Tanks in advance!
September 11, 2010 1:13 PM   Subscribe

We need a new hot water heater and are considering a tankless model. Do you have one and can you tell me if it's worth the higher price?

We've just bought a 100-year-old house in the city and every square inch of it needs work. Our HVAC guy is very trustworthy and recommends a tankless hot water heater. It's about three times the initial cost of the traditional kind and I don't know anyone who has one. I have researched it to death, but there's no substitute for experience. It's a big old house with two bathrooms, but only one will be used regularly. We have a dishwasher and basement laundry. Can I get some information first hand from fellow MeFites?
posted by raisingsand to Home & Garden (26 answers total) 9 users marked this as a favorite
I've lived in many houses with these and would never willingly go back to a tank heater. The downside is that it takes longer to get hot water to the faucet (not hours, but maybe 20 seconds longer, which can feel like forever when you are waiting); the upside is that your utility bills will be cheaper and you can have four people take showers in a row without running out of hot water, which is great if you have visitors. I have only ever used gas-powered tankless models; I'm sure the electric ones are ok but you might not get the cost savings with them that you do with gas.

If the federal tax credits are still in effect, that can make up a lot of the difference in initial cost between a tankless and a tank heater.
posted by Forktine at 1:29 PM on September 11, 2010

OK, here's just a datapoint from my European perspective. Here (nearly) everybody gets 380V to the doorstep and 230V are what you get out of your sockets. The full 380V are for stoves/hobbs and for tankles water heaters. So we have ome advantages when it come to big electircal appliances.
Tankle water heaters draw a lot off current. If you have an electrical system that can deliver the amps, a tankles water heater ist simply wonderful! If the wiring to the water heater is shakey, you're better of with a tank. Tanks do not draw as much current and heat up much more slowly (You used up all the hot water! I can't do the dishes (manually) after your shower). With a tank you eiter have to warm a lot of water if you want a nice tub full of it, or you can heat a smaller volume to a higher temperature. Either way, you're wasting some heat/energy with a tank. With a tankless system, you generate the hotness only when you need it and you get as much hot water as you want.
For convenience I would always go with a good tankless system if your budget and your wiring can support it. It's greener, too. (Both sytems could probably be connected to solar heating as well. The tanklss one would need a tank in fornt of it though, with the result that it does not have to increase the initial water tempereature by quite so much).
In addition, a tankless system needs not as much space, but that is probably not much of a concern in a big old house.

Addendum: Forktine talks about a lack of lag, when it comes to hot water. This is probably only true if you have individual units in front of the hot water faucets, with a central system you probalby will experience some lack. I have yet to see a tankless system that supports more than three or four hot weater outlets (at the same time) though, but this may be to lack of expereince. (Here electrical water heaters are a thing of older houses or appartments. Most newer houses get the hot water as an addition to the central heating infrasturcture.)
posted by mmkhd at 1:35 PM on September 11, 2010

Best answer: It depends what you want out of the water heater, and what the actual installation costs will be.

First, the installation costs. If it's an electric you might need one or more new circuits. IIR, when I was looking at tanklesses a more basic one required three 40 amp circuits. This would have probably required me to have the main panel replaced. If you are already running a bunch of circuits this might not add much to the costs though.

I went with a Bosch gas model, and I needed to have a new gas line with a larger diameter run from the meter. I also had them put in a few other things at the same time, and I already had to have pressure testing done because the meter had been pulled while the house was vacant before I bought it, but it was still more than I would have spent on only those things. There's also the vent, which will probably be bigger than what you currently have, so that's another expense. Venting to allow more air into the house may also be needed.

I never used my old water heater so I don't know if it's saving me any money. You can always turn off the water heater when you are out of town, or turn it off after you shower in the morning if not paying to keep the water hot is your issue with it being "worth" the higher price.

The advantage of a tankless is that you don't run out of hot water, it's quite possible that this could end up with you using more of it. You may consider this either a benefit or a detriment. Part of the reason I went with a tankless is that they take up less room, you can have on mounted to the wall above a washing machine or something.

Some things that are different than a tank model: the temperature can vary a bit if the water flow through the unit is changing, it needs a certain minimum flow to turn on (so, no small trickle of water for washing dishes), it's flow rate is somewhat limited (if you are going to have both showers and the washing going at once, get a large flow rate model), if the hot water is turned on and off repeatedly you end up with the water alternating between hot and cold in the pipe, and the temperature needs to be adjusted with the seasons. None of these really bother me much, they are just differences. I'm still happy with it overall, but that's partly due to the space savings, which may not be an issue for you.
posted by yohko at 1:44 PM on September 11, 2010 [1 favorite]

We have one and are happy with it for the most part. For us, the biggest consideration was the small footprint - we have an extremely small "machine room" and nothing else would do.

