On-demand water heater

[l5ducks]

Hi all, am considering buying an 'on demand' water heater. has anyone had experience with these? do they work well? have you noticed any energy savings or increase? any recommendations? how difficult is the install? thanks for any help, Greg

[hallerb]

Really should make up a FAQ

If its electric you will probably need a 400 amp service upgrade at a cost of thousands of dollars, 200 amps dedicated to water heating

If its gas you will need large gas lines and possibly a new meter, since fuel consumption is so high. New flue too, a tankless gas uses way more gas than a normal furnace

The energy $ saved will never occur in the lifetime of the unit:(

Regular tank 500 bucks installed

Tankless a couple grand

To save any money you must FIRST, save enough to pa that 1500 bucks. Warrantied lifetime of tankless is never more than 10 years.

Now in the winter the heat lost by a standard tank helps heat your home, so cut savings by 1/2

Plus there are sizing issues, you need a large enough tankless to support all fixtures that may be on at same time.

Thats a lot if 2 are showering at same time

In the case of a power failure you have NO hot water at all, with a standard tank theres still a couple quick showers available:)

If the water system fails for some reason a standard tank is a good source of drinking water. Terrorism might be the cause:(

Unlimited hot water can lead some to taking endless showers that run up energy costs:(

Did you know that standard tanks come in high output versioons?

Regular tank 35 to 40K BTU HIGH OUTPUT tank 75,000BTU

Plus you can go from say a 40 gallon tank to a 75 or 100 gallon high output tank so you will rarely run out of hot water.

The econmic numbers of tankless dont add up:(

[Dean]

I have an Energy star AE12 240volt,,it is intended as a point-of- use unit but is serves My bathroom shower and sink and occasinally the washer if I do'nt use the cold cycle only..It works well enuff for Me and handles the changes that Winter brings to incoming water temp,,the AE9.5 120volt unit did'nt provide this when installed at the same location.. A gas whole house unit is probably the most powerfull but with longer runs of pipe then pipe insulation becomes more needed.. I have no expierience with gas tankless.. The smaller units will provide hot water only within a narrower range of gallons-per-minute use so flow restricting aerators,showerheads and valves are needed..There are pipe size recommendations also but I have some copper,some old steel that is as yet uninsulated and it works well enuff for the estimated 20-30' runs it travels.. The best price I could find for My unit was at designerplumbing website,,only took 2 days or so to arrive by Fed Ex ground from Northeast US to Midwest but there was about 2 days to process order so

4 total.. Living alone with lower hot water needs than a family I believe it saves alot in that there is no tank to keep hot when idle,,I'll guess that they save in the long-run in most applications if purchase,installation and changes costs can be controlled..Any European Members should know more as I think tankless units have been widely used There for years.. When You find a unit of interest read the specifications carefully before purchase,,carefully and then some!! Dean

[Dean]

There are lots of tankless WHs here..

[Dean]

A tanked heater will add some heat to the house in Winter I agree but does'nt it also add heat in summer wich must be countered if air con is used wich would negate at least some of the winter savings? I think if a person thinks it through well enough for their situation a tankless *might* be the ticket to water/energy conservation..We have been spoiled for a looong time here in the USA but do'nt count on it forever,,conservation is and will be a growing issue..What was it Grandparents used to say? "Waste not want not"?.....Sorry,,I digress and do'nt intend to be argumentative.. Dean

[terry]

On Jan 31, 1:24 pm, "Dean" wrote:

here..

Replaced our 40 US gal electric HW tank ourselves recently (in Canada) for $300 Canadian (about $250 US) including sales tax. That included a new &#39;pressure relief valve&#39;. It has individual 3000 watt heaters top and bottom with the usual flip-flop upper thermostat. Like previuos ones it is well insulated by foam insulation; not fiberglass batting. As mentioned elsewhere we turned off the electricity to such a tank when going on vacation. Returning after two weeks the water was still tepid! Testament one would think to very little heat loss. BTW if your breaker and wiring from panel to tank is adequate you can (by moving one wire) arrange such a tank to operate both heaters through their own thermostats simultaneously, for quicker recovery. However only had to do this once when we had a &#39;whole slew&#39; of visiting relatives all taking showers! The &#39;Tank less water heaters&#39; seem to be popular in for example the UK. But one reads about them needing to be heavily wired for 40 to 60 amps? At 230 volts that&#39;s like 11 to 15 kilowatts while operating! The cost of electricity in Europe where tankless seem to be more common is probably somewhat higher than in Canada? They don&#39;t sound very cheap and are often the subject of repair enquiries on the < uk.d-i-y > news group. So hard to judge how reliable they are? While they may save electrical energy???? the economics of &#39;Tankless water heaters appears, to us, doubtful at moment? BTW when people here, well away from major North American population centres scrap old hot water tanks, the metal recyclers are more than willing to accept them. So that&#39;s partly encouraging? Comments from those with different mileage welcome?

