Anyone here have a tankless water heater?

[Javaman]

How do you like it? My girlfriend and I are thinking of getting one for our new home.

Any input would be appreciated.

thanks. :)

[bluerum]

1. I don't have one but I hear they are real electricity hogs.

[MissWaverly]

2. Don't do it, I had one and it stinks

My tankless was a furnace that also doubled as a hot water heater, in the summer it was running
just to heat the water and my fuel bill was through the roof.

Miss Waverly

[MercutioATC]

4. I believe you're talking about something completely different.

A demand heater (tankless) is more expensive to purchase but offers significant energy savings. No keeping 40-60 gallons of water hot all of the time...a demand heater is an in-line device that heats the water as it flows through it.

I hear they're great, but have a higher up-front cost.

[MissWaverly]

7. could be

but my system was called a "tankless" system.

[MercutioATC]

9. Was it called a "demand heater"?

I believe the OP is talking about demand heaters. They only heat water as it's used, so they save quite a bit of energy.

[Dead_Parrot]

12. A different beast...

...but technically "tankless". I've got a similar set of plumbing in my current house, that runs through a wood stove: Happily, mine is connected to a normal tank - if the fire's burning it takes the work off the electric heater, but if it's not the heater kicks in and does the job. Works quite well, especially in the weather we've got at the moment...

[MercutioATC]

13. My parents have a similar setup.

Their woodburner flue runs through a 50-gallon water tank, which then feeds into the normal water heater. It works very well for them (at least in the winter).

[Dead_Parrot]

16. Any particular name for the system?

That set-up is called a "wetback" in NZ, but it's not a term I'd want to bandy about on a US board... :hide:

[MercutioATC]

17. My father built it himself.

Simple, really, just an old water tank, some copper pipes, a 2' steel pipe the same diameter as the woodburner flue and a welder.

[Trillo]

3. Yes.

It works well enough. The only problem that I have with it versus a tank type is the tank types typically have a 3/4" inlet and outlet. The tankless, a Bosch (IIRC), only has a 3/8 inlet and outlet. This decreases maximum flow through the unit.

What it means in usage is that hot water can only be taken from one source at a time, the moment a second hot faucet is turned on, the amount of water flowing drastically decreases, and neither faucet gets much hot water. You do not want to be taking a shower when anyone else demands hot water from the same tankless unit.

One other point of note, is that it takes a few more moments for hot water to arrive at the faucet, due I believe to the necessity of it heating initially, whereas with a tank, hot water is already hot.

I did not notice a decrease in the $ amount of the gas bill, and I never was retentive enough to break bills down into precise gas usage. It is possible that gas usage decreased, but if so, it was only a slight difference.

Personally, I think one of these for each hot water faucet would be ideal, but costly.

I believe that they now have a tankless unit that has a larger than 3/8" flow pipe, the cost for that unit is even more.

Upon installation of the unit, it was necessary to increase the vent size that exhausts the gas fumes, the size installed for the tank type it replaced was smaller than the directions indicated was required.

What they say about never running out of hot water, as it typical with a tank type as it refills with cold water and needs time for its temperature to increase, certainly seems to be true.

[MercutioATC]

6. The initial cold water is water already in the pipe

between the heater and the faucet. Demand heaters don't need to "warm up", they create instant hot water.

[Trillo]

11. No. It takes about 5- 10 seconds additional time.

The water in the heat exchanger is usually cold when the flame comes on. It takes a little amount of additional time for the heat exchanger and the water within it to warm. In a tank type, the water is already hot.

When was the last time you placed a pot of water on the stove, turned the flame on, and it was hot instantly?

[MercutioATC]

14. O.K....I'll give you 5-10 seconds...

[China_cat]

5. We don't have one yet

but I'm very familiar with them from my in-laws having one from the early 50's on (in Holland, where they are the norm and tanks are the exception). It was gas, got lighted (newer ones have automatic ignition when water is turned on) only when hot water was needed was produced unlimited in less than 10 minutes.

I don't know about the electric ones but I think this is the year we get one for the house. But it'll be a gas model.

