switching to Electric from Natural Gas after big solar install in North East region

[Sunking]

As a practical matter, using current construction techniques, and taking reasonable cautions to ensure all sources of combustion inside a dwelling are properly vented, which includes considerations and measures for air for combustion as well as exhaust, and also moist air removal/exchange, it's pretty difficult to make a house so tight that the indoor air quality will suffer. Possible, but not very likely. Odor control then usually becomes a situation of hygiene and housekeeping.

Real issue in my two last homes I built with ICF. The HVAC system is designed to exchange 10% outside air. Otherwise my farts would hang around a week or build up to the point if detonation.

[reader2580]

I will give an example of how many KW it takes to heat a 1,300 square foot house in Minneapolis, MN. The previous owner was using somewhere between 45,000 and 50,000 KW a year for baseboard electric heating. It was costing close to $3,000 a year for electricity used for heat. I installed forced air gas heat and my electric and gas bill combined is $1,300 a year.

Personally, I would only consider electric for heat with ground source (geothermal) heat pump.

[J.P.M.]

I will give an example of how many KW it takes to heat a 1,300 square foot house in Minneapolis, MN. The previous owner was using somewhere between 45,000 and 50,000 KW a year for baseboard electric heating. It was costing close to $3,000 a year for electricity used for heat. I installed forced air gas heat and my electric and gas bill combined is $1,300 a year.

Personally, I would only consider electric for heat with ground source (geothermal) heat pump.

That's pretty typical in the way of a premium for electric resistance heat over nat. gas. Comes from cutting butter with a chain saw and using low entropy energy (electricity) when a higher entropy source will do (natural gas).

[reader2580]

That's pretty typical in the way of a premium for electric resistance heat over nat. gas. Comes from cutting butter with a chain saw and using low entropy energy (electricity) when a higher entropy source will do (natural gas).

I suspect natural gas wasn't available when the development was built in 1980 because some neighbors have oil heat. Nobody sane does oil or electric heat if natural gas is available.

My example was mainly to show just how many KW of electricity it can take for electric heat.

[J.P.M.]

I suspect natural gas wasn't available when the development was built in 1980 because some neighbors have oil heat. Nobody sane does oil or electric heat if natural gas is available.

My example was mainly to show just how many KW of electricity it can take for electric heat.

Well, without knowing what usage was for you and the prior owner, including how much of the electric use was attributable to heating, or use patterns that are most likely different, there's no way to use those figures to figure your relative cot. A better way to estimate is to compare costs is to simply multiply the cost of a kWh of electricity by 29.3, and compare that to the cost of a therm of nat. gas divided by the combustion efficiency of a nat. gas heating device.

Example: If a therm of nat. gas costs $0.40/therm and is burned at, say 90% efficiency in a modern boiler or furnace, and that delivered efficiency is knocked down another, say, 10% for duct/piping losses, it'll cost ~ $0.49 to provide 100,000 BTU to the dwelling. If electricity costs, say $0.10/kWh, and that electricity is used as the source of resistance heat to the dwelling, with no duct losses, it'll cost ~ (0.10)*(29.3) = $2.93 for the same 100,000 BTU delivered. If the electricity is used to power a standard heat pump, and that device has a C.O.P. of, say, 4.5 (an ~ SEER of 17-18 or so), and that's reasonably high, the fuel cost to deliver 100,000 BTU of heat will be ~ $2.93/4.5 = $0.65/100,000 BTU. The heat pump in this case gets close, but nat. gas still comes out ahead, at least for this example. The costs I used are for example only, but maybe not too far off actuals for some areas. For areas with high electricity rates, nat. gas kills electricity as a heat source, even when compared to conventional heat pumps, at least at current nat. gas prices.

[Sunking]

I suspect natural gas wasn't available when the development was built in 1980 because some neighbors have oil heat. Nobody sane does oil or electric heat if natural gas is available.

My example was mainly to show just how many KW of electricity it can take for electric heat.

Your terminology is wrong. Killo Watt and Killo Watt Hours are not the same thing.

How much energy does a 100 hp engine use? You cannot answer the question because it is non sense. Power and energy are not the same thing, related, but not the same thing.

Watts is power or rate in which energy is used.

Watt Hours is the amount of energy used..

Example a 100 watt light bulb burns 100 watts and in 10 hours uses 1 Kwh. Watts x Hours = Watt Hours. So when you say someone used used 50,000 Kw was meaningless. Tells me it was a 625 HP electric motor used in a Porche EV.

