ECN Forum Forums General Topics of the Trade General Discussion Area Tankless water heaters

Obviously, a storage cylinder or tank is the best option, for several reasons, if you have room for it.
1. The maximum current drawn is much less, leading to cheaper wiring and switching.
2. Flow rates are only dependant on the faucet size and pipe bore/pressure, 1.1/2 US gallons a minute @ 22kw is hopeless for running a bath.
3. Off-peak supply or heat-pump technogy can be used to reduce poco bills, dry the damp basement, ( or chill your wine store!)

We have a 15psi presurised 230v, 2.4kw x 200 litre (52 US Gallon) chauffe-eau, running off-peak, size 5ft high x 18" diameter, producing domestic HW at 60C (140F) which we find adequate. It's so well insulated it holds hot water for a week when turned off. Our Wash m/c and dishwasher take in cold water, and run at night on off-peak, with intergral heaters, using time-clocks plugged into the recepts..
Currently I'm researching a heat-pump chauffe eau for the renovation, but the cost is off-putting, it looks like they're about US $2500-3,000 here, with the dreaded 19.6% sales tax on top(!), which puts the capital payback to beyond the time when we'll both be drooling in a home for distressed gentlefolk! Anyone know of a reliable cheaper US model for export?

Alan





[This message has been edited by Alan Belson (edited 09-03-2005).]

The cheapest way to heat water around here is to scavenge waste heat from the AC compressor. That gives you free hot water and your AC runs better.

When it comes to hot water, I say "tanks a lot."

Although a trend is developing which will have us saying "Tanks for the memories."

Tank you all for listening.

... What's all this I keep hearing about thankless water heaters?? Putting myself in it's place as just a "water heater and an inanimate object",as most people refer to them,I believe that it's not the water heater thats thankless,but the penny-pinching home-owner who doesn't want to part with their hard earned 'scarole to have this poor, abused,denizen of the cellar installed by somebody showing much too much cleavage in the "steerage deck" if ya know what I'm sayin'...Do you guys out there think that it's actually easy being a hot water heater??? The constant pressure,the heat and humidity,the lousy lodging accomodations,... Yeah,maybe it's a thankless job,but someone's gotta do it right?? I'd be a might bit thankless too if'n I were subjected to those conditions day in and day out... That's it,my rant is over...so the next time you guys wanna pick on something,by calling it "thankless" try pitching it to something that deserves it,..like waffle irons,...now those darn things are thankless...
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Russ



[This message has been edited by Attic Rat (edited 09-03-2005).]

Russ:

You've done it again!!

My downstairs neighbor's gonna think a lunatic lives above, as I'm again ROFL from your post! (Well....maybe it's true...)

"Tanks a lot!!"

Tony

Very good point, I work in very large super markets and any heat that can be scavenged from the refrigeration equipment is used to heat the building and water. This saves money directly by using less fuel to heat and by shortening the run time of the condenser fans.

How is this accomplished with dwelling unit ACs and water heaters?

An AC unit is a heat pump. When used to cool a home in summer, heat is pumped out of the house to the exterior unit, whether this is a window or a split-unit design. A simple heat exchanger/circulator, (a desuperheater) can be inserted in the AC refrigerant lines to remove some of this heat and transfer it to a water storage tank at 60C / 140F. The heat extracted is essentially 'free', the running costs are simply those involved in capital, fluid circulation and control.
Actually, fitting such a device will reduce the cost of running the AC unit and prolong its life. There are some reservations:
1. The Heat Exchanger has to address the danger of refigerant gasses getting into the potable water supply, and must be sized correctly.
2. The device will be non-operational when the AC is off or reversed, (ie winter), so an alternative hot water heater is needed.
3. Cutting into the refrigerant lines might pose warranty problems and also requires a HVAC engineer to re-gas the AC unit. http://www.doucetteindustries.com
shows a typical unit and a savings chart. Go to: products: desuperheaters.
I'm still looking; I want a stand-alone air-water unit at a reasonable cost, which I can park in the boiler-room to extract heat lost by the boiler in winter or gained by solar effects in summer.

Alan





[This message has been edited by Alan Belson (edited 09-04-2005).]

Alan
Check this site out for cold air heat pumps. Not sure if its what you are looking for or not. The manufacturer is local to me in Maine http://www.nyletherm.com/spaceheating.htm

Walrus,
That is EXACTLY what I've been looking for! I e-mailed them this evening, so hopefully we can get down to the Customs and Excise/shipping nitty-gritty!
Thankyou.

Alan