Electric Tankless Water Heater

[Rockin RK]

My SIL is building a new house and wants a tankless water heater since the house will be all electric so will the water heater. She will be the only one living thereo no herd of kids to worry about. Does anybody use one or can educate me on the good and bad points of these.

Thanks in advance

Randy

 

[ShenandoahJoe]

The big difference from a tanked water heater is that you can't set the output temperature to whatever you want. With a tank, you can just heat it longer and it gets hotter. In a tankless heater, the critical factor is the difference between the input and output temperature. Be careful that you have the right sized heater for how cold the water gets in your area.

 

[srossman]

I looked at them briefly, but determined that they take a lot of electricity to run. I think it would require a 50 amp breaker in the box to run just one, and the temperature rise wasn't as much as I would have needed. Went with a propane tank-less instead and I really like it.

 

[stratton]

I heard the electric ones are not as efficient as a gas or propane. But still are better then a tank heater. As long as you don't have 5 teenage girls taking long showers every day then tankless is the way to go. Otherwise its just not sensible to use a tankless if they are constantly running. When i was considering a tankless i remember coming across an article that compared the cost savings with them to a tank heater. I believe a family of 4 or 5 with one average shower a day is the limit as far as cost savings with a tankless. Anymore then that it would be better to go with a typical tank heater. The tankless uses a huge amount of energy for a short period of time.

 

[nikdfish]

When we replaced a 16 year old water heater this spring, we went with the GE heat pump water heater (Geo-Spring?). Although it includes resistance elements for backup / supplimental heating, I set it for e-heat mode which prevents the heating elements from ever coming on. We have never run short of hot water. We got it on sale & even adding in a 10 year full coverage warranty we paid more than a hundred less than the list price...

I believe that only heat pump or solar pre-heat systems can really significantly reduce water heating costs. I think the only significant pluses for tankless water heaters is that they take up less space & don't have a tank as a potential point of failure - current well insulated tank models don't lose that much heat on a day to day basis...


Nick

 

[F1520]

Same here. Researched this with my neighbor recently. Electric tankless water heaters take a large amount of current to run. What size service does the house have? Is there also a well pump on the property?

The smallest Stiebel Eltron electric tankless water heater I could find requires 220v/50A and specifies a 60A breaker.

You can research several different brands at pexsupply.com and there are some specs on the different models here: Stiebel Eltron | Tempra Series Technical Data

 

[stratton]

Consumer reports say that it may take 22 years to recoup the cost of putting one of these things in. And the life expectancy is around 20 years, haha nice

Are tankless water heaters a worthwhile investment?

 

[srossman]

When we replaced a 16 year old water heater this spring, we went with the GE heat pump water heater (Geo-Spring?). Although it includes resistance elements for backup / supplimental heating, I set it for e-heat mode which prevents the heating elements from ever coming on. We have never run short of hot water. We got it on sale & even adding in a 10 year full coverage warranty we paid more than a hundred less than the list price...

I believe that only heat pump or solar pre-heat systems can really significantly reduce water heating costs. I think the only significant pluses for tankless water heaters is that they take up less space & don't have a tank as a potential point of failure - current well insulated tank models don't lose that much heat on a day to day basis...


Nick

Nick,
Is that a geo-thermal unit that you put in, or something else?

 

[nikdfish]

Nick,
Is that a geo-thermal unit that you put in, or something else?

No it's not geo-thermal, it pulls heat from the surrounding air. We have it installed in the basement/workshop space. It makes less noise than a dehumidifier. Power consumption is less than resistance heating as long as the ambient temp around the unit is above 45F. Even if unheated & unused for a while, I don't believe that space ever drops below the mid to upper 50's. Power draw in e-heat mode is like 550 watts.


Nick

 

[dmccarty]

We looked at electric tankless water heaters when we built our house 6 years ago. We have a nice big 80 gallon tank heater. :laughing: We bought the best insulated tank we could find.

The problems back then with electric tankless water heaters:
- Cost.
- Getting the output temperature from the supply temp could be a problem depending on flow rates.
- At the time the electric tankless heaters did not seem to work for what we needed or thought we need.

So we went a bought a good quality tank. I still would like to put in a solar hot water system but that seems iffy money wise on the payback.

