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# Thread: What are some of the drawbacks of switching over from gas WH to Electric?

1. What you need are the amount of BTU/therm (100000), and watts/BTU (3.412142). Then, look at the local utility rates. You'll quickly see that (at least in NH), gas is a lot cheaper to heat with. I haven't run the numbers recently, but all of the conversions needed have been posted here, or are available with a quick search on the web. You have your utility bills, and can find the cost/unit.

The caulk they used might be the source of the smell.

What you need are the amount of BTU/therm (100000), and watts/BTU (3.412142). Then, look at the local utility rates. You'll quickly see that (at least in NH), gas is a lot cheaper to heat with. I haven't run the numbers recently, but all of the conversions needed have been posted here, or are available with a quick search on the web. You have your utility bills, and can find the cost/unit.

The caulk they used might be the source of the smell.

'ceptin' you need to multiply the therms by the operational efficiency of the heater to get the DELIVERED BTUs. Typically 90% of the kwh used in tank heater end up as hot water entering your plumbing, whereas with gas fired tanks 60% is more the norm. For every therm used, figure you get only 600000BTUs (0.6 therms) out of the tank, and for every kwh used you get 0.9kwh out of the tank. So if you're paying \$1/therm you're getting 60,000 BTUs/\$. The same 60000BTUs would be delivered using 60000/(3413 x 0.9)= 19.5kwh So it takes 5.1cent's kwh to be cost-competitive with \$1/therm gas.

Do your own math with your own utility rates, but rare is the market where NG is a cheaper way to heat hot water. If you live in 5cents/kwh land maybe... (In my neighborhood heating water with electricity vs. gas in a bottom-of-the-line efficiency gas tank is a 3x cost multiplier!)

Putting an electric hot water tank on a timer has an almost vanishingly small effect on how much you pay, unless it's a big tank and your billing arrangement with the utility is peak-demand or time-of-day metered, and you heat it up only with cheap off-peak kwh, coasting through peak demand periods. Standby losses add up to about 0.5-1kwh over a 10 hour period and doesn't drop appreciably until the temperature of the tank is 10s of degrees cooler, which doesn't happen overnight. The vast majority of that small bit of power you didn't use in the off period gets spent bringing the tank back up to temp. The bulk of the energy spent in electric tanks is getting the 45-60F water up to 120F+. If you saved more than 0.1kwh/day (35kwh/year) you'd be lucky. That's less than \$10/year except in extreme electric rate situtaions (tiny oil-fired isolated-grid island utilities, etc.)

Still, nickel kwhs are rare, \$1 therms common... What it is in your neighborhood is on the utility bills.

3. Dana-

I'm not sure but are you making a case for the electric hot water heater over the NG one?

4. Originally Posted by vtxdude
Dana-

I'm not sure but are you making a case for the electric hot water heater over the NG one?
Do the math, you decide what makes sense for you.

For ME electric makes absolutely no sense at all!!! It would cost me at least 3x as much to heat with hot water (since I'm heating with ~80% efficiency using the heating system, not in a cheapo standalone tank at 60% efficiency), and electric would give me much slower recovery times etc. etc.

I'm just sayin' to do the math correctly you have to apply the proper efficiency factors, not just the raw fuel-energy equivalents, so that you can compare apples to apples, gallons of HW to gallons of HW, for what price. 1kwh=3413 BTUs only in a lab, not at the output of a hot water heating appliance. But even though the typical gas water heater is sending 40% up the flue and into the surrounding air rather than in the water vs. 10% in the electric tank case, gas is still a heluva lot cheaper in most places.

Put it this way: If you're paying a buck/therm for gas, you'd need to have 5 cent/kwh or less electric rates to be cost competitive with gas.

...or...

If you're paying the national average of ~12cents/kwh, gas would have to cost \$2.40/therm or less to beat electricity on cost.

This year my electricity is over 15cents/kwh and my gas is about a buck a therm year. I've not paid less than 12 cents/kwh in nearly 20 years, and I've NEVER paid over \$1.75/therm. Never has electric hot water heating been any less than twice as expensive as gas hot water heating in my location. YMMV.

Without knowing your local prices, there's no way of telling what would be the cheaper option for you. But in the vast majority of the US, gas is going to be a MUCH cheaper way to heat hot water- it's not even close. But it might be if your electric rates are exceptionally low, and your gas rates significantly higher than average.

5. Dana, you had a typo in your post, so it looks like you are saying electric is cheaper...

6. I'm at about 0.07/kwh here. Electric is easier and not much more expensive. I may switch to gas (at least for heating). I have an electric furnace. That thing kills my wallet as it is. I would really hate to be paying 0.15/kwh with that thing!

Dana, you had a typo in your post, so it looks like you are saying electric is cheaper...
DOH!?! (Should I correct it, or leave it for posterity? :-) )

Do the math, and it'll tell ya what to do, indpendent of my fingers tripping over themselves on the keyboard...

