4 ms·

It was down to -8F (not including wind chill) a couple days ago here. I have a small, old house but I'm considering replacing the old system I have now with a h

by pitaj 4y ago

It was down to -8F (not including wind chill) a couple days ago here. I have a small, old house but I'm considering replacing the old system I have now with a heat pump. My concern is two-fold: - my house is not well air sealed - my house is not well insulated So I worry that I'll need an extremely oversized heat pump in order to have enough capacacity for the coldest days. I suppose having a backup heating source would prevent needing such a large unit. Plus it would provide some amount of redundancy of the heat pump were to fail in the winter. The question then is, should I use electric backup heat, or stick with my existing gas connection? Electric is simpler and there's no exhaust fumes or CO risk to worry about, but gas is still cheaper here I think.

coryrc 4y ago
The best ROI is to insulate and air seal.
- hn_go_brrrrr 4y ago
  And if you can only do one, air sealing is almost always preferable.
jebarker 4y ago
We live in the Colorado Front Range in a 50 year old house that isn't particularly well insulated. We have a Mitsubishi high-efficiency air source heat pump distributing air through our existing duct work. We have electric backup inside the air handler. Last week it got down to -15F overnight. The heat pump ran throughout and there was only really activity from the electric backup during the occasional defrost cycle. We keep our house pretty warm too as we have a baby. In winter the heat pump seems to have no issues meeting our heating needs albeit at quite a bit higher overall utility cost compared to our old gas furnace. In summer the heat pump is much more efficient than our old AC unit and our solar panels cover >100% of our usage from ~April-Oct. Prior to installing the heat pump we did as much insulating as we could (mostly attic) and I think that was important for enabling the heat pump to keep up in the cold. The nature of the heating is lower level and continuous compared to the occasional blasting from a gas furnace, so you do want to prevent rapid leakage of heat from the house.
sokoloff 4y ago
My 2 cents: Find your local "design heating temperature" and then determine your tolerance for the house falling a few degrees below the setpoint during the 1% of hours that the outside temperature will be below that. Most people would be fine if their house fell to 67°F or 68°F for a few hours, especially since some of those hours are bound to be at night (where other people are setting their stats back to those levels anyway and you might well be asleep and never notice). If you have no other gas appliances and generally reliable electric supply, I'd be inclined towards going with electric backup. That avoids the $10-15/month gas meter charge, which pays for a fair amount of the more costly electric heat. If you have other gas appliances and cheap [at least for now] natural gas supply, going with a natural gas backup allows you to use the cheaper source of heat for both backup and/or in case electricity rates go up substantially versus gas. CO risk is minimal and you should have a line-powered CO meter in the mechanical room and some CO meter on each level of the house anyway.
- Scoundreller 4y ago
  > have a line-powered CO meter Thank you for stating this. If your furnace requires electricity to run, you don’t need a battery-powered or battery backup CO meter. Unless you have a wood stove or light fires indoors when it gets chilly. Otherwise you’re just wasting batteries.
Scoundreller 4y ago
What are your no-use natural gas costs like? Might make a wood stove, oil, wood pellets or maybe even propane cheaper. And then you’re not depending on two grids for standby/supplemental heat.
pinkorchid 4y ago
It may be worth insulating it first. It cost me just about $1500 to go from effectively no attic insulation to R60 for a thousand sq ft, and besides making a massive difference in comfort it reduced energy usage by about 50%.
r0m4n0 4y ago
I’m in a very similar predicament but the temperature where I’m at only go down to the 30s-40s mostly during the winter. I get some rebates where I’m at to replace a furnace so that brings replacement costs to be about equal between furnace and heat pump. I don’t have solar, kw per hour costs are around 13 cents. My AC is non op needing to be replaced (it regularly gets into the 100s for months on end) and my furnace is functioning at 25 years old and no problems, although when it turns on it sounds like a small bomb exploding in my ducts. I have 50% of my house with extremely drafty single pane windows, the other 50% have been replaced. House was made in the 1930s out of brick and appears to be well insulated otherwise though. I am afraid that my overall utility expenses will go up drastically with a heat pump though. Can a heat pump even keep up with a house that loses heat like crazy out of the windows? I seem to get contradicting information from the salespeople, the internet, etc. if anyone has any anecdotal info it would be greatly appreciated
- Qwertious 4y ago
  If your main heat problem is the single-pane windows, perhaps you could use the bubble-wrap trick? https://www.builditsolar.com/Projects/Conservation/bubblewrap.htm https://www.builditsolar.com/Projects/Conservation/bubblewra...
cbrozefsky 4y ago
Others have said it, but it bears repeating. Do the air sealing and then insulation ASAP. It increases comfort and the ROI is way higher than moving to a heat pump. I started with my old Vermont home with minimal insulation, single pane metal frame windows that would ice up, and drafts everywhere. After our first winter, we had the local efficiency program recommend a contractor who came out and measured air exchange and identified the order of work. New windows, sealing attic, re-insulating attic. We got a considerable tax credit for the work, and the comfort improvement was astounding. Just this last summer we made the jump to mini-split heat pumps. They are working well, but I doubt that would be the case without the air sealing. We keep them set at their lowest, 61F, and supplement with a wood stove in the living room, maybe burning 2 cords a year. As an aside, this is our first winter, and our bill for December was 300 dollars, at $0.18/kWh. That's about 25% lower than our estimated oil charges last year for the same period. However, this year oil is ~$4.6, almost 50% higher, so that hedge against fossil fuel price is really paying off. Add in the AC comfort that is largely offset by our solar array, and they are a worthy investment (oh, and 0% financing). None of this would be working without that critical investment in air sealing and insulation.
- pitaj 4y ago
  Thanks for your input. I am actually in the process of air sealing and reinsulating my attic. I will have to reevaluate after that is done.

