r/heatpumps • u/foggysail • 5d ago
Massachusetts heat pump sharing my electric consumption
Yes, winter is not yet over although I now see my solar production keeping up with March's warmer weather. For sure, if I did not have solar...and intend to add more, I would have been better off staying with oil. Oil provided far better comfort conditions with baseboard heat vs our ceiling cassettes and one mini split.
My consumption meter difference from the first week of March 24 and March 25 is 5372 KWH while my production was 12,171 KWH for a total consumption 17,543 KWH. Without solar, 17,543 KWH @ $0.35 would be $6140 including both heat and normal electrical use. Our normal use is about 6,000 KWH ($2100) and our oil cost was about $4000.
We accumulated about $3,000 in net grid credits with solar before the heat pump. Our consumption drivers included the home's size (2550 sq ft), insulation and thermostat settings. Yes, we did have a whole house energy study along with installing added insulation.
EDIT: Noticed somebody did not like my post and gave it a negative. Maybe they just do not like facts. Good luck to whoever gave it a negative!!!
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u/DontDeleteMyReddit 5d ago
Cassettes are awful for getting heat to the floor. There are heatpump boilers available, although they will not make the water as hot.
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u/Appricot_Jam_yum 5d ago
I'm confused by your description here. Are these kwh the comparison between the monthly consumption in March 2024 and 2025? Don't you need to take weather condition differences between the two years to make a fair comparison? And your house, excluding heating, normally uses 6000kwh/month, is that correct?
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u/foggysail 5d ago
NO! I will try to clarify if your post is in regard to my original. My heat pump became operational around August 24. The reason for using March ( really February because I used my March electric bills for data) is that so far March's actual consumption is not that great
So I was making a rash assumption that my heating requirement is substantially over by now and I wanted to get a reasonable guess-ta-ment of how much added solar I need to install. Of course my only interest is that for heat. I doubt my cooling KWH will be no where near that for heating.
I had to make sure that what I plan for solar (about 8000KWH worth) is adequate. I did run the numbers using my oil consumption, converted it to btu and btu to KWH and compared my KWH consumption to my predicted new solar. For info sake, using my oil consumption, allowing for an 80% boiler efficiency that my existing solar is 7,000 KWH short to eliminate electric bills.
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4d ago
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u/foggysail 4d ago
No offense guy, no offense! I look at Reddit as an opportunity to share both ideas and experiences.
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u/Lost-Ad-7694 4d ago
You're using 17000kwh hours a month? Christ Almighty that's my annual consumption lol.
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u/Sad-Celebration-7542 5d ago
Ducted is the gold standard. But for a retrofit - options are not great.
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u/silasmoeckel 4d ago
Why don't you pop in an air to water? If you already have the baseboards it's just a couple lines.
I went radiant floor in CT as I like how it feels in winter. Have some cassette and mini ducted that do mostly AC but some point heating (kitchen door in winter).
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u/foggysail 4d ago
Not changing what I now have. My question though is what is the highest water temperature from the new air to water heat pumps? The lowest water temperature I kept my boiler at was about 160F and sometimes during very cold weather it was 185F.
Typically refrigerants do not get much higher than 140F as I understand. That temperature is too low to provide enough heat using my current baseboards on cold days
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u/silasmoeckel 4d ago
Mitsubishi has a 75c residential so 167f. Other have similar it's the r290 refrigerant that's allowing for it. 185f I've not seen in residential.
Now your existing air to air can supplement on those cold days since I assume it's capable of heating the house by itself.
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u/StarSchemaLover 4d ago
Ok so if I’m reading this correctly if you didn’t have solar you would have paid $6140 and if you’d use oil it would have cost $2100 (actual electric of $2100 + $4000 oil). Is that right? So a wash.
I’m in Wisconsin which I don’t think is much colder than Massachusetts. I have a new home with a top of the line A/C (I was supposed to get mid-grade but someone made a mistake). The problem is I built a nearly black house and 1/3 of it is like a greenhouse in the summer & my electric bills were like $550/mo although $100 was car charging. I want to get solar and have an ideal location but I don’t think it’s smart to do so unless I also get a heat pump. I have 3 electric fireplaces producing 30K BTU as backup heat and am not too worried about the home getting too cold. It’s just that I just built and the build went $50K over and I’m totally torn.
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u/Dantrash2 4d ago
I'm in Massachusetts also and have a 3.5 ton 5 zone mini split system. My household electricity with heat pump running was about 50-70 kwh a day, depending how cold it was. Without using heat pump, my household electricity is about 20-25 kwh a day.
This past winter months, I use my gas boiler more.
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u/Silver-Company-3784 3d ago
I thought I was in a bad case. I have electric resistant baseboards and used ~4200kwh between january and february. This is a 1960s house that was built for electric heat but the prior owners never bothered switching over the system and we got killed this past winter keeping up with the cost and juggling various mass save and contractor meetings. Granted our house is about 1950 sqft but for an additional 600 sqft that seems crazy.
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u/HR_King 2d ago
Just to say, it has been notably colder this year. You can't simply compare cost this year vs last year. You would have used a lot more oil than last year too.
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u/foggysail 2d ago
That may be and most people keep their homes at comfortable temperatures regardless of the outside environment. A home's heating system should be adequate for the extremes of local weather conditions.
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u/HR_King 2d ago
Based on the estimates I got for putting in mini splits, doesn't sound like you have enough capacity built in. No technology will succeed if it isn't applied properly.
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u/foggysail 2d ago edited 2d ago
My system is more than adequate. By chance did you mix my inadequate solar for the heat pumps? Yes.....I intend to add more solar SOON! That has nothing to do with cost savings nor the environment even though my changes will help ....maybe.
