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Old 09-27-2011, 09:08 AM   #1
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Repairing converted Steam to Hot Water Radiator system - HELP!

OK. My parents house was built around 1910. It appears that the system was originally steam and later converted (a long time ago) to hot water. Upstairs radiators each have 2 shutoff valves and a steam release valve but none of the downstairs radiators have any of that.

It is set up in 2 zones (*upstairs and downstairs are separate).

We had a guy come in last year and replace the old oil burner and I believe he replaced both circulators. The circulators are on the RETURN side of each zone (is that normal or part of the problem?). The new circulators are pretty small (can't recall size...but much smaller than what was there.

Problem is with the downstairs zone only. (Up works fine.) 2 of the radiators are not heating up. I cannot tell you if this occurred in conjunction with the install of the new furnace or not (sorry, I wasnt there to test it when the guy finished his install) or whether it worked and suddenly stopped working. All other radiators heat up...but all at a very different pace.

So we shut down the system and started looking for problems. This is what we found thus far.

The radiators are fed from above but not in a continuous circuit as I expected but I guess since it is a converted steam system, that may explain it? Basically, a pipe comes out of the furnace and across the ceilings and a pipe T's off and down to the first radiator. That one works (I said that there are no shutoffs downstairs but for some reason this one (and only this one) does have a shutoff on the pipe going down to the radiator.)

When we tested the system we noticed that this radiator got hot quickly but no others were heating up at all. So we waited about 1/2 hour and decided to shut off the valve to bypass that radiator. When we did, the 2nd radiator on the circuit heated up immediately...but still no others.

We had no way to shut that one off so we could not test further to see if the two that were originally not working would start to work.

So now I start looking at returns. What a nightmare. The "boiler room" as we always called it has a dirt floor with a 2-3" slab of concrete. So we dug down to start looking at the returns and noticed water around the return pipe close to the furnace. So I painstakingly took out the concrete and exposed the buried pipe. They used steel pipe..not concrete! I found a leak in the line. Not a huge hole, but enough to make a fine thin stream of water spray out at full pressure. Pressure on the system still got to 12 lbs with no problem so it still functioned.) The pipe though is completely shot, rusted from outside, needs to be completely dug out and removed. Unfortunately the 2nd elbow is under a brand new kitchen floor and there is absolutely no access ...brick cellar......ugggh.

So my question to any experts is this. How in the world can a converted steam to hot water system work when there is nothing forcing the water around to bypass these t's to send water to the next radiator? Since the feeds and returns are t'ed together, doesnt water just take the path of last resistance in a circuit? How did it EVER work. Could the new (possibly undersized) circulator cause this to happen? Should I put shutoffs on every downfeed to each radiator so I can reduce flow as necessary and force water to the next radiator in the line? I'm just not entirely convinced that this tiny leak is the whole problem here and I believe we may have just stumbled upon that situation.

Any thoughts on a simple way to replace just a section of return pipe so that I dont have to go to the next elbow to replace the entire pipe I dug up (forcing me to cut up a perfectly new floor) ? Weld? Its should be entirely replaced, but I just want to solve this as simply as possible for now and deal with major rehab later when my schedule allows if possible. Does anyone here fully believe that the leak would cause all the other problems? Is there anytjhing else I should do with the suystem now that it is empty of water (and still relatively warm out?)

Thank you so much all for ANY input.

Last edited by JonathonT; 09-27-2011 at 09:16 AM.
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