Water Heaters

Well, they haven't made water heaters like the one I have in 16 years. Anyway, we are planning on replaceing it soon. It's an old 50 gallon natural gas by American Appliance mfg.

I had considered getting one of those newer tankless units but my mom dosen't want one; most only have enough capicity for one shower at a time and the larger ones need electricity to run.

Are there any good brands to consider ? I heard State/A.O. Smith is a good brand.

You should do some more research on the tankless models. On Ask This Old House they put one in a house. The plumber guy said the newer models can provide plenty of water.

Plus, you are not heating water to sit in a tank when you don't use it most of the time.

Run away.

Quickly.

I have used 3 of them, of different sizes. There are some _very_ important things about them to consider, that are not apparent until after you buy one.

Consider one of these, It's like a big thermos, the hot water never gets wasted and you have a 40 or 50 gallon reserve, runs off a zone just like any other standalone. I have had one for 15 years, stainless steal, last forever. Very neat product.

http://www.mcelroys.com/BOILERSRADIANTHEAT/IndirectWaterHeaters/SuperstorUltra/default.aspx

I have used 2 point-of-use models at sinks and 1 whole house model. All were electric.

POU units were 240v 40 amp, which is QUITE large for a point of use unit. Units were unable to maintain hot temp except in summertime.

Whole house model: 240v 120amp. Microprocessor control. Cost ~$1500. Envirotech brand. Nice, but still only able to maintain 1.5 showers in the winter (and this is in mississippi).


Problems/considerations/notes/etc, in no particular order.

1. You want 120F hot water at the SHOWERHEAD for a good hot shower. That means you lost 5-7 degrees coming through the pipes. That means you need 127F at the heater outlet. Most heaters are rated at temps lower than this. When they need to deliver water this hot, the flow really suffers.

2. Incoming water temp. Don't believe the charts the mfg has. Mfg said MS was 55F ground temp in winter. We measured 37F, and this was when ambient air was ABOVE freezing. This KILLED the performance of all the heaters.

3. Temp stabilization. Some heaters simply turn "on", and are flow activated. The water temp coming out will fluctuate with the flow. This is a BAD thing. That means your shower will get colder (with no warning) if another faucet is turned on. It also means the reverse. Can you say "scald me!"?

4. Unit we had used microprocessor temp control. That meant that until you exceeded the capability of the heater, the temp stayed rock solid. What they DIDN'T tell you was that the elements were pulsed rapidly on and off. Guess what that caused? Some lights in the house flickered. When asked, the mfg said "yeah, we knew that would happen". And this was a new house, specifically wired for a 120A heater, with 400A supply to the house.

5. Cost. Yeah, they are more efficient. But you can buy a crapload of electricity for what these things cost. And, in a power outage they store NO residual hot water.

6. Service. Some models have non-replacable elements.

7. Air pockets. Since they operate with such high power elements and so little water surroounding them, air pockets can cause instant element failure. Ask me how I know this.

8. I would NOT buy one again. If I wanted instant hot water at a sink, I would put in a circulating pump (and I plan to on the next house we build).

9. Gas models may differ some, but they also cost even more than the electric models.

10. Spend your money elsewhere and it will reap better financial rewards. Insulation, caulking, etc.

11. If you go electric, do you have any idea what copper wire costs now? If has doubled from 2 years ago. Then it has doubled again in the last 2 weeks. It's so bad that people are stealing copper gutters off people's houses around here and selling it for scrap.

Check out this thread.

-john

This is a litte copy/paste from an entry I made in this other thread.

