Tankless Water Heater

[Bebop]

If anyone has one, does it able keep it in the Wisconsin winters? Do you see any savings?

Thanks.

[gparris]

If anyone has one, does it able keep it in the Wisconsin winters? Do you see any savings?

Thanks.

Most tankless systems are rated at produciing ## gallons per minute....However, the one fact that you need to know is that this number is based on the incoming cold water temperature.  
If your system receives cold water (to be heated) below the "bell-curve" for producing the ## gallons per minute, the ability of your system to reach it's stated output will be diminished.  

Each manufacture must provide a "bell curve" chart that will allow you to see the target output based on the incoming temperature.  
If you know the incoming water temperature on your coldest days (winter), then you can use this.

We looked into this here for our home, but opted against it, as it was unable to produce the 12.5 gallons per minute we needed to a custom shower system, continously.    
Noted, it was rated to produce 13 gallons per minute at 120 degrees.

Also, the setting for your temperature output may affect it's ablity to produce.

If you were in a warmer climate say the South, Florida, California, Texas or Nevada, it would work well, but not here in the frigid tundra called the Midwest.

[digdugm]

I have a Bosch (125ng I believe) and I love it. At the max temp. (lowest flow) it does like 45 deg.s and it seems to be plenty. I have a really small house, if it was bigger I would have gotten a bigger one, or better yet two in different locations. My gas bill was down 25% last year on average, more so in the summer when its just the water heater and the dryer running on the gas. You do have to get use to running the water alittle longer on start-up (the heater doesn't start till the water starts flowing). Its great, the wife and I are real happy with it, just over a year now.


edit.
just did a test basement sink (closest to cold coming in and the furthest from the heater) full cold- 42 deg. and full hot 110 deg.
It's not for everyone at this point, but there always imporving.

[gparris]

Great to hear of that, but my research is from about 5 years ago, when I was first building and the custom shower (and whirlpool tub) do take a lot out of the hot water system (at my place).
Having lived in Texas, California and Florida, my experiences were much better and cost effective with those hot water systems as inquired about.

[Bebop]

I have used tankless in the past, but it was in a much warmer climate.

The manufacture's numbers never reflect the real world's.

I just checked my cold tap and it's about 45 degrees. It nice to know it's doable for some.

[Ralph Kramden]

We also have a Bosch tankless water heater, and it's worked out great. We've had it for about 6 years, never had a problem with it.

[jkane]

Cold tap at 42-45 deg!  Where do you guys get your water from!  Mine comes from underground and is about 55-60 degrees year round.

So how much are the tankless water heaters up front?

[Doug Mohr]

Last summer I installed a Rheem GT-199DVN which is a commercial tankless water heater.

Some of the reasons I went with a commercial unit instead of a residential unit are:
That it can heat water up to 180 degrees instead of the residential 140 degrees. That becomes very useful when you run a pressure washer to de-grease stuff I do keep it at 125 normally to prevent scalding.

It provides an output of 7Gal/min at 45 degree rise and a 2.5gal/min at a 130 degree rise.

If you need a higher volume with a higher temp rise, you can chain multiple units together so they can share the load.

Ironically, since I switched, I find that I use MORE gas than before because I now use warm water to wash the cars, use hot water to pressure wash, and tend to use the jacuzzi more often now than when it took 3 hot water tank recovery cycles (about 2.5 hours total) to fill the tub with the old water heater.

So I haven't saved any money, but I sure live more comfortably

Doug

[Doug Mohr]

Cold tap at 42-45 deg!  Where do you guys get your water from!  Mine comes from underground and is about 55-60 degrees year round.

So how much are the tankless water heaters up front?

$500-$1200 depending on the capacity, but there is often a energy tax rebate which brings down the price slightly.

[Dan the Man]

Water from a well source will be constantly in the 50 deg. F range. Water sources from open bodies of water like Lake Michigan or the Mississippi river that feeds the Quad Cities can range from in the 40's in winter to as much as 60 deg. F in summer.

Water heaters are sized on the rise over a GPM. Traditional water heaters are usually sized based on a 100 deg. F rise assuming 40 deg. water coming in and making 140 deg. F water in the tank.

The instantaneous units have a lower delta "T" and heat water in a nominal 50-60 deg. F rise. The lower the flow the higher the rise for a given capacity.

The Wisconsin weather has nothing directly to do with the size or heating capability of a water heater.

Doug - I would highly recommend AGAINST cranking the unit up to 180 deg. F. Your choice of a commercial unit was wise, but 180 deg. F water is dangerous and depending on your water piping system it could cause failures. Copper is fine, CPVC OK but if the system used PEX tubing (cross linked polyethylene) that should be trouble.

Tankless water heaters are an energy efficient alternative and make sense in a lot of applications. No one should be afraid to purchase one in lieu of a standard unit.

[Ralph Kramden]

It's not only the energy efficiency. The best thing is the ENDLESS supply of hot water, and no tank to rust out.

[mhz40]

An endless hot water supply is nice, but hardly cost effective.
One web site stated a typical home (using 64 gallons a day of hot water with a 77 degree rise) would save a household $64/year, based on 2005 natural gas prices.  Granted, gas prices have certainly gone up and rates are likely to increase.  So, round it up to $100/year savings in natural gas.  If you spend $800 more for a tankless unit, payback is 8 years out--- unless of course you CHARGE it and ride that 15% credit card debt.

[Bebop]

Most energy efficient appliances take some years for them to payback. It also depends on how long one stays at the same house.

The water heater I'm replacing is over 23 years old and never been drained. I'm supprised it still works. I don't want to press my luck any longer.

I'll get quotes for both and weight my options.

[Doug Mohr]

Doug - I would highly recommend AGAINST cranking the unit up to 180 deg. F. Your choice of a commercial unit was wise, but 180 deg. F water is dangerous and depending on your water piping system it could cause failures. Copper is fine, CPVC OK but if the system used PEX tubing (cross linked polyethylene) that should be trouble.

I wouldn't take it up to 180. I leave it at 130 unless I am using the pressure washer. Then it goes up to 160, but if I'm not home alone, I shut off the rest of the house at the hot water heater. I hook the garden hose to the hot side drain, shut off the supply valve to the manifold (I do have PEX) and just run the hose out the basement window to the pressure washer. That poor hose wouldn't take too much higher of a temp. The "Farm" hose is rated at 185 degrees, but I wouldn't press my luck :stpat

Thanks for the safety advice.

Doug

[Michael Thomas]

I have five Takagi tankless units installed at my home, office and three rental units, and also see them at home inspections here in Chicago,  they can work well in our climate if properly sized and installed.

All five are now working well, but there were a few issues getting them installed and working properly.

I've put up  page about the hitches I encountered and how to avoid them at:

Avoiding Tankless Water Heater Problems for Installers, Home Inspectors and Homeowners - Paragon Inspections, Evanston / Chicago Ill