by pitaj 4y ago

coryrc 4y ago

The best ROI is to insulate and air seal.

hn_go_brrrrr 4y ago
And if you can only do one, air sealing is almost always preferable.

jebarker 4y ago

We live in the Colorado Front Range in a 50 year old house that isn't particularly well insulated. We have a Mitsubishi high-efficiency air source heat pump distributing air through our existing duct work. We have electric backup inside the air handler. Last week it got down to -15F overnight. The heat pump ran throughout and there was only really activity from the electric backup during the occasional defrost cycle. We keep our house pretty warm too as we have a baby. In winter the heat pump seems to have no issues meeting our heating needs albeit at quite a bit higher overall utility cost compared to our old gas furnace. In summer the heat pump is much more efficient than our old AC unit and our solar panels cover >100% of our usage from ~April-Oct. Prior to installing the heat pump we did as much insulating as we could (mostly attic) and I think that was important for enabling the heat pump to keep up in the cold. The nature of the heating is lower level and continuous compared to the occasional blasting from a gas furnace, so you do want to prevent rapid leakage of heat from the house.

sokoloff 4y ago

My 2 cents: Find your local "design heating temperature" and then determine your tolerance for the house falling a few degrees below the setpoint during the 1% of hours that the outside temperature will be below that. Most people would be fine if their house fell to 67°F or 68°F for a few hours, especially since some of those hours are bound to be at night (where other people are setting their stats back to those levels anyway and you might well be asleep and never notice). If you have no other gas appliances and generally reliable electric supply, I'd be inclined towards going with electric backup. That avoids the $10-15/month gas meter charge, which pays for a fair amount of the more costly electric heat. If you have other gas appliances and cheap [at least for now] natural gas supply, going with a natural gas backup allows you to use the cheaper source of heat for both backup and/or in case electricity rates go up substantially versus gas. CO risk is minimal and you should have a line-powered CO meter in the mechanical room and some CO meter on each level of the house anyway.

Scoundreller 4y ago
> have a line-powered CO meter Thank you for stating this. If your furnace requires electricity to run, you don’t need a battery-powered or battery backup CO meter. Unless you have a wood stove or light fires indoors when it gets chilly. Otherwise you’re just wasting batteries.

Scoundreller 4y ago

What are your no-use natural gas costs like? Might make a wood stove, oil, wood pellets or maybe even propane cheaper. And then you’re not depending on two grids for standby/supplemental heat.

pinkorchid 4y ago

It may be worth insulating it first. It cost me just about $1500 to go from effectively no attic insulation to R60 for a thousand sq ft, and besides making a massive difference in comfort it reduced energy usage by about 50%.

r0m4n0 4y ago

I’m in a very similar predicament but the temperature where I’m at only go down to the 30s-40s mostly during the winter. I get some rebates where I’m at to replace a furnace so that brings replacement costs to be about equal between furnace and heat pump. I don’t have solar, kw per hour costs are around 13 cents. My AC is non op needing to be replaced (it regularly gets into the 100s for months on end) and my furnace is functioning at 25 years old and no problems, although when it turns on it sounds like a small bomb exploding in my ducts. I have 50% of my house with extremely drafty single pane windows, the other 50% have been replaced. House was made in the 1930s out of brick and appears to be well insulated otherwise though. I am afraid that my overall utility expenses will go up drastically with a heat pump though. Can a heat pump even keep up with a house that loses heat like crazy out of the windows? I seem to get contradicting information from the salespeople, the internet, etc. if anyone has any anecdotal info it would be greatly appreciated

Qwertious 4y ago
If your main heat problem is the single-pane windows, perhaps you could use the bubble-wrap trick? https://www.builditsolar.com/Projects/Conservation/bubblewrap.htm https://www.builditsolar.com/Projects/Conservation/bubblewra...

cbrozefsky 4y ago

Others have said it, but it bears repeating. Do the air sealing and then insulation ASAP. It increases comfort and the ROI is way higher than moving to a heat pump. I started with my old Vermont home with minimal insulation, single pane metal frame windows that would ice up, and drafts everywhere. After our first winter, we had the local efficiency program recommend a contractor who came out and measured air exchange and identified the order of work. New windows, sealing attic, re-insulating attic. We got a considerable tax credit for the work, and the comfort improvement was astounding. Just this last summer we made the jump to mini-split heat pumps. They are working well, but I doubt that would be the case without the air sealing. We keep them set at their lowest, 61F, and supplement with a wood stove in the living room, maybe burning 2 cords a year. As an aside, this is our first winter, and our bill for December was 300 dollars, at $0.18/kWh. That's about 25% lower than our estimated oil charges last year for the same period. However, this year oil is ~$4.6, almost 50% higher, so that hedge against fossil fuel price is really paying off. Add in the AC comfort that is largely offset by our solar array, and they are a worthy investment (oh, and 0% financing). None of this would be working without that critical investment in air sealing and insulation.

pitaj 4y ago
Thanks for your input. I am actually in the process of air sealing and reinsulating my attic. I will have to reevaluate after that is done.