Anyone regret switching to electric heating?

[jboy210]

I am trying to be as green as we can and considering switching to a heat pump. However, I am not sure the numbers make sense.

We are in the SF East Bay. In the winter months, we don't generate much because of low sun, big old trees, and cloudiness/fog. We are lucky to get 8-9 kWh/day at the winter solstice in these conditions. This is about 85% of our home use with gas heating. If we happen to hit a stretch of clear weather, we might jump up to 14 kWh/day. Home is 3100 Sq feet over 2 floors. Insulation, windows, and doors have all been replaced in last 8 years, so it is pretty tight.

We have 2 Teslas, a 3 and X, and drive about 5K/year total and charge 60% of the time at home.

As much as I would like to do my part to decrease emissions, I am not thinking this makes any financial sense. Also, I do not want to be wishing after year I was still on gas heating as I stare at a large electric bill. Gas bill is up to $125/mo. What do others think?

 

[bmah]

I am trying to be as green as we can and considering switching to a heat pump. However, I am not sure the numbers make sense.

We are in the SF East Bay. In the winter months, we don't generate much because of low sun, big old trees, and cloudiness/fog. We are lucky to get 8-9 kWh/day at the winter solstice in these conditions. This is about 85% of our home use with gas heating. If we happen to hit a stretch of clear weather, we might jump up to 14 kWh/day. Home is 3100 Sq feet over 2 floors. Insulation, windows, and doors have all been replaced in last 8 years, so it is pretty tight.

We have 2 Teslas, a 3 and X, and drive about 5K/year total and charge 60% of the time at home.

As much as I would like to do my part to decrease emissions, I am not thinking this makes any financial sense. Also, I do not want to be wishing after year I was still on gas heating as I stare at a large electric bill. Gas bill is up to $125/mo. What do others think?

Not exactly addressing your point, but I remember thinking during the lovely PG&E PSPS events of 2019 and 2020 that it sure was great that we had natural gas for heating, water heater, and cooktop, because those could work more or less normally without using up our limited solar production and battery capacity.

Bruce.

 

[zƬesla]

We switched to mini-split heat pumps but still keep the old oil boiler for potable hot water and backup heating when it gets really cold. Hoping to install a heat pump water heater at some point so boiler doesn't have to be used at all in summer.

 

[holeydonut]

When it's wintertime do you (or your wife) care if the air hitting you is "I just lit dino farts on fire and got some hot hot hot air on my face" vs "slightly warmer than ambient"?

The 3 HVAC sales-guys I spoke with when researching my HVAC overhaul said that if your wife wants to only feel hot hot hot air, then don't even think about heat pumps. They said customers who get heat pumps often complain the air they feel during the winter isn't warm enough. They often have to send techs out to inspect and tell the now disgruntled homeowner that's the way it is.

I'm sure h2ofun will say he's never had this problem. But what do I know, I light dino farts on fire because I'm not willing to take the chance of fielding complaints from family members.

 

[arnolddeleon]

I've been heating with a heat pump for over a decade. It was installed as a "hybrid" configuration (gas furnace plus a heat pump) but over the last 5 years or so I just lock out the gas furnace.

I LOVE heat pumps. The things people get wrong about heating them is trying to use them like gas furnaces. The secret to comfortable AND efficient HVAC is small changes in temperature/not letting the thermal mass get away from the comfort zone. Basically if you are looking to get blasted by hot air at some random interval then might not be happy. In the winter our heat pump is almost always running continuously as the lowest level. It it just making up the heat loss of the house. If it is super cold then it steps up to the next level. By the way the same applies for cooling. I've embraced the always have the AC on mode (I usually run my HVAC in auto mode). This way the AC runs before I start feeling get too hot. This prevents thermal mass too hot which forces the HVAC to run super high. I don't like getting blasted.

For me the perfect HVAC is one that I never notice.

We have Powerwalls and outages are extremely rare in our area. I haven't ripped out the gas furnace because it makes no sense to do that so I have that backup option. Production wise I bank credits in the summer and use them in the winter.

 

[jboy210]

I've been heating with a heat pump for over a decade. It was installed as a "hybrid" configuration (gas furnace plus a heat pump) but over the last 5 years or so I just lock out the gas furnace.

I LOVE heat pumps. The things people get wrong about heating them is trying to use them like gas furnaces. The secret to comfortable AND efficient HVAC is small changes in temperature/not letting the thermal mass get away from the comfort zone. Basically if you are looking to get blasted by hot air at some random interval then might not be happy. In the winter our heat pump is almost always running continuously as the lowest level. It it just making up the heat loss of the house. If it is super cold then it steps up to the next level. By the way the same applies for cooling. I've embraced the always have the AC on mode (I usually run my HVAC in auto mode). This way the AC runs before I start feeling get too hot. This prevents thermal mass too hot which forces the HVAC to run super high. I don't like getting blasted.

For me the perfect HVAC is one that I never notice.

We have Powerwalls and outages are extremely rare in our area. I haven't ripped out the gas furnace because it makes no sense to do that so I have that backup option. Production wise I bank credits in the summer and use them in the winter.

