]

Beenthere is not that great, he's just old and seen it all.

Sent from my PC36100 using Tapatalk 2

And bald. LOL

[pacnw]

Open forum, so do not want to get too detailed.

As Beenthere said, evap in the supply above the oil HX, defrost limit switch, dual fuel stat with OD sensor AND move the original fan/limit switch if normal older style mechanical type.

I have seen this several times this year, customer going on the cheap picking company and they melted the evap pan. Most likely cause, fan/limit switch in original spot and it allowing too high temp before activating( won't get anymore specific than that in this forum).

[VanIsleRefrig]

thanks for the input you guys this site is awesome