Nukeman- I'd think in Lynchburg you could do pretty well with an air-source heat pump for both heat & AC, which should be considerably cheaper to run than gas if your rates stay that low- less than half what you're paying now. (I'd definitely look at it if I had your utility rates.)

8. Originally Posted by nukeman
I'm at about 0.07/kwh here. Electric is easier and not much more expensive. I may switch to gas (at least for heating). I have an electric furnace. That thing kills my wallet as it is. I would really hate to be paying 0.15/kwh with that thing!
We are up to about 0.12/kwh here. We hit 0.14-0.15/kwh when I was in Texas.

Gas is running about 0.75/therm here this winter, but about ~\$1/therm is normal.

9. Our neighbors use a geothermal heatpump and they also have a gas furnace. They are older people (80+) and keep in really warm in there. I was in their house last Feb. and I was sweating with a T-shirt. lol

What I don't like about heat pumps is the low air temperature they put out. It would be easy to install one as I already have central AC.

To give you an idea, the peak that the two of us have used is about 4400 kwh in one month. LOL That is not heating upstairs for the most part, turning off heat at night and when away, and keeping the main floor at like 67F. We have since added a layer of R30 to the attic and the peak since that time has been more like 3300 kwh. House is a bit over 3000sq.ft, 40 years old, single pane glass.

If I kept the whole house toasty all of the time, I would probably have a \$600 electric bill. At 0.15/kwh, I bet I could hit \$1000+! ouch!

At least our winters are short and mild for the most part. There is less than 3 months of significant heating. I am remodeling the basement now, so it would be probably the best time for running a flue for a HE gas furnace if I were to go that route. Only thing that I don't like about gas is paying for having the service during all the months where I am not using any gas. Not a big deal, but something to consider.

Kent

10. Originally Posted by vtxdude
No I believe you!!! maybe I am missing what you are saying....so let me ask this....the water heater appears to be drafting correctly....but I still get some sort of smell after it has been running for a few minutes...flame in sight window seems a bit lazy....seems to be soot under hood a bit....and the combustion smell

Could it still have all these things and be burning correctly? I'm not being wise here..I am asking an honest question
You were missing what I was saying because I was saying that just because your CO detectors weren't going off doesn't mean you weren't getting spillage as a properly burning appliance won't be producing CO to trip your detectors.

I'm glad you go this problem fixed.

11. I'm looking at my last electric bill from PSNH.....I think when I add it all up it comes close to .15 cents a kwh

12. Originally Posted by Doherty Plumbing
You were missing what I was saying because I was saying that just because your CO detectors weren't going off doesn't mean you weren't getting spillage as a properly burning appliance won't be producing CO to trip your detectors.

I'm glad you go this problem fixed.
Gottcha...so I could still have spillage but if the burner is burning correctly the spillage won't be containing CO

Well problem not fixed really other than negative air pressure is gone....still have smell..my last ditch effort before going to electric may be to have my venting re run with new pipes.......the plumbers before the HVAC guys put foil tape around all the joints which had this ick smelling adhesive...the HVAC guys said that tape isn't meant for vent pipes but for duct work sealing holes etc.....they peeled it off but the residue form the adhesive is still on the pipes in a lot of spots..they then put the fire proof caulking on the joints...from what i have read none of this is really necessary...the smell I'm getting is similar to the adhesive but I would have thought it would have cooked off by now

Worth having new vent pipes put in to rule that out?

Do any of you use the foil tape on the connections of the pipe?

13. Originally Posted by vtxdude
Gottcha...so I could still have spillage but if the burner is burning correctly the spillage won't be containing CO

Well problem not fixed really other than negative air pressure is gone....still have smell..my last ditch effort before going to electric may be to have my venting re run with new pipes.......the plumbers before the HVAC guys put foil tape around all the joints which had this ick smelling adhesive...the HVAC guys said that tape isn't meant for vent pipes but for duct work sealing holes etc.....they peeled it off but the residue form the adhesive is still on the pipes in a lot of spots..they then put the fire proof caulking on the joints...from what i have read none of this is really necessary...the smell I'm getting is similar to the adhesive but I would have thought it would have cooked off by now

Worth having new vent pipes put in to rule that out?

Do any of you use the foil tape on the connections of the pipe?
The "HVAC guy" doesn't seem to know much about how a vent works and drafting. If a vent is working properly it should be PULLING IN air to the venting system not spilling it out of small holes here or there.

See venting works on buoyancy. The hot flue gases are lighter then the cold dense air in the room around them so they want to rise. So they go up the vent and as they do this they heat the vent up. Because the vent is warmer then the air around it the vent naturally wants to draw in air because of the differences in buoyancy in the air.

So if you're getting spillage in the vent connectors like you are it's not because you have a few holes here and there. It's because you aren't getting the differences in buoyancy you need to create proper drafting of flue gases through the vent.

Vents like to go straight up off appliances not horizontal for 8' 1st then up. Especially when you are going up, over, up, over and then up again. I'm afraid you have a poorly designed venting system.

