Coal Stoker Coil Question

[homeguy]

Hello,

I just bought a new 90k btu automatic coal stoker and am thinking of installing a stainless steel coil above the coal bed. The coil stretched out is around 6 feet long so there is a decent amount of surface area. I'd like to run the water from my oil fired boiler (drain valve) into the stove's coils and back out into the boiler (relief valve). I would use a small circulating pump and run the water through the boiler continously. I would make sure the relief valve was plumbed outside incase the pressure gets to hot and it blows. Currently I keep the boiler at 150L/170H The stove should do about 80% of my heating and it would be great if I could move some of the excess heat into the boiler via the coils. My goal is to heat a basement (stove is on the first floor) with the oil fired boiler with the help of the hot water from the coils. I was wondering if what I want to do is feasable? I would really appreciate any advice. Also, if the stove is 8 feet above the boiler do I need a pump or will the water pressure inside the boiler circulate the water?

[wenchris]

I am thinking of putting a coil in my stoker as well. It would be used for domestic hot water only. The only coil I have found is the Hilkoil which is about 3 ft long. What type are you going to use? Has any one else installed one and would like to share their thoughts feel free. Thanx Jimmy

[homeguy]

Domestic hot water will require more plumbing. You wouldn't want the hot water from your stove's coil to go to the tap. Therfore you would have to use a mixing vavle or an aqustat to turn off the circulator when the water tank got to temperature. Then there might be the problem of heating the water in the pipe that isn't circulating which could cause steam and cause a broken pipe. I'm eager to hear form those who have tred what we want to do.

[Richard S.]

Most people hook them to a hot water heater, actually I don't know any one that hasn't. Right now my father has it going from the furnace directly to the wat heater. He used to loop it, naturally circulate. Last time he changed the water heater I guess he got lazy.

[homeguy]

NEPAForum Admin: Hmmm... Could you elaborate on how your father has his coil hooked up. When you say he has it going from the furnace to the hot water heater-Do you mean that he has a coal furnace and rund that directly into the hot water tank? You also wrote he use to loop it, naturally circulate and then he got lazy (: -what do you mean I'm a little confused..... Also, what is the temp of the water at the tap?
Thanks and you have a great forum!

[Richard S.]

First a little background. This is a big hot water boiler I'm referring too and the coil is very large, probably about 20 feet taking a guess. He has a extra somewhwere and that would be my guess. when he originally hooked it up about 25 years ago he had it going directly to the hot water supply, no hot water heater. He had to switch it becasue it was too hot.

. When you say he has it going from the furnace to the hot water heater-Do you mean that he has a coal furnace and rund that directly into the hot water tank?

Correct that is how he has it set up now.

You also wrote he use to loop it, naturally circulate and then he got lazy

He had it looped by adding a return line from the hot water tank from the drain on the botton of the tank. I'm not a plumber and I'm not exactly sure if that if he had it reversed with the drain being the hot water feed for the hot water tank but basically you have the cold water supplly coming in from the street with a check valve. This goes to a T. On the one side of the T is another check valve to force the water to go into to the coil which in turn was fed to the cold water supply on the tank. The loop was completed by feeding it back to the other side of the T. Since the water in the furnace is hotter than what is in the tank it's going to want to force its way into the tank which will give you a natural circulation.

Also, what is the temp of the water at the tap?

Pretty constant even with it being fed directly, as a bonus it will last practically forever. With that set up you could run the disawasher, clothes washer and still take a shower.

If you have teenagers this may not be a very good idea as your water bill will go through the roof.

[tjv]

There are many things to consider in attempting this. Above all you must locate a proper high temp blow off safety valve and a high pressure blow off valve into a safe area such as outdoors or into a metal sewer pipe capable of the volume and high temps. USE NO PLASTIC PIPE NO MATTER WHAT MFG TELLS YOU
I know many have hooked these up and they work well but under certain conditions they can be a potential bomb.
That said start searching for "thermo syphon hot water system" You will find many good ways and safe ways on how to design and install these.
Personally I installed a seperate new tank to heat with the stove and feed original tank with it . Worked great ..actually to great so i cracked hot water tap at night to keep it from blowing off. PS makes sure your systym has "make up water"(tap water is alweays available in case it blows off from heat or pressure.
If you search the posts on http://www.otherpower.com within last 18 months you can find a real good design for a heater.

[tjv]

PS While at it look up "super heated steam" You may change your mind especially if you use wood to fire.

[George-NJ]

Cap & I are making our own hot water coils, see the pics in the Hand fired forum. I'll add my pic here as well.