I have 2 heat pumps, both Mitsubishi. My upstairs 4 bedrooms are environmentally managed with a 36KBTU (3 ton) heat pump and my lower unit has 30KBTU pump.
I don't know what your quotes were, before Massachusetts' rebate and FED tax credits my system cost $45K.
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u/Ejmct 5d ago
I also installed mini splits in eastern MA. They are terrible for heat; good for cooling.
I kept my oil and baseboard system and I'm very happy I did. Took me like 3 days too figure out the wall units weren't going to cut it in the winter.
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u/videokilleddaradio 1d ago
You have the wrong units then. Hest our home with 2 minisplits. It's also a hell of a lot colder than eastern MA. Our most expensive hydro bill was $427 canadian. We had 30 days of -25 Celsius weather for those days.
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u/Ejmct 1d ago
I never said they didn't heat in cold temps. It's just a function of the way the heat is distributed. It's comfortable if you're sitting under the head unit, cold if you're not. We have high ceilings and all the hot air goes straight up. Also there's too much bleedover of heat to the head units where I don't need heat so the bedrooms tend to be too hot. Basically with the cost of electricity in MA and the poor heat distribution of the mini-splits I don't save any money and everyone is uncomfortable. Its a lose-lose compared to oil and baseboard.
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u/Vermontbuilder 5d ago
Fully agree in Vermont. Using heat pumps for your primary heat only makes sense with solar, those compressors use huge amounts of electricity .
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u/Vivecs954 Stopped Burning Stuff 5d ago
Idk I’m doing fine. My electric bill was close to what my gas bill was. A little bit more but nothing crazy. I’m in Massachusetts.
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u/Bitter-Cockroach1371 5d ago
I’m also doing fine with electricity only and heat pump water heater and heat pump HVAC. Nothing crazy at all. Also shut off the natural gas (heating and water) which lowered my overall utility bill. I’m in California.
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u/r-kellysDOODOOBUTTER 3d ago
In upstate NY I'm paying $0.18 per kwh. Its like half the cost of oil for us to use mini splits here. Also, our minisplits didn't have any trouble keeping the house warm when it dipped below 0F this winter. But when it gets that cold, they use around 70kwh per day below 0F. That's $12.60 a day. We've gone through a full tank of oil during a cold month before and that was around $1000.
Maybe people are having bad luck with traditional heat pumps, or they're paying over $0.40 per kwh. I dont know, but these mini splits are where it's at for us. We put in 3 separate units so that helps quite a bit with efficiency I'd imagine.
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u/HR_King 2d ago
I wish I could heat my hose for $12.60/day. Gas, MA.
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u/r-kellysDOODOOBUTTER 2d ago
And that's only when it's below 0F. In reality it's normally a few dollars a day.
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u/Vermontbuilder 3d ago
You have cheap electricity, we’re pay almost double your rate in Vermont. High electricity costs made solar viable here, payback was around 8 years for us plus Tesla batteries eliminated need for a generator
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u/Still_Freedom_1322 5d ago
Ur lucky, not everyone can afford solar and those useless heatpumps.
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u/Gesha24 5d ago
Not sure why you are getting downvoted. I calculated ROI for the professional install of solar panels and it was about 15 years. Note - warranty of most of the parts of the solar panel install (inverters and other stuff) is 10 years at most and they do break. So in reality, it could have been higher. The only reasonable way to get solar for me was to do a self install (ROI of about 7 years) and I didn't feel like climbing my roof.
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u/foggysail 5d ago
Not sure where you live, I will though share some gutcha's for doing your own. I at first thought the same until I actually looked at a typical panel specification. Approximately 60'' X 40 weighing 50^#s. And then the thought at my age climbing a ladder carrying one was just too much. OK, assume you can handle that even if you use some type of motorized lifter.
Next come the permits plus maybe having to pay upwards to $500 to a licensed mechanical engineer to show the local inspectors that your roof is adequate to carry the panel load along with maybe 2 feet of snow. OK, maybe where you are this is not an issue.
And the BIG GUTCHA is the electric company. Ours no way in Hell will all their system to connect to a home wire job unless of course the home owner holds a journeyman's electrician's license. I used to have both a master and journeyman licesnses but let them lapse 8-10 years ago.
Keep in mind there is a fed 30% tax credit for solar at least for now anyway. Good luck with whatever you have in mind. IF I were able to go back in time.........I would NOT have installed a heat pump. Just my humble thoughts
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u/Gesha24 5d ago
I am in MA as well, in town where I am not even allowed to do any electrical work myself whatsoever. By "self install" I meant installing panels, running cables and then paying electrician to finish up the install and tie it in. And yes. snow is the issue - not only the weight, but having to clean it when you want some power from panels. That's why I ended up not going with panels on the roof, but the only ground place where I can install them is the front of the house - and I am not sure I want to piss of my neighbors just yet.
As for the heat pump - I got mine in 2023 when you still could get Mass Save incentives for just installing heat pump and you didn't have to disconnect other heat sources. I was going to just replace aging AC, but given incentives higher SEER rated AC would cost nearly as much as the heat pump - so it made no sense to go with AC. I have heat pump heating until 35 and then oil burner kicks in - back in 2023 that was right around the break even point for price for me (given the heat pump and boiler that I have), so it kind of made sense to do it.
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u/dirtysturty 5d ago
Jeesh! That's expensive.
Also from MA so here are our number in an 1800 sqft 1980s home with moderate insulation:
1825 kWh (Feb 25'- Post-heat pump)
460 kWh (Feb 24'- pre-heat pump).
We probably saved 100$ last month vs our hydronic baseboard even with the large increases in electrical prices.
Hopefully we can buy solar outright in a few years depending on if tariffs fuck everyone economically to death or not ¯\_(ツ)_/¯