Electric Tankless Water Heaters

[rockdude]

What is the good and bad of having one based on real life use. Any recommandations on brands and size.

[Birddog]

They are not as good/efficient as gas, but I'm assuming gas is not an option. OTOH, they have come a long way and are greatly improved. The biggest downfall that I know of is that most won't serve as many appliances as as similarly sized gas unit. They are constantly improving though. Lowes carries the Bosch brand.

Birddog

[Lifelover]

I researched and considered them a while back.

As I recall the biggest problem with them comes when you only want a fairly slow flow of warm water.

They all require some minimum flowrate. If you are shaving or washing you hands and you just need a trickle of hot water, they do not respond very well.

Of course they offer Zero supply when there is no electricity. You standard home tank could easily provide you 2 or 3 warm showers hours after loss of power.

Also, they require pretty extensive retrofit (electrically) for an existing home. Not a big deal for new construction. But would require you to run a dedicated circuit for each unit.

If you decide to use one please report back.

[Birddog]

Lifelover reminded, me, they usually have a much higher electrical requirement than a tank type heater. 80 amps or more whereas a tank type is usually around 30.

[RPS]

What is the good and bad of having one based on real life use. Any recommandations on brands and size.New construction or retrofit?

[texbike]

We have a Bosch unit that we've used for the past 6 years.

In 2002 we remodeled a small 1200 square foot home and decided to go with a tankless water heater in order to make the most of the limited space that was available in such a small house. It made sense for us as all of our plumbing for kitchen and bathrooms was within 20 feet of the unit. We mounted the unit under the kitchen sink (which took up very little space and gave us a closet which we desperately needed).

It has worked great and delivers hot water on demand where we need it. However, there have been a couple of issues (cracked heating element and a defective flow rate switch) which led to the unit being replaced once and serviced the other time under warranty.

The unit does take up 4 breakers (not sure of the size) in our electric box and the flowrate does decrease when more than two applications (showers/baths, washing machine, sinks, dishwasher) are on at the same time.

While it has worked well in this application, I'm not sure that I would choose an electric, tankless for a larger house. We have another house that we will be remodeling in the next year and will probably go with a gas tankless this time. There have been a number of rennovations in our neighborhood over the last year that have used the gas units and have mounted them outside of the house instead of inside. It looks like an efficient approach that minimizes the space that is taken up by the unit.

Texbike

[Louis]

If you are considering one primarily to save on energy costs I would investigate a bit how they truly compare to the tank type.

I say that only because my home is all electric (including a pump to get the water from the 350' deep well to the house) and in the spring and fall when neither the A/C nor the heat are required my electric bill is around $35 - $40. That leads me to conclude that having a tank type just sit there most of the time really does not use that much electricity. My tank does not have any "extra" external insulation nor have I gotten around to install pipe insulation near the tank, but I've purchased it and plan on doing it eventually.

A while back I did consider get an electric on-demand type but the extra electrical work required discouraged me.

Good Luck.

[rockdude]

Retrofit. I need to exhange my services panel sometime and at that point it would be ez to get the correct amount of power to the unit. Also, our Hot water heater is 10+ years old, no problems yet but I am sure they are coming.

New construction or retrofit?

My main goal would be to same on my electric bill. I am sure we would have to get one of the larger ones because of the temp of the water coming into the house from the well. I must say, me and my wife don't use much hot water.

[Lifelover]

Retrofit......
My main goal would be to save on my electric bill....... I must say, me and my wife don't use much hot water.


If you don't use much hot water than you most likely are not spending much on heating it.

If you aren't spending much heating it, than you can't save much.

Water heater tanks are well insulated and very efficient.

Ensure you hot water pipes are well insulated and forget about it.

[rePhil]

Wifes relatives own a plumbing company in the midwest. Maybe technology has advanced but when I asked about a year ago he said they had to replace the tankless ones he installed with conventional gas type due to unhappy customers.

[Z3c]

Depending upon what you are doing, you might want to consider adding a solar water heating system to your existing system... Very efficient and pretty simple, no electricity involved, only plumbing.