14. Originally Posted by nukeman
Our neighbors use a geothermal heatpump and they also have a gas furnace. They are older people (80+) and keep in really warm in there. I was in their house last Feb. and I was sweating with a T-shirt. lol
Do they keep it at 60 F in the summer? I've seen this a few times and scratch my head over why folks will try to grow icecicles indoors in summer, and scorch the wallpaper in winter. I run about 80 in summer, 69 set point in winter (corresponsing to 66-67 F through most of the home...except the central hall above the main ductwork where the thermostat is located.)

What I don't like about heat pumps is the low air temperature they put out. It would be easy to install one as I already have central AC.
That's a concern I've had as well. I would want gas back up. Electrical strip heaters are thermodynamically inefficient for fossil fuels. Electrical generation efficiency here is tied to the old coal plant nearby...less than 35% thermal efficiency for the delivered juice. An 80% efficiency furnace clobbers a strip heater in that regard.

The other factor for me is that where I grew up we had blizzards every 5 years or so that would knock out electric from a few days to a week. We had a nice 1930's (?) era Autocrat wood cookrange/oven and a large fireplace, plus a single large propane heater, so it really didn't hurt us other than being stuck with kerosene lamps and candles and needing to move some refrigerator items to a cooler on the back porch. I've since experienced this sort of long electrical outage even in ice storms in the city down in Texas. With a generator it should be possible to run the furnace at least periodically in a northern climate. I plan to install a panel in the next year or two so that I can run the furnace and a few other circuits this way as needed.

To give you an idea, the peak that the two of us have used is about 4400 kwh in one month. LOL That is not heating upstairs for the most part, turning off heat at night and when away, and keeping the main floor at like 67F. We have since added a layer of R30 to the attic and the peak since that time has been more like 3300 kwh. House is a bit over 3000sq.ft, 40 years old, single pane glass.
Ouch, that's over half my annual electrical use. If you normally use 1,000 kwh in a non-heating/non-cooling month then that would be perhaps 7 HSPF or 3400 kwh * 7 = 23.8 million Btu. With an 80% gas furnace this would be 23,800,000/0.8/100,000 Btu/ccf ~ 300 ccf natural gas per month! That assumes I've done the calcs correctly...but I've never had a heat pump so I might be way off.

Gas or electric for the water heater? I assume electric since you mention not having any gas payment unless you install a gas furnace.

Lynchburg's average daily temps are about 7 F higher than ours from Dec-Feb. We are heating about 2800 sq. feet...and unfortunately, due to missing insulation between the spaces, a three car garage as well...though not intentionally...and not permanently. Our gas use should peak under 200 ccf/month this year, down from about 230 last year barring a much colder month this year. The 7 F difference is worth about 30 ccf/month, perhaps more, based on my empirical furnace model.

I want to install a sealed combustion high efficiency two stage furnace to knock about 15% more off. And I need to insulate the ceiling of the large garage cutting another 7-15%. I've already remedied several uninsulated spaces, greatly improving the comfort of several rooms, plus saving energy. Sealed combustion will allow me to complete my sealing of various air infiltration penetrations into the utility space and reduce other infiltration routes as well.

Only thing that I don't like about gas is paying for having the service during all the months where I am not using any gas. Not a big deal, but something to consider.
Yes, this is a considerable cost adder when going from no gas, to some gas. I had this same problem down in southern Georgia. We had about 0.08/kwh electric, an electric water heater, and high efficiency outdoor gas furnace. Why it still had an electric water heater I do now know, I was just renting temporarily. The electric water heater plus monthly gas hook up charge was the worst of both worlds during cooling season.

If I was to set up a home today from scratch I would go with gas water heating (storage...perhaps condensing), gas furnace (condensing, sealed combustion), and a gas clothes dryer. I would probably also set up an 8 month/year passive solar water heater loop. I suppose if money was no object I would use a ground source heat pump, passive solar water heat, and PV solar instead of the above. It's debatable whether it would make sense to then use gas for water heating and the dryer. My wife would like a gas range too...and I would like one for some wok recipes and Indian food--wouldn't have to use the big burner and lilttle propane cylinder outside anymore.

15. We have big swings in our bill. In case you missed it, we have an electric furnace (not heat pump), so it is nothing but heat strips. The furnace has its own 150A breaker/disconnect. When we bought the home, the inspector saw that breaker and asked if the house had another sub-panel. We said: "We don't think so". Then he looked more and said: "oh, that is just to feed your furnace." I terms of \$\$, we are at \$50-\$70 in non heating/cooling months, ~\$100 in summer, and can easily hit \$300 in winter. Usually run about 78F in summer (control humidity) and about 67F in winter (a bit chilly, but can't afford to really go warmer).

The winter bills are painful, but at least the system is simple and produces nice, warm air. If I went gas, I would go for the 95% type.

Our older neighbors used to live in Ohio. A house that they had there originally had an electric furnace. They dumped that and switched to gas in a hurry when the found the previous owner was using 10,000 kwh/month in the winter!

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