Home made heat exchanger

Hi guys I'm looking for some help from all you D.I.Y. guys out there or pros for that matter. I'm in the process of installing my coal stoker with a boiler in my shop and I priced out wall hung heat exchangers. Holly cows are those things salty $$$$ ouch. Well I'm thinking that there's has to be some kind of way to convert car radiators and gang them together. Then install a fan behind them to force the heated air into the shop. I sure could use some help... has anyone pulled this off?

Thank in advance!!!

Pat
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If you could find heavy duty truck radiators, you might be able to pull it off. Remember that you might have 15-20# of pressure in them. If you wanted to control the fan, use an L6006C aquastat so it only blows when the water is hot.

Thanks stoker-man that gives me something to think about.

Pat

Go for it! Make sure to post results & pics.

I've had this idea of an auto radiator type set up to make heat to power a clothes dryer. Try that while you're in the inventive mood & let us know how it works.

I made a water to air heat exchanger out of a A/C condensing unit. It was the condensing unit for the milk cooler room on a dairy farm. The fan motor is 240 volts and I have it wired with a switch so I can run it on 120 (slow) or 240 volts (normal).

For a clothes dryer conversion I would use a kick space heater. Small enough it would likely fit inside an electric dryer cabinet.

See: http://www.beacon-morris.com/html/kicks ... in_flo.asp

The A/C condensor or evaporator makes more sense, now that you mentioned it. They can withstand hundreds of pounds of pressure and should be easily available for scrap value at an HVAC place.

Yanche that's a great idea too. I was also thinking about ganging together a few copper finned baseboards (less the sheet metal coverings) section of piping.

Pat

I know this is quite an old thread but I'm interested in the answer the to last post. Is it possible to make a heater for a garage ganging together some baseboard units without the covers (just fins). I would back it with a fan and use an L6006C or a relay to trigger that fan. I have a standard 2 car garage that is decently insulated. If I took on this project I would do what I could to up that level as well. Thanks!

That fin will give up about 300 BTU per hour per foot at 140 degrees -- more if you circulate higher temperature liquid.

http://www.slantfin.com/documents/326.pdf


Is this enough to satisfy the heat loss calculation?

A customer of mine used an old Caddy radiator to heat the garage where his coal boiler was. He used an old hanging gas heater whose exchanger was done for and tossed everything but the end with the fan and the front. He just fabricated a sleeve that fit around the radiator and sandwiched the ends together. It would turn on and bring his garage to temp in a minute or less. If you think about it , car radiators dissapate alot of heat. And you can get 30lb radiator caps. He used clear tubing and stainless clamps to go from the radiator to the pex. Necessity is the mother of invention. I should go visit with a camera. It really was a good Idea.

Just the baseboard, with cover, on the wall would give you 600 BTU per foot. It works well in my garage. I'm not sure scientifically, but I think you get better heat output using the covers because of the chimney effect over the fins.

look for some used ones, iv'e picked them up cheap in the past.

also look for big cast iron radiators, i like them even better.

Here's my opinion on heating home use work shops and garages. Since they are rooms that are often poorly insulated and almost always only used infrequently the heating needs are much different. What you want is a heater that heats the air and does it quickly. Think about it when you use it, it's the room air that touches you and that's what you want to be warm. During the times the room is not heated or the thermostat turned down the walls and everything in the room gets cold. It just doesn't make sense to have a heating system like radiant heat that must first heat up the objects in the room first before they can the radiate heat to your body. So use a water to air heat exchanger with a boiler or a stove with an air circulation blower system. It really needs to be oversized, certainly larger that a normal steady state heat loss calculation would show. All the home brew ideas will work, the auto radiator will work better than finned baseboard elements. A cast iron radiator with a fan behind it will also work.

I see completely what you mean about using just radiant heat would always take forever to bring the garage up to temperature because I would be heating all my concrete walls. What I'm picturing in my head is using 3/4" copper with fins and switching it back and forth on itself in an S-shaped pattern. I would have to run the calculations to see how wide it would need to be and how tall. I would then back it with a fan (or probably fans) to get the hot air moving around the garage. I'd rig these up to turn on when the zone is open and possibly even run afterwards for a few minutes to get that last bit of heat. Just toying with ideas...if this system works I can basically write my own BTUs based on how much finned copper I use.

Here's my heat exchanger. I used a blower from a junked warm air furnace. Usually free for the taking. And a small used modine. The black thing taped to the pipe on the right is a 6006A aquastat and the bulb is pressed right against the pipe, covered with pipe foam insulation and wrapped with tape. The blower motor comes on at 140 degrees automatically.