Scott

[RPS]

Retrofit. I need to exhange my services panel sometime and at that point it would be ez to get the correct amount of power to the unit. Also, our Hot water heater is 10+ years old, no problems yet but I am sure they are coming.If it were me and I could "easily" upgrade the size of the panel, I'd do it anyway -- regardless of whether I went with a tankless system or not. You can never have too much power IMO. ;)

My main goal would be to same on my electric bill. I am sure we would have to get one of the larger ones because of the temp of the water coming into the house from the well. I must say, me and my wife don't use much hot water.The amount of energy to heat water between two temperatures is the same in both cases, so that's not going to make much difference. If replacing one water heater with one tankless, I'll assume all your existing piping would remain in service (i.e. – whole house use), so heat loss from piping should be very similar. Additionally, (and the one I hate most about my house) all the heat in the hot water that is left to cool off in the lines is wasted the same. Therefore, the only advantage I see is the savings associated with heat loss from the tank itself; and if the tank is not too large, is well insulated, and you don't keep the temperature set very high, the amount of energy savings should be relatively low IMO.

Comparing new construction could be a lot different because it allows more design flexibility. Depending on the home’s layout, you could consider multiple single-point applications. And of course that could affect the total power demand considerably and also affect the cost of water piping.

[Blue Jays]

Quick way to get LOTS of hot water for washing bicycles.

[rockdude]

It does not seem like there are many fans of tankless systems. Maybe I will just scratch the idea. I will check into solar assisted water heaters next.

[rwsaunders]

We have used these units with a decent amount of success for the past 10 years or so, but they require either LP or natural gas to operate.

http://www.palomatankless.com

[Blue Jays]

Or go with a gas tankless hot water system.
Plenty of capacity for showers and washing bicycles.

[Tobias]

I will check into solar assisted water heaters next.If you live in an area where you run your air conditioner a lot, you might also ask about preheating water with heat from your AC. As I recall it seems units were made years ago to capture the heat off the compressor. It's free heat and can save energy at the AC too. I don't recall details though, or whether cost effective.

[rockdude]

If you live in an area where you run your air conditioner a lot, you might also ask about preheating water with heat from your AC. As I recall it seems units were made years ago to capture the heat off the compressor. It's free heat and can save energy at the AC too. I don't recall details though, or whether cost effective.

We are very luck, where we live there is no need for a AC. We are working on getting the house insutlated to the point where we only need to use our Wood Buring stove for heat. May not happen because of all of our windows.

[girlie]

www.houseneeds.com

My mom sells them...M,T,R 866-432-8123 x5534 Nancy.

Starting January 1, 2009 there will be an energy credit of $300.00 when you file your federal income tax.

If you call tell her you are from the bike forum......she will give you all the ups and downs....sitting at home chatting with her now:)

girlie

[RPS]

If you live in an area where you run your air conditioner a lot, you might also ask about preheating water with heat from your AC. As I recall it seems units were made years ago to capture the heat off the compressor. It's free heat and can save energy at the AC too. I don't recall details though, or whether cost effective.They are/were called Heat Recovery Units. I looked at one to help heat a swimming pool in Florida because it would also reduce the cost of air conditioning. It's basically a heat exchanger that helps cool the freon in a central AC's condenser unit (the unit outside). In my case it was too expensive to install because the air conditioner and pool piping were on opposite ends of the house.

[Louis]

They are/were called Heat Recovery Units. I looked at one to help heat a swimming pool in Florida

RPS,

That's interesting. Over the year how much of an overlap is there between the time you need to cool the house with the A/C yet heat the pool?

Louis

[RPS]

RPS,

That's interesting. Over the year how much of an overlap is there between the time you need to cool the house with the A/C yet heat the pool?

LouisGreat question Louis. Depends a lot on your tolerance for "cold" water in the pool. After the first year or two, my wife and I found ourselves only using the pool about 3 or maybe 4 months a year -- the kids a little more. For us to enjoy the pool the water had to be at least 84F and sunny. When it got in the high 80s then it felt perfect.

In the Orlando area where we lived we ran our AC most of the year -- but about 9 months fairly steady. During winter sometimes but not as much (we wouldn't have used the pool in winter anyway).

Had the HRU worked as advertised, we could have extended the use of the pool about 2 or 3 months a year -- almost doubling its use.

[rwsaunders]

If you live in an area where you run your air conditioner a lot, you might also ask about preheating water with heat from your AC. As I recall it seems units were made years ago to capture the heat off the compressor. It's free heat and can save energy at the AC too. I don't recall details though, or whether cost effective.

We have used heat exchangers with geothermal systems for heating swimming pool water (for our clients). The units range from $3,500 to $5,000, so calculate your energy cost for heating your pool and most likely your payback should be 3-5 years.