New Electric Water Heater: 1 Large 220v or 2 30 Gallon 120v

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riddick021

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Looking to install a new water heater for my 1000 sqft 2 bathroom home with 3 adults. No gas pipe near by and limited space for required clearance anyway. I've been reading a number of threads about 1 large water heater vs 2 smaller ones. I think most of these threads assume the same heating element and voltage with the only difference being the tank size.

My question is this. Would it be more efficient and faster recovery to use 2 120v 30 gallon units installed in series or just get one 240v larger size tank (not sure of the size I need yet. 3 showers in the morning before work). I might be completely off base here, but I'm assuming I can achieve more efficiency by putting one of the heaters on a timer so it only turns on during the high demand shower times.

Last thing I have gas in the building, but the changes to framing, running the gas pipe, and venting would probably cost more that I could recover in a reasonable amount of time from the savings in switching. Am I right in assuming this?
 

Reach4

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I could maybe see two electric water heaters if they are near different loads. But mostly I would tend to think that 2 would be less efficient because they have more surface area per gallon.
Last thing I have gas in the building, but the changes to framing, running the gas pipe, and venting would probably cost more that I could recover in a reasonable amount of time from the savings in switching. Am I right in assuming this?

It depends. What is a reasonable amount of time? How hard is it to run the gas and exhaust? Do you have an accessible crawl space for running the pipe? I would think that in most cases, for a house occupied year round, the natural gas water heater would pay for itself in a timeframe that I would find reasonable. Some water heaters only need a run of PVC out of a wall for the vent.
 

riddick021

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It depends. What is a reasonable amount of time? How hard is it to run the gas and exhaust? Do you have an accessible crawl space for running the pipe? I would think that in most cases, for a house occupied year round, the natural gas water heater would pay for itself in a timeframe that I would find reasonable. Some water heaters only need a run of PVC out of a wall for the vent.

Reasonable timeframe for me would be within 10 years. We have a crawl space and the gas pipe would need to be run about 15 feet with about 5 elbows. The vent pipe would need to go through 7 or 8 joists to reach an outside wall if using PVC pipe. I already have power at this location and would change the water heater myself for electric. I would hire someone if I decided to switch to gas which I imagine would make things much more expensive. The property is located in western ct.
 

WorthFlorida

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It may not be possible to find a 120 volt water heater in the 30 gal size. If you were thinking that a 120v is easier to install because you might tap into a near by power, you're wrong. All appliances must have their own circuit. To run a 120v line vs a 240v line is the same except wire size and the number of conductors. If you have no expansion room in the electric panel don't bother unless you want to upgrade the electric.

With electric water heaters it takes the same amount of power to heat a given amount of water with 240 or 120 heating elements. The difference is the recovery rate. That is how fast it can bring a given amount of water to temperature. Look at any spec and the recovery rates are always listed. If you can find a 120 volt water heater you would not be happy with the amount of hot water it can supply. The 120 volt water heater might be available for the trailer/camper market where 120 volt is the norm. You'll most likely find "mobile home" listed water heaters and the big difference is the connections are on the side of the tank, not the top because of space restrictions in mobile homes.

You're using the word efficiency incorrectly. With two water heaters and turning off one would result in lower cost. Efficiency is converting power into heat. Gas has an efficiency rating because not 100% of the btu's is converted to heat where as nearly 100% of the electric power is converted to heat. Therefore, electric may be more efficient but may cost more because of the cost of electric vs gas.
 

Jadnashua

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Many times these days, they'd use flexible gas line which can be bent, and not use any fittings except at the ends. Because it is flexible, you need to use more clamps to hold it where you wish and out of the way, but it is fast and easy to install. In most places, NG is far less expensive when heating water, but installation costs might narrow that or eclipse the benefit...it's more of a pay me now, or pay me later thing. Fired WH tend to not last as long as electric. I don't think you'd be very happy with 120vac units, so add in the cost to run new 240vac circuit(s) for the WH. THen, you have to consider if your power panel has enough spare capacity to run two electric WH or not...if not, that upgrade cost could be large as well. In reality, your gas line might not be big enough as is to support two gas WH, either.
 

Master Plumber Mark

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Normally in my area an electric water heater cost about 550 a year to heat the water
and it cost about 250 a year to heat with gas....

An electric water heater installed by a plumber
would cost about 950??

If you were to install a Rheem power vent unit out the side of the house my guess for
a plumber to do the gas work and install probably about 2500.

you will recoup about 250 a year in gas vs electric so do the math
and it depends on when you decide to finally move on.....
 
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