Since it's only activated when you call for hot water, it has to be cheaper once online than keeping a 30-gallon tank hot for hours or perhaps even days when no one needs hot water. How much cheaper I couldn't say, since we don't have a basis for direct comparison, so it's unclear how many months or years it would take to break even on your investment.

If you live somewhere with cold winters, you should keep in mind that the temperature of the ground water is a huge factor in the performance of the tankless unit. In the summer, when the temperature of the water in the pipes outside the house is nice and warm, our unit has no problem producing an endless supply of hot water for however many taps we have going. In the winter, everything changes and the unit struggles to supply a long shower. There are various strategies you could pursue to address this and YMMV, but definitely something to think about.
posted by Right On Red at 1:48 PM on September 11, 2010

Also, if you have anyone in your household who might have trouble with scalding themselves you should be aware that at times I have had hotter water than usual emerge from the pipes, for instance if the water is turned on and off elsewhere when one faucet is on.
posted by yohko at 1:51 PM on September 11, 2010

I love my tankless water heater. I never have to worry about taking a long shower or whether someone else just took a shower. I also don't have to seethe about the water heater keeping things warm even if I don't end up using hot water for 24 hours or more.
posted by rmd1023 at 1:52 PM on September 11, 2010

Best answer: Have had mine (Rinnai-gas model) a year in our almost 100 year old house. If your 100 year old house is like most and has tiny closets, they are great. (Did people only wear 3 outfits 100 years ago?)

We are in Austin and have never had issues with it running out of hot water or keeping up like Right on Red pointed out. It can take while to heat up the water depending on how far the unit is from the faucet. Fortunately, ours is mounted on the outside wall of our master bath so the shower and tub heat up very quickly.

From what I remember sizing them appropriately for the size of the house and your climate is important when picking one out. Mine is pretty powerful and can run multiple hot water sources at once. I like that.

I seriously doubt the extra cos will ever be recouped through energy savings, but I am saving energy, I didn't need to lose closet space to a tank, and it will never leak.
posted by murrey at 2:02 PM on September 11, 2010

Consumer Reports did a report on tankless heaters within the past year or two, and they determined that they weren't yet ready for prime time. The recommended against installation, as I recall. You may want to see if you can find the article, which you may or may not agree with (or which may or may not be applicable to your situation).
posted by OmieWise at 2:03 PM on September 11, 2010

Oh, here is the article, or at least one article, on their site. It's from Oct 2008.
posted by OmieWise at 2:05 PM on September 11, 2010

We had a tankless water heater in our 300 year old farmhouse in Spain for two full bathrooms, an outdoor shower, a kitchen sink, and a washing machine (altho I think the washer heated the water using its own element, idk). It was powered off of an orange gas can that we replaced periodically. It was awesome and I missed it enormously when I moved into a place with a regular tanked water heater.

The only problem we ever had with it was hard water deposits/build-up in the pipes, which eventually made the water pressure too low to trigger the pilot light. So depending on your water source/quality, you may need to flush the lines more often than with a tanked heater.
posted by elizardbits at 2:23 PM on September 11, 2010

Here in New England power outages of multiple hours are not unusual, every few years extending to 1+ days. With the tank, there is a reserve of hot water good for a couple of showers. Don't know if this would apply to your location.
posted by Kevin S at 2:53 PM on September 11, 2010

One more consideration if you live an area prone to natural disasters, your hot water tank is a source of many gallons of potable water if your water supply is cut off. Living in California, it would be a headache to buy sturdy storage containers, find a place to store them and then replace with fresh water periodically.
posted by metahawk at 2:58 PM on September 11, 2010 [2 favorites]

I was considering one for my rural house and the problem that I wound up having was that the flow rate that I have in the house from the [gravity fed] well was not going to be enough for the tankless heater for some reason that I don't specifically recall. So I would have had to have had some sort of pump installed and I opted not to do that. Most of my research was fairly positive as far as the cutie Bosch dealies, but none of the plumbers in my area really wanted to touch them and I'm not sure if it's because they were a headache or the plumbers just didn't have much experience with them.
posted by jessamyn at 3:13 PM on September 11, 2010

We have one. Perhaps it was the install or the unit, but we are not happy with it. We have determined that we need to build a little shelter for it because when the monsoons hit (we're in Arizona) or strong winds and some rain, it tends to "flood" the unit causing the pilot light to distinguish. This irritates me because it's an outdoor unit and shouldn't need an additional shelter, especially since rain is a few and far between occurrence in the dessert.

