Glenn FleishmanI now have almost four years of electricity and natural gas use for my house via our utility companies. We put in a heat pump in May 2022. Previously, we had two window ACs in bedrooms that we ran almost entirely at night (and only some nights) and a bunch of fans. Last summer, with intense heat, you can barely see an increase in usage—particularly when you factor in inflation and a slow climb upwards in rates. (These are all two-month billing periods and average temps.)
This winter, with some bitter cold temps for Seattle last month, it looks like we paid about 5% less with the heat pump than the same period last year. But it's likely we used substantially more therms to heat the house. (Still compiling that data; it's hard to get apples-to-apples.) This chart shows hours used for AC, heat pump heat, and nat-gas heat. (We're still using the nat-gas furnace a bit; need to consider whether turning it off turns into a maintenance problem.)
Based on sheer hours during the coldest parts of December, it's possible we saved something like $75 to $100 in fuel over two months. Hard to pay off a heat pump with those savings, but the overall comfort and the switch to mostly electrical heating and cooling for environmental reasons and efficiency, *and the elimination of all the noise in the summer from fans!* absolutely worth it.
Davy Buntinx@glennf Which heat pump, if you don't mind me asking? (We're renovating.)
@dbuntinx Had to look it up! American Standard Gold 17 SEER Heat Pump
Model #: 4A7A7036A1000B
It's a 36000 BTU model, which has seemed about the right size for running it efficiently. I think if we'd gone smaller, we might have had to run it a lot more, reducing its lifespan and costing more.
Jeff Clatworthy@glennf Hi Glenn. Took us a bit to get our head around just how much of a difference it makes stabilising a total house’s thermoclimate with a heat pump (air conditioning). Once it’s done, there’s less temperature fluctuation, and lower overall power use required to maintain. 🙂
@jeffcgd I hadn’t thought about that. A furnace is really WUMPFFFF and then pffffff cooling down. I do notice that the temperature seems more even. We love the reduction in noise. And we're not igniting fire in our house—none of that burned dust smell. (We have to figure out if we shut the furnace down entirely if we were to need it—heat pump dies and it's days to fix it—whether we could just fire it up. I should ask around.)
kcǃ@glennf how expensive was the heat pump and what kind of footprint does it take up? (I’m thinking of getting one for our small San Francisco home and am very curious)
@exkclamation We spent $10K for a modest house (1200 sq ft main floor; not using heat/cooling in day-lit basement) — 2-stage model. We didn't have any of the piping in place. So they had to "plumb" 40 feet of flexible piping and install the outdoor unit. They can be quite small! Ours is nearly a cube and the volume of maybe a standard refrigerator/freezer if you turned it into the cube.
@exkclamation However, we could locate the whole unit outside and tie it into an existing furnace unit that was set up to also add a heat pump. (For once, I future proofed 15 years ago when we had to suddenly replace our dead furnace.) You might do better with a ductless mini-split that has a fan inside in a unit you mount up on the top of a wall and then the outside part is much more modest.
@glennf thank you for the info! Much appreciated!
@glennf thanks! We're at 900sqft, so seems comparable!
Did you also get rid of previous heater? Or wait... (thinking) perhaps if you are in the PNW you just had baseboard heaters? We have a big box gravity-feed heater now (no blower, just heat floating up to the house), and wondering if it can take over the existing ducting.
@exkclamation We're not that moderate in temp! We have a nat gas furnace with integrated heat pump coil, so they just wired that up. We didn't remove the furnace as its integral to the install. We use it now as an automatic boost in the morning then it doesn't run the rest of the day
Jemal Cole Loves Each of You@glennf Electrifying everything is its own reward, but the best deal going is heat pump water heaters which pay for themselves pretty quickly!
John Griffith@jemaleddin @glennf any suggestions on which brand heat pump hot water heater? Our current hot water tank is in the basement.
@johndgriffith @glennf not from me! There was only one model (from A.O. Smith) available in the supply chain last summer, so we took that one. In general they have slightly larger tanks and cost a little more up front, but pay for themselves in like 2 years. (My wife is an environmental economist who works in regulating energy companies, so I leave this kind of thing to her.)
Drew Pickard@glennf I love the idea of heat pumps, but the downer for me is the big minisplits on the walls. We're thankfully electric already so I don't know if I can sacrifice the beauty of our bare walls 😅
I guess we'll see with our next evolution of the Seattle Summer™
I guess we'll see with our next evolution of the Seattle Summer™
@drewpickard We already had ductwork and I somehow had the foresight 15 years ago, when replacing a suddenly dead furnace, of buying a slightly more expensive set up with the potential to add a heat pump later. So we have an external unit between us and the neighbor’s (who got a heat pump before us!), fortunately both on the non-bedroom sides of the house. No additional ductwork inside!
parkerparkerparker@glennf very interesting! How did you gather this data?
@parkerparkerparker The smart thermostat we use has an app that provides stats! It's not a great app, but the stats are awesome!
@glennf Yeah the stats look very useful. I wish my Nest thermostat did a better job here. Thank you!
Argot_Robbie@glennf Should you stop using the gas furnace completely, the utility may take that as a signal to shut off your line after some months. You may only discover this years later, during a stretch of record cold temperatures.
This is the voice of experience.
I would clear this with your gas utility, or just run the furnace 2-3x a year to make sure the gas supply is there, unless you are sure you'll never need it (newer heat pumps have solid low-temperature performance).
@hydrocabron We've still got a tankless gas water heater. But that is great to know!
Wes@glennf how are you tracking the data?
@Justwes My utilities offer this as downloadable and chart-based info!
@Justwes oh, the hours used comes from the smart thermostat's app
@glennf that is very useful. The heating app I have for our gas heating has some ok tracking detail but the data is trapped in there and not as robust what you’ve shared
Peter Smerdon@glennf Have you factored in the replacement cost of the inefficient existing devices?
If you maintained the status quo you would have to replace the wall ACs and furnace at some point.
You now have a heat pump at the beginning of its service life.
If you maintained the status quo you would have to replace the wall ACs and furnace at some point.
You now have a heat pump at the beginning of its service life.
@psmerdon You are smarter than I. The natural-gas furnace has a 20-30 year lifespan and it's 15! It costs $1,000s to replace. The AC units are relatively cheap—I think we spent in the very low hundreds. Also, I do think with excessive heat in Seattle, having a comfortable but not chilled refuge (we set our cooling to 79°F in the summer), we're likely giving ourselves longer, happier lives.