Later,
Dan

 

[mjarrels]

Had one in the Philippines, 220 volt. Incoming water not that cold, hated hitting that switch while standing in the shower.

mark

 

[JimRB]

I have a geothermal heat pump with a waste heat hot water generator. My 220v to the hot water heater is turned off about 4 months of the year. I live near Atlanta Georgia so I use a fair bit of AC. When it gets cold the generator does a fairly good job of heating up the water but not nearly as hot as in the summer. 2 people in the house. You can get those hot water generators with a standard AC or heat pump also. Note that I do not have booster heat and the geothermal keeps up ok on those rare 10F days.

 

[kenmac]

For worry & virtually maintance free, less expensive to repair. I would choose a tank over tankless anyday. Your call

 

[Kays Supply]

An issue not discussed is maintenance, If you live in an area that adds multiple chemicals to the water , or the water is just naturally hard, the heater requires a yearly cleaning. To hire me to do it runs about $200. If the heater isn't installed with correct fittings the first cleaning could be $300 plus. Add that into the mix and see if it will ever payoff. I have all but refused to connect them. I put the pipes out of the wall and leave it for the homeowner. When they don't function like they expect, I don't want the call back. Most of my customers want to have a recirculating pump installed. That is a real problem with the tankless. That's my 2 cents worth.

 

[kenmac]

Several years ago. I went to a Rheem tankless class. At that time they were recommending 6 mo to 1 yr for servicing

 

[PILOON]

I somewhere read that they could be OK if you don't have a high temp spread.
Seem to recall that 40 deg was the ideal spread.

If taking cold ground water (40 deg?) it won't be efficient due to spread, but heating southern shallow pipe water should be efficient as would be taking water from an above ground cistern which would be ambient air temp.

Also if in a northern climate and you have a power failure, better be quick at draining it as the thin copper tank will burst real quick and you'll be needing a replacement.

 

[studor]

If you do not have propane, natural gas or your own windmill or solar plant, tankless is a last choice. The energy consumption to heat requires very large draws and unless you want to use your electric meter as a fan, as others have said, get a tank. I looked long at tankless a few years ago when rebuilding a log cabin and decided that the additional cost for the heater, panel upgrade, wire etc far outweighed the three hundred bucks for a good tank and the cost to run it over five years or so-- JMHO

 

[Alan L.]

If I was all electric I would go for a good tank model. I have a propane tankless that works fine, but it cost alot more than a regular water heater and doesn't save much if any energy. Seems like it burns about $30 of propane per month. During my research my impression was that the electronic ones need a ton of juice to do their job.

On the positives side, my wife can fill her 85 gallon tub and I can shower as long as I want without running out of hot water. On the down side, there is a filter I need to clean out once a month or so, otherwise the hot water flow is noticeably reduced.

The biggest mistake I made was only putting one in the house. The kitchen is about 50 feet away and it takes quite a while to get hot water there.

The best thing is its in an outside wall and takes up zero space.

 

[Obed]

We stayed at a friend's new house that had a tankless water heater. You had to turn on the faucets almost full blast in order to get hot water to come out. The tankless water heaters will not heat water unless the water flowing through the water heater is at a high enough volume. We had considered getting a tankless water heater until experiencing the flow rate issue. We often use hot water at a low flow rate while washing at the sink, rinsing dishes, etc. If you have to have the faucet wide open, you will use a lot more hot water than otherwise.

For the house we are currently building, we are looking at a 60 gallon natural gas water heater with a 7 day timer for turning off the hot water heater at night. There's a significant distance between our water heater and the bathrooms; we'll have to see how long we have to run the water to get hot water to the bathrooms. If it takes too long, we might just add a 2.5 or 6 gallon water heater close to the bathrooms. The small tank would provide for immediate hot water for washing at the sink. For baths, once the hot water in the small tank is used up, the water from the 60 gallon tank will have reached the bath.

 

[Jim in ICT]

Had a Rinnai installed three years ago when we built the house. Runs off of Natural gas using city water. Sized large enough that we can have 2-1/2 showers going at once and not run out of hot water. Witha a family of four and three bathrooms available, it's rare that we have more than one going at any one time. Warmup to the showerhead is a bit longer than I'd like, but part of that is the manner in which the manifold and Pex tubing is routed. Overall, no issues or problems with it.