electric tankless water heater problem

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  #1  
Old 12-21-04, 05:20 PM
blaquepapilion
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electric tankless water heater problem

I installed a tankless water heater in my house, the old water heater just wasn't working for my family of 7. I like the idea of hot water on demand but the problem is we can't run the dishwasher and take a bath / shower without blowing the breaker, or wash clothes and wash our hands. plus the dishwasher has hot water but the hot water faucet in the sink that it is connected to has none. HELP
 
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  #2  
Old 12-21-04, 05:42 PM
G
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You will need to get an electrician to run an separate line from the breaker box to your tankless water heater.
Your dish washer MAY have its own Heater to heat the water.
You will need to get a plumber.
 

Last edited by GWIZ; 12-21-04 at 05:47 PM. Reason: spelling error
  #3  
Old 12-21-04, 06:07 PM
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It may take you a while to come around to accept this advice, but sooner or later, you're going to go back to a regular water heater tank. You might as well do it now and save all the money and trouble.
 
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Old 12-21-04, 06:42 PM
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The biggest advantage to tankless water heaters is energy saving. The biggest dissadvantage is not being able to supply enough hot water.

A "regular" water heater is very slow to heat water (long recovery time), but it has a lot of hot water "stored". Unless you fill up a 100 gallon jacuzzi or take hour long showers there should be enough hot water available.

A tankless water heater has no stored water. It has nothing to keep hot, so it only runs when you need it. It however suffers from a big problem. You can't use more hot water then the heater can heat. If you do you will get warm or even cold water. It's very important to size them properly. It's not uncommon for a tankless water heater to require a 100A breaker if it replaces a "regular" 40 gallon electric heater. Heating up water flowing at a fast pace takes an incredibly high amount of electricity. Frankly if you take long showers it's probably less expesive to just use a regular heater.

How exactly did you run this new heater? Did you follow the instructions? Which breaker is tripping?

Having hot water in one spot and not having at the other is probably a different problem.

The other problem I've run across once is having low water pressure or low volume in the house. If the incoming water line can't supply enough water for the heater the heater will overheat. In another words, if you have a tankless heater rated at 10 gallons per minute and the cold water pipe can't keep up with this the heater will cycle on and off due to thermal overload. Probably not your problem, but something that can happen.
 
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Old 12-21-04, 08:39 PM
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There are demand water heaters out there that can supply an unlimited amount of hot water for showers and the dish washer at the same time but they demand a BIG amount of current from your house electrical system to do the job. Like was stated in a previous post, the big advantage to a demand heater is the energy savings of not keeping water hot 24/7/365. Why do that when you only actually need hot water for just minutes a day? Demand water heaters are very popular in most other parts of the world. The US is about the only place where tank type water heaters are used. You can also buy a demand heater that heats with natural gas or propane. Of course, if you have one you must vent it to the outside and they are about 1200 bucks. Not an attactive thought for most people and that's probably why most will just opt for the tank type heater. It sounds like you need an electrician and a plumber to straighten things out for you. Most reasonable electric tankless type heaters would require you to have 200 amp service and will use somewhere between 50 and 75 amps while running. You will need a feed with a separate breaker to do that. If you only have a 100 amp panel you can get by but you will have to scale back your expectations of how much hot water you can use at any one time and you will still need to have a dedicated electrical feed to the heater.
 
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Old 12-21-04, 11:38 PM
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Something else to consider is where you live.

It will be 25 below zero tonight here in Northern Minnesota so I would imagine the water coming into the house will be a little on the cool side.

Ice cold water into a tankless will not come out as hot if you lived in say, Florida.

I'll agree with John on this one, especially with a family of 7.
 
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Old 12-22-04, 09:43 AM
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I tend to agree. I have never owned one but a friend has one and she is less than throughly impressed with it. Not that it is real bad and she is gone for long periods so I am sure that was the thinking behind it, I doubt she would do it again, With a large family where water is being used constantly I dont see much of an advantage.
 