[J.P.M.]

Real issue in my two last homes I built with ICF. The HVAC system is designed to exchange 10% outside air. Otherwise my farts would hang around a week or build up to the point if detonation.

You are correct. I would have been more accurate using the word "conventional" instead of "current". For those who may not know, ICF == Insulated Concrete Form. They can be made VERY tight. However, SK: I need a little clarity on that 10% number. is that .10 air change volume/hr. ?

Also, and off topic: Hope you didn't get ripped off and got talked into a typical air/air HX. If you did, consider deep sixing it. Generally poor construction, poor design and thermal performance so bad it's probably worse than no heat recovery at all, and no better after a few hundred hours of use. Worst part, they breed stuff and wind up being bacteria cesspools, especially in warm, high dew point climates. Trust me on that one. Spent ~ half an engineering career designing HX's. Good design is possible, but I've yet to see a residential unit that's worth spit.

[reader2580]

Your terminology is wrong. Killo Watt and Killo Watt Hours are not the same thing.

Give me a break. It was an honest mistake and I mean KWh. I'm pretty sure you knew that too.

[reader2580]

Well, without knowing what usage was for you and the prior owner, including how much of the electric use was attributable to heating, or use patterns that are most likely different, there's no way to use those figures to figure your relative cot. A better way to estimate is to compare costs is to simply multiply the cost of a kWh of electricity by 29.3, and compare that to the cost of a therm of nat. gas divided by the combustion efficiency of a nat. gas heating device.

I made a reasonable assumption of how much electricity use was heat and how much was for other uses. The total KWh used by the house previously was even higher. There was a separate meter for the electric heat (since removed), but I'm not interested enough to ask the electric company for three year old records of how much electricity was used for electric heat.

It is pretty unrealistic to heat with resistance electric heat in Minneapolis with PV solar. It would take a 35KW array at minimum to generate enough power.

[doctorman]

Well, without knowing what usage was for you and the prior owner, including how much of the electric use was attributable to heating, or use patterns that are most likely different, there's no way to use those figures to figure your relative cot. A better way to estimate is to compare costs is to simply multiply the cost of a kWh of electricity by 29.3, and compare that to the cost of a therm of nat. gas divided by the combustion efficiency of a nat. gas heating device.

Example: If a therm of nat. gas costs $0.40/therm and is burned at, say 90% efficiency in a modern boiler or furnace, and that delivered efficiency is knocked down another, say, 10% for duct/piping losses, it'll cost ~ $0.49 to provide 100,000 BTU to the dwelling. If electricity costs, say $0.10/kWh, and that electricity is used as the source of resistance heat to the dwelling, with no duct losses, it'll cost ~ (0.10)*(29.3) = $2.93 for the same 100,000 BTU delivered. If the electricity is used to power a standard heat pump, and that device has a C.O.P. of, say, 4.5 (an ~ SEER of 17-18 or so), and that's reasonably high, the fuel cost to deliver 100,000 BTU of heat will be ~ $2.93/4.5 = $0.65/100,000 BTU. The heat pump in this case gets close, but nat. gas still comes out ahead, at least for this example. The costs I used are for example only, but maybe not too far off actuals for some areas. For areas with high electricity rates, nat. gas kills electricity as a heat source, even when compared to conventional heat pumps, at least at current nat. gas prices.

Got my first Natural Gas Bill from National Grid... boy I was misinformed...

Gas Supply is 42 cents per Therm
BUT
DELIVERY FEE
NY STATE FEES
SURCHARGES
and bunch of other BS fees
Brings it up to 1.23$ per THERM

so at 1.23$ per therm at bare minimum (a rate that will always go up like everything else)
the calculations of Gas vs Solar is much more doable if the electricity is used well
Heat Pump plus a very efficient tankless boiler (this I still have to consider if I want gas or electric) if I go above 25KW then for sure electric but at 20KW solar system in NY I think Gas boiler still the way to go.

Lennox XP25 COP is between 1.8 to 3.3 or so depending on the size of the system, furnace, air-handler, temperature etc


so Gas BTU costs close to 1$
Heatpump BTU from solar electric of 5-7cents at COP around 2.2 is close in price

considering NG prices going up, even if not supply the delivery & taxes will go up and my solar system will be paid for in 5-7 years it will be more of a Free solar vs NG at 1.5$-2$ per therm sooner or later.

