Shutting off radiators?

[nola mike]

OK, not sure where to post this, but since my boiler is gas-fired, I figured I'd stick it here. I have an old school (ca 1915) cast iron radiator system in my house. Last year I installed a wood stove, and to my surprise, it damn near heats the entire house. But not quite. My wife will NOT mess with it, and she works from home. So we need a bit of supplemental heat, mostly for her office and the baby's room upstairs. The problem is that when you turn on the thermostat, the whole system cranks up, which a) takes forever, and b) lasts forever. Great for long, even heat, but not what I need now. All of the radiators have valves on them in various states of repair. Ideally, I'd like to shut down the water supply to most of the radiators so that just select rooms would be heated. I tried to clean/fix a few of the valves last year. However, the valves have a pinhole in them that allows water to flow even when turned off. It seems that the radiators get just as hot when the valves are closed. I don't understand their purpose, since the radiators are in parallel. I don't see any reason for any water flow when the valve is closed. Does anyone have any thoughts on this, or how to modify the valves so that I can turn them off completely?

 

[woodsmaster]

Install new thermostaticly controlled valves. Then you can heat each room to the desired temp. They run around $50.00 each.

 

[nola mike]

yeah, I looked into the tstat valves. Pricey to convert 15 radiators though, and I really don't need that level of control. Like I said, I'll only be heating 1 or 2 rooms with the radiators. Additionally, since the main tstat is located in a different part of the house, I'm not sure what happens when all of the valves shut themselves off. Either the boiler just recirculates/heats water constantly, or worse, the circ pump is pumping against a totally closed system.

 

[begreen]

Maybe cheaper to replace the wife? J/K :lol:

Would an electric oil filled space heater or two work for her needs?

 

[nola mike]

Ha, I have a few divorced friends...It's NEVER cheaper to replace the wife!
Yes, the electric heater would work for her needs, and is what she does when I'm not looking. Unfortunately, running one 8-12 hours/day is as expensive as firing up the whole gas system for that length of time. And of course this is not really about cost (doesn't get THAT cold for that long in VA), but just wanting to heat with wood as much as possible.

 

[nola mike]

OK, so after some googling, I think I've determined my problem. Seems that the pin hole in the radiator valve was there to prevent freezeups and limit flow, while still allowing a trickle. The reason that the radiator is still hot even though the valve is all the way closed is that the system was originally designed and used without a circulator pump, so the flow through the entire system was much less. With the addition of the pump, even this small pinhole allows enough flow to keep the radiator hot. So I think that I'm going to fill the holes with a bit of epoxy and keep the original valves. Looking online, it looks like replacement valves aren't quite the same dimensions anyway--there's maybe an extra 1" off the elbow, which may make replacement difficult.

 

[kettensäge]

Is the thermostat in one of the rooms that will not be turned off?

 

[nola mike]

yeah, thermostat's in the same room as the stove, which screws things up even more.

 

[EatenByLimestone]

Cover the radiator with an insulative cover. The heat won't escape and will stay there. The only heat lost to the system will be from the uncovered radiators.

 

[nola mike]

Just an update. Ended up sticking a dab of epoxy in each of the holes. Disassembling 100 year old valves caused a lot of leaking, which was a pain. Now with the valves fully closed the flow was minimal, but still present. So I redrained the system and when I filled again, I simply didn't bleed the radiators that I don't plan on using. So now most of the time, only the radiator in my wife's office (in the far corner of the house) is used, allowing me to use the stove for the rest of the heat. Good compromise. With only one radiator in the system, it heats up much faster. Since the t-stat is in the same room as the fire, we just turn the heat on for about 30 min until the radiator is hot. It will stay warm for a few hours after that.

 

[woodsmaster]

With air in the system It could cause corrosion. Oxygen + water = rust.

 

[nola mike]

Eh, i think it would take another 100 years to rust through one of those radiators.