Another thing I don't like about it - and perhaps it's not the unit's fault - is that it has been very sensitive to our hard water. Our plumber guy told us we most likely need a water softening/demineralizing system in our home to help with erosion on the tankless water heater. There is already significant erosion on the unit and it's not even 7 years old yet. I wish that the unit came with a softening system installed because it seems we're not going to get good use out of the tankless due to this problem. It just seems a waste of the unit when we need to tack on an additional $1,800 for a softening/demineralizing system.

My biggest gripe with ours, however, is that it takes FOREVER to get hot water. And for us, it's not an additional 20 seconds. It's like 5 minutes - and we live in a small small one-story house. We have to run the kitchen sink water for 5 minutes before we can turn on our dishwasher, since they are on the same line. Without turning on the sink water, the dishwasher water would initially come out cold. I don't mind waiting for the water. What I do mind is wasting all of that water. Often, I'll catch the running water in a bucket and use the "cold" water to water plants and whatnot. But I can't do that all the time.

In our old house we had a regular tank heater. We lived in a two-story house. I honestly don't see much in the way of savings between our tank heater and our tankless. However we have added one or two more people to our little family, so maybe there's some evening out there.
posted by Sassyfras at 3:36 PM on September 11, 2010

If you live in the US, here's my take. Electric tankless water heater = no way in hell. Gas = awesome. Power outages are not a problem with gas, and you can take endless showers and run every faucet in your house full blast with scalding hot water. If you live in Europe, then what mmkhd said.
posted by Crotalus at 3:36 PM on September 11, 2010

An additional point - which jessamyn brought up - with our system (it's a Rinnai), there is only one plumber in the area that deals with them. So, look into that - make sure there are people in your area (and hopefully more than 1) that can service them.
posted by Sassyfras at 3:38 PM on September 11, 2010

In the USA, gas tank-less water heater; will never live with a tank again, ever, love it that much.
posted by JujuB at 5:12 PM on September 11, 2010

We have a Takagi T-K2 tankless heater. I don't spend much time thinking about it, it works great. There's not really enough flow for shower + laundry + dishwasher at the same time, but then again you have infinite consistent hot water so you can just remember to start the laundry later.

The one big drawback is that the heating element only switches on after a certain amount of demand. Some of our sink faucets have just a tiny trickle, not enough to convince the tankless heater to turn on. I end up having to run two or three hot faucets for a few seconds to get it going.
posted by Nelson at 5:27 PM on September 11, 2010

Best answer: Tankless (gas) is just fine, in my experience. Yes, you do have to wait a little longer for hot water, but you can save significantly on energy costs. We have a larger model and there has never been insufficient hot water, even with multiple showers and a dishwasher or washing machine running. If you use air conditioning, remember that you will save on air conditioning costs by not having a tank of hot water in your house all summer and if you don't use air conditioning, remember that you will have a cooler house in the summer. You also should bear in mind that a tankless system should last longer than a normal hot water tank, so your amortized cost will be less than you think.

I don't think there are any units on the market anymore that use pilot lights, so I wouldn't worry about that issue. However, you do need electricity to run your tankless heater.
posted by ssg at 5:39 PM on September 11, 2010

Best answer: I replaced a 20+ year old electric tank model with a gas Rennai tankless in early June, and so far, I'm very happy with it. Make sure it's sized appropriately for your use. I can take a shower and run my washing machine at the same time, and me and the sheets are all clean from hot water when we're done.

As others have said, for faucets that are on the other end of your house, it will take a while for the hot water to get there. In my case, that's the kitchen, but the luxury of knowing I'm not heating water 24x7 for short periods of use and being able to have hot water for multiple usages at the same time is worth it.

They're not cheap, and I'll probably never re-coup the cost from the electricity savings. But I'm OK with that.
posted by JaneL at 7:32 PM on September 11, 2010

One thing I don't see mentioned often here is putting electric tankless heaters at the point of use. I have a tank heater in the basement that brings water to 70F. It uses minimal gas, since it's only heating water from the source temp (varies seasonally here in Minneapolis) up to room temperature.

In the bathroom, there is a heater which can raise the water by 40F with the shower and the sink running full-on. It's electric. 20A @ 110V. Minimal danger of scalding, even running hot-only.

In the kitchen, I have another that can bring the full flow of the sink up by 70F (to 140) for the full flow of the sink. That's wired with 220, but was easy to wire since it's right above the breaker-panel. My dishwasher has a built-in heater which will take the water to 160+ to sanitize dishes.

That covers everything but the basement, and the washing machine there runs with the "hot" input at 70F, but I wash everything in cold anyhow.

