hot water (not ww)

[bill walton]

Does anyone have experience with instant hot waterheaters. I'm looking for some recommendations on brands, sizes, etc. to balance against manufacturer claims.

Thanks in advance
bw

[Jim Chilenski]

Bill,

I can only tell you a little from my recent experience. Two weeks ago I realizied that my gas hot water tank was leaking. I decided to have it replaced with a tank less water heater and began to call plumbers in my area who had experience installing them. I found a plumber who had installed several of them and he came out and looked over my installation site. Unfortunately he was unable to install one because of problems with my venting system. My existing hot water tank was a 40 gallon model that used a 3" double wall vent from the basement through the roof of the second floor. This double walled vent has a galvanizied inner pipe surrounded by an aluminum outer pipe. The first brand of tankless heater, a Noritz, requires a 4" vent system. The next one that we looked at was the Bosch unit which while using a 3" vent, requires that it be stainless steel. Now because my vent stack runs thought an inner wall it must be a double walled stack to prevent it from becoming too hot and causing a fire. So to replace my vent stack with one that would work with the tankless heater would have cost $1200. Plus another $1000 to $1200 for the water heater. So I ended up having him install another 40 gallon gas water tank.

Now the one thing that I learned from this is that you need a really good vent stack to install a tankless heater. If you think about it they run with extremely high heat. The units have about maybe 10' of pipe inside in which to raise the temperature of the water 60 degrees. That means that the burner is throwing off a lot of BTU's and needs to have vent that can handle that. Also, because natural gas gives off water vapor when burned the vent must be corrosive resistant. My plumber was willing to install a tankless unit with a new vent through the side wall. But I was worried that the vent would be too low and that anyone walking by it could get burned if they accidentally touched it. A lawsuit waiting to happen.

So, I was unable to go tankless. I still believe that they are better than a standard gas hot water tank. Hopefully your situation will be better than mine.

Jim

[Russ Filtz]

Gas would give the best performance, but many are electric. When I researched it for a work project, the best units were higher voltage, 240 and up! 120 just doesn't have the cajones to push the water temp up fast enough. Either live with a trickle of "hot" water or use barely lukewarm. It will be worse in winter months.

Check the websites, the units are rated on temp rise from ambient at certain flow rates. You need to match the specs with your usage. Is it just for washing hands, or will you be doing loads of laundry, etc.

[Bernhard Lampert]

I have 3 tankless electric water heaters in my house, each one supplies a wet cell (master bath, kitchen/utility and kids bathrooms). Overall they are more efficient than conventional waterheaters: only heat water when needed, installed near point of use, etc. Mine are only intended to supplement solar heated water if needed, but since the solar stuff is not installed yet, they are used to heat all domestic hot water.
Now the disadvantage: Even though they cost less to operate overall, they pull an enormous amount of current at time of use. My large heater has 3 #8/2 (40A each , 220V) wires feeding the heater. The other two heater have 2 heating elements (2 x 40A circuits). I have a 400A service, so there is no problem and the heaters never went to full capacity (they just heat to the set temperature). I also oversized my heaters. I have Stiebel-Eltron heaters (along with their solar heat); this company has been making electrical appliances for about a 100 years. I have no complains, would buy them again. Good solid product, simple installation.

Cheers,
Bernhard

[Bill White]

THe company I work for sell both Rinnai and Rheem. Rheem has good info on their web site. Need to be sure about your personal home needs, but the units I have sold have been well received by the homeowners.
Calculating "pay back" time is a bit iffy, but most experts say the 7 yrs. is about average 9 yrs. This includes unit, ducting, and installatiion.
Rinnai requires installers to be licensed. Rheem does not.
These puppies have been in Eurpoe for a long time. Not new technology, just new to us Yanks.
I agree that the gas units seem to be better.
Bill

[Grady Cowardin]

Sometimes I think I am a bit too hardcore of a DIY'er!
http://i68.photobucket.com/albums/i13/qwikkota/wh1.jpg
What a nightmare getting my unit in the attic was. I was not lucky enough to have a garage installed unit and we do not have basements here. Once my buddy and I got it up there the install was not too bad and the only connection I had to solder was the relief valve drain. Needless to say the old one is still up there

On a product review note this is a Kenmore 40 gallon gas with 9 yr warranty. The tank is made by A.O. Smith one of the top manufacturers. Water gets very very hot and the inlet tube has a plastic insert that extends to the bottom of the tank and curls around the bottom about 3/4 of a revolution to help keep sediment from settling. For some reason women like to set the shower temp to "shrimp steam" and our old unit just wasn't up to snuff...

