OT: Tankless Water Heaters

[joosttx]

We are having some plumbing work done and it is a good opportunity to replace our very old water heater.

My plumber is recommending a tankless water heater which we will mount on the outside of our house. I think it is a fine idea. The brand and model he is recommending is a Navien NPE-240. Anyone know anything about this brand and model or thoughts in general about tankless water heaters.

[Willy]

I don’t know anything about your brand but we put in a tankless water heater about 8 years ago and it’s worked perfectly and lowered our PG&E bill dramatically.

[htwoopup]

I had in a house built near the shore. Different brand though. I am sure your plumber knows, but mine didn’t until I followed up with heater manufacturer and made plumber change....do NOT use that ridged bendable pipe for the gas supply for ANY of the gas supply. Somehow the ridges that make the pipe more hose-like/ bendable messes up the flow rate unacceptably. At least it did in my case causing weeks of why is the water only warm.

Also, mistake I made was having both heaters next to each other. One of them was for two baths far from where it was installed. They are so small (even the biggest ones relative to old school tanks) that I should have insisted to the architect that that one be mounted close to the end to avoid the long run of cold so there would truly be almost instant hot water.


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[Bentley]

i have a Bosch, works great. Suggest buying bigger than you need if you have teenagers

I dont know that brand, but they are more common in Europe and South America so someone might weigh in. I offer that if you trust your plumber you are likely OK.

[glepore]

Navien is an excellent heater. Consider one with built in recirculation to avoid a long wait at far faucets.

[Blue Jays]

Keep in mind tankless water heating systems need regular maintenance at about $300 annually for budgeting purposes.
They can also save space in your residence if that is of any importance.
You might also wish to explore gas vs. electric versions with your plumber, too.

[ultraman6970]

Surprise me that here in the US those units are not used as in other places around the world... Super efficient, if dies you just go buy another one, connect the lines and good to go, even depending on the design pretty much the only thing that can fail is a piece made of rubber. Which is piece of cake to fix even with a bicycle tube.

[Louis]

Originally Posted by Blue Jays

Keep in mind tankless water heating systems need regular maintenance at about $300 annually for budgeting purposes.

$300 / year for maintenance is IMO outrageous and would disqualify tankless from consideration, given that a "normal" WH with tank requires essentially no maintenance (unless you want to try to flush it every now and then, but that's really not a must-have).

[ultraman6970]

What maintenance are we talking about?

[htwoopup]

Originally Posted by Blue Jays

Keep in mind tankless water heating systems need regular maintenance at about $300 annually for budgeting.

I dunno, in the 9 years that I owned the house I never had mine serviced (nobody told me I had to so I didn’t). They never broke after I had them correct the improper install of the gas supply and nothing came up negatively about them in the inspection report when I sold the house.

The AC...now that was a whole other thing ;-)



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[NHAero]

Electric is really only applicable at point of use for small flows, because the amperage gets so high quickly. To get a 65F temperature rise at 1.0 gallon per minute is 9.6kW, or 40A. Compare that to the smallest NPE Navien (the advanced model) at 150,000 BTU/hour, or 44 kW. That would be 183A at 240V.

Originally Posted by Blue Jays

Keep in mind tankless water heating systems need regular maintenance at about $300 annually for budgeting purposes.
They can also save space in your residence if that is of any importance.
You might also wish to explore gas vs. electric versions with your plumber, too.

[joosttx]

Originally Posted by htwoopup

I had in a house built near the shore. Different brand though. I am sure your plumber knows, but mine didn’t until I followed up with heater manufacturer and made plumber change....do NOT use that ridged bendable pipe for the gas supply for ANY of the gas supply. Somehow the ridges that make the pipe more hose-like/ bendable messes up the flow rate unacceptably. At least it did in my case causing weeks of why is the water only warm.

Also, mistake I made was having both heaters next to each other. One of them was for two baths far from where it was installed. They are so small (even the biggest ones relative to old school tanks) that I should have insisted to the architect that that one be mounted close to the end to avoid the long run of cold so there would truly be almost instant hot water.


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Thanks. My (our), not the kids, bathroom is on the other side of the wall. We are getting I think the biggest one.

[verticaldoug]

Originally Posted by htwoopup

I dunno, in the 9 years that I owned the house I never had mine serviced (nobody told me I had to so I didn’t). They never broke after I had them correct the improper install of the gas supply and nothing came up negatively about them in the inspection report when I sold the house.

The AC...now that was a whole other thing ;-)



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I've had a Noritz Tanklesss on my loghouse since 2000 running off of propane tanks. Never a hiccup and almost zero in maintenance.

I'd never go back.

[donevwil]

Noritz here as well, but was "that" close to getting a Navien until it proved not ideal and more expensive for our intended application. I wish I remembered the details, but I think we had to opt to a lower efficiency system to meet the exterior and venting needs and the Noritz ultimately proved more viable.

Maintenance is all me, general cleaning when spider webs get crazy and draining/flushing once a year because we've got hard water here in Petaluma. Probably doesn't need to be done that often however.

Have you considered a recirc system? That's the one drawback to tankless, have to run water for quite a while to get hot especially at the furthest bathroom. Ultimately we'll add a manually initiated recirc to that bathroom which will also prime the whole house.

[Dave]

When I built my new home, I solved one of my biggest complaints that nearly every home suffers from - long waits for hot water to some sink or showers. I installed insulated PEX pipe that runs in a loop from the water heater, that passes below each sink and shower, with a small circulating pump to keep the water in the loop hot all of the time. I get hot water in a few seconds to any sink or shower in the house.

The pump uses less electricity than a 60W light bulb. Taco now makes sophisticated pump models, so the pump probably runs less than half the time.

If you have to run water for a long time to get it to a sink, a lot of water and energy are wasted, every time the sink is used. The cost of that can easily exceed the cost of the heated loop.

My standard gas water heater only costs $20-30 per month to run, with 3 people in the house. You can buy high efficiency gas water heaters, but the price is so high that it may not save any money over the life of the heater and may cost more, if even one service call is required. Of course, you can still say that less gas was consumed.