Will I ever make back the cost of installation in savings? It'll take a while. But I have hot water pretty much instantly (within 5 seconds) of turning on the tap, which makes me happy. And my gas bill has dropped to nearly nothing in the months when the furnace isn't running. I figure I'm saving at least $10 a month, so that's something.
posted by DaveP at 8:16 PM on September 11, 2010 [1 favorite]

We recently purchased a house and I was interested in replacing our tank with a tankless. Two plumbers went over the issues with us, to explain where the costs would come from. It is unlikely we would recoup the cost of the heater and installation over the life of the mortgage, so we will likely simply replace the tank. But I'll still answer this question based on the fairly substantial research we did.

When installing one, there are a few considerations.

You need sufficient BTUs of gas feeding into the house. If you have a gas furnace that heats your home in the winter, for example, you may not have enough BTUs left for a tankless. This could require the utility company providing more capacity to your home, if this is even possible, which raises the cost both from the utility and from the plumber putting in new lines.

You need a different kind of exhaust put in for the tankless, than what you use for the (gas) hot water tank. This can raise the cost substantially, depending on where this is installed.

The tax credits cover a portion of the cost of the tankless heater itself, but do not cover installation.

You will need a heater of sufficient capacity to support a constant flow of hot water to multiple outputs (dishwasher, clothes washer, shower, bathrooms, kitchen).

If the tankless is far away from the outputs, then there will necessarily be a delay by simple thermodynamics cooling the pipes between the tankless and the outputs. In other words, distant feeds may not seem like they get "instant" hot water, although your gas usage should go down since you're not constantly heating a big tank of water.

With respect, your HVAC guy will profit more from suggesting you install a tankless, by simple virtue that these devices require a lot more work to install. As with any job of this size, perhaps get two or three quotes and decide if you can amortize the additional cost over the life of the home loan.
posted by Blazecock Pileon at 12:35 AM on September 12, 2010

Response by poster: Thank you all so much for the information. I've marked a few best answers, but learned something from every one of you. We live in Memphis, so cold winters, natural disasters, power outages and hard water are not an issue. I like the point that it will keep my house cooler when using air conditioners, as we are STILL in the 90's here this week and always have at least three weeks every year of temps over 100. Our HVAC, plumber and electrician are very trusted sub-contractors for my husband's business and depend on us for a regular portion of their income, so we're good there. The installation point is in our basement "machine room" and will be directly underneath the dishwasher and kitchen sink, 10 feet from the clothes washer, and about 20 feet from the main bathroom. The only point relatively far away is the upstairs guest-room bathroom, so I'm not too worried about a wait time. Special thanks for the gas vs elec points, I would like to know I still have hot water we lose electricity during an occasional storm.
posted by raisingsand at 7:22 AM on September 12, 2010

We just got one after quite a bit of dithering about tank vs. tankless. We got an Eternal model, which has a small 1 tank unit with in it that prevents sandwiching and flow reduction with multiple faucets on at once. Also it is supposed to be better for older houses. The unit is in the basement, directly below our bathrooms, and even the bathroom on the 2nd floor gets water pretty quickly. We are very happy with it. The initial costs were about twice what it would have been for a tanked model, and our plumber has quite a bit of experience with them. We figured with a couple of the rebates and energy savings of ~$200/yr we would break even in 4-5 years.
posted by sulaine at 8:12 AM on September 12, 2010

Special thanks for the gas vs elec points, I would like to know I still have hot water we lose electricity during an occasional storm.

The gas tankless models I have used still required electricity to operate -- the gas supplies the heat, but there are often electric ignitions, exhaust fans, and temperature controls.
posted by Forktine at 8:15 AM on September 12, 2010

I've had two tankless water heaters running in my house for about seven years. One of them is what's now known as a Takagi (it was sold by Bosch at the time) TK-1. This unit has a few foibles, namely its computer seems to get unhappy about power line fluctuations. At one time I had to take out the burner jets and clean them, which worked perfectly. This unit gets a C+. The other is a small heater with a standing pilot that has been absolutely flawless. We have frequent power cuts and the hot water is still available when there's no power. The closest model remaining on the Bosch tankless site is the 1000P but my old heater puts out about 3 gpm, not 2.1 at 55 degree rise. This unit gets an A from me.

For very hard use I see Paloma tankless heaters used at camps, hot springs, and friends' off-grid houses. When the Takagi finally dies I will put in a Paloma PH24 heater because all the Takagi's "performance-optimizing" electronics seem to kill reliability without enhancing much of anything.
posted by jet_silver at 2:20 PM on September 13, 2010

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