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Old 12-22-04, 01:21 PM
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I agree with the standard tank type also. I had a family of six, and the 40 gallon often would not handle our needs. I would consider a 50 gallon standard tank water heater. Also, I would buy water saver shower heads, and water saver aerators for the sinks. They cut the G.P.M. but produce good pressure.

Another energy-saving idea, when using a tank type water heater, is to buy a timer. Cut off electricity at about 10:PM (or earlier, depending on your family's usage), and cut on an hour before the first person wakes up. The insulation on the tank will keep it at a very reasonable temp. while power's off at night.

Just my $0.02.

Juice
 
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Old 12-22-04, 01:35 PM
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tankless heaters have very low GPM and temperature rise characteristics. Even the best gas heaters do not compare to a tank version, and the electrics are not as good as the gas versions. If a 40Gal won't do for your family, you might see if you can segragate portions of your hot water system and put in two tanks or one really large one. Gas heaters tend to recover faster than electric. I would call a reputable plumber to see if they can offer a solution.
As far as blowing the breaker, the breaker or wiring could be missized. The breaker should hold even if the heater is maxed out continuously. There might be a short in one of the heater coils if they are staged based on demand.
 
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Old 12-22-04, 02:04 PM
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I have two 40-gallon tanks in series. I run both of them in the winter and turn off the first on in the summer (when we use less hot water).
 
  #11  
Old 12-24-04, 05:59 PM
blaquepapilion
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TanklessII

we had our electric upgraded to 200 amps last year after we bought this old house, i ran the wire from the breaker through the garage ceiling across my family room and down to my basesment where the heater is installed , i also had to install a new plug for the water heater. everything worked fine untilabout 2 mths ago. yes i have teenagers and they take one hour showers why? don't know. I was tired of getting ready for work and having no hot water. I live in DE, maybe it is because of the weather. my plumber suggested going back to a regular heater. But when we lived overseas we always had tankless water heaters and yes, we lived in base housing. I'm going to keep working at it , i really enjoy the space i was able to add an additional freezer in my basesment
 
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Old 12-24-04, 06:15 PM
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Tankless water heaters that I am familiar with are "point of use", not "whole house". You have one in each bathroom, one for the kitchen, and one for the laundry. A single unit can usually keep up with a single demand.
 
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Old 12-24-04, 07:39 PM
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Gas fired tankless water heaters are one thing, but electric??? You are far better off with the standard water heater. I closed off my electric water heater and let the oil burner solely heat the water here.
 
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Old 12-24-04, 09:02 PM
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Who installed the unit? It sounds like it is not connected to a circuit of the proper rating. A large tankless electric may need THREE double pole 240 volt 40 amp breakers and associated wiring. DO you have this?

What is the GPM rating of your unit? Is is rated to supply more than one load at the same time?
 
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Old 12-27-04, 09:04 AM
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So, everything worked fine for a while and then the problems you originally described started? I'm thinking bad element. The unit probably operates in stages. Perhaps the final stage element is bad.

Just to chime in along with the others, in our house we commonly run multiple showers at the same time (3 bath rooms, 4 kids). With a 50 gallon gas water heater set at about 140 degrees (anti-scald on all shower faucets...), we have never run out of hot water (going on 6 years). We also have hot water circulation so we don't have to wait 5 minutes for hot water in the kitchen (farthest from water heater). Not only would we have to give up many of the conveniences we've become used to to use a demand system, when I analyze the savings, I come up with about a 10 year payback. We won't likely be in this house in 10 years.

Doug M.
 
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Old 12-27-04, 09:10 AM
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A further note to Doug M.'s setup. With a circulation system, you realize further storage capacity in the hot water piping which is in addition to the tank's 50 gallons. Sounds like a very nice system. Wish I'd had that setup when my two daughters were teenagers still living at home!

Juice
 
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