It got down to about 14F last night and my heat stayed on all night. We had the thermostat set at 68. The thermostat would read 68 but the heat stayed on like it couldn't get the temp above 68 to cut it off. We live in a two story house with only one unit. If I dropped the thermostat to 65 the heat would shut off. Is this normal or should I have someone come check it out?

What kind of heat do you have... I am guessing it's a heat pump. And those will NOT work as well the colder it gets outside. And with tempratures in the teens. Its struggling as you have seen.

You may want to have it checked out... running constantly is not good for it.

Did you have any problems with it during the hottest part of the summer?

Is the outside unit icing up?

Yes it is a heat pump. It seemed to work fine during the summer as far as I could tell. I just don't know if it has to do with the size of the house and the fact that the downstairs is an open plan which is where the thermostat is located. The fact that if I turn the temp down it will shut off makes me have questions. It just seems as if it can't get it over the hump to cut off at the temp I had set with it being so cold outside. It cut off the night before when it wasn't as cold. I need to monitor it during the day to see if it cuts off then or if it is just running constantly.

THe efficiency of these goes down as the outside temprature goes down... also as they get older they have to work harder to keep up... if its running constantly its going to ice over outside, and obviously its efficiency goes down the tube and then it gets in a vicious circle and will eventually burn itself out...

How old is this unit? I'm going to guess its maybe 10+ years old or close to it.

But first, go outside and look at it and make sure its not covered in a block of ice.

I just bought the house back in March and the house was built in 2007 so it is no where close to 10+ years. I had read on other sites that in extremely cold weather that it will run constantly because it isn't meant to handle that cold of weather. Before I left to go to work this morning I checked it and there was no ice on it. I rented a house before and had it ice over there so I knew to look for this. As I said before if I adjusted the temperature down it would cut off.

Ok... its good you knew what I was talking about... Its possible it's a little undersized for the house and its right at its limit... assuming you haven't had trouble in years past when it got this cold. That's question #2. Has it worked well previously in these tempratures? If it has... then its possible the refridgerant in it is on the low side. Just like on the hottest summer days.. it needs to be at the correct pressures to work well on the lower limits of tempratures as well.

That's going to require an HVAC guy to check... its not something the average person can do.

I am assuming you've changed your air filters and they aren't clogged up.

As I said before I just bought it in March, so I haven't experienced temperatures like this since I moved in, so I don't know how it performed previously. From what I have read online a lot of people say that it is common for a heat pump to run constantly when below 30.

Ok... I misunderstood then, you did say that (on a reread)... I had thought I read you had it longer. My bad.

If that's the case... you have no baseline to comare to, and it will run a LOT longer when its this cold out (like below freezing). But it should reverse cycle occaisionally to melt any ice buildup. Keep an eye on ice buildup which would be an indication of a problem.