With electric rates going through the roof in my area, I’m strongly considering replacing my 25 year old electric tank water heater with a tankless electric model. Does anyone have experience with a whole house unit, or at least field experience with them to share?
I had the same idea with my new house. My initial problem was the temperature of the well water. Without sitting in a bladder tank, it comes out of the faucet at 37 degrees. (gotta love that water fresh off the glacier) In order to save additional funds, plans call for a storage tank in a conditioned area (basement) to let the temperature rise prior to heating.
The power requirements for the larger model I needed was 2 - 60 amp circuits. Your mileage may vary. HERE is a link to a sizing chart from one of the manufacturers I looked at. Good luck.
Thats right, lots of current required for hot water with good flow.
Don’t forget, hot water is good at the tankless output, but if you need it 30, 40, 50+ feet away it causes a lot of waste. A recirculation pump is a much better upgrade.
It appear so. I’m not really interested in substantially upgrading my electrical service to accommodate an obscene amp draw for my hot water, particularly for my shower that I took the flow reduction valve off of. And my municipal water supply is around 45 degrees year round.
http://smileys.smileycentral.com/cat/28/28_3_9v.gif
Or perhaps I should take a close look at tankless fuel oil water heaters … :raised:
According to your math, this would equal even more waste.
I would say go tankless if you can get the power to it.
Had a tankless gas water heater in england in the 80’s, never ending supply of hot water.
I don’t know about tankless electric, but tankless gas is the best thing since sliced bread.
They are installing them on the multi million dollar homes here in SW Florida. I think they are a great idea. When it comes to power, we (USA) are the biggest wasters of energy. Europe has been using these for YEARS. They actually had a couple per flat (house) One for the kitchen area and one for the two bathrooms. Of course it depends on your layout, but then when you walk within the bathroom you hit the switch that turns on the heater and presto…endless hot water. When you leave the bathroom you cut the switch off…Remember just because you have 1 water heater does not mean you must only have 1 tankless water heater…
Dr.Hoover AO Smith White Paper
look before you leap!
As neat a technology as tankless water heaters are they don’t represent a cost saving to more conventional means over the life of the product.
I have considered buying one for over 20 years but every time I sit down to do the math it doesn’t work for me.
They are a convenience that comes with a price.
They certainly have their applications but for most users a conventional water heating sytem will be more cost effective.
YMMD
I definitely agree - I’ve had two gas tankless heaters in my home for 15+ years and like them a lot. However, most of the savings come from the difference between the cost/MMBtus for gas vs electric. I don’t think I could justify it on standby losses alone. Note also that when in a mostly cool / cold climate, if the water heater is located in a heated area of the home, the heater losses are not really ‘lost’ but contribute to the overall heating requirement. If you really want to go tankless, you may want to consider the economics of propane in your area.
On a very large home, there were two large gas tankless water heaters side by side.
The plumber actually said this:
“I wish I had got the owner to sign a statement indicating that he declined the recirculation pump I told him he needed” “This system is going to be a problem, he will have to install a recirc pump eventually”
And I said “yep, that is exactly what I think”
Its not just about “hot water”, its about having it where you want it and when you want it.
Fortunately, I wouldn’t have that problem. :mrgreen: If I were to mount my tankless unit near where the current tank is, my kitchen sink would be the furtherest application away from it at around 10 linear feet of supply pipe. And I already have plans to renovate my kitchen and bathroom, so I have no qualms with replumbing them to accomodate a new hot water system.
What resources have you used to come up with these calculations?
I have found whole-house natural gas tankless heaters for only $500 more than comparable capacity tank models. Plus the tankless models have a projected serviceable life of 20 years, compared to 8 - 10 years with the tank heaters. And according to Brian’s link, I would enjoy 24 - 34 percent less energy use.
But the kicker is that I am not interested in the substantial investment of being connected to the natural gas grid, so I would be contemplating the significantly more expensive fuel oil models. :neutral:
There you go. 
You must be more than 100 ft. from the gas line then.
Do you really want to pay $4 a gallon for fuel oil to heat water?
I still maintain it much more about convenience than cost savings.
Another issue not mentioned is available flow rate.
Additional reading:
There is no economics of propane in my area.
To me it’s a no brainer between keeping a 30-, 40-, or 50-gallon tank of water hot all the time using gas or electricity all the time, 24 hours a day, 7 days a week, and just heating up enough water to do the job at the time of the job.
Plumbers don’t like tankless water heaters because they are so good that there are fewer calls to the plumbers of the life time of the appliance versus the tank heater.
I’ve only had tankless for four years now, and they paid for themselves by the end of year one.
That would be unusual RR.
The best payback I have seen so far is is almost 7 years.
Of course as they say, YMMV
Since tankless heaters come on when there is demand [water flowing], they have to use something to sense when the water is flowing and the flow has to match the burner output to prevent the water turning into steam when the flow is low. They do make variable output burners but they are very expensive.
Modern tank style heaters, especially the electrically heated type are very efficient due to better insulation and can keep the water inside warm for several days. Gas and oil fired heaters have to vent the exhaust gasses so they can’t be insulated as efficiently.
There are several ways to set up a tank heater to only heat water when needed.
A very simple way is to install a switch to turn it on when you get home and off when you leave. This requires you to remember to do it.
A timer can be installed to only allow the water to be heated at set times. As long as you have a regular schedule
Motion sensors can be installed so water is heated only when someone is moving in the house.