Tankless Electric Water Heaters?

Question

I have a rental unit that is overdue for a new furnace. The old one runs on oil and heats the house and the hot water.

It seems like high oil prices are here to stay. I could replace it with a natural gas one, but I'm concerned about safety issues. (And who know can predict how long natural gas will stay cheap?)

I've heard about these new hot water heaters that are electric and tankless - the water is heated 'on-demand'. I can't find a lot of good info about them online but I'm interested in learning more.

The rental unit's heat is from hot water running through radiators, it's hydronic. So I'm wondering, has anyone used one of these tankless units for the entire heating system, not just the hot water faucets?

Al Williamson · Answer

Dave Meyer gets my vote. It the tenant pays electrical bill then you'll never see a return on your investment. Tom D. I think you already know the right answer by your initial question. On demand electrical heaters are not intended for whole house heating systems. They are intented to quickly heat a small amount of water only when it's needed. P.S. - the US has a LOT of nat. gas. I would bet on NG staying cheap for a long time.

Dave M. · Answer

Looks like you still may need to replace the furnace. Take a look at Rinnai's page: http://www.rinnai.us/hydronic-air-handlers/ If what you are looking to do is just use a tankless water heater to supply hot water for both plumbing and your hydronic heat it may not work. If you go the electric route the "whole house" models require either 200 or 300 amp electrical service. Who pays for utilities? If you're paying more money for a tankless vs. standard water heater and the tenant gets the potential utility savings I would not consider it. If you pay then it may make sense.

Eddie P. · Answer

Electric tankless units pull lots of amperage 60,80, 100 amps depending on the size. So you need to have an electrician evaluate your home prior. It gets expensive updating the panel breakers and wiring to handle the draw of electricity these require. A few years ago I replaced the older tank units with tankless units in a handful of rentals and ended up going back to tanks. Like the previous poster said, they are great if you have a small home and only are running hot water in one shower or faucet at a time. If you try to run multiple faucets or fill a tub, you will get warm water at best. I did hear from a plumber the natural gas units are much better, and heat faster.

Rob K. · Answer

If you have natural gas available, I don't know why you would consider anything else to heat your house. Gas is cheap, clean, and efficient. Our country is full of natural gas and prices have come down. I've heard that fuel oil is common in the northeast. It is rare in my area. The people that do have it always complain about how expensive and stinky it is. As far as tankless water heaters, I've heard that they are very expensive ($2,000+). You can buy a natural gas water heater for about $300 and it will last just as long.

Account Closed · Answer

No experience with an electric tankless, but had a gas one installed that I was not happy with. If you have a small house with little plumbing it might work okay. I found that water was often only warm.

Gary Houck · Answer

I work for an electric utility as an engineer. Every customer that I have come in contact with that has an electric hot water heater has had them removed. We charge them extra on their bill every month for an excess facility charge(you end up having to install a larger transformer) to account for the large intermittent load.

Steve Babiak · Answer

This past year I converted a house from oil to natural gas. When the gas line installers were there, they asked me if the hot water heat was going to be "tankless" - and then explained that due to the capacity / pressure characteristics of the gas main that a tankless gas hot water heater could not be supported. Just in case anybody considers doing this with gas. Since the USA sources most oil from foreign lands, I can't see oil prices coming down. Natural gas is being produced in the USA, and it seems like the supply is rather abundant with shale fracturing. And consider that many electricity producers are running natural gas turbines as part of their production. But there is a federal website that helps to determine cost effectiveness of heating fuel source: http://www.eia.doe.gov/neic/experts/heatcalc.xls http://www.eia.gov/

Tom D. · Answer

Thanks for the link! Is your install for the room heat too, or just the faucets? I see references online to 'whole house' tankless electric heaters, but often they're referring to multiple bathrooms/kitchens, not the actual room heat, which is what I'm trying to find out more about. If so, why did you choose electric tankless? Is it because of high efficiency, or is it just less hassle than fossil fuels? I'd appreciate any info you can give.

Karen Margrave · Answer

www.builderonline.com Search on this site. We are putting a tankless hot water heater in a house we are building. It's the first time we've used them, so not sure how well they work, but they do get high marks from people.