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Comment by BooneJS | Hacker News Reader

I'm in Wisconsin, and we peak in 90's Fahrenheit with humidity in the summer and will have a week in February where we'll never get above 0F. I know geothermal works up here; we had it in a previous house but we paid (in 2012) $9600 just to have the 4 150 ft wells dug. What would air-source heat pumps look like up here? I've seen very few new homes in my area with them.

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Vermont, and perhaps Maine as well, have initiatives to transition housing to high-efficiency heat pumps that are still efficient enough to be better than just resistive heating even in negative F temperatures. Obviously they will not be efficient in something like -40F, but I believe nowadays they break even in -20F, but don't quote me on that exact temperature. And even accepting that you'll get <-20F a few days a year, it is likely still a net-energy win, and I would suspect, suitable for use even without a fixed backup system. I'd imagine if it's good enough for Vermont, it would be good enough for Wisconsin. The state has websites listing suitable models that might be a good starting point for you.

Hmm we just got a new furnace and none of the installers offered high efficiency heat pumps. The ones available started to become inefficient at 20F above 0. It really wouldn’t of been practical to get this. Maybe some day.

Unfortunately too even with the spike in prices gas is still significantly cheaper than electricity even with the efficiency. But I was thinking about solar down the road which is the only reason I considered it.

Sure but most of Maine doesn’t have natural gas service. Outside of Portland, you generally may have some gas service along Rt 1. Otherwise, at best you can get bottled propane, but you have to consume a good amount to get decent pricing. It’s usually tiered. This calculators been around for a long time and gave us a pretty reasonable estimate when we did our system.

It’s also not an either/or thing. My house (southern Maine) has oil forced hot water heat, with an older 84% efficient boiler, and a mini split. We have no natural gas service, and propane isn’t cost effective. We run the split through both shoulder seasons, and we turn the split system off when it’s consistently below freezing or oil drops below $2.00/gal (our breakeven point). The heating bill is surprisingly reasonable given the climate. As a bonus we have great AC from the split, and I don’t care what anyone says, it’s needed these days!

Are you in Maine or somewhere else?

Similar story to the other two in this thread- air exchange heat pumps are available that are rated to work below 20* F. In the end, I switched to wood (natural gas isn't available where I am, and propane is expensive). Currently using a high efficiency stove and a gassification mass heater. Our central heating barely turns on in winter at this point, and the thermal efficiency of both systems isn't too far from the propane furnace either. (The mass heater is stupidly efficient, the wood stove only in the 85% range I think).

Your way is the best way. Even if you did have natural, since you’d now not be using it 9ish months of the year instead of 6, the standby/connection charges make it increasingly uneconomical.

I know a fellow who was on oil heat and the nat gas grid was going to extend to them, but they’re going to install mini splits and keep oil as their deep freeze protection.

The cost is mostly in the installer based on the anecdotes of a well known technology youtuber in illinois. They are scared of installing heat pumps and carrying them allegedly. You may be able to buy compatible hardware on your own and get an installer. But aside from that one week you can get ASHPs that go down to 5F without losing efficiency. You can even get multi-head units that can move heat from where you might not need it (near a fireplace or stove) to where you do (bedrooms) ditto in reverse for cooling. But I'd suggest doing some research.

Thanks. We're considering building our ideal home to live part-time and eventually retire to, and we'd like it to be free of natural gas. Obviously heating w/ natural gas is the norm up here, but induction cooktop, solar water heater, and a heat pump can replace that. The heat pump coupling is the high order bit I need to research. Ground is the pricy but default option.

Check your prices, that's more likely to be a bigger determiner than other things. For me it wouldn't make sense just because natural gas is so much cheaper right now. That is however subject to change. That said if I was installing AC I'd probably still do it just because Natural gas prices have been a touch volatile lately.

If you skip the gas entirely you can make the house envelope tighter since you don't need to pull in cold oxygen for burning and vent the toxic emmisions.

If it's a new build, and you have the ability to make that decision early and adjust everything else, it tilts heavily away from gas or any other combustion within the home's envelope.

> What would air-source heat pumps look like up here?

Air heat pumps dont work in 0F, you need an alternative. My heat pump has resistive heating coils for when it gets cold. https://en.wikipedia.org/wiki/Air_source_heat_pump#Efficienc...

Current models work down to -10F without going linear. They'll still technically work beneath that but are basically the same as resistive electric at that point.

This isn't true. I live in MN and have a mini-split heat pump and a whole home air source heat pump that runs dual duty with my natural gas furnace. I currently run the cut off to switch at 20F. However both units will heat down to -20F. The mini-split struggles at that temp but the large unit still kicks out enough heat for the entire home.

I also replaced two natural gas water heaters with one 80 gallon air source heat pump water heater. It can run fully heat pump but also has coils. A "high demand" mode can run both simultaneously, but 95% of the year I run it in "efficiency" mode which is purely heat pump operation. It costs about $80-90/annually so far.

The problem is that it can’t do it through the whole season, so you’re playing for a whole second system that you barely use for that week-month.

You may have to install your own because the installers won’t know what to do with one.

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