Lets talk tankless water heaters

Note: This is not the tired old "can I use one to supply my MLT" thread.

Well, I think my old water heater is finally done. It may actually be the original one with the house, which would make it about 20 years old. The wife and I would like to get a tankless model both for efficiency and the extra space in the garage (she says for storage, I say for brewery). Regardless of the space, I intend to arrange for both Natural Gas and Water to be conveniently located for the brewery at the end of the installation
Anyone out there using one? Any thoughts? Here is what I'm considering now.

Rheem RTG-53X-NG
$630 new – two appliance – Outdoor install, checking with HOA but shouldn't be issue, as long as my wife doesn't mind the way it looks. It will be next to the walkway approaching the front door. No Venting = Cheap install.
http://www.faucetdirect.com/index.c...nish=Natural Gas&CS_003=746228&source=smarter

TAKAGI T-K3 NG
$772 new – Two appliance – Indoor Install with 4” stainless Class III vent. I’m not sure what kind of vent we have now but it's galvanized and vents vertically from the heater to the roof. We may only have to replace with stainless, or increase the size of the roof vent (more $)
http://wamhomecenter.com/productcart/pc/viewPrd.asp?idcategory=981&idproduct=5697

Bosch AquaStar Model 2400E
$725 Refurb- $999 new– Two appliance – Indoor with 3” stainless Class III vent.
http://www.cpotanklesswaterheaters....e_house_tankless/natural_gas/2400e-ng-re.html

Bosch AquaStar Model 1600H
$454 refurb - $575 new – One Appliance – Indoor with 5” double wall type B vent (might be what we have now)
http://www.cpotanklesswaterheaters....e_house_tankless/natural_gas/1600h-ng-re.html

Take a look at the BTUs on those things and the gas piping requirements. Most of them need 3/4" gas input and that run better tap into a larger trunk no too far away. There's a good chance your tank heater's current supply will not keep up. My parents have one that was installed with an inadequate 1/2" line and they have to run their water pretty slow to have it keep up.

Yeah, that's another plus for the outdoor installation. It will put it within a few feet of the main NG line shutoff to the house.

Yes, great reason to install it there.

Do you have a recirculating hot water pump? Just about every major mechanical system has given out in our house except the water heater (house is only 14yrs old). I'm anticipating it going out when I least expect it (dead of winter or while I'm on vacation) and have been doing research on the tankless heaters. Problem for me is that we have a recirculating hot water pump system since our house is pretty large and the water heater is way out in the garage and not centrally located. With the water pump, we will need to install a small tank water heater for the recirculating system and the tankless for actually keeping up with demand. That plus we'll have to have a double walled vent for both exhaust and intake. It all comes down to making the upgrade pretty darn expensive and I don't know how long it will take to pay for itself.

Have you looked at Rinnai?

http://www.foreverhotwater.com/exterior.php

I would be wary of the any "Energy Efficient" claims on the label. We bought a rheem that was advertised as being highly energy efficient but when we actually had it installed and looked even more carefully at the label, it barely fit the category of "energy efficient" and there would have been much better choices. In sum... as "HOW efficient is energy efficient"?

Thanks...All good stuff to think about.
I don't have a recirc. but see how that would complicate things.

I haven't seen a Rinnai in the same price range as the others, but the company looks solid.

The performance specs for all the tankless look fairly similar, and are all significantly better than the tank ones. That said, I am not expecting a big return unless the price of natural gas spikes like other well discussed fuels. The price is just a few hundred more than the tank style and that is a price I'm willing to pay to use less in my life. That and the space. If you consider $300-600 per sq.ft in Carlsbad, the damn thing almost free!
At least, that was one way I justified the big flat screen mounted the wall.

I can see you have made up your mind, so do it for the brewery!

One word of caution:

The CO. I work for installs High-Efficiency hot water boilers. We are called upon from time to time to service Tankless water heaters in the area for the simple reason that they are fairly comlicated machines. They have microprocessors, mulitiple sensors and safeties etc., so most plumbers havn't the slightest idea (or specialty tools) how to service them when they break. Ask your plumber if he has worked on many before.

Sea said:

I can see you have made up your mind, so do it for the brewery!

