Need advice on purchase of a tankless hotwater heater - and how to get it installed!

February 6, 2008 7:49 PM

Need advice on buying a tankless water heater - and how to find someone to install it!

I live in a really small place, me and the dog. I want to buy a tankless waterheater.

I want to buy a smaller one - but how small (2.7g per min too small?) for a small (900 sq ft) 2 story town house? What is a good model that is economical to purchase as well?

How do I find someone to install it? I could go through Lowes or Home Depot.... but I am not certain what the logical first step is... and I need to get this done while I actually have a little extra money.

posted by caveat empress to home & garden (15 comments total)

Lowes can have a contractor contact you if you have questions.

One important thing to know about the tankless systems is the large amount of heat that needs to be vented away from them. If you don't have a chimney, you may be out of luck.
(at least that's what my plumber told me)
posted by kuujjuarapik at 8:03 PM on February 6, 2008

I think these are really cool, but I was told by a guy whose line of work involves energy efficiency stuff that one of these wouldn't pay off in $$ savings for my wife and me - that it generally takes a larger family to make up for the up-front cost in savings.

Not trying to dissuade you - there are other good reasons to buy one of these if you want one. But if ROI is your main goal, you may want to do some more research.
posted by altcountryman at 8:07 PM on February 6, 2008

Venting could be a problem... I need to look into that too!

Any suggestions out there in the best energy efficient standing water heater I might look into? The one I have now is not efficient, and either way I need to do something about it!

My water heater IS in the room w/ my washer/dryer and heating/cooling unit could any of those items exhausts be rigged to use with a tankless?
posted by caveat empress at 8:09 PM on February 6, 2008

This one needs no vent, it uses microwaves. flash
posted by hortense at 8:46 PM on February 6, 2008

I assume you mean a gas heater, not an electric one, which doesn't need venting. How does your current hot water tank (assuming it is also gas) vent? Do you plan to install it on an outside wall? You can install a horizontal vent directly out the side of your home (or less directly out horizontally, but that is more costly and more of a pain). I'm pretty sure you can't combine the exhaust with any of your other exhausts as gas tankless heaters use special high temperature stainless steel pipe.
posted by ssg at 8:58 PM on February 6, 2008

I have this gas Takagi on-demand water heater, which uses outside air for combustion. The heater can't share a venting system, but it comes with a very simple setup. The vent is basically a box set in a hole in the wall (not the ceiling)--slightly more complex than venting a dryer. A quiet fan pulls combustion air in through one half of the vent and pushes exhaust out the other half. The fan runs only when someone is running hot water.

Other, fan-free systems vent through the roof and use inside air for combustion. There are probably other setups as well.

My heater is installed under the counter in my kitchen. The vent in the wall has to be something like 18 inches (can't remember exactly) above the unit, so the unit is below the counter and the vent pipe extends up a bit before it goes through the wall, which required some kludging with the countertop.

My heater handles both the kitchen and the bath in my small 2-story house. It's sized so someone could wash the dishes while another person takes a shower, and this has worked the few times I've tried it. The main problem was with water pressure dropping off, not lack of hot water. I had a regular plumber install it, and he had no trouble.

I did a lot of research and don't recall reading that it takes a large family to make up for the up-front cost. However, I use propane, which might be more expensive than natural gas or electric. Another economic plus to consider is that a tankless heater lasts longer than a tank. My plumber said I would go through 2-3 standard water heaters during the life of one tankless.

One drawback is that the hot water isn't instant. The water has to flow through the coils a couple of seconds before the heater decides I'm serious about wanting some hot water. Then there are another few seconds while the water heats. So if you're more concerned about conserving water than power, my tankless heater isn't for you. Other models might heat more quickly.

A much smaller negative for me is that the Takagi uses electronic ignition (no pilot), so when I lose electric power, I have no hot water. But I love the fact that it doesn't use any propane at all unless I tell it, "Give me some hot water."

One advantage that some people overlook is that a tankless heater takes up a lot less space.

I was very happy with the place I bought it from (linked above). I was less happy with support from Takagi when I accidentally froze the water heater due to my clueless installation (I forgot to include the damper that keeps out cold air). They replaced the entire unit for surprisingly little money but it took several phone calls in which I received conflicting information.
posted by PatoPata at 9:03 PM on February 6, 2008

To clarify: I put the water heater in place and vented it. The plumber just connected the plumbing.
posted by PatoPata at 9:07 PM on February 6, 2008

There are two tankless water heaters at my house. The smaller is a Bosch Aquastar 125, which might be no longer made. This heater has a standing pilot, which is good when the power goes out - as it does frequently. The ductwork from this heater cost more to install than the water heater did, but it requires a small (3", I think) duct. If your old water heater was gas you can probably use that ductwork since this heater is convective (no fan). The larger heater was sold by Bosch (240FX) but it's really a Takagi TK-1. It has an exhaust blower and electronic ignition so it doesn't work when the power's out. The ductwork to that is 4" and it cannot be shared with other appliances.

The smaller heater can run a shower just fine but probably not -both- a shower and hot water for the washing machine. The larger can run two showers, or (easily) one shower and the washer. Both have been stone reliable. Plumbers are alleged to not like installing these but mine did the job with no hitches. Our local hardware store sells the Aquastar 125 now, and they will set you up with a plumber, but it's better to either have a known good plumber, or to find one yourself IMO. They will come out and give an estimate free in most cases.

