Gas or Electric Tankless Water Heater?

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Jadnashua

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Most electric tankless systems have a quite small gpm output. From an efficiency viewpoint, it really depends on your local utility rates, but for the typical home, gas, if you have it available AND that means a big enough supply line, meter, and regulator, you have a chance of making it a whole-home supply that can feed more than one thing at the same time. An electric one big enough to feed a whole home would likely require significant panel and supply upgrades. They're okay for single point of use, but rarely sufficient for whole home use, at least as Americans use hot water.
 

Dj2

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What did you have until now?

If gas, stay with gas. If electric and if you have gas to the house, switch to gas by doing all the necessary things to do the conversion. If you can't do it, call a plumber.
 

Gary Swart

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Might want to rethink the tankless idea if you will need major electric or gas supply upgrading. Consider also the frequent cleaning and care need for tankless.
 

WorthFlorida

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Jadnashua

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FWIW, a decent sized gas tankless WH is likely in the range of 200K BTU...converting that to watts, that's about 58.6Kw. At 240vac input, that's 244A. Since that load is outrageous, and most people could never support one that big, the things tend to be much smaller, and as a result, have a MUCH smaller hot water temperature rise, OR a much smaller maximum volume (often, both). IMHO, an electric tankless is a joke except for maybe a single point of use (most likely a sink, or a really low-flow shower).

An electric powered TANK WH works because it can take its merry time to reheat the water (assuming you get one big enough to meet your needs - doesn't work well at all for continuous or commercial use where you need continuous hot water).

The two arguments for tankless are: lower standby losses (the newer tanks are often quite good in this respect), and longevity (most people never service their WH, and only replace it when it leaks - try that with a tankless that costs lots more to buy and install and you'll have a useless piece of junk - throw in that there often aren't that many qualified service people for tankless, and the costs often just don't compute.

A third argument is that they are often smaller, and people want or need the room.
 

Dana

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The rate structures under New York's statewide "Energy Vision" utility regulation reforms are going to be changing. So far they are not assessing residential "demand charges" as a means of recovering grid infrastructure costs, but if they ever did an electric tankless would be a signficant financial liability.

If you have the space, an heat pump water heater would use 1/3-1/2 the total power of a standard electric tank, and a peak draw about 1/8 that of an electric tankless, and it would reduce the air conditioning load a small amount. (If it's in a basement, it'll help dehumidify the basement.)

A gas tankless almost always requires installing a dedicated run of 1-1/4" gas line between the tankless and regulator (with no side branches), and sometimes requires upgrading the meter as well, depending on how much other burner you have. It'll buy you some floor space but doesn't buy a whole lot in efficiency.

If your house is heated with a hydronic boiler, the best solution might be installing an indirect hot water heater as another zone on the heating system. The extra load would improve the as-used AFUE of the boiler (which are almost universally way oversized for the space heating load), and would not require upgrading the gas service.

indirect_water_heater.jpg
 
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