On Demand Water Heaters

[Flybye]

We are home from Kauai. Just got in yesterday afternoon. We are exhausted, to say the least from the red-eye flight home. We have been greeted by a leaky water heater. We have know that it was on its last leg for at least a year but have been helping it limp along. It is an electric heater that we purchased with the home. Now we have to get back to reality and get busy drying out carpet and fixing the heater.

Do any of you have an on demand water heater? This is one option that we are seriously considering. It is pretty pricey, as we will have to vent it to the outside, get it hooked up to natural gas, and have a new water softener put in.

The other option for us is to piggy back two gas water heaters which would still involve venting and purchasing a new water softener and getting the heater connected to gas.

We need enough hot water for a family of five. I understand that there is a two appliance max at a time that can run on the heater.

Any advice or opinions?

Thanks...


I'll post pictures later....we took a bunch!

[maillotpois]

From what I have heard, talking to people in the business, this is the way to go. Environmentally better, saves money in the long run because you're not holding a big pot of hot water staying heated all the time - just when you need it. I would absolutely go this route if we could.

However, the other thing you need to check out is to make sure that your plumbing is adequate to support this type of water heater. One of the guys I talked to, a client who specializes in radiant and on demand, said that in a lot of older houses not only do you have to deal with the venting issue (he recommends just mounting them on the outside to deal with that), but the plumbing may need to be upgraded as well. (Has to do with the BTUs and all, but I don't recall the specifics.) So check on that with your house.

You might see if there's some sort of energy saving rebate program available in your state for upgrading to this system.

[LBTC]

Fly, I asked DH about this as he spent some months as an apprentice plumber recently, and learned a bit about it. A direct quote of his reply:

Ok....going to an on demand heater is an expensive proposition. The pay back is a long time, and the initial cost to install is probably 4-5 times the cost of a gas hot water tank. The venting is the same as a high efficiency furnace, so it would be best if she can install it on or near an exterior wall. Electric tanks are more efficient when idling, versus a gas tank, but the recovery is slower. The on demand systems take awhile to provide heat if you want a quick blast of hot water, say to wash your hands. The bonus to the on demand is that they use no energy when not in use, and they never run out of hot water. They just have an initial huge cost to install and long payback. Remember that she will be looking at gas lines, venting and plumbing. If she's good with that.....go for it.

The cheapest way to do this is to twin 2 electric tanks. I've done it, and it's fine.

That said, I do seem to recall that he said that in an older house there may be water line upgrades necessary, also, so it may depend on the age of your plumbing, too.

Best of luck with this. Sending fast flying butterflies so their wings will help to dry out the carpet!

Hugs,
~T~

[sundial]

We are home from Kauai. I'll post pictures later....we took a bunch!

Welcome back! Where's the pics?? Oh, and take a pic of your new water heater(s) too. :D

[IFjane]

flybye - we are also considering this. We purchased a home in 2001 that was built in 1981, along with the electric water heater (we have no idea if it is original or not). Last year we replaced the heating system with a high-efficiency gas furnace with a heat pump backup - love it! Big investment but much lower monthly energy bills. I expect the same thing from the hot water heater.

Please keep everyone posted if you decide to go ahead with this. We are waiting until the hot water heater dies as well....

[tulip]

The condo I reserved has a regular hot water heater (but a half-sized one since it's a half-sized condo!) The developer said that the electric on-demand water heaters have some reliability problems, and there's no gas in the building (unfortunately for me, as I like to cook, preferably on a gas stove).

[tc1]

And is a lot less aggravation. You might be surprised at the amount of cost and bother required to retrofit an on-demand system.

The thing about electric heaters is, you should replace them every ten years. What happens is they develop rust and pinhole leaks at the top. By the time this is discovered, the heater has been leaking small a small amount for weeks, if not months.

For fast drying of the mess, go to a rental store and get a commercial blower/fan, and a dehumidifier. I also rented a commercial carpet cleaner when this happened to us, and was able to get the carpet better than it looked when we moved in, with no mildew.

