Should I switch from Electric Furnace to Heat pump or Gas?
July 26, 2017 1:04 PM   Subscribe

My house is in Portland Oregon and in last winter the heating bills were crazy. I don't want to pay $200 plus a month to warm one person anymore. I have a mid-2000s electric furnace. I have the choice of installing a heat pump vs gas furnace. I have got a few estimates from contractors but still can't make a decision. I am mainly interested in the utilities savings of heat pump vs gas. Did you transition your heating from electric to heat or gas? How was the experience, did you notice significant energy savings? Maintenance cost differences?

The advantage of heat pump from what I can see is that it has the versatility of cooling in summer. The disadvantage is that it still use electricity and I don't know if it will have significant savings over electric furnace to justify the installation cost (likely around $10k)

The advantage of gas is that from what I heard natural gas is much cheaper here in Portland. Also I can install a gas stove which is a want. The initial installation cost is somewhat cheaper then heat pump, tempered by the need to connect my house to gas main.

Also, I have already done a energy audit with a company and they didn't find any glaring problems with insulation of the house.
posted by Pantalaimon to Home & Garden (12 answers total) 1 user marked this as a favorite says average winter lows in portland are mid 30s. If that's just the night time low you may be OK with a heat pump.

When air temp is below 40, heat pumps don't work so well, and the system will resort to electric to heat up the house (heat the coolant circulating in the heatpump).

You can also get a heatpump with a gas backup (what I have, but I'm 2000+ miles away). We already had gas at the house, and were replacing a 1990 era gas furnace with a heatpump + gas backup.

I'm a fan of gas because when the power goes out, my hot water tank still works, and I can still cook and boil water/make coffee on the range :)
posted by k5.user at 1:09 PM on July 26, 2017 [3 favorites]

Do keep in mind that last year in Portland was abnormally cold for extended periods of time (not that this isn't something to be dealt with but it won't always be that bad...I hope).

You're approaching this from a gas vs heat pump angle, but there's a 3rd option which is to mount solar panels (either lease, or buy) to run your current electric heat system off of. If your electric furnace is in good working order, this might actually be your cheapest option, given your current setup. Things would be different if your electric furnace was crapping out and you needed to replace. There are some low-to-no cost ways to get panels up on your house. If you go this route, I'd contact the Energy Trust of Oregon for options. They'll steer you right.

Gas is very cheap in Portland. For reference, my heating bill in this past winter (780sq ft house, single story, decent insulation) usually peaks at $70/mo with the daytime thermostat running at a 67-68. That bill includes our hot water heater. If you decide to go that route, it's probably best to convert your major appliances to gas as well (not all at once, just plan on doing it over time). We will be moving our stove over to gas this winter for that very reason.

Even though I want solar panels for environmental reasons, the cost of converting our newer hot water heater and furnace to electric doesn't make sense on top of the solar panels. If our furnace was electric powered, we would've put panels up day 1.
posted by furnace.heart at 1:27 PM on July 26, 2017

When air temp is below 40, heat pumps don't work so well, and the system will resort to electric to heat up the house (heat the coolant circulating in the heatpump).

This is somewhat old information. Heat pump technology is advancing rapidly, to the point where they are a regular consideration for construction here in Vermont. Many can operate in compressor cycle mode down close to zero degrees.

The purely economic decision would be natural gas. The comfort driven decision would be heat pump (even in portland I'm sure there are days a bit of cooling/dehumidification would be pleasant). The environmental decision is .. complicated, but in theory electricity can be, or can become, sustainable in a way natural gas cannot.
posted by meinvt at 1:33 PM on July 26, 2017

The purely economic decision would be natural gas.

There are certain businesses like Solar City that will install solar on your roof for zero-to-minimal cost in Oregon. They usually install more than your house needs to power itself with the intent to sell power back to the grid, which they collect as payment instead of you directly purchasing the panels. They also collect your tax credits for installation instead of you receiving them. This might be the cheapest option, given the house's current infrastructure. Gas might be the most economic, but not necessarily. Here in Portland it highly depends on what way your house and rooflines are facing.
posted by furnace.heart at 1:41 PM on July 26, 2017

Gas is what you heat with. Whether a boiler with radiant water baseboards, or just a heater blower thing. Any version of electricity to heat, is expensive.
posted by Oyéah at 1:57 PM on July 26, 2017

The environmental decision is .. complicated

Not really, heat pumps work by sucking warmth out of the atmosphere, for every watt/joule you put in, you get more than one out in heat. Gas is one for one, so heat pumps are more efficient even before you start talking about renewable electricity.