One word of caution:

The CO. I work for installs High-Efficiency hot water boilers. We are called upon from time to time to service Tankless water heaters in the area for the simple reason that they are fairly comlicated machines. They have microprocessors, mulitiple sensors and safeties etc., so most plumbers havn't the slightest idea (or specialty tools) how to service them when they break. Ask your plumber if he has worked on many before.

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That, my friend, is my biggest concern, followed closely by how well they actually provide water for a shower. Any real world experience would be valuable as I haven't pulled the trigger yet.
I know of several companies in the area to service them, but won't be happy if it is a weekly event.

My friends beach house has a tankless system installed, granted it is a small one bedroom with a galley kitchen and only one bathroom. The unit is right outside of the wall with the kitchen and bathroom, and it works amazingly well in the small space, and is exceptionally eficent. We have had the shower, the dishwasher and the kitchen sink all pumping hot water at once, without much noticable effect. You only use it when you use hot water, and it saves a ton on usage especially if you don't use much. As for larger homes, no clue as to how they work.

One thing people with water heater tanks often overlook is simply putting insulation around their tank. The $20 sleve pays for its self in about a year, the rest is all cash in the pocket.

I've used them in the past, but that was far enough back that they had pilot lights. A 125,000 BTU unit will handle one or two showers without a problem. A 175,000 is probably a better bet.

I don't have one now because propane units are very expensive. I figured it would take 10-15 years to pay back the cost over a tank heater. Of course, that's for one person. I had a "new" Aquastar NG that I dragged up here with the intent of converting it to LPG. That was almost as expensive as buying a new one. Traded it to a local brewery for beer.

Most tank heaters have 3" vents.

We have the big Aquastar tankless water heater. It really puts out some heat. Even in the winter with 50F incoming water we can run 2 hot showers. It will run hot water into a bath tub at full volume. However with our spa tub (seldom used) we have to fill it at half volume.
The down sides is it takes a couple seconds for the heater to kick in. This usually isn't a problem but if your turning the water on and off like during clean up you may start getting hot and cold surges coming out of the faucet. Otherwise I love the space I gained in the basement and never being short on hot water.

You do need to find an experienced installer and it will probably require running a new gas pipe from the main line. These things have much bigger burners than a standard heater an so need bigger gas lines to feed their appetite.

Craig

Germey said:

That, my friend, is my biggest concern, followed closely by how well they actually provide water for a shower. Any real world experience would be valuable as I haven't pulled the trigger yet.
I know of several companies in the area to service them, but won't be happy if it is a weekly event.

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The #1 reason for dissatisfaction with tankless heaters is undersizing, both of the unit itself, and or the gas line. Sized properly, most people are very happy.

The #2 reason is that some models over the years have had a lot of problems. I think the industry as a whole has improved, but I have only had direct experience with Bosch, and Takagi tanklesses, and haven't really seen any problems with either.

I would recomend lurking on some plumbing forums and seeing which, if any, brands the professionals are grumbling about.

The truth of the matter is that these are complex machines. Even with the best of luck, it would be niave to think that any of them would go as long as a standard H2O Heater without needing service.

A friend of mine has one (don't recall the brand) and he is mostly satisfied with it. The only problem he has encountered is using the shower during warmer months. The combination of warm ground water and a low-flow shower head translate to not enough temp differential to kick on the heater. He has to turn the sink faucet on a little bit too while showering so that the draw is enough to switch the heater on. He says it's only a minor inconvenience, though, and he plans on drilling out the restricter in the shower head to fix the problem.

Oh yeah, my parents have that same problem in the summer too. You would think they'd build in an adjustable differential setting so you can alleviate it.

Thanks to all for excellent feedback. I am going to call a plumber this morning and make sure there are no particular problems with an outdoor install, but I think that one makes the most sense on paper. Our ground water temp stays pretty steady here so hopefully that will help with the differential, but there are those hot mornings after a hot night where I would only be pulling a trickle of hot water.

David_42, while browsing, I saw no price differential between the Propane and the Natural Gas. The one I am likely going to buy is available in LP for the exact same price < http://www.faucetdirect.com/index.c...r/Rheem/categoryId/4025/finish/Liquid Propane >
With the price of LP lately, I would think the payoff would be even more.