My favorite hot springs, Orr Hot Springs, has cabins that use small Paloma heaters for their hot water. They appear to get very little maintenance and yet the water's always hot and plentiful in the showers there. Should I have to replace the smaller Bosch I will very likely get a Paloma.
posted by jet_silver at 9:42 PM on February 6, 2008

I have a Takagi and love it. We had it installed during a bunch of other construction, and the plumber did most of the work. The main thing it needed was a larger gas pipe than our previous water heater did, so they had to run a new gas line up to it. Otherwise, it wasn't very difficult. It does vent through the roof, but so did the old water heater.

I love that it takes up so much less space. My gas bills definitely dropped after we got it, but we made some other changes at the same time so it's hard to know how much of it is because of the water heater. I don't think it takes any longer to get hot water than the tank did, and it very definitely stays hot longer. We never run out of hot water, even with 4 people taking showers.
posted by gingerbeer at 10:58 PM on February 6, 2008

that it generally takes a larger family to make up for the up-front cost in savings.

That really doesn't make any sense to me since the whole point of tankless is that you're not heating water you're not using, so you should save more the less you run the hot.

But perhaps I'm missing something.

I had 2 years of tanked and 6 of tankless in Japan, and the tankless was pretty good, except when the goddamn snow would blow into the heater (mounted on the balcony) and snuff it out. ggggrrrr.
posted by panamax at 11:08 PM on February 6, 2008

The Bosch 1600H doesn't need electricity to light the gas.

Almost all tankless heaters need a 5" stainless steel ("Type III"?) exhaust all to themself. This is often larger, and of a higher quality than exists in the house already. Some, like the Bosch 1600H, can share a 5" exhaust.

Nearly every plumber has installed tankless water heaters by now, as they're surprisingly common.

Many tankless water heaters can be mounted on an outside wall, three feet below an overhang and a foot or so (I forget the exact number) from any opening window. The Takagi heaters are like this.

Takagi is well thought of. As is Bosch.

Here's the math:
-Turn on your shower head full blast for a half minute, measure with a 4 cup measuring thing. Multiply the result by 2. Convert to gallons via google. That's your max single use "gallons per minute". In a small house, that's the only number you need if you promise not to run the dishwasher while taking a shower. :)
-Run your cold faucet for a minute or two, then fill a big pot. Toss in a thermometer (instant read, rectal, whatever). That's your "base temperature". You'll probably want your max water temperature at 105 degrees fahrenheit or higher so...
-Subtract your "base temperature" from your desired max temperature and you'll know how much your tankless water heater needs to heat the incoming water.

You'll need to buy a tankless water heater that can fulfill your "gallons per minute" number for the temperature change required.

In example, I believe the Bosch 1600H does at least 55 degrees fahrenheit raise for about 4 gallons per minute. My cold water is 50 degrees, my shower head flows just under 4gpm, so I'll get at least 105 degree water forever from my shower.
posted by lothar at 11:22 PM on February 6, 2008 [2 favorites has favorites]

I bought house with an Aquastar tankless system and although it worked okay, it often broke down. Finding someone to repair it was a major headache. I live in a major metro area and it was still difficult to find a repair guy. Lots of places sort of said they knew how to work with them but nobody wanted the work. Once I found a guy to fix it and tipped him big. The next time I called, he didn't want to mess with it at all. Finally, I just said, screw this, and had it ripped out and replaced with a standard water tank. Never regretted that for an instant. So, yes, they work, but God help you if they don't.
posted by lpsguy at 5:58 AM on February 7, 2008

We have a Bosch AquaStar and had it installed by HomeDepot. Love the water heater, but I'd never roll the dice with HomeDepot install ever again. They contract out and seem to have little concern for the quality of their installers. These guys had never seen one before and sat there trying to read the installation notes that came with it. Sadly, these two weren't the most literate of installers and the job took them the better part of two days.

Contrast this to our experience with getting a new furnace and air conditioner. We looked for a heating and cooling company and got recommendations from Angie's List and interviewed a bunch. Things really couldn't have gone any smoother.

So I guess what I'm saying is work directly with an installer of known quality. It pays off big time. You could try plumbers, but our local heating and cooling company sell and install water heaters as well. Thanks Standard Heating and Air!
posted by advicepig at 7:09 AM on February 7, 2008

I adore my tankless water heater; we got it about 2 years ago IIRC. It's also definitely worth it to work with a good local company on installation.

We almost had a tank water heater put in a few months before that, and the Lowes experience was so annoying (lots of extra stuff needed to get up to code, but we didn't know that until the installer got there!) that we bailed.

We found the installer -- and by extension the unit -- by calling around in the phone book. Had a couple of different people come out, compared costs and our general impressions of them, and picked one.

Ours is a gas unit that sits on the outside wall of our house and vents directly outside. It requires electricity to run, which was a bummer last winter when we lost power for 4 days.

It takes longer for the water to get hot, but when it's hot, it STAYS hot. For people who love showers and baths as much as we do, it's amazing.

There's 2 of us in a 1000 sq ft house with 1 3/4 baths. I think we got the lower or mid-capacity unit; you can't really do hot laundry or dishes at the same time as you take a shower, but with one person that shouldn't be that big a deal.
posted by epersonae at 9:00 AM on February 7, 2008

I am late to this discussion, but I have an Aquastar, and it is one of the best purchases I have ever made. I have had it now for about 5 years, and I love it.

There are only two of us in my house, and my natural gas costs dropped by a third simply from not heating a tank all the time. So the costs are recouped quickly, I don't know why someone would say it only pays off for large families.

I bought it from Home Depot and then called around to find someone was willing to install it. It has to be vented out the side wall, so you do need a special venting kit. It is more expensive too, intially, the installation was a little pricey. I have a whole-house unit, and it easily runs two applications at once--I can run a dishwasher and a clothes washing machine at the same time.

I highly recommend these. It is a no-brainer.
posted by chocolatetiara at 11:01 AM on February 8, 2008