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View Full Version : Heat pump doesn't stay off but for a couple of min.


hvac77
Dec 28, 2010, 06:26 AM
Hello
My heat pump will come on and run for about 15 to 20 min then turn off but it will turn right back on between 2 and 5 min. it doesn't matter if I'm on electric heat or heat pump. I'm on my 3rd tstat and I even relocated my tstat. The house is 2 years old and its my upstairs unit and I would think my upstairs wouldn't run as much as the downstairs but it run 50 times more. Its 1300 sqr feet and is a payne 2 ton 13seer heat pump with 15kw electric heat.

smoothy
Dec 28, 2010, 07:00 AM
When was the last time they checked refridgerant pressures? Low pressures will result in longer run times. On every cycle.

I know its only 2 years old but they can still leak even if they were just installed.

Also... what are the outside tempratures where you are right now... low temps can make them run a very long time as well as the temprature drops and they work harder to keep up.

hvac77
Dec 28, 2010, 02:29 PM
Freon is fine

smoothy
Dec 29, 2010, 06:58 AM
But what are the outside ambient temps where you are right now?

Teens? 20's, 30's, 40's, below zero?

Heat pumps lose efficiency and run longer as the outside temps drop.

hvac77
Dec 29, 2010, 03:33 PM
Temps have been in the 20s at night and low 30s during the day. When it drops down to 30 or below I switch it to e heat. I'm not to concerned about how long it runs. It's the small period it stays off. I have timed it and one afternoon it was 28 outside and I had it on e heat and the thing run for 14 min witch I thought wasn't to bad but when it turned off it was only off for 2min. I know if the unit is oversized you will have short run times and short off times but I'm having average run times and very short off times and like I said it doesn't matter if I use the heat pump or electric heat. The heat pump its self seems to be running fine it will cycle on and off even when the temps outside is in the mid 20s. I also only keep it 68 upstairs.

smoothy
Dec 30, 2010, 09:34 AM
You are getting down to the range these aren't terribly efficient.

I assume the outside coils aren't icing up? You may want to take a good look at that, running long cycles like that can make it ice over... and the ice blocks airflow making it run harder and longer and thus creating this self perpetrating cycle.