I need help choosing the best HVAC/Boiler for my house.
had 4 HVAC guys and companies estimates from $15K to 40K$ all different units and stuff... I can not trust any of them yet.
it is hard to find a true professional HVAC guy who know what they are talking about and cares enough to calculate the cheapest system that gets my job done.

another concern I have with tankless high efficiency boilers is how fast can they heat the house. to my understanding these units work well when they heat up the house slowly and keep it there vs my old boiler with tank that would release all the energy in the house in 15 min and we would jump from 55 to 65F in 30 min or so.

Thank you all for educating a first time homeowner... there is a lot to learn and If I do not learn it for myself I will be taken advantage by the contractors who just want the job done and cash out.

[bcroe]

Pretty late, but here is another version of equivalent units. Bruce Roe
-----------
With gallons or cu ft of oil or propane or nat gas; BTU, Joules, KW, KWH, THERMs, TONs, SEER, EER, & COP, I needed a table of formulas to directly compare things. My own preference is to reference everything to KW or KWH. Exact conversion ratios subject to a bit of international fine tuning.

Also the exact units (KW DOES NOT = KWH) help avoid confusion, and failure to cancel properly indicates error. First things are divided into TOTAL ENERGY or ENERGY FLOW, and some industry comparison factors. Keeping in mind, ENERGY FLOW X time = TOTAL ENERGY.
____________________________________________
TOTAL ENERGY
1 Barrel of OIL = 500 lb OIL = 58.095 THERMs
1 gallon PROPANE = 91,690 BTU = 26.8717 KWH
1 cubic foot NATURAL GAS (US) = 1028 BTU = .301277 KWH
1000 BTU = 1,055,000 JOULEs = 0.293071 KWH
1 THERM = 100,000 BTU = 29.3071 KWH
1 JOULE = 1 WATT SECOND 1 KWH = 3,600,000 JOULES = 3412.142 BTU ++++++++++++++++++++++++++++++++++++++++++++++++++ +++
ENERGY FLOW
1 Watt = 3.412142 Btu / hour = 1 JOULE / second = 3600 JOULEs / HOUR
1 TON = 12,000 BTU / HOUR
++++++++++++++++++++++++++++++++++++++++++++++++++ ++++
ENERGY COMPARISON FACTORS SEASONAL ENERGY EFFICIENCY RATIO (seasonal overall) air conditioner BTU / hour divided by SEER number = W consumed from a scientific notation view, the SEER has units of BTU / WATT
EER = 3.41214

[bcroe]

Had some more, but the program won't accept it. Bruce

[J.P.M.]

Got my first Natural Gas Bill from National Grid... boy I was misinformed...

Gas Supply is 42 cents per Therm
BUT
DELIVERY FEE
NY STATE FEES
SURCHARGES
and bunch of other BS fees
Brings it up to 1.23$ per THERM

so at 1.23$ per therm at bare minimum (a rate that will always go up like everything else)
the calculations of Gas vs Solar is much more doable if the electricity is used well
Heat Pump plus a very efficient tankless boiler (this I still have to consider if I want gas or electric) if I go above 25KW then for sure electric but at 20KW solar system in NY I think Gas boiler still the way to go.

Lennox XP25 COP is between 1.8 to 3.3 or so depending on the size of the system, furnace, air-handler, temperature etc


so Gas BTU costs close to 1$
Heatpump BTU from solar electric of 5-7cents at COP around 2.2 is close in price

considering NG prices going up, even if not supply the delivery & taxes will go up and my solar system will be paid for in 5-7 years it will be more of a Free solar vs NG at 1.5$-2$ per therm sooner or later.

I need help choosing the best HVAC/Boiler for my house.
had 4 HVAC guys and companies estimates from $15K to 40K$ all different units and stuff... I can not trust any of them yet.
it is hard to find a true professional HVAC guy who know what they are talking about and cares enough to calculate the cheapest system that gets my job done.

another concern I have with tankless high efficiency boilers is how fast can they heat the house. to my understanding these units work well when they heat up the house slowly and keep it there vs my old boiler with tank that would release all the energy in the house in 15 min and we would jump from 55 to 65F in 30 min or so.

Thank you all for educating a first time homeowner... there is a lot to learn and If I do not learn it for myself I will be taken advantage by the contractors who just want the job done and cash out.