(We switched to gas for water heat after Hugo. Cold showers for 3 weeks were NO fun...but we had gas to cook with)

[Dead_Parrot]

8. I used to have one...

a gas powered, on demand model (turn on the water, it regestered the pressure drop and fired up the burner) - Very nice, saved a lot of money over the tank version we had. IIRC, it depends on how much water you use as to what sort of saving (or not) you'll make: If you use a lot of hot water throughout the day, they're less efficient than a tank; but if you're both out of the house during the day and just need it morning and evening, it should pay for itself nicely.

No experience with electric models, I'm afraid... :(

[emcguffie]

10. I have one.

It has its good points, and its bad ones.

Before, there was never ENOUGH hot water. Now, it is -- hard to regulate. If you don't have the hot water turned on HIGH enough, it will eventually cut off, and you'll get cold water.

It may be that we have something set up wrong. I do not know.

But for myself, I am happy not to run out of hot water.

THen again, it may be that the dishwasher NEVER gets hot water.????

[Javaman]

24. Which brand do you have? nt

[rooboy]

15. I had one and I hated it. It never tanked me once. n/t

[demigoddess]

18. they've had them in europe at least since the sixties, when we were there

they take a little getting used to, but I have seen them on tv and they look much improved by technology. I would take the chance and try it.

[Steven_S]

19. I have installed 3 of them...

Two were gas and one was electric. They have 1/2 inch inlent and outlets. They are only good for one fixture at a time, unless you are running 2 faucets with flow restrictors. Washing machines and showers at the same time won't work. They are good for single occupant units or disciplined families, for obvious reasons.

There are units that can handle multiple fixtures but are very expensive.

The electric ones require 2 dedicated 40 Amp circuits to power them - and they will make the meter fly. Most small residential houses can't handle the amperage if they only have 100 Amps to begin with.

Last time I bought one they were $700.00 and I charged $600 to remove the old tank and install a gas unit. It took about 3 hours with alterations.

[Ian David]

20. There's a hot water heater that goes right next to your sink

I'm not talking about the super-hot faucet for making coffee.

In Japan, they're apparently pretty common.

They had one in the Japanse House in thw Boston Children's Museum.

[jxl]

21. I have a tankless water heater.

It's an AquaStar. Powered by natural gas. I have one that ignites the gas with 2 D batteries rather than electricity. I do not have an electric-powered exhaust. The reason I chose this model is that if there is a power outage I still have hot water.

I have had two minor problems with my heater. The first was one that just needed an adjustment. The second was one that required a new part. In both cases, I called the help line of AquaStar and the tech person walked me through a careful diagnosis. In the first case, the tech helped me adjust the heater. In the second case, the tech was exactly right about what was wrong and we were able to install the part ourselves. So, in both cases, I had no service call charges (and quick response).

Two notes about cost. Part of the reason that the units are mose expensive is that the units themselves are more expensive. But a second cause is that you need heavy duty aluminum pipes that go out the roof for exhaust. Before I contracted with a plumber to install my unit, I would ask if they can use "black pipe." Most water heaters are installed with flexible, ribbed pipe. The AquaStar people have told me on the telephone that black pipe gives more gas and therefore more heat (though they say plumbers deny this). Given the stellar service that I have gotten from AquaStar, I am more inclined to believe them than my local plumber. I think it may take time to locate a plumber who will do this work and it may, therefore, be more expensive. I would do it if I were installing one again.

One oddity (and I haven't tried to talk to the AquaStar people about this) is that when my whole-house fan it running, the burner won't light. This is a minor problem -- I just turn off the fan and turn on the water.

If you use hot water all through the day, you may not save that much money. But if you are out of the house all day, I think it's a great way to save energy.

If I were building a home (rather than retro-fitting one), I might put in two small units near the bathroom/kitchen areas rather than one big enough for the whole house.

The point about having hot water for only one faucet it true for my unit -- but I think you can buy bigger ones than I have. Also, you often have the same problem with a tank type heater.

I would buy one again.

