Lennox EL18XPV Operation

JustinS

Since my system is fully-communicating with an S40 thermostat, I expected the heat pump to operate for longer periods of time instead of cycling on/off the way my baseboard heat does.

It's currently 35F in Massachusetts where I am.

As you can see in my Sense power meter, the heat pump is turning on, running for about 15 min and then shutting off. It seems to just operate at a relatively constant level



Looking at the performance data for my heat pump, it seems to indicate that once the outside temp reaches 17F, the heat pump MIN/MAX output are the same. This seems like it would no longer have the ability to modulate as a variable capacity unit?

This doesn't seem correct, I checked American Standard and they're not like this. I've checked several different Lennox models and they all seem to be listed like this.

Am I not understanding something? I understand the max capacity reducing with lower temperatures but why does the min capacity increase?



Here's the NEEP information on my heat pump

https://ashp.neep.org/#!/product/50687/7/25000/95/7500/0///0

pecmsg

The compressor can only slow down so much. Depending on the model it can increase to 20 or 40 above 100%. 

You could have a sizing and or refrigerant issue also. 

mattmia2

Maybe it isn't producing useful output at anything other than max at that point or it would move the refrigeration cycle in to some point where slugging or something like hat was possible so as the outdoor temp drops it increases the lowest speed it will modulate down to.

JustinS

pecmsg said:

The compressor can only slow down so much. Depending on the model it can increase to 20 or 40 above 100%. 

You could have a sizing and or refrigerant issue also. 

Hi, thanks for the reply - not sure what you mean by 20 or 40 above 100%? My understanding was that this unit can modulate 35-100% in 1% increments.

pecmsg

Inverters can operate 1O0+%