On misinformation : Most folks are. Divide the gas bill by # of therms .on bill for $/therm. That's what you work with for current price. The current commodity price of nat. gas is currently somewhat lower than in the past and expected to stay that way for a while (or not ??). Credit fracking. Education rather than relying ion B,S. hearsay works well in these situations as you are finding out.

As for trust, self education is about the best method I've found to attempt to separate fact from B.S. A bit off topic, and a long boring story, but one of several (and probably the chronologically the first) reason I changed careers from peddling to engineering was because I couldn't get straight answers to my technical questions from people I saw as having questionable technical expertise and seemingly equal or more questionable motives. It all started by trying to stay warm in Buffalo in the winter and not go broke doing it. I believe I have some empathy for your situation.

I'd also respectfully suggest you consider most bang for the buck rather than simply "the cheapest system that gets my job done". There is a difference.

Remember: the goal is the most cost effective way to provide energy to a dwelling that meets your goals, whatever thy may be. not solar for its own sake. BTW: The best way to save the planet is to use less of everything, not simply get more of it for what seems like a deal, but may well be no more than a short term cost saving fallacy generated by con men.

On heat pumps: The C.O.P. of heat pumps will drop as the outside temp. drops. This creates a bit of a bit of a problem for heat pumps in cold climates such as yours. Follow this for a 150 words or so: The first, most cost effective way to lower a home's fuel usage for heating (beyond simply lowering the thermostat and putting on a sweater) is to seal the building envelope and insulating the crap out of the outside building envelope. If you do that, one (pleasant) consequence will be that the building will not need heat until a lower outside temp. is reached. That temp., called the balance temp., which has a usual/nominal value for heating of 65 deg. F., may well be lowered by astute and persistent conservation measures (and/or normal or excessive internal heat generation from cooking, lights, hot showers, people, etc, and some passive solar gain - intentional or otherwise). I lowered the balance temp. in my buffalo NY home to ~ 44 F. That's an unusually low balance temp. but possible.

For fast heating of the air in a residence, get forced hot air. heating water and circulating it through "radiators" - actually, the heat comes about half from thermal radiation heat transfer and half from convective heat transfer, +/- some. Same with "radiant" floor heating. I had that in my house in Albuquerque and it felt great on my feet in winter, but I saw or measured no particular benefit as to its efficacy in heating the building.

Here's the point on heat pumps: Bottom line, a lot of sensible, cost effective conservation measures will lower the effective C.O.P (or SEER if you chose to understand that terminology and IMO, it's shortcomings), because the heat pump will not be operating at higher ambient outside temps. where the heat pump C.O.P. will be relatively high. How much will the C.O.P. be lowered and what will that cost ? - depends on the balance temp. At some level of use reduction, the perhaps unintended (because it's unknown) performance penalty - the decreased C.O.P. of the heat pump - will make it less thermodynamically effective and so less cost effective from a seasonal standpoint, and tending to operate mostly or more in the coldest parts of the year, precisely when it will operate at its least efficient or lower/lowest C.O.P. Some of the things the mfg. literature doesn't tell you. I'm not saying heat pumps are bad. For mild(er) climates they can be cost effective and a good choice, particularly when the equipment cost of HVAC is effectively reduced by needing/having only one unit for both heating and cooling. I am saying that as the climate gets colder, they get less cost effective for heating in a non linear way, At some very low outside temp., some units get to an effective C.O.P. of less than one become they may need to heat the coils and get the ice off them via - you guessed it - resistance heating or other measures - but the dwelling still needs heat.

Good luck>

Take what you may want of the above. Scrap the rest.

[CharlieEscCA]

I'm missing something here. If the C.O.P. decreases because the you lowered the balance point, it really shouldn't change whether the heat pump makes sense or not.

If you had not lowered the balance point, sure the heat pump would be more efficient in the temps between the "lower" and "higher" balance temp points, but you would have to use the heat pump, which means more cost vs not having to use the heat pump because you are still above the "lower" balance point temp.

[DanKegel]

... using current construction techniques, and taking reasonable cautions to ensure all sources of combustion inside a dwelling are properly vented, which includes considerations and measures for air for combustion as well as exhaust, and also moist air removal/exchange, ...

Yeah... just trying to point out he needs to do that, in case he's DIYing it. For cautionary tales and advice, see e.g. buildingscience.com/topics/mold (or their other topics).