Electric vs. LP gas water heaters

[Kaleva]

I'm remodeling an old, two story Victorian home with an attic and full basement (when one is walking back and forth from the basement to the attic, it's a FRICKING 4 story house). My question has to do with what kind of water heater I ought to put in. Electric or LP gas (natural gas is not available).

The home will have a kitchen on the main floor with a combination full bath and laundry room above it on the 2nd floor. On the other side of the house, there will be a half bath on the main floor with the master bathroom above it on the second floor. Three people will be living there with as many as six when the older kids visit when they are home from college.

Some info:

Incoming water temp. is 40 degrees F.
Desired water temp is 120 degrees F.

1 gal. of water weighs 8.35 lbs.
1 btu is the amount of energy required to raise 1 lb. of water 1 degree F.
1 kwh = 3413 btu's
1 gal. of LP gas = 95,475 btu's
1 gal. of LP gas costs $1.99
1 kwh costs .07120

Below is the Energy Factor and approximate costs of Bradford White LP gas storage, electric and on demand LP gas water heaters:

Electric storage-.93
LP gas storage-.62
LP gas on demand-.82

Cost of electric storage-$400.00 to $500.00
Cost of LP gas storage-$400.00 to $500.00
Cost of LP gas on demand-about $1200.00

To raise the temperature of 40 gals. of water 80 degrees (from 40 deg. to the desired 120 degrees), it would be cheaper to use an electric storage water heater compared to an LP gas storage water heater. The on demand gas water heater may be cheaper to operate in the long run but the initial cost is much higher. I'm also thinking of putting in two separate water heaters to reduce the long hot water piping. One heater to service the kitchen and combination full bath and laundry room while the other serves the half bathroom and master bathroom.

From what I've read, it's the energy required to heat the cold water to the desired temp. that makes up the majority of the operating cost. So, I was thinking of tieing in the two water heaters together. The output of each will be tee'd to the input of each thus mixing the 40 degree cold water input with the 120 degree hot water from the other water heater. Check valves will be installed to prevent cold water from mixing in with the output hot water.

I'd be very appreciative if anyone here would look over my numbers and ideas and provide feed back.

P.S. I've always heard that it's cheaper to use a gas water heater then an electric heater but from what I see, that may not always be the case so I believe this post warrants being in this topic forum.

[Warpy]

1. Another thing to consider when thinking of a tankless, on demand

water heater is replacement cost. Since they last 4-5 times as long as tank water heaters do, that is in their favor.

Piped natural gas is cheaper than electric which is cheaper than LP.

I'd probably go with electric, either tank or on demand, and think about putting a few solar panels up to help eventually.

About all I'd consider using LP for is heat and cooking and I'd have a wood stove backup for both.

[Kaleva]

6. People not checking and replacing the anodes is a big reason why storage heaters don't last.

[naaman fletcher]

2. neither..

get one of those instant on hot water thingies. Why pay to keep all that water warm at 3am?

[RC]

3. You still have to pay to heat the water, but the hot water will also be mixed with

the cold when you use it, thus you will have warm, not hot water, for the same cost of hot water.

"The output of each will be tee'd to the input of each thus mixing the 40 degree cold water input with the 120 degree hot water from the other water heater."

[Kaleva]

5. You're right. I'll have to put in check valves.

Edited the Op to say that.

[conscious evolution]

7. I agree.

I lived in a place that had two gas WH's tied together.Not worth the extra gas cost.
Two WH's are not a bad idea,just make sure they are seperated.Your idea of using one for each zone is not a bad idea.Something to consider-The kitchen/laundry WH can be smaller then a standard WH as these areas do not use as much hot water as bathrooms do.

I would recommend a gas tankless over an electric tankless.Electric tankless heaters require a lot of power to operate.If your electrical panel and service feed is not big enough it will cost quite a bit to upgrade.
My second rec would be a electric tank heater or heaters.You can put a timer on them and shut them off at night and save on power.

[madrchsod]

4. the price of lp compared to electricity over the life of the heater

it would seem the price of lp would fluctuate more than electrical rate.

[kristopher]

8. What kind of heating system do you have/plan?

It might make economic sense to integrate the heating/hot water systems.

http://hes.lbl.gov/hes/makingithappen/nrr.html

See:
Combined (Indirect) Hot Water & Heating Systems
Combined (Integrated) Space & Water Heating

In the future, hot water systems will provide one means of energy storage for renewables.

Currently the gas options are going to result in fewer GHG emissions.