Cheers,

Its not the temp differential that is the problem but the flow rate through the unit. They all have a minimum flow rate required before they turn on. This is necessary to ensure it doesn't turn on when there is no flow and cause the water inside the unit to boil. When I turn a faucet on trickle it quickly goes cold, despite having cold ground water year round.
It is never a problem for me as I just adjusted to always turn the water on at least half flow. If you are concerned about a low flow of hot water be sure to check out the specs on the units you are interested in. There is some variation in the minimum required.

Craig

CBBaron said:

Its not the temp differential that is the problem but the flow rate through the unit. They all have a minimum flow rate required before they turn on. This is necessary to ensure it doesn't turn on when there is no flow and cause the water inside the unit to boil. When I turn a faucet on trickle it quickly goes cold, despite having cold ground water year round.
It is never a problem for me as I just adjusted to always turn the water on at least half flow. If you are concerned about a low flow of hot water be sure to check out the specs on the units you are interested in. There is some variation in the minimum required.

Craig

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I just read another way to deal with that is to reduce the temp setting. That way, you achieve your desired shower temp by using more hot water. The only reason for having scalding hot water (other than shorter time to boiling the pasta) is to reduce the amount of water you use out of the tank. That motivation is now moot.
Plumber says he's installed several outdoor units in Carlsbad. Rheem unit is ordered!

I have a Rinnai and love it. I've never lacked hot water and my house has 2.5 baths, dishwasher, laundry sink, etc. The only drawback is, depending on where it's located, the proximity to faucets may provide for an extra long time to get hot water. The thing with tankless is that it's best to have them centrally located in the house, but this frequently interferes with venting, and venting takes priority. It takes me a full 2 minutes to get hot water on the other side of my house from the Rinnai. But since I have a well and a huge septic field, it doesn't really bother me. The benefits outweigh the costs.

I'm also familiar with Noritz and have built houses with them installed. If I were to be in the market for one, I'd get a Rinnai or Noritz, but I'm unfamiliar with the quality of the other brands mentioned.

Germey said:

I just read another way to deal with that is to reduce the temp setting. That way, you achieve your desired shower temp by using more hot water. The only reason for having scalding hot water (other than shorter time to boiling the pasta) is to reduce the amount of water you use out of the tank. That motivation is now moot.
Plumber says he's installed several outdoor units in Carlsbad. Rheem unit is ordered!

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Good point, however the model I have has a factory preset of 120F. You have to buy an expensive add-on regulator to adjust the settings. Of course 120F is just about ideal so there is no reason to change.

I'm sure you will appreciate the unit.

Craig

Well, I cancelled my order and will probably get a traditional tank heater. Several codes prevented the outdoor installation that I envisioned, and the estimate for the re-work to install an indoor one was $600-$1,000. That was just for the labor. Ducting and other installation hardware was going to be about $400! I could probably do all the work myself, but I am still dealing with a broken leg and don't think the job can wait that long. Swapping the tank unit is definitely something I can do with an uninjured friend who appreciates good beer.
I think someone here (or maybe it was the Plumber) said that it makes perfect sense in a new construction, but is just too expensive in a retrofit. I concur!
There is an off chance I might go electric tankless, but probably not.

I will still be splitting off a NG trunk for the brewery though.
Cheers, and thanks again for the advice and input.

Last I looked (a couple years ago), electric tankless just couldn't handle a whole house. You could essentially only have one hot water source on at a time or it would get cold.

Tough luck on the gas tankless. Well, you tried...and it's better to have hot water than not!

Sorry to here about your bad luck. There is no option for outside mount in Ohio but our retrofit was not nearly as expensive. The unit we had installed used the same chimney and the plumber just had to run a new gas line on the ceiling of the basement. I guess it really depends on your installation.

As an alternative there are some new gas tank water heaters that are much more efficient than the old style. My brother just put one in his house. The tank is better insulated and the heat exchanger is condensing which boosts the efficiency into the 90s%. His unit has the exhaust vent on the bottom of the tank and uses PVC for the vent. He uses it to heat to whole house with radiant floor heating and provide hot water. I'm sure there are smaller units for hot water only but I'm guessing they are considerably more expensive than the normal units.

Craig