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JeanneJ
Electric Tankless Water Heaters
JeanneJ

I live in a single family home in Texas. The home I all electric. We will soon be replacing the water heater. Currently we have 50 gallon. I'm thinking of replacing it with a Tankless. Can anyone tell how a Tankless performs when compared with a conventional heater? Any advice would be appreciated.

ed21
Re: Electric Tankless Water Heaters
ed21

Tankless electric water heaters take a lot of juice to heat the water. You might need an electric service upgrade. They sometimes can't heat the water enough. The extra cost of the unit and service upgrade will take a long time to break even compared to a tank heater. Chances are you will need a new tankless before then.
Does your 50 gal provide enough water? Mine was good enough even when there were five people in the house.

keith3267
Re: Electric Tankless Water Heaters
keith3267

These should be banned from the market place. It only costs about $3/month to maintain 50 gallons of hot water, the rest goes into the heating of the water itself and that won't change by going tankless.

You may have to upgrade your service panel to handle the power these things need, but even then, it still may not heat water fast enough for you. These draw so much current (about 90 amps) that the will load down the distribution transformer serving your house.

If you have a transformer that serves your house only, it is probably a 15kVA which will supply 62.5 amps at 240 VAC. As it goes over 62.5 amps, the voltage from the transformer will drop, causing lights to dim etc. To overcome this, the local utility will have to install a larger transformer and they may not be willing to do this for two reasons, one is the initial cost of a new transformer, especially a larger one and then the increased costs of the no-load losses, also known as iron losses. These losses are before your meter so the utility has to absorb them and that would ultimately increase utility costs for all the customers, not just you.

If you have a transformer that serves several houses, it will be larger and less affected when the tankless water heater kicks on, unless the other customers are also using high current appliances at the time, like AC units or kitchen stoves, or their water heaters.

If you want to save on your electric bill, you could get a heat pump for your water heater, but they are very expensive and payback is almost non existent at this time. A good well insulated conventional electric water heater will be your least life cycle cost option when all costs are considered.

Mastercarpentry
Re: Electric Tankless Water Heaters
Mastercarpentry

You might also want to consider gas, either natural or LP. LP costs vary wildly but sometimes you can get it at better prices than you'd pay for electric and since you're going to replace the WH soon anyway it's worth considering all possibilities, not just one. There's a rarely seen or used benefit to a tank-type WH and it is having that many gallons of water on hand for emergencies should you experience a long-term service interruption. Even just 30 gallons will flush a toilet many times and when you really need that the value is immeasurable!

Phil

ordjen
Re: Electric Tankless Water Heaters
ordjen

Good points all. Too often we focus on the immediate operational "savings", forgetting the real costs and payback periods.

About 20 years ago I had to replace my furnace. A 87% furnace would have run about $1400. A 96% efficient furnace would have run about $1000 more. At the then cost of natral gas, the payback period would have been about 20 years! Further, to get those high efficiencies, expensive electronic parts are used. When the furnace fails, it is not some cheap flame rod, but some circuit board costing hundreds of dollars. Not to mention a mandatory service call because the furnace innards now look like the engine compartment of your car!

The super efficient furnace now uses outside air for combustion. This means that the furnace is not simultaneously changing the household air and sending it up the flue. So, the household air becomes stale. Now the wife opens the windows to "get some fresh air". So much for efficiency! Of course, you can install an electric air exchange unit. There goes your imagined savings again!

HoustonRemodeler
Re: Electric Tankless Water Heaters
HoustonRemodeler

I have two 70 amp on demand heaters sitting in my workshop we pulled out of a new construction. They didn't work as thought, and had the side effect of causing severe voltage drops when the turned themselves on.

Fencepost
Re: Electric Tankless Water Heaters
Fencepost

Another myth of on-demand heaters is that they reduce the need to build more power plants. In reality, if everyone who had an electric tank water heater switch to electric on-demand, we'd need to replace our entire electric grid and build even more power plants! That's because you can't plan your power grid based on average demand, but on peak demand. Where a tank water heater might have an instantaneous demand of only 20A, a demand heater requires three times that. So in the morning when everyone in the city is showering, the peak demand is higher than ever, even though the total energy use is lower

MSSP
Re: Electric Tankless Water Heaters
MSSP

Electric tankless are no good. Stay with your 50 gallon electric tank heater. You will be much happier in the end,

ed21
Re: Electric Tankless Water Heaters
ed21

Just to add to the don't do it crowd. I had a client that wanted small on demand heaters in the rest rooms in order to eliminate complaints about cold water. It didn't take very long to find out they were a maintenance problem and the heaters only lasted about five years anyway. For some reason installation often seemed to be problematic.

sissy
Re: Electric Tankless Water Heaters
sissy

I have an all electric home in VA and went with a propane tankless .I got one that is stainless steel inside and it has a tiny reserve tank in it

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