[Kaleva]

10. I put in a fuel oil hot air system for 3 reasons

1. The old system was fuel oil so the tanks were already in the basement.

2. Drywall dust doesn't play havoc on a fuel furnace as it could on a gas furnace. Some manufacturers will void the warranty on a gas furnace if they find drywall dust in the furnace.

3. The output air temperature of a fuel oil furnace is much higher then the output air of a high efficiency gas furnace. 180 degrees compared to approx. 110 degrees. The trunk line to the upstairs zone is rather long and I didn't want the air coming out of the registers to be cool. 80 to 90 degree moving air feels cool to a person.

The original system was steam with the old fashioned cast iron radiators but I went with air so I can put in air conditioning, whole house humidification, and high efficiency air filtration.

The upstairs will be zoned separately from the main floor by the use of dampers in the trunk lines.

The upstairs registors will be mounted in the ceilings near the outside walls. The vanes are such that 2/3d's of the output air will be directed along the outside walls and windows while 1/3rd will be directed toward the inside walls.

The bedrooms, living room, dining room and kitchen will have reversible ceiling fans.

I have sealed as much of the duct work joints as I can with mastic or foil tape to prevent air leakage and insulated the upstairs trunk line. The individual heat runs coming off the trunk lines are insulated flex duct.

The walls now have R-19 insulation and the attic will have R-60 blown insulation.

I'll be putting in jump ducts from the bedrooms to the upstairs hall to equalize the pressure in the upstairs. There will be a single 20 X 20 inch return register in a wall near the bottom of the stairway.

[kristopher]

12. I'd look into the possibility of integrating a boiler...

A quick call to the installer should clarify the potential.

Sounds like you're going to have a nice place; congratulations.

[HillbillyBob]

9. Do you live in a freezing zone?

If not a solar water heater panel, which yes does cost to install, but no fuel costs or used as a pre heater and an inline lp would be a good economic and ecologic if you have a south facing slope on the roof and dont have a problem with an association or zone rules.

We live where it freezes, so we will be installing an solar closed loop system I have the heater part, I have to build a structure because we will be replacine rebuilding the roof before too long.

The closed loop set up we have heats 25 gallons of antifreese(non toxic kind and will produce temps up to 180, that will be piped through a heat exchanger in the electric 50 gallon tank which can then boost at need.

It is also big enough to heat a second tank for infloor radiant heat. We plan to use solar electric panels to run the circ pumps.

[Kaleva]

11. Solar is very rare where I live. Some have geo-thermal systems but that's pricey.

[HillbillyBob]

14. Just because it is rare does not elminate the option

Solar is coming down in price and availability and a lot of systems are diy now. As for orientating solar water heating is more forgiving that solar electric which needs to be oriented due South and your latitude + 10 degrees.
So if you are at 45 degrees lat you would want 55 for solar electric.
Solar water you can have 35 to 50 degree tilt facing up to a few degrees east or west.
I would suggest a closed loop, but you could also use what is called a drain back which requires another tank or expansion room to let the water drain back.

The system I have has an integrated tank but was intended for a non freeze area and the type of evac tubes hold water so instead of an open loop it will be a close loop using a non toxic antifreeze solution, require fluid change at 5 to 15 yrs intervals. The longer interval is when you use purified water as your mixer.
We have a modular house so putting it on the roof is out it has to be a free standing structure next to the house. The roof is supposed to be able to take it, but we have to redo the roof in the next year or 2 so I don't want to put it up then have to take it back down.
At any rate you could save $ over the long run since solar water heating seems to last at the very least 20 yrs, and in summer you would likely not need the energy eating heaters to come on.

[Kaleva]

15. I don't know how well the unit would work covered in snow.

And I don't think my wife would go for a free standing unit next to the house. Plus, there are several large oaks and maple trees lining the street near the home.

[trof]

13. We added a solar water heating system 2 years ago.

The cost was about $5000 minus a $1500 tax credit.
One 4' X 10' collector on the roof and an 80 gal. storage tank hooked into our 50 gal electric water heater.
Collector is self draining if temps approach freezing.

I know you're in a colder climate than I am, but even on our coldest days (30s) I'm still cranking out 90-100 degrees at the collector.
Highest recorded water temp in warmer months is about 145F.
As long as solar water is above 120, our electric heater doesn't kick in.
Good luck.

[madokie]

16. We have electric

and my reasoning is that a gas heater has a flue that is drawing air our of your house all the time whether the water heater is on or not so that air has to come from somewhere so it comes in around the light fixtures around doors and windows etc. causing it to feel a little drafty at times.