(also, they cool you down/dehumidify in summer)
posted by smoke at 2:16 PM on July 26, 2017

I just replaced my ancient gas furnace for a heat pump system in Portland. I can't find the exact one now, but you can plug in your house info (the number of cooling days/heating days in your location, size of the house, etc.) and get operating cost estimates for various configurations of HE gas furnace, heat pump with lower efficiency furnace backup, etc. It ended up being pretty much a wash in terms of the time-to-recoup the installation for me, but electricity is in principle more renewable, the heat pump is definitely more energy efficient, and I got glorious glorious A/C since our summers have been creeping out of comfortable the past 4-5 years.

I should say, though, that I already had gas plumbed to the house, and am keeping it for the range, grill, dryer, so that wasn't a factor. And I am in the process of putting in a tiny gas fireplace, which will reduce my wintertime supplemental heating costs the next time we have a cold winter (like 2011) and be cozy if we have another wet/snowy one (like this past one).

If you check back next spring, I can give you actual data re: the operating cost comparison.
posted by janell at 2:34 PM on July 26, 2017 [1 favorite]

Ugh. I can't find the exact *calculator* now.
posted by janell at 2:45 PM on July 26, 2017

Many can operate in compressor cycle mode down close to zero degrees.

The way this works is that there's a thermostat built into the outside unit that will turn on a heating coil that will (in theory, anyway) heat the outside unit up just enough it won't freeze over. It uses more power than just the heat pump compressor itself, but it uses less power than heating the whole house with resistance coils. That usage is factored into the energy rating of a heat pump, and even with it they're pretty efficient in places where it doesn't stay cold.

Personally I've had really bad luck with heat pumps. I lived through two failures in ten years at one apartment, and one of those failures probably counts as two because a faulty component was replaced about a month before the new one failed and the technician declared the whole thing a total loss. I then lived through another failure of a unit in a brand new apartment. And in the time between when we made an offer on our house and when we had our final walkthrough inspection, somebody stole the outside unit for the heat pump, which the seller's insurance replaced … only to have the replacement fail four months later. We replaced the whole system with a gas furnace. Our gas bill has never hit the same level the last electric bill did with the heat pump, but presumably that was partly because the compressor was already dying, causing it to run more and heat less.

Aside from local utility rates and my bad luck, I think the big argument for gas is that when it runs in winter the air coming from the vents actually feels warm. Heat pumps put out air that is, technically, warmer than ambient air temperature, but not by much. If you need to heat the house in a hurry, or if you come in from the cold and feel chilled, a heat pump will get there eventually but it doesn't have the immediate impact of a gas furnace.

Oh, and if you do go down the gas path: when we replaced the heat pump with a gas furnace they were going to have to remove the existing (gas) water heater so they could put the new air handler in, and rather than have them reinstall that we had an on-demand, tankless, gas water heater installed. That thing is awesome. But here's the thing: there are two of us. We can take longer showers, or we can have my entire family stay for the holidays and seven people can shower back to back, and never run out of hot water, but it didn't save us a dime on our basic gas bill. Our summer gas bill (cooking and hot water only) was about $15/mo before the switch, and it's about $15/mo now. If you live alone I guess it could save you a little money (since it would only have to heat enough for one person's showers) but I'm not sure you'd ever break even on it. Tankless water heaters: affordable luxuries, but luxuries nonetheless.
posted by fedward at 7:53 PM on July 26, 2017

How is your house's insulation? If your house is drafty, it could be worth a $5K air-sealing-and-insulation upgrade first.
posted by samthemander at 8:54 PM on July 26, 2017

samthemander: I already did energy audit and insulation is fine.
posted by Pantalaimon at 8:59 PM on July 26, 2017

As you point out, it's pretty solely up to you weighing air conditioning versus gas stove and water heating. The costs will be generally the same in function and installation, though I'd expect gas to be a little less once you have a gas water heater, but you'll pay an extra $130 or so per year in gas infrastructure costs. Gas will be more invasive to install. You can always buy a window air conditioner. Electric is the only option that can be carbon-neutral.

The only wrong choice you could make is to keep the resistance heater!
posted by flimflam at 10:21 PM on July 26, 2017

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