O'course putting all the stuff back into the storage room is another topic altogether.

[divingbiker]

I attempted to get an on-demand gas water heater when mine died last year, but it was going to cost so much and take so long to get it done (and I'd be without hot water in the meantime) that I ended up getting another gas heater. My only experience with on-demand heaters is at my office, where each kitchen has a small heater under the sink. Those are unreliable and annoying.

[Pax]

My dad (who was a retired contractor) decided the on-demand stuff was too expensive when they bought their place in FL, since it was an electric hot water heater, he just installed a switch (like a light switch). They would flip it on before bed and have hot sowers in the morning and then flip it off on their way out the door to work. It was a $2 solution, don't know if it would work with gas though?

[Flybye]

Well, after much decision and debate, here's what we have decided...........

As much as we would like to be responsible and save the planet, we still have to feed our children!

We just can't talk ourselves into putting in the on demand water heater when it will cost roughly $1,500 more than if we go with either electric or gas. Not only is the cost a huge deterrent, but the power venting system is troublesome, our home was built in 1970 and the pipes may not be up to snuff, and we have heard that since our ground water is so cold in the winter, we may only get our temperature up to 105 at best in the winter.

We have decided that it just isn't worth it at this point.

All of your opinions and knowledge helped a great deal, as we really didn't know too much about these heaters. You all brought up things that we hadn't considered.

The carpet is pulled up and we have a fan on it.

We are waiting for the plumber.

Thanks again! Mahalo!

[Flybye]

My dad (who was a retired contractor) decided the on-demand stuff was too expensive when they bought their place in FL, since it was an electric hot water heater, he just installed a switch (like a light switch). They would flip it on before bed and have hot sowers in the morning and then flip it off on their way out the door to work. It was a $2 solution, don't know if it would work with gas though?


I like this idea and we will be sure to ask about it!

[7rider]

I like this idea and we will be sure to ask about it!

My in-laws did something like this...had a timer attached to the w.h. somehow....so it fired up the water up b/f evening showers (they showered at night) and dish-washing.

[mimitabby]

I'm getting a tankless gas water heater TOMORROW!!!

[IFjane]

ooooh ooooh ooooh Mimi!!! I wanna know how you like it - that's exactly what I want to do...

[mimitabby]

i'll let you all know. one of the wonderful parts of this is I get a new room because the old waterheater blocks it from being usable. the new one is much smaller and mounted on the outside of the house!

[Trek420]

I like this idea and we will be sure to ask about it!


I like it too. I have something similar on the (gas) heater. Thermostat is downstairs but heater is upstairs and I forget to turn it down at night. I don't want to trundle downstairs but there's a little switch.

Did not think I could have that on the water heater. :rolleyes: Smart guy that Queen Dad :D

Mimi, tell us all about how the install goes :)

[Mr. Bloom]

We have two water heaters. The original gas water heater installation. We subsequently added an electric one. The water system draws from the electric one first, which then draws from the gas one. Theoretically, we can never run out of hot water since the gas reheats much quicker. In reality, we don't ever run out of hot, but after we've gone through 100 gallons, it's comfortably warm, but not hot.

It used to be we couldn't fill our jacuzzi with hot water...now we have plenty to do that even when SilverDaughter is taking one of her typical 30 minute showers...and the high efficiency washer is running:D

We get through four morning showers comfortably now.

We considered an ondemand heater prior to doing this because our water heaters are at one end of the house and the pipe run upstairs and too the other end of the house (about 100+ ft)...meaning we had to run water for nearly five minutes to get hot. But, even pondering a $300 monthly water bill (mostly sewer) it wasn't cost effective for us to install on demand. They're very good for low use applications, but not for normal living...

[Mr. Bloom]

The carpet is pulled up and we have a fan on it.


I'd encourage you to go to the rental place and get the mega fans...

[Tuckervill]

So what about the PIPES needs to be fixed up?

I have an old house with cast iron pipes. We're looking to add a master bedroom, and that will include all new systems (water, heat, a/c, water softener, but not new pipes or electrical, I hope). I know the tankless system will be expensive, but it's justifiable by not having to provide space for a water heater in a cramped space.