*************

incoming temp:
do NOT assume it will be "X". MEASURE IT yourself. In case you don't understand the importance of this, let me explain. MEASURE IT YOURSELF!!! I live in mid mississippi. Envirotech said "heater model xxx will be fine for the WARM mississippi temps". I had measurable incoming temps of 42F during a typical winter. Also, you CANNOT calculate for worse case @ 33F. You'll end up with a heater that will dim the lights in your subdivision when it switches on.

elec supply:
These things REALLY like the juice. Do your light flicker or "blip" when your a/c kicks on? Well, envirotech's 28.8 Kw model pulls about 3-4 times that much power. EXPECT YOUR LIGHTS TO FLICKER CONSTANTLY when this thing is used at ANY other setting OTHER THAN full on or full off. If you need more details, PM me. You WILL have to upgrade your elec supply and panel box(es). These heaters require 100% duty cycle breakers. Practically all residential breakers are 80%. If used with this thing, they will heat up and flip. This will eventuall lead to failure/fire/etc. Most electricians do not know the difference between the 2 breakers, or that there are more that 1 type. Your biggest problem with the electrician will LIKELY be convincing him that it is actually possible to use that much electricity at one time. He will try to size the wire/etc too small. It will heat up and prematurely degrade the insulation. This will lead to failure/fire/etc.

You will really have to have a twig up your butt to get these things installed and working correctly the first time.

And finally.

Check and see what flow rates are required for the unit to turn on. Oftentimes they are high enough that some faucets, dishwashers, or other low flow devices will NOT trigger an activation.

I'm going for a GAS water heater, not an electric one; too expensive to use electric heating here in the CA. I live in an old neighborhood anyway and only have 100 amps of service at most plus the neighborhood's electrical system has old transformers and we already have problems with brownout in the summer.

My mom dosen't want tankless anyway, we're just sticking with a tank model

beyond what has been already talked about here I'll give you what I have learned from looking into it myself.

Tankless can save you money if you dont use very much hot water. If you use a lot of hot water then they dont. Also for a shower the smaller units just dont work, you will need the 100+ amp one, this is a HUGE electric load. If you're in an older house you may have to upgrade your service to run it! And the same thing for the gas, they use a very high gas pressure, if your pipe is too small you will not be able to install one until you upgrade the pipe to where you want to put it and you may have to upgrade the underground service depending on the install.

So even if you wanted one you might not be able to get it without adding a LOT of cost for infrastructure upgrades.

My mom has a 120+ amp model for the guest room area that they added onto their house for the grandkids to visit. Mostly it's not used, but when we're there or when the other grandkids are there they use a LOT of hot water. So that makes good sense. It costs them nothing 8 months out of the year, but those other months can raise their electric bill by $500 or more! (thats bathing/showering etc for 4 or 5 or more people added on, but at least it does make enough hot water)

as has been already mentioned an anti-scald valve is important if the temperature output can be ramped up beyond 127 or so. These will keep the temp at your shower or tub the same as other users of the water come in and out, but will add several hundred to the cost of the install.

So for some specific uses I think they are great. But it makes no sense for mom to replace the water heater she's got in the rest of the house with another tankless units. They dont have the amerage there to run it and the savings would be minimal.

Oh, and one other thing, especially about the electric units. Find out how your electricity is measured. Many areas have peak metering, meaning they charge you more if you're using more than a certain amount of power. And when a 120 amp heater kicks in that will definitely count as a peak usage. So the electricity might cost you significantly more than the lower levels, but longer time necessary to run a regular tank heater.

Also the timed rates in some areas is something to consider too. If you have a peak rate for the daytime, you can put your tank on a timer. Turn it on at 7 for an hour to heat up before you shower to go to work. If the peak rate kicks in at 8 you're all set. If you shower at 8 with the tankless, then you're going to be putting that 120 amps of power into the higher rate time frame, and the peak meter extra charges and so on. It adds up in a hurry.

It's still close enough in cost that you need to do some calculation and a little thinking to make sure you save enough money by switching. It's not really totally clear cut that a tankless is always better and always saves you money. But if you skimp on a smaller less than 100 amp unit, it just wont keep up and you wont be happy with it, so whats the point of saving a few bucks.

I have 8 year old American Appliance water heater that is working just fine--but I figured I would look around now for a "smarter" replacement before it dies.

As James and others have stated, the standard gas water heaters only use 40-50,000 BTU's of gas flame, whereas the tankless hot water heaters use 110,000 (for the smallest, one shower models) to 190,000+ BTU's (for the 2+ shower models). So, you may need a larger gas pipe from the meter to your water heater for more gas, a new flu (larger and possibly redone to support the steam found in the more efficient water heater exhaust gases--some even drip water), and you may even need an external air inlet to support the sealed burners in some larger units.

