Heating System Question

[Keonobi]

Anyone know about home hot water heat systems?

Last year we bought a house built in the 50s that has a hot water heating system with radiators.  I believe they call it a 'one pipe' system, meaning a pipe leaves the furnace and goes around the basement, with t-joints periodically that go out to the radiator in parallel to the main line.

The problem I have is with the radiator in our downstairs bedroom, our house is a two story with only one heating zone and all the upstairs radiators produce heat (as well as the rest of the downstairs radiators).  Only the one downstairs radiator doesn't.  When I go into the basement, both the supply and return pipes for that radiator get hot, but the radiator itself never seems to get more than slightly warm.  I'm thinking there is a problem with the shut off valve because it just turns and turns, but is there a chance its a blockage within the radiator?  If it is a blockage I'll have to replace the radiator, right?  If its just the valve I think I'll just have to replace the shut off valve.

Anyone here know a lot about these kind of things?

[Jesse James]

I'd think blockage right away...  Corosion perhaps.  Kind of like a bad radiator in a car due to corrosion clogging the system. 

I don't know how one would go about fixing that short of replacing the radiator...  I don't know if you can "flush" those systems or whatnot.  They seem like they're maybe built out of non-corrosive materials, or so I thought.  My grandmother's place had heating like that...  My first guess is a clog though, or possibly your shut off valve got broken and you really cannot shut it off or open it up anymore, thus the turning, and it's maybe mostly shut but not totally. 

[EdSolo]

Sounds like both a bad valve and a clogged radiator.  I would guess that you may have copper piping for a house that old.  The radiator could be made of cast iron which would rust over time.  Even though I have plastic piping, I do have rust scale in my water.  Over time that could build up in the twists and turns in the radiator, thus slowing the water flow through the unit and decreasing its performance.  At the very least it would seem you might need to remove it in order to inspect the internals or try to flush it out.  If the shut off valve just keeps turning, then I suggest replacing that as well.  You may want to get a ball valve instead of the gate or globe valve that is already installed.  While a ball valve can wear out if material gets caught behind the ball, it is easier to open and close and gives a nice tight shut off seal.

[Keonobi]

Yeah, I've been thinking about replacing the valve with one of the thermostat types.  The whole house is on one zone, so the only way to directly control heat in any given room is to close/open the valve, but getting that balance takes a lot of expirementation, and I think a lot of the other valves aren't in great shape either.

If I get the radiator disconnected, will there be an easy way to tell if there's internal corrosion?

I'm thinking I'll spend tomorrow working on this a replacing the bleeders on the other radiators.  I'd rather only drain the system down once and even then before its gets too cool out.

[Jesse James]

I'm thinking you would see it right away.  I know when you flush radiators you usually can tell if the core's going bad on them right away.

[Keonobi]

I posted my question on a heating system website and the folks there think its highly unlikely that its corrosion on the inside of the radiator, apparently its extremely uncommon.  Based on how I described the valve turning and turning, they think that there's an issue with the valve.  I guess its common for this type of system to have whats called a 1/4 turn valve, meaning a 1/4 turn opens it from fully closed.  The recommended I crank the heat and try turning just 1/8th of a turn, to see if the stops within the valve have been broken, and all my turning has simply been opening and then closing and then opening and then closing (etc) the valve.  Otherwise its likely a broken valve.  If that still doesn't fix is I think as a last resort I'll check on the corrosion.

Checking if 1/8 turn works....free
Replacing valve....probably $10 in parts and a couple of hours to drain system, take apart connections, refit and refill
Replace whole radiator...probably $300 for the radiator, plus a couple more hours to take drain system, etc.

I think I'll eliminate the simpler things first.

Still, if when I take off the valve if a bunch of rusty water pours out, I'll know right there, I suppose....

[Jesse James]

Yeah I'm not familiar with the systems much...  Corosion happens in car radiators fairly frequently depending on the type of car/radiator, so I thought it might be a possibility as it gunks them up and prevents flow causing cars to overheat, etc.  My grandmother's system was in her duplex she rented so we never had to fix the system if it had a problem as it was the landlord's issue...  Not many houses heated like that anymore I don't think...  Sounds not too difficult to fix though.

[Keonobi]

Update:

So I guess it was one of those quarter-turn valves, I was able to push down on the valve and turn it enough to get flow through that radiator.  I think the valve stem is broken though because if I didn't push down with a fair amount of pressure, the turning didn't seem to open the valve.  I think I'll still have replace the radiator next year, including replacing that valve (I saw that they sell valves that have a local thermostat, and since its a small bedroom it might be good to have that).

Yeah, I think most new houses have forced air systems, radiant, or baseboard heat.  But maybe that'll work in my favor and I'll be able to get off craigslist or someplace a replacement radiator of the same size, since sizing is very important.

Thanks for the advice guys!

[Matt_Fury]

Good luck with that.  At least in the short term it seems like a relatively inexpensive fix.