Tankless Water Heater

4 Responses to “The Pros And Cons Of Electric Tankless Water Heaters?”

1. fluffern
   November 26th, 2009 @ 5:01 pm

   The biggest problem is clogging due to minerals in the water. While you can clean the system eventually it has to be replaced. Changing out the “guts” can cost $500.
   Tankless is not unlimited at the moment. For example, most tankless water heater manufacturers use a very unrealistic temperature rise, say 4.6 gallons of heated water a minute as long as it only has to heat the water 45 degrees. In Arizona where the ground water is warm, no problem. But is a northern climate in winter or cold well water, ain’t going to happen. For example, in Michigan the ground temperature of water varies from 37 degrees to 51 degrees. That means the average tankless heater will furnish 4.6 gallons of 96-degree water in the summer and 4.6 gallons of 82 degree water in the winter. That’s not hot!
   If you want hotter water, delivery rate goes way down. Raising the temperature to 90 degrees in the winter could lower the delivery rate to about the same 2.5 gallons of water per minute used by a standard showerhead. Heaven help the poor shower taker if someone in the kitchen or another bathroom turns on a hot water tap.
   Check your manufacturer’s info. For example, State Industries has a nice usage chart in their Aurora On-Demand Residential Gas Water Heaters brochure. They suggest, “If one kitchen faucet, one shower and a washing machine are all in use during your busiest period,” a family needs their biggest residential water heater, the GAX-236. If another shower were added, the family would need two GAX-236 tankless heaters.
   So examine your family water useage. When are the dishes washed, laundry done, showers taken. I’m not sure two super tanks are enough if there’s a teenager in the house!
   Two systems would require two heavy duty gas lines and two vents. The cost for two big units would be $7,000.
   Another option where the household will be using 3 or 4 hot water sources at the same time, is to install the biggie 199,000 BTU tankless in tandem with a 52 gal conventional electric water heater and a Grundfos re-circulating pump. This is about 45% cheaper than two tankless.
   The combination would give the family a peak demand supply of 200 gallons of hot water in the first hour when they needed it most. The electric water heater remains in the background with an extra 52 gallons of hot water supply any time the tankless water heater can’t meet requirements.
   Since electric water heaters are so well insulated, they only lose about 1 percent of their heat a day, so energy loss is minimal.
   For a one or two person household with low water needs (somebody showering at the gym helps, LOL! and cold water laundry), a tankless is fine………remembering the problem with high mineral water.

2. Jeffrey C
   November 26th, 2009 @ 5:25 pm

   I would recommend a gas tankless heater such as a Rinnai. With and electric heater you have more demand than it can handle if using two or more hot fixtures with a rinnai you can have all hot fixtures running and not have a temp change. will have to consider people in the house and number of bathrooms. the biggest draw back of tankless heaters are clogging of the screen on the cold inlet side…this goes with gas and electric tankless models…if you are on a well this could be more common and will need a sediment filter on your main line…and a big draw back of the electric models is, as i have serviced quite a few, is the heating elements blowing out due to say getting done with a shower and the elements are still hot and turning on a another hot water source and the cold water surge that happens cracks them…hope this helps

3. AstroGro
   November 26th, 2009 @ 6:39 pm

   I own one. It’s only me and my wife in the house so it works fine for us. We replaced a giant gas heater. The gas bill was huge ($60) and the only thing we had was the water heater. Our electric didn’t go up at all that I could tell.
   There are drawbacks. We use flourescent energy conserving bulbs in the bathroom. When we use the hot water these bulbs flicker. The hot water manufacturer says it’s because the SCRs in the tankless heater fire on and off rapidly and somehow this effects the flourescents.
   Also, to set the heater up so you save the most money, you need to adjust the temp of the tankless heater to where you can take a shower at the furthest bathroom with just hot water turned on. That way you aren’t blending cold water with the hot. If you do that and someone uses the kitchen sink while you are showering you will get a dose of cooler water. Not really cold, just cool.
   Also, we have a jacuzzi bathtub that is pretty large. We couldn’t turn the faucet on it all the way open for full pressure water otherwise the water coming out of the faucet was only tepid. So we had to fill it slowly. This takes about 20 minutes. Before with the hot water heater we could fill the tub in about 3 minutes.
   We were using the Titan tankless heater. It uses a single 60 Amp breaker. We looked at another style but it required two breakers and we didn’t have room in our breaker panel.
   So if it’s just two of you then you should be fine. If you have a family and will be taking two showers at once you might want to reconsider or look into two tankless heaters (one for each bathroom).

4. Upbeat
   November 26th, 2009 @ 8:48 pm

   I don’t own one but I know they are much more expensive than a regular water heater. I am eager to see what the answers are to this question, as I am considering one myself.

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