Question about heating the house when severely cold outside

[CathyA]

Just curious.........
Is it normal for a furnace (geothermal) to have trouble keeping the heat up in the house, when its below zero out? I'm thinking there's a limit, right?
I have my thermostat set for 66 and it's only reaching 64. I don't want to stress it by turning it up, in case its old and having trouble.

[Gregg]

There are lots of pieces and parts to any heating system, but they all pretty much boil down to one thing... The greater the difference in temperature between outside and inside the harder it will have to work to keep the inside warm. If your system is in good repair turning it up a few degrees when it gets really cold simply means it will cycle on and off a little more often. That will end up costing you a few bucks at the end of the month, but it should not stress your system. If it does its definitely time to get the system serviced because you can bank on the fact that when it does fail it will pick on the coldest day of the year to do it.

[CathyA]

Thanks Gregg.

We have a closed loop geothermal. We've had it preventatively maintained for 18 years now. (every 6 months). But.....the last time we had problems, it had frozen up (in the summer), and the guy who came out said its about at the end of its lifespan. WHAT?? It better not be!

We have a new thermostat because the old one pooped out.........but it actually has less bells and whistles than the last one. The service guy mentioned something about a 2 degree difference. I still don't understand what he meant. So that may be figuring in to why it only says 64, when I have it set at 66. I did go up a degree on it and now my auxillary heat is on. (but VERY expensive to run). I just told DH last night that it was time for its 6 month servicing, but I wasn't going to call them now, 'cause they're probably over-worked with people whose furnaces aren't working at all. I think I jinxed us.

I've closed off a couple rooms and also blocked off our entranceway with a sheet, hoping that will help on all the cold air coming in through the ill-fitting front door. Yeah, we're pretty stylish here. :)
Next week is going to be even colder..........

[jp1]

When was the last time the air filter was changed? If airflow isn't as efficient as ideal then you'll get less heat output. Normally you won't notice it because the system still has extra capacity. But if it's super cold out that little bit of inefficiency could be the difference between a system struggling to keep up and one that can keep your house at the set temperature.

[ToomuchStuff]

Blocking off rooms can also affect airflow. (generally it helps though)
Have you gone around looking for air leaks (those make a big difference)?

[Tanglefoot]

Geothermal systems can be challenged by very cold outside temperatures. They are merely a heat pump and only have so much thermal transfer under ground to work with. Deeper, vertically-installed ground loops are better suited, as winter frost layers can sometimes permeate 6 feet or more into subsurface. If you routinely experience the cold, outside temperatures and the extraction rate of your system isn't sufficing, you might consider a supplementary heat source such as a solid-fuel stove.

[lmerullo]

I don't know much about your system - but dh is in HVAC and I could ask....however, my thought is: what temp is normal for your home? I know if I turn the heat down - as in going away for a weekend or longer - upon return, the time to have the home feel warmer is SEVERAL days. Those areas that don't get regular circulation retain soooo much cool that it comes back into the rooms for a good long while. I know the linen cupboard (exterior wall) will be very cold for almost a week. The same for kitchen cabinets, too. So, my point is, if you've just put the heat on recently, is it possible you need to allow a few days for the structures to be warmed?

[razz]

We have an air to air heat pump and it only works well to -8C (17.6F) degrees and then the auxiliary kicks in. I supplement with wood heating in an airtight stove and fireplace.
My understanding is that a geothermal system is supposed to last a really long time for the cost of the initial installation to make any sense.

[CathyA]

Thanks everyone.
Imerullo........ I think you're right. I'm thinking that maybe it got cold so fast that the house was just really slow to warm up. I did set the temp up one degree later, and the aux heat came on. Now its off, and maintaining the 66 degrees that its set at.

razz....yeah, I was thinking that too. We also had to have all the ductwork put in, so it was VERY expensive. But it has saved us a ton of money, in how efficient it is. And in summer, it cools the house incredibly well and hardly costs anything.

[SteveinMN]

The guy who was just in to tune up our furnace mentioned in passing that, at -17 F, our furnace likely would be on all the time to maintain a set temperature. It's not the world's most anemic furnace and it needs no repairs; it's just the rating that furnace has for producing heat. I can imagine that geothermal, not using a combustible fuel, would find less-cold temperatures just as challenging.

[Gregg]

This next few days is going to tell a lot of us whether our systems are up to speed or not. Bundle up everyone! And don't forget to bake your bread, dry your clothes, wash your dishes, etc. in the evenings so you get that little extra bump of heat when you need it most!

[sweetana3]

And pray for our firefighters and police who are trying to keep us safe in these brutal temperatures. We have opened warming shelters for both humans and animals. Our feral cat group gave away 230 shelters for those cats who cant or wont come in. Animal Care is checking on animals people report as being left outside.

Stores were mad today. Seeing that it should be above freezing by the end of the week, I could not see stocking up.

[RosieTR]

Good luck with the cold! Even simple stuff like rolling up an old towel and shoving it against the door to the outside, or taping blankets to the (especially large, north-facing) windows may help. When it does get warmer, consider having an infrared assessment done to your house to see where the air leaks are unless you already know. Less than $20 in caulk can save a lot.
We are thankfully not approaching anywhere close to the upper Midwest temps but still keeping the house at 63F. Even though this is our normal setup, it still seems colder somehow when the outside temps are cold. Maybe it just looks cold.....