[rurallib]

22. Got one about two years ago

Love it. Figure it saves me @ $20 or more a month so it will pay for itself soon enough. And we finally have enough hot water to shower completely and then another person can shower without a wait etc.

[Javaman]

23. Which brand do you have? nt

[Coastie for Truth]

25. Ruud

Back in the old days (in the Rust Belt - Buffalo, Pittsburgh, Cleveland, Detroit, Chicago, Milwaukee, etc.) Ruud hot water heaters were very common. The colder water flowed through the Ruud in a pipe, the pipe was literally wrapped around a gas flame.

When you turned on the hot water, the pilot light would ignite the heating jet.

The water was hot (if you fussed with the setting you would get steam).

My parents had one for years (their house was built in 1927 and they had the original Ruud for about 40 years). We had one (our house had been extensively remodeled and rebut in the 1930's, and that was the model of Ruud we had)

This is what the old ones looked like--
<>


It gave hot water - and lots of it -- even with three showers going. ;)

[phantom power]

26. One comment about the way they work:

A tankless heater gets rated by degrees temperature-rise, at a given flow rate. For instance, I looked at one that was 50 degrees rise at 7.5 gallons/minute, and 70 degrees rise at 4 gallons/minute.

So, how hot the water is coming out depends on how hot it was coming in. You can probably mediate that by installing a temperature-mixing valve on the output side. So that it will mostly be at a well controlled temperature.

In a tankless setup, I gather that the way you use hot water is a bit different. You set the system to provide water at 110, or 120 degrees, and you mix it with less cold water at the point-of-use. If you take a shower, you don't mix in much cold water, if any.

I've never used one, so I don't know how it works out as a lifestyle. Oh yes, and they also cost about $1000 bucks.

[Trillo]

27. One of the water supply modifications I was considering

to try to mitigate the single-faucet flow issue: The water pressure in the Bosch, (I think it might say Aquastar, bought it at Lowes a few years back, about $500) has been pressure regulated down to about 70psi using a whole house pressure regulator. Street pressure at this location is often around 95-100psi, which is a good 20-30 psi difference. I've checked the specs on the tank itself, and IIRC, it is rated to safely withstand 150 or 300psi.

Therefore, I've considered bypassing the pressure regulated water inflow to street pressure which is higher, then regulating the hot-water outflow psi downward to match whole-house cold water pressure. I don't know how close I can synchronize the two pressures, I suspect I can get it within 2-3 psi using standard hardware store regulators and pressure gauges, but that's just a guess.

All regulators are not 'approved' for hot water, so that's one small issue, but not insurmountable. I don't know if a pressure regulator's 'approval' for hot water is just a bureaucratic stamp, of if they are manufactured with a different diaphragm material that's more resistant to hot-water.

The last municipal water district I lived in this manifold would not have been useful, as street pressure was about 75psi. I tend to prefer the in-the-house pressure at about 70-75psi, so there would have been no psi difference to advantage. Some people might prefer a lower pressure, the point is it depends on conditions at the site of installation.

It occurred to me that if I installed this type of pressure bypass with regulation after the unit, it would increase total volume through the unit when a second faucet was opened. It seems that since the water is at a higher psi, the water would be traveling faster through the heat exchanger under a second faucet demand, and the problem might be that the temperature of the water could be somewhat lower (this relates to your statistic, temperature rise versus psi). It also seems, however, that the flame regulates it's own height when first turning on (presumably for faster initial heating), so perhaps the tankless unit would temperature compensate for the higher psi flow under second faucet demand. Unfortunately, the instructions that come with the unit are designed for 'consumers' and installers, and precisely how the unit works and is designed & engineered is largely unrevealed. If there is an adjustment to set the hot water temperature at the unit, it is not disclosed with any of the consumer supplied documentation.

The straight hot water is truly too hot without mixing with cold water for most uses with the factory setting, so a bi-metallic mixing valve, something like Watts manufactures, would also increase total flow through the hot water supply pipes, since a small, temperature regulated amount of that water would bypass the heating unit. This might also mitigate the two faucet demand problem.

The only way I know of finding out is to build the water inlet and outlet manifolds to test it, and I've put off building them for a couple of years now....