Tankless Water Heaters

[OldJeff]

Thanks everyone for the information.

We are leaning heavily towards doing this, and thanks to you guys we now know to wait for the new year and cash in on the 300 dollar tax credit. I wonder if SWMBO would think that some lumber would be a good way to spend that tax credit ? ...sorry got off in daydream land there for a second, she will want to spend it on something silly like the electric bill or groceries.

[Stick]

Ok, here's an off the wall question.......anyone have any experience with tankless heaters on a rural well with extremely hard water? Are they more or less susceptible to hard water deposits clogging them up than a conventional tank type heater? I have to pull the bottom element in mine and clean the deposits out at least twice a year, or they build up to the level of the bottom element.

Another comment.......I have a house where I work, that I'm only at for 8 days out of 18. First 2 years I was there, I tried turning the hot water tank off every time i left, and I often found there was still some hot water left 10 days later when I got back. Then I just left it on. I see zero difference in the electricity bill. Modern tanks are insulated so well, they don't draw much power to keep them warm if no water is used, the only real difference seems to speed of warm-up.

[mschrank]

quote:Originally posted by Stick

Ok, here's an off the wall question.......anyone have any experience with tankless heaters on a rural well with extremely hard water? Are they more or less susceptible to hard water deposits clogging them up than a conventional tank type heater? I have to pull the bottom element in mine and clean the deposits out at least twice a year, or they build up to the level of the bottom element.

When I purchased my tankless heater, I also bought these fittings. Makes it easy to hook up some hose and a pump to flush the system.

[scorrpio]

Our house is rather old, and the hot water system is fairly interesting - I haven't figured it out yet completely, as we bought the house only 4 months ago. We got an oil boiler pumping hot water through baseboards for heat. Somewhere inside the boiler is also hidden an extra coil for hot water. However, that coil goes to a 40-gal electric water heater. I am not sure if the heater even works - it is about 20 years old. At this stage, it only acts as a buffer to store the hot water. There are valves to rerout the water so that cold water goes directly to heater and boiler coil is not used.

Overall, the system works well - we never have to wait more than 10-20 seconds for the water to get hot in the 2nd floor bathroom, even after a two-day absence.

From entirely physical point of view, tankless heaters are more economical. Heating a gallon of water from temp1 to temp2 takes same amount of energy weather tankless or not. But with tank, as you store this water, some of that energy dissipates and goes to waste - even with best insulations. As long as heater efficiency is same, tankless is a more economical solution - and the closer to the tap, the better.

Far as circulation pumps go, you have your main hot water feed running in a loop, with pipes branching out to taps. When no taps are open, a pump keeps moving the water around the loop, so the heater keeps it hot. Unless hot pipes are heavily insulated, I find this solution very wasteful, as you are constantly expending energy to keep pipe water hot. If you have a central heater in a smaller home, I'd say a star configuration is better - a dedicated pipe runs to each bathroom or kitchen directly from heater, and that minimizes the time it take for hot water to reach a given tap.

[mschrank]

quote:Originally posted by scorrpio


Far as circulation pumps go, you have your main hot water feed running in a loop, with pipes branching out to taps. When no taps are open, a pump keeps moving the water around the loop, so the heater keeps it hot. Unless hot pipes are heavily insulated, I find this solution very wasteful, as you are constantly expending energy to keep pipe water hot.

I agree, but note that many of the recirculation pumps have a timer feature that allows you to set them to pump only at specified times, i.e., start just before you wake up, and off during the day while you are away from home.

[stewchi]

While it is true that the circulation pumps will cost you energy in what is lost or dissipated in the pipes, this is also true for a non circulated system. Every time you use hot water you are pulling hot water from the insulated tank to the pipes were it will dissipate. The benefit of the circulation pump is it is doing this for you so you don’t have to wait pouring water down the drain. My guess is for households that don’t frequently use hot water that you would be wasting some energy. For households that have frequent hot water usage the savings in water loss may compensate for energy lost in the pipes. Of course this is another advantage of the star configuration, less energy wasted when waiting for hot water to was your hands, you only loose the energy in the single line to the sink.

I think the recirc pumps are great for sinks, I don’t think the dishwasher, washing machine or shower/tub needs one. I am already in the habit of turning the hot water one before I get in the shower. I don’t mind the wait, I am busy getting undressed. It is when I need to wash my hands or face and have to wait longer for hot water than it takes to wash my hands that frustrates me.

[billwmeyer]

It sounds like there are two types of tankless being discussed here. One is a whole house water heater, the other is smaller for individual locations, like a sink. I have a Bosch whole house tankless heater and I like it very much. I also did it to save space and to have endless hot water. I am very satisfied with it but it does have it's quirks. It does take longer to get hot water to a tap. This is not a big problem, you just learn to turn on the tap a bit sooner than you would have, and waste a little bit of water. Also, regulating the temperature is a bit tricky, but once you get it there it does stay.

My biggest problem is that in winter, when the temperature of the water coming into the house drops, it drops the temperature of your hot water. I am sure that I can rectify this by going to a larger natural gas supply line, but I haven't had that opportunity yet. I do have a rather small feed into my unit.

I would buy another one.

Bill

[averysnow]

One disadvantage of a recirculating system is wear on the pipes. Hot water is harder on pipes in any case and if you constantly circulate water through them, they will wear out much sooner due to the increased friction. If you're plumbing in copper, use a thicker grade such as type 'L'.

Also, I think tankless water heaters are a bum deal. I have a 40 gallon hot water heater and I have never heard/seen the burner turn on unless someone has just used the hot water. That shows how efficiently they're insulated - and mine is about 10 years old.

-Eric

[mschrank]

quote:Originally posted by averysnow

One disadvantage of a recirculating system is wear on the pipes. Hot water is harder on pipes in any case and if you constantly circulate water through them, they will wear out much sooner due to the increased friction.

You might want to use the "wink" smiley with comments like this...otherwise some might think you're serious.

quote:Originally posted by averysnow


Also, I think tankless water heaters are a bum deal. I have a 40 gallon hot water heater and I have never heard/seen the burner turn on unless someone has just used the hot water. That shows how efficiently they're insulated - and mine is about 10 years old.

-Eric

I'll agree that conventional tank type heaters are very well insulated...my old one only kicked on after hot water use as well. But while I do expect some cost/energy savings (plus the state tax credit), I pointed out in an earlier post (as have others) that two other big advantages are space savings and endless hot water. OK, so I only gained about 16 sq ft of floor space, but in a small utilty room this seems like a lot. I now have room to re-arrange the washer/dryer, and will have room for a small work area for LOML's scrapbooking.