[Paul M. Eldridge]

Hi Dean,

Personally, I think they make no sense whatsoever. The current draw, in the case of an electric model, is enormous and even if your home has a 200-amp service, a tankless water heater could easily push it beyond its limit (e.g., an 18 kW tankless heater draws between 75 and

80-amps). And if you happen to live in an area, as I do, where winter inlet temperatures are just a hair or two above freezing, good luck! Raising the temperature of water some 70 or 75 degrees takes considerable energy and with two or more simultaneous draws (e.g., a shower and dishwasher or kitchen tap) there&#39;s an excellent chance someone is going to be left very unhappy.

Likewise, if you&#39;re in the habit of shutting off the water when you lather-up in the shower, you might want to kiss that idea goodbye unless you don&#39;t mind being blasted with ice cold water when you turn the taps back on (and if you have to leave the water running to ensure the minimum flow necessary to keep the elements energized, what happens to all those savings?).

Let&#39;s get to the heart of the matter. The average household uses between 4,000 to 5,000 kWh/year for domestic hot water purposes (we&#39;ll assume 400 kWh/month). If a conventional tank heater has an energy factor of 0.94, the standby losses work out to be 24 kWh/month or 288 kWh/year. At $0.10 per kWh, we can reasonably assume these losses are less than $30.00 a year. If a new conventional water heater costs $300.00 to $400.00 installed and the equivalent tankless unit is $1,000.00 or more with the necessary wiring upgrade, how long would I wait to reach break even and is that even realistic?

For a further take on this, see:

Lastly, all eight million or so residential households in Ontario are being converted to time-of-use meters and, in future, I suspect these meters will be far more commonplace than they are now. How much you will save (or be penalized) under time-of-use rates will depend on how much load you can shift to the off-peak periods. Practically speaking, you can&#39;t shift your water heating to off-peak times unless you have a storage heater. So if your power utility converts you to time-of-use rates (as in the case of Ontario) or you decide to take advantage of the potential savings where such rates are available, the very last thing you&#39;d want to do is install a tankless water heater.

This is the long-winded answer. The short answer is "are you nuts?". ;-)

Cheers, Paul

here..

[Dean]

Paul Short answer to Your answer/question,,"maybe".. To expand a bit,I do&#39;nt claim to be the "average bear" in any way,shape or form..Greg asked,,I answered the best I could without going on forever..I do&#39;nt have all the details in the world..Just My own modest expierience wich I can and will impart as I choose..TY.. Dean

here..

Hide quoted text -

[Paul M. Eldridge]

Hi Dean,

I have to apologize, I didn&#39;t realize it was Greg who had asked this question and not you, and I certainly didn&#39;t mean to imply your experience or opinions were in any way less valid than my own.

I soured on tankless heaters after spending time with one down in Atlanta where water supply temperatures are much higher than here in Canada. Everything I mentioned I had experienced first hand, plus the fact that the water never got what you might consider truly "hot". There was one other issue I didn&#39;t mention because it was most likely unique to this home; that is, the central air shut down anytime the unit turned on (there was a load controller) and so the compressor constantly cycled on and off anytime someone turned on a tap or the washer or dishwasher ran through one of its cycles; I suspect that a/c wasn&#39;t long for this world.

Again, my apologies for the oversight.

Cheers, Paul

[Jim Yanik]

[e-mail] wrote in news: [e-mail]:

One thing to remember;if you lose power,a tank water heater still keeps hot water for some time. I had warm-enough-to-shower water for 3 days after Hurricane Charlie.

On-demand heaters;NO hot water if the power goes out. (I doubt gas-fired ones work during elec.outages.)

[Paul M. Eldridge]

Hi Jim,

That&#39;s a great point. I was without power for about a week after Hurricane Juan, but my supply of hot water held on for the first two days, with moderate use (it&#39;s a 30-gallon indirect hot water tank tied to my oil-fired boiler; a larger tank would have likely extended that another day or so).

If you should wake up one morning to discover the power&#39;s gone out, this could be the difference between heading off to work or school having showered or not.

Cheers, Paul

[<josh]

My gas Takagi draws less than one amp maximum, lower than that most of the time, so during power failures it can easily run off the pocket-size inverter I use for my laptop computer in the car. If we had power failures more often I&#39;d put it on a UPS like our phones and home network.

With three kids in the house, I&#39;m hooked on the tankless system -- no matter who has been running what for how long, there&#39;s still plenty of hot water for my shower, even if the power is out.

[Jim Yanik]

wrote in news: [e-mail]:

At 120V that would be over 100 watts,considering startup surge.That&#39;s more than 10A at 12V.(considering conversion losses)

You can "unplug" your on-demand gas water heater&#39;s controller/igniter,and plug it into an inverter or UPS? I thought they were hard-wired. Have you actually DONE this? how long do those UPS run with the power out? Just long enough to shut down the PC? 15 minutes?

where&#39;s the hot water come from when the power&#39;s been out before you begin the shower? does your tankless system have some sort of battery backup?