Tankless Water heater


Old 01-10-07, 12:42 PM
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Tankless Water heater

What gpm do I need? I have 3 full baths. standard home set up. 50 gallon Gas Water heater installed now. I am replacing th 50 gallon, want to go tankless.


Last edited by mechrus; 01-10-07 at 01:10 PM.
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Old 01-10-07, 01:16 PM
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We have no idea how cold your water is for most of the year, how warm you want your water to be when it's heated and if you envision all 3 showers going at the same time. Once you know that, you'll be able to shop for your temperature rise on the basis of perhaps an expected 6gpm to 8gpm rise.

Figure at least a few hundred thousand BTU for a tankless this size. Do you have skinny little gas pipes? They won't cut it. You'll also need to add some wiring into the equation. Then you'll have to worry about minimum flows as well.

This is a boiler forum. Having a boiler makes the decision very simple. An indirect fired tank attached to an efficient boiler is as good as it gets. If you are worried about flue losses with your gas tank, I would first explore more efficient tank type solutions. Tankless are fine for cramped European apartments but if you have the room for a tank, why put yourself through a lot of agony?
Old 01-11-07, 05:25 AM
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I have had a Bocsh/AquaStar (natural gas) for 4 years now and love it. Origionally, I tried an electric instant water heater and found it to suck. They make a larger one for more than 2 fixtures at a time or you can install 2. They require good exhaust. I live in Phila., Pa and during our coldest winter the AquaStar is capable of making the water TOO hot, so I just dialed it down and perfect. Mine has a pilot flame because the starters usually go to often and when you're in the shower.
Old 01-11-07, 09:33 AM
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Originally Posted by mechrus View Post
What gpm do I need? I have 3 full baths. standard home set up. 50 gallon Gas Water heater installed now. I am replacing th 50 gallon, want to go tankless.

Be careful with those tankless heaters they are efficent if INSTALLED PROPERLY AND BY A PROFESSIONAL.If u have three baths no matter who makes it you'll need a 194000 btu one to avoid press. and temp drops also if u go with that one no residental gaspiping in place can handle such a high demand so you'll need new gas piping along with a new high press. gas meter installed by gas company.Those instanstaneous hotwater heaters are great but must be thought out completely,and trust me i've been in hvac for 12 years.
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