So what about the pipes?

And my rental house which I formerly lived in has two hot water tanks--one provides heat for one of the furnaces, too--and it was HEAVENLY to have!

Karen

[mimitabby]

they didn't seem too worried about my pipes they seemed more concerned about my GAS pipes, but after examination, they were found to be more than adequate.

[mimitabby]

Well, the heating unit was installed. The guy said "if this was mine, I would take the insulation that used to be wrapped around the old waterheater (dated 1981 btw) and fill it into the box. So i cut some out and did that before he hauled it away.

THe water comes in nice and warm, but it does seem to take longer; that's because instead of heating all night and gradually radiating somewhat up the pipe, the heater does not heat at all until you ask for it.

Tonight someone will take a bath or shower so I'll have more to report.

I cleaned that little room out, it was pretty gross, almost like outside; that's how black the dirt was that was there.

[Flybye]

Mimi - Yeah for you!! May all of your showers be heavenly warm. I really wish we could have gone the route you are going.

We have two water heaters being piggy backed and a water softener being installed today. As we speak, in fact.

Let us know how you like your shower!

[tinyhouse]

I just did research on this very issue. I too wanted to choose an environmentally friendly water heater and felt it would be worth the extra expense to do so. However, I read a great deal about on-demand heaters and ended up going with a (gas) tank instead. Here's why:

They end up wasting MORE water because it takes awhile for the water to come out of the faucet hot. I'm not interested in wasting water. I also found out that you can't run as hot of a shower and occasionally after a ride in the rain I have a chill I can't shake so I like a nice hot shower.

[mimitabby]

yes, miss tinyhouse (please explain your name please!) i think there will be a bit more waste of water. But I just got done with my very first insulation job!! (cough cough) I insulated the wall where the pipes are that feed into the heater and back out. Next I will insulate the pipes themselves. All we had was exterior wall and studs, no wonder it's cold.

I also insulated underneath my bathtub. i can't wait to see how much of a difference that might make. that tub has always been cold!
now soon as i quit itching and coughing, I'll be a happier camper. (I wore a kerchief over my face and safety glasses.)

[tinyhouse]

Wow Mimitabby it sounds like you did a great job of insulating. Our old Victorian was built in 1897 - so I think insulating pipes probably would have helped us too had we gone that route. Hope the coughing goes away soon!

tinyhouse refers to both our small victorian and our dream to own a tiny tiny house someday (preferably one that we build out of strawbale) which we hope to locate on a little tiny piece of land :)

[mimitabby]

oh how wonderful to have a house that old. We are fortunate to have a 1957 craftsman (i think) it was built VERY VERY well, but it does not have much character, which I am SURE yours does.

[tinyhouse]

Actually, it doesnt have as much character as you would imagine - the previous owner did a remodel and left out period detail. I love craftsman homes!

[mimitabby]

Well, I got the clothes into the gas clothes dryer and stepped into the tub and drew a bath. I really couldn't tell if the tub itself felt warmer because of my insulation job, (I think so) or if it was just my imagination. I had a nice hot bath. Meanwhile, the heat came on (also gas) and at that point, DH came and took his shower. He had plenty of hot water too.
I was quite pleased.

[tulip]

I lived in an apartment for seven years in North Carolina that had solar hot water panels on the roof for heating water and a booster gas hot water heater. It was a very good setup. We never ran out of hot water, and our bills were very low because most of the heating came from solar.

Just another way of thinking about these things.

Tinyhouse: I am very interested in tiny houses, and in fact gave a presentation last year about them to a bunch of architects. I'm buying a tiny condo, and I'm excited yet a bit wondering about living in such a small place. It'll be like a Airstream or a ship--a place for everything (which is not too much, by choice) and everything in its place. My tiny Bike Friday will fit in well. It's nice to know that you are into tiny houses, too!

