100 Gal water heater vs. Boiler??

Our 4 year old gas A.O. Smith 100 gallon 199000BTU water heater has sprung a leak and from the looks of it has been there for atleast enough time to start rusting. There is now a steady stream of water running out, we shut it off, and my 40 units are without hot water!

I called A.O. Smith this morning as we put this unit in just under 4 years ago and spent $7800 on it. I found out today that it only came with a 3 year warranty on the tank and 1 year parts! I am absolutely furious this should have lasted 15 years at least! They said there is nothing they can do.

I called the installing company we used and they had the same sad story and informed me this attempt I can get an American water heater of the same size for $6500 installed. I have checked around even with Lowe’s which carries one but said it would take about a week to get which is too long.

So, my question is does anyone have any previous experience with boilers? I am trying to find another option than a water heater made for 15 units. The current system is set up with 2 recirulating pumps as well as a large 250 or so gallon holding tank in our basement.

Will a boiler work and if so what about the differences in natural gas consumption? Tenants pay gas but I still need to know if all the details…who installs boilers? and would a boiler last longer than a water heater?


High Soup,

            Have you thought about the idea of using an insta-hot unit, they make large units! It may be considerable cheaper to buy and install, and they will produce hot water at a level in relation to pipe size, 1", 1.5", 2", 3" etc.

You might want to look into this as it removes the need to recirculate or store in tanks, wasting energy keeping a supply hot in a tank all the time.


I am looking at info on tankless but the building is 40 units 3 stories plus basement so I dont know if they make anything cost efficient in that size

I lease all of mine from the local gas company and it covers all the parts and labour. They’ll even send a repair guy at 3am if it breaks down. I pay $1,900 a year for the AO Smith model and it’s still running after 7 years. I used to own tanks, but I had the same prob.–a few months after the warranty expired, all the expensive parts started breaking and it was like $500+ each service call. Some kind of Murphy’s Law. After the first two repairs, I said screw it I’m renting. I’m convinced that you can’t save money by owning one.

my patch is holding…

Lowes quoted me at 5450 and the other plumber wants 6450 so that is a much better deal of course its not ao smith its american water heater co but it looks like the exact same model so I am about to push the button and get it ordered.

I checked and my gas co does not lease anything…

Please read the fine print on the warranties… In a non single family residential setting most water heater boilers do not have warranties past 3 years.

AO Smiths are not crap water heaters and I am surprised you are having problems with it… Did you follow the maintenance schedule on the unit and flush it out? Every town has different levels of minerals in the water and some of those minerals after rubbing against metals can wear them… If you dont flush out your tank as requested those particles can sit in the tank and over time wear the walls out.

If the gas company does not have a program, look for a plumbing maintenance company… They may get you on a program where they warrant the unit when you pay for a quarterly maintenance program etc… While its an added cost, it woud have saved you $7000 your going to pay for your new one.

I have been busy. First off we plugged the hole temporarily. hammered a small widdled down piece of non treated wood in the hole to stop the leak and told the tenants that they would need to boil their cooking and cleaning water for a few days, which they did not seem to mind and were very glad just to have the water back on.

I had a boiler company out and they think that the heater, which he said is completely rusted out btw, is getting too much condensation building up inside of it due to the fact it is receiving water directly from the cold water main. He thinks that when the other company installed it that they should have recirculated it to my holding tank before it came to the heater.

Morgan Miller Plumbing in Kansas City installed the AO smith as well as thousands in other numerous repairs over the last 5 years. It appears my previous assumptions regarding the quality of their work was indeed correct. This particular water heater is only rated for 10-15 apartments, and they installed it knowing I have 41 units in this building. When I first started they were charging me $800 to cut out and replace a drum trap, but at the time I had no plumbing experience. Now we do nearly all repairs to the hot and cold water lines, faucets, and quit often we do our own pipe rooting. Paid for the snake machine in the first month. As for this Plumbing company the service people I dealt with were pretty much ok but the prices seemed really steep for the labor involved.

I am having another boiler co check it out on Monday as the quotes I got seemed a little bit more than we were expecting. I will elaborate more once I am finished getting more info. We are looking at a 98% efficiency boilder, 81% eff. boiler and I did get a quote from lowes and the crappy plumber for another 100 gallon heater. Lowes came in $1250 cheaper than Morgan Miller Plumbing! Said it would take about a week to have installed from when I ordered it, but I am leaning towards a boiler.

The 81 % efficiency has small copper tubing for the heat exchanger, the 98 % has a stainless steal. When I asked about expected service life differences he said that the stainless steel heat exchanger in the more efficient one he didnt think would ever need to be replaced?

I currently have a ray-pak digital asme certified pool heater which we got a great deal on. Its nice and is similar to some of the smaller boilers I have seen. I think a boiler may be suited better for this application.


You have a great application for a boiler. Most actual water heaters are made for residential use. You have an indirect tank of 250 gallons. I would look at a condensing water heater such as the type made by triangle tube. This is a 95% efficient boiler compared to your water heater which is likely in the 780’s or 80’s for efficiency. You should be able to get tax credit money for this too.

You may be limited by the gas pipe diameter, but if you have 200k BTU now you can probably repalce with that. Boilers can go much higher in rated output also.

You need a new company. In Kansas City I highly recommend Geoff Hey at Hey Mechanical. He’s put in half a dozen or more units for me in both commercial and residential applications. He has experience with boilers, does very neat work, and knows his limitations. (913) 789-7730.

Forgot to post on the final decision! We ended up going with a 98%% efficient hybrid tankless water heater through LBA plumbing locally. It was cheaper than all other options presented, with higher efficiency and after 2 months working perfectly. Our gas billing is 2 months behind but I feel that we’ll atleast see a small decrease in our gas due to the efficiency gain.

I didn’t realize I was ressurecting old threads.

Good for you!