Tank less water heater

[SteveB]

netnanny

[Douglas Johnson]

Agreed.

One or two seconds.

Only at very low flow.

Truth. But there are a number that don't need line voltage.

Dead flat false. We have two hot water heaters in the house. We replaced one with a tankless. Our summer gas bill promptly halved (both dollars and volume). The heater we replaced services the kitchen and laundry where the hot water use is fairly low, so standby losses are a large percentage of the cost. I figured a five year payback, much less with gas cost up.

And raise your air conditioning bill in the summer. Or do nothing if the heater is in unconditioned space.

When our twenty something daughter moved out, both the gas and water bills took a significant drop. The tank water heater has enough recovery to feed a low flow shower head all day. Sigh.

-- Doug

[Oren]

I do.

A local fire dept. Captain built a 6000 + sq ft house - single story.

4BR, 4 Bath. The house is zoned; having two tank less water heaters. A four member family. Parents on one end of the house and kids at the other.

Each zone has hot water when the unit calls for it. The units are outside, plumbed, framed in the wall and has easy access. They vent outside.(?).

I didn't get to read the manual, but I suspect this was a very good unit. They have been in the house for one year now (desert SW). When I seen the fireman again, I've got to ask about his experience.

[hallerb]

it will likely be good helped by warm incoming water, since heaters are outside, cant be a area with freezing temperatures.........

[hallerb]

please cite this claim..... of 20% up the flue.........

[Oren]

It freezes in the desert here. How does this relate to the tank less water heater and the performance?

Exterior tank less heaters.... gas piped... PEX pipe to all the hot water features.

I'm not afraid to consider a tank less heater, and I see the worthiness of having them.

[Robert Allison]

They have a thermostat that turns on the burners for a few seconds if the temperature is cold enough to freeze water. It continually monitors for this and protects the lines and the nheater from ever freezing. Haven't looked at any in a while, huh?

[Wayne Whitney]

I don't have a citation, but it is easy to derive this number. A typical 80% combustion efficient gas tank water heater has an energy factor of 0.60. The energy factor of 0.60 means that temperature rise of the hot water delivered during the standard 24 hour test period represents 60% of the theoretical heat content of the natural gas burned during that period. So 40% of that theoretical heat content is lost to the user.

Since the combustion efficiency of the burner is 80%, 20% is lost as soon as the fuel is burned. The other 20% represents standby losses. Most of this is due to air being warmed as it rises through the flue. For example, a good electric tank water heater might have an energy factor of 0.93, and such a tank has no flue. So through the outside of such a tank, 7% of the theoretical heat content of the electricity used is lost to the user. Thus we might infer that for our gas tank water heater, likewise 7% is lost though the outside, meaning 13% is lost up the flue.

These numbers are rough and depend alot on the amount of insulation on the outside of the tank. But obviously there can be no insulation along flue or heat exchanger, so that is a large source of standby losses.

Cheers, Wayne

[nospam]

In the South West desert every heater will do :)

[ransley]

Mine operates sucessfully 2 years with the original 2 D cells for the Battery ignition - No AC Needed, no power vent. Its amazing how many Lian Miss informed ASSes will put down a Tankless since the either they " dont sellem" "Dontservicem" and what ever Biased, BS, LIAN, reasons I can`t figure. What Bull Shit these Crap Heads, Shit Heads, are, yes full of Bull Shit......Obviously TANK sales employees or orther idiots, associated with TANKs..........

[hallerb]

chilly nite likely replaced by warm day, gound temperature probably doesnt get to below 40 degrees, hot water heaters must accept low incoming temperature water.....

way easier when water comes in at 50 leaves at 120..........

40 degree incoming water is togher for all heaters to cope with. much hared for tankless

[ransley]

Look up Energy Factor ratings on WH, Your burners are about 80-83% efficent on non condensing units but Energy Factor which is the true Energy rating taking into account heat loss are on average 60 for Hw tanks. The center is uninsulated and goes out the chimney. Foam insulation on tanks are very good and heat loss through the insulation is minimal, the real waste is up the center and out the chimney. Tankless Energy factor is the burner efficency rating mine is 82, no tank does that well except electric. so compare all 3 tankless, electric and gas , the difference in electric to gas tank is the center flue and it adds to a 20% - + loss.

[hallerb]

now is what your saying your tankless is 82% efficent

as compared to a regular tanks 60%??????

so your saving 20% a year on heating your water?

[Wayne Whitney]

Replacing a 0.60 EF (Energy Factor) tank with a 0.80 EF tankless should reduce your usage by 25% (1 - 0.6/0.8). That assumes your usage pattern matches the standard usage pattern of the the EF test. If your usage is less than the standard, your savings will be higher (as the standby losses will be comparatively greater), while if your usage is greater than the standard, your savings will be less.

Wayne