Do you have a comparison of your electrical consumption in the winter before and after using only the heat pump for heating?

 

[skepticcyclist]

Not here. It would require rewiring to add 240 v outlets in my house, which doesn't contain any, as well as a panel upgrade to add more breakers. Plus even with solar I would end up paying much to heat the house. Gas is still many times less expensive for each degree of heating, and does so much faster. Plus being in SoCal the amount of heating needed is so minimal anyway.

But we did put in a mini-split AC unit in two of our rooms so we don't have to run the central AC as much. This is also a heat pump in the winter

 

[jboy210]

Not here. It would require rewiring to add 240 v outlets in my house, which doesn't contain any, as well as a panel upgrade to add more breakers. Plus even with solar I would end up paying much for to heat the house. Gas is still many times less expensive for each degree of heating, and does so much faster. Plus being in SoCal the amount of heating needed is so minimal anyway.

But we did put in a mini-split AC unit in two of our rooms so we don't have to run the central AC as much. This is also a heat pump in the winter

How much was the mini-spilt? We have one room, my office, that is on the West side above the garage and gets pretty toasty in the summer.

Also, does anyone have a similar situation, room above garage, and have any thoughts of cooling?

 

[Big Earl]

I am trying to be as green as we can and considering switching to a heat pump. However, I am not sure the numbers make sense.

We are in the SF East Bay. In the winter months, we don't generate much because of low sun, big old trees, and cloudiness/fog. We are lucky to get 8-9 kWh/day at the winter solstice in these conditions. This is about 85% of our home use with gas heating. If we happen to hit a stretch of clear weather, we might jump up to 14 kWh/day. Home is 3100 Sq feet over 2 floors. Insulation, windows, and doors have all been replaced in last 8 years, so it is pretty tight.

We have 2 Teslas, a 3 and X, and drive about 5K/year total and charge 60% of the time at home.

As much as I would like to do my part to decrease emissions, I am not thinking this makes any financial sense. Also, I do not want to be wishing after year I was still on gas heating as I stare at a large electric bill. Gas bill is up to $125/mo. What do others think?

How many therms of natural gas do you use per month in the winter? You can easily convert that to expected electricity consumption.

 

[BGbreeder]

How much was the mini-spilt? We have one room, my office, that is on the West side above the garage and gets pretty toasty in the summer.

Also, does anyone have a similar situation, room above garage, and have any thoughts of cooling?

I would wonder how insulated your office floor is, especially if the garage doesn't have an insulated door. I had an office over an area exposed to the outdoors, and the floor only got warm-ish after I blew in 24" of insulation. Obviously, the reverse case for you.

I think that mini-splits excel for climate control in isolated areas like yours with significantly different heating/cooling needs.

All the best,

BG

 

[Mark Purcell]

My all electric conversion, tale of two winters

Canberra 1960s 4br brick house.

2020 operating costs: $6,100 (Dec - August)
Gas: $3,200
ducted gas heating, instant gas hot water
Electric: $2,900
Resistive hot water & panel heating, lighting, cooking, EV.

2021 operating costs: $800 (Dec - August)
Jan: installed 13.3 kWp solar
EV charging now mostly solar
Mar: ducted gas heating replaced with ducted electric 18kW RCAC
May: resistive and gas hotwater systems replaced with electric Reclaim hot water heat pump - gas disconnected

About 1.5MWh of EV charging at home mostly on Solar and another 2.0 MWh of 'free' destination charging. 13,000 km driving vs $0.10 / km for petrol is another $1,000+ of benefit.

Next steps improve house thermal performance to further reduce 31 kWh daily usage before next winter.

 

[jjrandorin]

How many therms of natural gas do you use per month in the winter? You can easily convert that to expected electricity consumption.

Is that a conversion you could post / link to? I have gas heating and cooktop, and for us here in southern california who have what used to be called "the gas company" (and is now called "socal gas", gas seems very cheap to me. I dont think it pencils out to take it out from a financial point of view, unless you have a bunch of "extra" PV that is otherwise unused.

 

[LincolnsDoctor]

We switched to mini-split heat pumps but still keep the old oil boiler for potable hot water and backup heating when it gets really cold. Hoping to install a heat pump water heater at some point so boiler doesn't have to be used at all in summer.

We also installed mini-split and kept the oil boiler as back up, and have solar plus 2 Powerwall. When we lost grid power for 3 days we only had enough electric to run the oil burner

In my experience mini-splits always blow warm air in winter, at least down to 0 degrees

 

[arnolddeleon]

Do you have a comparison of your electrical consumption in the winter before and after using only the heat pump for heating?

I don't and if I did it wouldn't necessarily be that valuable to you. However you should be able to get a good estimate on how much you will consume. You should know roughly the efficiency of you current heating system (e.g. a 94% gas furnace). You can then find out how much gas you consumed (should should be able to factor out water heating and cooking since you probably didn't heat in the summer). That should give how much energy you consumed for heating roughly. Then you can pick the efficiency of the heat pump you want to model and convert it back to kWh.

