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GEAF 04-02-2010 11:24 AM

Lennox xp15 heat pump, power outage blip
I have a Lennox xp15 heat pump and honewell thermostat. We had a 15 second power outage/blip this morning while the heat pump was running.
Outside temperature is 41 degrees, inside currently 66 degrees, set to rise to 70 degrees.

About 30 minutes after the power blip, I realized I didn't feel any warmer in the house, so I put my bare foot over the register and it is blowing cool air(no warmth at all). It is blowing relatively hard, and the heat pump is on.

I went to the garage and reset the breaker to the HP and furnace. I had to "wait" at the thermostat for about 10 minutes before the HP heat came on, but now 30 minutes after being on, it is still cool air blowing. Usually at 41 degrees outside, I feel some warm air coming from the register.

Any suggestions? HP is only 2 years old.

new info edit 9:40am: now I'm feeling warm air coming from the register. So for some reason, it has taking an hour and 20 minutes for the HP to push out warm air.

oberkc 04-02-2010 12:04 PM

A couple of things come to mind, but I don't think they fully explain what is going on in your house....

- I know that power outages and thermostat resets have a delay before the equipment comes on. I understand that it is not a good idea to turn on a heat pump immediately after it has been running, so this is a safety feature.

- Sometimes, when the difference between set temperature and room temperature is too great, the back-up heat supply kicks in. I wonder if that was affecting your heat pump?

GEAF 04-02-2010 12:23 PM

Thank you oberkc. The HP was running at full strength at the time of the 15 second power outage. I didn't think to check the thermostat right after the power blip, until about 30 minutes later, when I realized I wasn't feeling any warmer and checked the register. I assume the quick power outage caused the HP to suddenly shut off and turn back on again, which can't be any good for it. The HP and thermostat correctly did the safety delay, when I reset the breakers though, but the heat still did not come out of the register, even though the air was blowing out vigorously, like the HP was on.

I don't believe it was my back up propane furnace, because then I would have felt warm air coming out of the register, and I actually have that setting turned off in my thermostat programming.

The air coming out the register now is actually much warmer than my last edit post, so it seems to be working fine now, so that power blip while the HP was on must have been bad for it. Heavy winds are forecast in about 2 hours here in the Seattle area, so I'm getting my house up to 73 degrees temperature with a fireplace insert and HP combined right now, so that the HP could shut off before another outage hits. Of course that means my fireplace fan will shut off too, but then I'll have to get the generator out....I live in the country.

yuri 04-02-2010 01:07 PM

That is a quite sophisticated unit. If you have frequent power bumps etc you may want to have a communications wire run from the L terminal of the system monitor in the outdoor unit to a Lennox SignatureStat thermostat that accepts the communications. It can then give you error codes at the tstat. My friend Marty probably knows more about them. Talk to your installer about it.

Marty S. 04-02-2010 05:10 PM

If it happens again feel the large freon line , it should be very warm. Power drops or spikes can ruine capacitors so maybe the fan ran but not the compressor. Compressor could have also overheated and it took that long for it to cool down, the fan would still run though giving the impression the HP was working. Built in time delay is only 5 minutes. Check the capacitor , it should read within 6% of the given range. If it's bad write down the complete model and serial number and get one from the installer. The part is under warranty.

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