Electric Tankless Water Heaters

Missy M · #1 03/31/08, 06:17 PM

Who here has an electic tankless water heater? Your opinions on it would be helpful. I was considering a whole house electric tankless water heater, but don't know what to choose or how well it would work or anything about brands?

somepunk · #2 03/31/08, 08:26 PM

Jay Shafer from Tumbleweed Houses uses a tankless water heater in his small house. Ask him what he thinks...His website is something like www.tumbleweed.com

mamajohnson · #3 03/31/08, 08:36 PM

Well, I will be able to tell you soon.
We ordered one today. Our water heater went out over the weekend.
So, we are getting the tankless one.
Hope to see some positive input here myself!

Callieslamb · #4 03/31/08, 09:04 PM

the electric ones were not as efficient as the gas.....but I am not sure. Might check that.

Bonnie L · #5 03/31/08, 11:46 PM

We loved our propane tankless water heater - until the tubing got plugged up with minerals.

Somehow we missed reading or hearing that you need soft water.

idahodave · #6 04/01/08, 12:13 AM

I had a 9 kw tankless....now I have a tank. It did heat the water OK, but was really sensitive to flow and water temperature. In the shower we had to regulate the temp by adjusting the flow rate. Turn a hot water spigot full on and luke warm water came out, slow the flow down and it would get steaming hot. As the pump cycled the shower would change temperature. Really don't think there's so much loss in a heater tank that you can save enough to pay for the wiring to an instant heater. My tank is in a closet, and the heat loss doesn't warm up the closet up at all.

Shagbarkmtcatle · #7 04/01/08, 05:44 AM

In our area, they only work for point of use. Like under a sink, or to heat a bathroom group.
Most houses do not have a large enough service entry to operate one unit for an entire house. In other words most of the wiring to most houses is not big enough to run the load.

mamajohnson · #8 04/01/08, 07:36 AM

Shagbarkmtcatle,
are you saying that regular 220 electric is not sufficient?
This is not real encouraging! I have a very expensive tank in route now!
Do you think by putting a bit of solar heated water going to the tank, instead of 50 degree well water it would help with the heating?

michiganfarmer · #9 04/01/08, 07:51 AM

Quote:

Originally Posted by Bonnie L

We loved our propane tankless water heater - until the tubing got plugged up with minerals.

Somehow we missed reading or hearing that you need soft water.

that is good information to know. I have been thinking about putting a bathroom in my upstairs bedrom, and have considered tankless water heaters

Hooligan · #10 04/01/08, 08:57 AM

Been doing some research on these heaters becasue we want to switch over to a tankless.

It's my understanding that the electric models can't produce the same amount of btu's as a propane/ng/kero model. As a result they don't work as well with high flow rates or with low starting water temps.

All the advice I have received is to go with a propane/ng/kero model for best performance.

idahodave · #11 04/01/08, 11:12 AM

I don't know how big of heater you bought, but it will probably need a 40 to 50 amp 240v circuit. You will need a new breaker and bigger wire from the panel to the heater. Look at the wire and breaker size requirements that come with the heater.

Anything you can do to raise the temperature of the water going into the heater will help. When our well pressure tank (of room temp water) was depleted, and cold well water started through the heater we could tell the difference in the shower.

cfabe · #12 04/01/08, 11:36 AM

The electric tankless heaters require a LOT of current. A normal hot water heater hookup is 30 amps 220v. The electric tankless heaters suitable for a whole house with two simetanous uses can use over 100 amps. You really should consult with an electrician to see if your house service can support such a load and to design the new feed. I would consider a tankless electric for new construction where the service can be sized appropriately, or if you happen to be considering a service upgrade, and the heater is going to be installed near the electric panel. For most retrofit applications they're not a good choice.

The gas tankless units have similar problems that may require larger gas lines or gas service laterals to be installed.

The reason for all this is in a normal water heater the heater only puts out a small ammount of power, usually around 40,000 BTU. That's why it takes it 30min-1hr to heat up the tank from cold. A tankless heater only has a few seconds to heat up the water as you're using it, so they often need 150,000 BTU or more.

Sand Flat Bob · #13 04/01/08, 02:34 PM

For use on a whole house system, electric, I would and did , buy a high efficiency very well insulated electric tank type that was 40 gallon in size. To me, it is much cheaper than a tankless to go to the tank type, and it is a very long time before, if ever in its useful life you would save enough electricity to offset the initial cost.