[mimitabby]

Oh, I'd love to have solar power. But in the winter in Seattle that would be a joke. Too bad there isn't cloud power! :p

[emily_in_nc]

re. Tinyhouse:

I've always told my DH that someday I want to live in a "tiny cottage". I just love the cottage style, and would love a compact little place with about 1/3 to 1/2 the possessions we have now, where we wouldn't lose our "stuff" because we have too darn much of it!

When we spend time down on our 30' cruising sailboat (most definitely a tinyhouse!) I realize how much we have that we could get along without. But we love our home and especially our yard (11 acres in the woods with trails for hiking, running, and mountain biking), so we're not quite ready to pursue the tinyhouse dream. But it's on the back of my mind for someday.... :p I just love the idea of simplifying that much! Would love to live carfree too....

Emily

[IFjane]

re. Tinyhouse:

I've always told my DH that someday I want to live in a "tiny cottage". I just love the cottage style, and would love a compact little place with about 1/3 to 1/2 the possessions we have now, where we wouldn't lose our "stuff" because we have too darn much of it!

When we spend time down on our 30' cruising sailboat (most definitely a tinyhouse!) I realize how much we have that we could get along without. But we love our home and especially our yard (11 acres in the woods with trails for hiking, running, and mountain biking), so we're not quite ready to pursue the tinyhouse dream. But it's on the back of my mind for someday.... :p I just love the idea of simplifying that much! Would love to live carfree too....

Emily

But Emily - I can't think of anything better than having a tiny house on 11 acres! Do you know anyone with a bulldozer? :eek:

[lette]

Mimitabby, and others that have a tankless/on-demand system, are you still happy?
We are ready to replace our tank, and seriously considering a small one application gas model. Only two people, and we never run another water appliance when the other is in the shower.
All your knowledge appreciated,
Thanks, Lette

[Biciclista]

we've gotten used to it.
I like it. I like the electric/gas bills. I like the fact that when we have guests we never run out of water. i don't like being the first person in the bathroom in the morning, because you end up running about a gallon of water to get to the hot stuff.
there's some parts that don't really make sense to me (in relation to how long it takes to get hot waters which times) but I like it. it's small and efficient and when i'm not in a rush, i just take that gallon of cold water and reuse it.

i like the fact that when one of us is in the bath, it's not going to screw anything up if the other starts the dishwasher or the washingmachine.

[Tuckervill]

Wait, Mimi, is it because the water heater is a long way from the shower? Cuz I already have that problem in my house with a regular hot water heater. Worse in winter time. Or, is it because it takes that much water run through the system before it heats up? (that doesn't make sense to me.)

I don't like to waste water, but I already do, because of that very problem.

Karen

[Biciclista]

getting one of these isn't going to help your particular problem Karen; what you are going to save is on energy wasted by heating a tank of water 24 hours a day. Now you're only heating water when you need it. I think the "worse in winter time" problem is not much different; but here in Seattle the temp extremes are just not that extreme.

[smilingcat]

When I visited my cousin, my uncle and his family and my aunt in Japan, they all had those tankless water heater. I didn't notice any difference between the tanked system here in US and the tankless system used by my relatives.

I've been trying to get my plumber neighbor to install one. He is driving me bananas!!

My plan is to use solar water heater system using the evacuated glass heat pipes and use a 40 gallon? storage tank. Then use the tankless system as a back up. The idea is to use much of the solar as possible so that the tankless will remain off for the most part or only have to heat the water by additional 10-20 degrees instead of 60-80 degrees. This way I don't have to worry about running out of hot water in the evening.

So my patience is being tried...

Smilingcat

[derailed]

A comment, if I may.

On top of every tank-style water heater is a large heavy nut.
This nut is connected to a long, zinc rod.

It's not easy, as the tank must be off and completely drained, but replace this rod every 3 or 4 years, more often if your water is troublesome.

This will drastically mitigate tank-rot.

There are how-to guides all over the web explaining in detail.

[tulip]

When I first posted in this thread, I was looking at a condo. But I ended up buying a little house instead. The old hot water heater was toast, so I replaced it. The cost difference between a tankless and tank heater was so great, that in my case it just did not make sense to go with the tankless ($4,000 vs. $800).

