steam radiator conversion

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martygriz

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Jan 15, 2010
3
Southern CT
I have an old, 3000 sq ft home with an oil furnace and steam radiators. We are interested in converting the radiators into hot water units (they have two pipes- supply and return)and heating with an indoor wood boiler (garage or basement). I would like to convert the first floor to radiant (floor joists are open in cellar). Friend has a Tarm, but I also like the looks of the Grenwood. Is it possible to convert the steam system to run with a wood furnace?
 
My understanding is that trying to convert a steam system to hot water is more trouble and expense than it's worth. Some steam rads, on the other hand (newer ones) are interchangeable. So it's usually not the radiators that present the problem, it's the piping, which is very different in a steam system than in a hot water setup.

However, Wood Gun (see banner ad which rotates on the top or bottom of this page) does make a wood-fired steam boiler, from what I understand. I think that's your only realistic hope.
 
My house had steam when I moved in. I put in a Tarm and converted the oil boiler to HW instead of steam as a backup. I put in baseboards on the second floor, staple up radiant on first floor, and also a baseboard/radiator combo on first floor for the really cold weather. I then sold the the steam radiators to someone at scrap metal price.

A lot could go wrong running HW through a system meant originally for steam. Steam systems are usually in older homes and those homes also typically don't have much insulation in the walls. Regardless of what fuel is heating your house, it is essential to have a decent amount of insulation. I wish I had realized that and factored in having celulose blown into my walls into my project costs. I will get around to eventually and in the meantime I am burning a lot more wood than I otherwise would.
 
I like the old cast iron radiators, so i'll have to think about that. Also don't want to tear up the walls to get copper up to the second floor for baseboards. No insulation in the walls- old post and beam house. If I put radiant on the first floor I could perhaps put hot water in the upper radiators. What problems could arise with hot water conversion??
 
martygriz said:
I like the old cast iron radiators, so i'll have to think about that. Also don't want to tear up the walls to get copper up to the second floor for baseboards. No insulation in the walls- old post and beam house. If I put radiant on the first floor I could perhaps put hot water in the upper radiators. What problems could arise with hot water conversion??

Leaking gaskets, a flooded house, etc. (just kidding). I believe these have gaskets between each section that builds up each radiator. Lots of potential problems...

Without insulation in the walls a radiant floor will not heat your downstairs when temp outdoors is below 20* or when it is very windy. It just can't keep up well. That is why it is wise to also add a regular heating zone on that floor as well, not to mention insulating the walls! For second floor baseboards, I ran PEX up one corner of the house and ran the baseboards along exterior walls of rooms and went straight through the walls to the next room and then back down in PEX when the loop was complete.
 
steam radiators do not operate under the pressure that a pressurized hydronic system does, generally 12- 15 psi. that pressure increase often is enough to cause them to leak at the section connections. the taps are not at the ideal location to flow water through the entire radiator, although some have multiple taps.

They are nice looking and a great heat emitter if you can get them to hold pressure.

Be careful trying to powder coat them. The high oven temperatures can cause them to leak also. Good luck with the project, it can and many have done it, just be aware of the pitfalls.

hr
 
I have used steam radiators for hot water heat repeatedly and never had a leak or problem, the only thing to make sure of is that they are not steam only. by this I mean they have to be connected across the top, I have seen some that are individual sections only piped together at the bottom which will still work but require an air bleeder on each section. another HUGE benefit is that they heat effeicently on lower temperature water. I removed nine from a house in 1979 and piled them outside uncovered until last fall, sandblasted, painted them and installed them in my house, no leaks and turned the wood boiler temp down to 165. just my thoughts. Dave
 
Actually, you can use the older steam rads with no top pipe in a hot water system without putting bleeders in each section, but it's an engineering challenge. The rad pictured is in our kitchen, and has been in service for about 4 or 5 years. It really kicks out the heat.

Basically, you need to plumb bleeders, shut-off valves and unions into each side, then turn the radiator upside down to fill it. It's not that hard once you figure it out.
 

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