Tankless Water heaters
Has anyone installed a tankless water heater for a whole house application ?? I would like to have a plan to act on when my current water heater decides to fail. I currently use a 75 gal tank heater. I have a two family rowhouse with a total of 4 adults. My concern with a…
Has anyone installed a tankless water heater for a whole house application ??
I would like to have a plan to act on when my current water heater decides to fail. I currently use a 75 gal tank heater.
I have a two family rowhouse with a total of 4 adults. My concern with a tankless heater is the gpm capacity during the winter months.
I had also thought about chaining the incoming water line into a small tank heater then into the tankless heater. Keep the tank set to a cool temperature (~60 degrees F). In this way in the winter the tank will heat the outside cold water to 60 then the tankless will take over to heat to use temp. In the summer however, the water coming in from the street would be warm enough so that the tank heater will never need to kick in. This way there would be enough hot water for all.
Any comments, Ideas?
Totally agree. MasterPlumber rocks!
Phripley – second that last bit! Masterplumber is the boss here.
Meanwhile, I have a project where we’re installing tankless electrical on-demand for a townhouse floor and will report on the results.
We have a tankless heater with our oil heat (a “coil”). Ours is a 4 story, 3 family brownstone with 10 residents. In the winter time there is occasionally not enough hot water in the shower at peek times.
We bought the house with the heating system already installed so I can’t say how many gallons/minute it is rated for.
I suspect that the reason the hot water is a problem in the winter time is that the tap water is feels about 20º colder than in the summer. I love cmu’s idea of a warming tank that just drew energy from the ambient heat of the boiler room! Cool idea.
Meanwhile I have National Grid coming on Friday to give me a quote on converting from oil to gas.
MasterPlvmber, you should have your own blog! Why work so hard providing content for Mr. B to wrap ads around?
SenatorStreet, small electric pre and post heaters each have their own benefits and have become a way out of many problems encountered when using tankless or instantaneous water heaters. They definitely do subtract efficiency points though.
Having a staging tank with *no* insulation and *no* heater, near your boiler may be worth it, especially if you have a boiler room. I have seen the suggestion that you could use the old water tank stripped of insulation and gas disconnected. In winter it may enough absorb stray heat from the boiler to raise the incoming water to 55-60. In summer it will reach near basement temperature, so there’d also be some savings there.
If you believe anecdotal evidence, tankless saves you up to 40%. Studies seem to say 15-20%.
Also, there’s the low-flow problem where it cuts out unless the flow is 3/4 gal/min or so. Fine Homebuilding had a long article recently on plumbing tankless so this was not an issue, but it would add hundreds if not thousands to the install.
If you do the staging, could you post the results when you get them?
I’ve been researching tankless for a couple of years and I think it’s definitely the way to go. I had my girlfriend’s brother-in-law, a master plumber, give me an estimate. He told me I wouldn’t save much money over the life of a standard water heater but he’s old school and has no direct experience with tankless. Given that I live alone I can’t see me not saving a bundle on gas bills.
Here are a bunch of comments from house bloggers around the country about their experiences with tankless:
tinyurl.com/5mdkeg
It’s not a cheap upgrade though. Quality tankless heaters are pricey but the major expense (if you go with gas) is the required stainless steel flue liner. Rinnai appears to be the product standard for tankless heaters.
I don’t think you’ll buy much efficiency with having a staging tank. You’ll still have a burner keeping a tank of water warm 24/7. One thing that some of the bloggers (above) did was to install multiple tankless heaters close to the bathroom/kitchen. That addresses another problem with tankless: the long cool water run times. If I had 200a service here that’s probably what I’d do because the units are pretty small.
60 was just a number. My cold water is colder in the winter than the summer.
If you keep the small tank at 60 all year round, why wouldn’t the tankless heater kick in summer and winter? And isn’t city water cold during summer months too? It comes out of my tap cold year round.