 

[Big Earl]

Is that a conversion you could post / link to? I have gas heating and cooktop, and for us here in southern california who have what used to be called "the gas company" (and is now called "socal gas", gas seems very cheap to me. I dont think it pencils out to take it out from a financial point of view, unless you have a bunch of "extra" PV that is otherwise unused.

A therm of natural gas is equal to 100,000 BTU. An 80% efficient gas furnace would burn 1.2 therms for 100,000 BTU of heat to the home (plus ~600 Watts of electricity for the blower). 1.2 therms is about 35 kWh of energy, so probably closer to 12 kWh from a heat pump (COP 3).

On average, natural gas will likely be equal to or slightly less expensive than a heat pump, but you're going to use significantly less energy.

 

[jboy210]

I would wonder how insulated your office floor is, especially if the garage doesn't have an insulated door. I had an office over an area exposed to the outdoors, and the floor only got warm-ish after I blew in 24" of insulation. Obviously, the reverse case for you.

I think that mini-splits excel for climate control in isolated areas like yours with significantly different heating/cooling needs.

All the best,

BG

Garage door is insulated. My father-in-law was in garage door manufacturing in Wisconsin and drilled that into me. However, it still gets very hot in the garage, 100+ even after the sun goes down. And the garage faces due North so the sides of the garage get sun from 6 Am to 7 PM. The office floor cavities are filled with insulation. But the office floor and walls up to your hips hang like a rectangular box into the sloping garage roof. So, the floor, and 3 of the 4 walls are partially exposed to the 100+ degree temp of the garage. I try to open the garage door in the evening and morning, but even then, the office can be in the 80s at 10 PM. If you walk to the next bedroom down the hall, it is in the mid to upper 70s.

I am talking to my contractor about putting vent fans in the side of the garage. But they are skeptical that they will have much of any effect since the ambient temps in the Tri-Valley are high-90, low 100s from 10AM into the early evening, most of the summer.

 

[Big Earl]

Garage door is insulated. My father-in-law was in garage door manufacturing in Wisconsin and drilled that into me. However, it still gets very hot in the garage, 100+ even after the sun goes down. And the garage faces due North so the sides of the garage get sun from 6 Am to 7 PM. The office floor cavities are filled with insulation. But the office floor and walls up to your hips hang like a rectangular box into the sloping garage roof. So, the floor, and 3 of the 4 walls are partially exposed to the 100+ degree temp of the garage. I try to open the garage door in the evening and morning, but even then, the office can be in the 80s at 10 PM. If you walk to the next bedroom down the hall, it is in the mid to upper 70s.

I am talking to my contractor about putting vent fans in the side of the garage. But they are skeptical that they will have much of any effect since the ambient temps in the Tri-Valley are high-90, low 100s from 10AM into the early evening, most of the summer.

A mini-split sounds like it would serve your office quite well. Any competent HVAC contractor should be able to quote the job pretty easily.

 

[h2ofun]

I have enough solar that I can keep my house hot in the winter, and cool in the summer. I have 10 mini split heads, even though I do not run them all the time.

YEP, you cannot run them like a gas unit. I set them and NEVER change the temp!!!! If I kick the heat, or cool up, it can pump out super hot air or cool air, but thats not the point. Set a temp and leave it alone.

Since I have a zero round overall ZERO energy bill, cannot get batter than that!!

 

[arnolddeleon]

Not here. It would require rewiring to add 240 v outlets in my house, which doesn't contain any, as well as a panel upgrade to add more breakers. Plus even with solar I would end up paying much to heat the house. Gas is still many times less expensive for each degree of heating, and does so much faster. Plus being in SoCal the amount of heating needed is so minimal anyway.

But we did put in a mini-split AC unit in two of our rooms so we don't have to run the central AC as much. This is also a heat pump in the winter

FYI many (most?) mini splits just require power to be run to the outdoor unit. This simplifies the installation so power doesn't have to be run to the inside unit. A power cable comes along the refrigerant lines that need to go between the unites anyway.

A modern heat pump can beat a 100% (I know that the doesn't exist) efficient gas furnace for producing heat given the same input of natural gas. This is true even assuming a 40% efficient gas plant. A heat pump can "produce" (technically move) 3 to 4 (and even more) times the heat energy over what goes into it. So if you start with one unit of natural gas energy you will more than likely get more heat out of the heat pump. This is just the energy/physics question. How electricity and natural gas are priced is another kettle of fish.

Also a mild heating climate that requires air conditioning makes a heat pump pretty much ideal. All the infrastructure is already in place. The annoying thing is historically American HVAC manufacturers have put crazy premiums into turning a "air conditioner" into a "heat pump" so people didn't buy them. Of course the rest world knows that an AC is just a heat pump. For those not a familiar, in the US when we say heat pump we basically mean an air conditioner that can go "backwards". The difference in parts is small, basically a reversing valve and control logic (grossly simplified).

 

[dhrivnak]

We have been moving to all electric that we can then offset with solar. HP works great in NE TN even at 10F