The new electric tank hot water heaters are very efficient--more efficient than the gas tank heaters because gas heaters need to be vented, and that allows some of the heat to escape. The plumber said the electric tank heaters lose 6% and the gas ones 30%. The new electric tank heaters are like a giant thermos--very well insulated and once the water gets heated, it takes very little energy (about 1.5 hours per day) to keep it at the proper temperature.

A tankless water heater was not appropriate for my situation. My plumber said that Rinnai tankless heaters are the best of the tankless, FWIW.

[Biciclista]

Tulip, the price differential is scary, yes. But modern water heaters even though they are more efficient, they do not last as long as the older ones could.
Ours was 27 years old when we replaced it, and although it was an energy hog, it never leaked. I was assured by everyone that came to give a price quote that new ones didn't last more than 12 years.

[Norse]

Our 8 year old gas water heater has been a problem every winter from day 1. When the gas furnace is kicking in, the water heater pilot light frequently goes out - not enough oxygen in the basement apparently. Many "experts" have looked and scratched their heads, adding bigger holes and venting to the outside, drilling holes to the garage... but nothing has seemed to work. Every winter, we need to relight the heater about every other day. So, we want to replace the darned thing.

I really like the idea of the tankless heaters but based on our existing venting problem, it sounds like that will not work well. We also have an older house (1955) with older plumbing. Our idea is to replace the heater with a gas heater with electronic ignition. I have always preferred gas to electric because of the perceived efficiency and better for the environment issue but Tulip's comments have me thinking maybe we should go electric? Thoughts?

[Biciclista]

The tankless heater is on an outside wall fyi.

[Norse]

The tankless heater is on an outside wall fyi.


I don't think that would work well in Minnesota. Right now, it is a balmy -6 outside. :eek:

[Biciclista]

ha, you're probably right. the box is insulated but i don't think that puny insulation would do much at -6!!!!

[smilingcat]

my electric water heater is sitting inside a shed next to the house. If you were to do this, you can insulate the tankless and keep it out of the extreme weather. Also simplify the venting issue with natural gas powered tankless.

Plan is to rebuild the shed to accomodate a water tank for the solar and have enough space for the tankless system. I have to bug my plumber again. :mad: My next major project for 2009. Was supposed to have done it in 2008. I hate un-necessary delays.

[Biciclista]

Smilingcat, tankless is tiny, like the watercloset for a toilet.

[ny biker]

When I first posted in this thread, I was looking at a condo. But I ended up buying a little house instead. The old hot water heater was toast, so I replaced it. The cost difference between a tankless and tank heater was so great, that in my case it just did not make sense to go with the tankless ($4,000 vs. $800).

The new electric tank hot water heaters are very efficient--more efficient than the gas tank heaters because gas heaters need to be vented, and that allows some of the heat to escape. The plumber said the electric tank heaters lose 6% and the gas ones 30%. The new electric tank heaters are like a giant thermos--very well insulated and once the water gets heated, it takes very little energy (about 1.5 hours per day) to keep it at the proper temperature.

A tankless water heater was not appropriate for my situation. My plumber said that Rinnai tankless heaters are the best of the tankless, FWIW.

Tulip, this is good to know.

I think I might need a new water heater for my condo, and everything is electric here. I don't know for sure how old my current water heater is but I think it might be approaching 15 years old. (Former owner told me it was "about 10 years old" when I bought the place, which was almost 5 years ago.)

I live on the 2nd floor of a 3-story garden style condo building, and the water heater is in an attic space on the 3rd floor which is not easy to get to. I'm trying to get my hands on a ladder tall enough to get me into the space so I can check it out. Originally I was going to put an insulating blanket around the heater, but now I'm figuring that I will probably just replace it, rather than keep it and wait for it to cause a big mess when it starts to leak. And a newer one should cost less to run since the insulation will be better.

Thanks to everyone for your input on this subject. It's so great having all this information available.