Coal Fired Hot Water Heater

Freddy, after you get the stove black on that little stove your working on, i'll need to borrow it to "give it a try".

JB Sparks wrote:Glad this subject came up. I picked up a used electric hot water heater to use in my system somewhere. i strip the outer sheetmetal and insulation off, took out all the fittings and with a flashlight took a look inside. Whatever the coating was on the inside was crumbled up in a heap at the bottom of the tank. So with a jet water and a poker i was able to get it all cleaned out.
Question, what can i do to recoat the inside of the tank so it can be used as a pre-heater for my DHW? I was told if i didn't recoat it with something that my hot water would turn black from the pre-heated water sitting in the raw steel tank. Anybody know anything about this?

Some of them were glass lined I think. You don't want your domestic water in a raw, carbon steel tank, you will have a disgusting mess. I don't think there is any practical way to reline a hot water heater, it probably will be a less than rewarding exercise.

The "glass lined" domestic hot water heaters are actually, porcelain enamel. It's a specially formulated, highly durable glass permanently fused to metal under extremely high temperatures. Not something you can do at home. At one time American Standard made cast iron bathtubs in Baltimore. A friends father worked the night shift applying the porcelain. The tubs were glowing cherry red and his job was to shake just the right amount of porcelain powder on the tub. It instantly turned to a liquid which would be swished around in the tub by turning and rotating the tub. Obviously not by hand but with attached lever arms. His arms and chest muscles were larger than a weigh lifters. Not the guy to arm wrestle in a bar bet!

Here's a web link on what you can do:

http://www.doityourself.com/stry/porcelainenamel

Thanks guys,
It looks like it would be as cheap and a whole lot easier just to buy a new electric hot water heater and strip it down like i did the old one i have. i'd really like to get a preheat hot water tank set up. The incoming cold water coming into the house during the winter seems like it's just above freezing.
Do you think that it is worth the expence?

I'm thinking it would be worth the price. I just don't know how long it would take to pay for the initial system. Partly because I haven't figured out the best option to go with yet. There is so many great options to choose from. Which one is the best? Anymore suggestions? We haven't reached data overload yet! Thanks, DOUG

this baby probably holds 1+gal., max working pressure 125lbs.

Hi Doug,
Thanks for the reply, yeah i'm wondering the same thing. a new hot water tank at Lowes is about 250.00 for a fifty gal. tank. that has to get paid back by a savings in coal use. I'm still going to put in a bypass in the DHW zone circ. that Freddy recommended to me, that should take the 20* drop in boiler temp. out of the situation. I'm also thinking with a preheat tank could be useful in a solar application for summer time water heating. The other three zones of baseboard heating the boiler just lopes along in idle most of the time. I'm still amazed how well this Harman works.
BTW i saw the pics of your set-up, very impressive and very professional looking,you get a well deserved "well done".

WNY wrote:Why not Just put a hot water coil in your coal stove and circulate thru your hot water tank.

What? that's trying to make the stove into a boiler! Unheard of.

Whatever the coating was on the inside was crumbled up in a heap at the bottom of the tank.

You sure it wasn't lime scale that fell off of the elements?

Why "strip it down"? Leave the insulation and the outer skin on it, it's there for a reason. Leave the elements in as well, use the TPR and drain ports, just use thread tee fittings.

If the "Bucket A Day" ever fails you can always make a diving helmet out of it...

A good used hot water heater tank to look for is a Weil McLain indirect hot water heater. See:

http://www.weil-mclain.com/downloads/li ... luslit.pdf

These indirect heaters have an inter stainless tank inside a steel outer tank. Boiler water circulates between the two tanks heating the domestic water. These tanks are made in Holland and are re-branded by Weil-McLain and others. There was a design deficiency at the thermostat sensor well. An "O" ring seal fails and the tank slowsly leaks. There is/was a warranty recall. It's a free exchange for a new tank at the plumbing wholesaler. Homeowner pays for labor. At the wholesale level the bad tank must be made available for inspection by the Weil-McLain rep. After that they are junked. If you have an "in" at a plumbing wholesaler you can get the tank before it's junked. I managed to get two free. If you have welding skills the tank is fully repairable. In any event the stainless tank portion is almost always useful.

It's well worth looking for a junked tank. These indirect hot water heaters wholesale for $1000 +/-.

Yanche, Thats worth looking into, I hope the wholesaler i have an account with deals with these tanks. Welding no problem.