I am also looking at solar hot water heaters too... It appears that this may be a more cost effective use of solar energy (vs the Solar photo-voltaic panels), plus the panels are smaller because they are more efficient at collecting heat (than solar pv panels). On the other hand, there are plumbing changes, new, and probably larger, water storage tanks, and more maintenance. If you have a swimming pool, the solar water systems are a slam dunk in cost savings over time. For domestic hot water, it is probably still not a bad investment. Although, many of the "simple and cheaper" solar hot water systems I have seen around my area appear to have been abandon after only 10 years... It looks like you need to really do the research and find a good vendor/system for long life (glass vs plastic construction, copper water channels, etc.).

For my place, I am not sure I have any good places for the hot water panels (I already installed 3 kW of solar pv panels last year) and tanks (typically, it is recommended that you plan on 20 gallons of hot water per resident per day, and 1.5-2 gallons of storage per square foot of solar collector--perhaps 40-80 sq.ft. for my area south of SF CA--, plus you will still need a gas or electric backup water heater for winter/cloudy days). And you will need to worry about freezes, very hot weather, corrosions and leaks, etc. Some systems need AC power, others use a single solar panel for the electricity, and others are completely passive.

Still looking,
-Bill

John N said:

Check out this thread.

-john

Click to expand...

excellent advice.
the tankless heaters are discussed in the last 3 pages..

and who is this "**DONOTDELETE**" guy? he is truly a brilliant poster ..

gas is the way to go with tankless..my 2 year old Takagi II is doing fine --after I reset the temp to 120..idiot electrician set it to 180!! steam was blasting out of the bathroom faucet!! attempted murder in my opinion..

John N said:

Check out this thread.

-john

Click to expand...

excellent advice.
the tankless heaters are discussed in the last 3 pages..

and who is this "**DONOTDELETE**" guy? he is truly a brilliant poster ..

gas is the way to go with tankless..my 2 year old Takagi II is doing fine --after I reset the temp to 120..idiot electrician set it to 180!! steam was blasting out of the bathroom faucet!! attempted murder in my opinion..

To add a bit to the above threads... I have a gas tankless in my house (actually, condo). It dropped right in place of the "tanked" gas heater. Temp control is fine; performance of the unit overall is fine. BUT!!! When you're showering it sounds like a freaking 747 taking off in your attic! (At least in my attic, where the water heater is.)

FWIW, after doing a bunch of research, I still may eventually go to an on-demand setup, but if I do it will be a high capacity gas unit which I will feed into a small (5gal?) "normal" unit. The small unit to provide hot water in slow flow situations. Of course, I haven't tried this, so YMMV.

-john

I did just that, I had a 60 amp 240v electric demand heater feeding a 5 gallon electric. It took the quick swings off and also allowed hot water for low flow devices like dishwasher and wash machines, neither of them would turn on the electric on demand unit.

A O Smith has a good reputation. Even with prices going up, gas is more efficient.

The closest I found to a very efficient tanked water heater that did not have a huge burner (for commercial use) is this one (but I don't know the price):

A.O. Smith Residential Water Heater page:
A.O. Smith Condensing Water Heater

I also found a listing for the efficiency of many of the US suppliers of water heaters:

GAMA ratings of some residential gas water heaters (PDF):

Still trying to convince myself to go the "right way" with solar hot water... Guess I will have to call around and see what is available locally.

-Bill

BB said:

Still trying to convince myself to go the "right way" with solar hot water... Guess I will have to call around and see what is available locally.

Click to expand...

Seems like solar would work well in conjunction with an on demand unit. If it is hot enough, the on demand unit won't kick in. Otherwise, it heats it just enough to get to the target temp. And you still get hot water in bad weather. Seems like the best of both worlds.

-john

If I was doing new construction, I'd consider have point of service heaters using preheated water with a heat recovery device like this one:

http://oikos.com/esb/49/gfx.html

-john