This was my solution,

Bob

Old Vet · #14 04/01/08, 04:02 PM

I have one setting on my pourch now and you can have it if you come and get it. I looked at the size of the wire it would take and have not done any thing with it. It would take a 50 amp circut and a 30 amp cirtut to hook it up.

Shagbarkmtcatle · #15 04/01/08, 05:47 PM

Quote:

Originally Posted by mamajohnson

Shagbarkmtcatle,
are you saying that regular 220 electric is not sufficient?
This is not real encouraging! I have a very expensive tank in route now!
Do you think by putting a bit of solar heated water going to the tank, instead of 50 degree well water it would help with the heating?

The one we are putting in at our farm cabin, is for only a sink and shower and we have to use #2-220volt circuits for that one. THis is not cost effecient for a long period of time. We are only there at the cabin for 2-3 days at time. So yes, I am saying that regular 220 volt will not be sufficient

pmondo · #16 04/01/08, 06:11 PM

around 120 amps as i see it for this one

Energy Factor0.95
Efficiency95%
Weight22 lbs.
DimensionsH: 15.25" W: 15.5" D: 4.5"
Water Connections3/4" Male NPT
Volts240/208V
Kilowatts27/20 kW
AMPs120/101(3 x 40 AMPs)
Wire Size8 gauge (6 conductors & ground)
PhaseSingle
Flow Rate at 45°F Rise4.0 GPM
Flow Rate at 50°F Rise3.7 GPM
Flow Rate at 60°F Rise3.0 GPM
Flow Rate at 70°F Rise2.6 GPM

nathan104 · #17 04/01/08, 08:09 PM

I just bought one of them but havent put it in yet. I have a small model to provide water to two bathrooms. Our unit requires a dual 60 amp breaker and #8 wire ran. We will have to run new wire about 70 feet as the water heater we are replacing had a smaller wire requirement. Most installs or tank water heater replacment installs are going to require new wire to be ran. And, I wouldnt even suggest trying it with anything less than a 200 amp service.

For our use, we will have to put in low-flow shower heads to slow the flow down so it can provide sufficient heat. For ours, if your ground water is 50 degrees, with a regular flow shower head(approx. 2.5 gpm), it will raise the water temp by 32 degress for a hot water temp of only 82 degrees. But, with the low flow shower heads(1.5 gpm), the temp rise is 54 degrees for a hot water temp of 104 degrees. When the kids use the tub, we will just have to fill it slower than usual instead of full blast.

Ill install it myself including running the new wire and circuit, so I save on labor, but the heavy wire is still expensive for a long run. It makes a lot of sense for our purpose though. Right now we have a 50 gallon tank water heater supplying water to those two bathrooms which only use hot water when the kids bathe, and the second bathroom is a guest bathroom used a few times a year while guests are here.

Should have it put in in the next two weeks. Will let you know how it turns out.

critterchick · #18 04/01/08, 09:06 PM

Hmmm...this is good information. While I know absolutely nothing about all the wiring involved, I was considering a tankless for a single bedroom house but I do like my long hot showers in the winter and I'd be quite irate if I spent in excess of $400 for a tankless that wouldn't maintain a constant, hot, temperature for more than a few minutes. Do y'all think a regular heated tank with a pressure tank would work more reliably and as economically?

mamajohnson · #19 04/01/08, 09:56 PM

well, our tank should be here tomorrow. The installation sounds like a challenge, especially on the electrical end. I need to see what our service is. I think it is a 200 amp, not sure. Seems like I looked where the hot water heater is wired in now and it was 2 60 amp breakers. Better double check that too. We are planning on installing within 5-6 feet of the breaker box, so that should be a plus.
My dad set this house up, he did things to excess sometimes, which might be a good thing, huh?

So, from what I am reading we will most likely need to
1) install a water filter on the incoming line
2) be sure there is sufficient electricity coming in
3) install a solar tank for pre-heated water coming into the tankless.

mamajohnson · #20 04/01/08, 10:21 PM

Quote:

Originally Posted by Old Vet

I have one setting on my pourch now and you can have it if you come and get it. I looked at the size of the wire it would take and have not done any thing with it. It would take a 50 amp circut and a 30 amp cirtut to hook it up.

well now, if your not to far from east texas I may take you up on it!