[Al Willits]

Statements of they are more efficient are a bit misleading, also make sure you have enough water heater to supply not only the amount of water you need but the temp rise needed, many are installing these and finding they have a lot of warm water, but not hot.

There are two basic kind of gas ones, one that adjusts water flow to keep temps and one that adjusts burner input to keep the used flow at a certain temp.

Also remember these things take more maintenance than standard water heaters, Bosch recommends a every other year rebuilding of internals to keep running correctly, do some thinking on how much water and what temp you need, consider inlet water temps as that will make a difference and how often you need hot water.
Add warranties, maintenance, installation costs, venting requirements and the cost of electricity versus gas and you have a lot to look at before installing one of these.

I work for a company that services them, along with the standard units and out of 375+ techs only a couple have these, consider we are in Minn also, but that should tell ya something...imho

They have there use, just don't buy the cheaper story with out checking into what you need.

Al

[Tyler Howell]

I understand that some of the units have PVC (through the wall) exhaust

[bill walton]

I'd be using an electric unit and my interpretation was that I'd need two 40A 240 ccts. We live in the Fl Keys and the tap water is never below 70 so There's not a great deal of temp rise needed. I was not aware of the maintenance requirements though. I'll have to think carefully.

Thanks again for these and any additional comments that roll through here.
Bill

[sascha gast]

I just replaced my 50g water heater and had them install a large Noritz unti. Don't mix up instant heat with endless hot water, it still takes the same amount of time as it did before for the hot water to reach the faucets, but once hot, that's it, no more cold water for me.

I have been very very happy, not only did I gain lots more shop space back, but I simply love the performance. My fiance can shave her legs all she wants now and I still have hot water after that

sure they are not cheap, mine was around $2600ish, including about 15 feet of stainless exhaust. I would do it again in a heart beat

[Craig D Peltier]

I have a article on how to install one yourself if interested PM me with your email addy and I can scan it in.

[John Daugherty]

I have a Takagi tkd 20 tankless. We've had it about a year now. I installed it myself. I had to use stainless vent pipe. If you've never priced stainless pipe it's a real eye opener. I had to have a two foot section and a 90 and it was around 100 bucks. Mine is in a basement on an outside wall vented through the band. If I recall correctly the price was between 8 and 900 installed.

I really like it. I can run two showers at the same time and never run out of hot water.
There is a 300 dollar tax credit for most of the tankless heaters. When I compared the price for the tankless with the price of a higher end tanked gas WH and factored in the tax credit the price was so close that I went with the tankless.

Your much better off if you can place it on and outside wall and vent through the wall. The cost of stainless will add up quick!

The only down side is that there seems to be a little longer lag compared to conventional from when you turn on the HW until it gets to the faucet.

[Jim Becker]

What Jim brings up (venting requirements) is the only reason I don't have tankless in the existing envelope of our home...our addition will get one to service the new master bath and laundry. In the existing home, we could not use the original chimney vent as it was too large and too long. We could not install a "high heat" vent through either of the two window areas and the walls are 18" thick stone and subterranean. At the time, none of the units with enough capacity supported low-heat PVC venting. So we had to go with a "shorty" 50 gallon high-efficiency, direct power vented tank unit that uses PVC for exhaust.

One must follow the venting rules for any of these things.

[Michael Weber]

I know that at least the Rheem brand (actually made by Poloma Industries of Japan) has models that can be installed on an outside wall so no venting needed. Of course you would'nt want to mount one by the front door but if you had a discreet outside wall to put it on that might be an option.
mike

[Jim Becker]

Michael, even on an outside wall there are venting requirements. They are generally easier to deal with, however...provided you don't have 18" thick stone walls, of course...