That one radiator...

subaru400

My system is finally running so good thanks to the people on The Wall being so generous with their knowledge! I even invite friends over just to check it out lol. In the past, it was nearly impossible to balance my system, but after relocating two mains this summer, my cycles are tuned in, and 12 if my 13 radiators heat up perfectly and at the same time. The 'lagger' is located on the top floor, and is one of three up there. The other two come from what we'll call the East branch of the boiler, and this one comes from the West branch. There are 4 others on this branch, all of which are a floor below. They heat up fine, as do all the radiators on the East branch. The valve is fully open, and I've tried multiple venting solutions on this one, currently a MaidOMist that is wide open, which works as well as any others I've tried, which means it hasn't solved the problem. If I remove the vent completely, I'll occasionally get steam at just about the same time the cycle ends, so it may be possible to make it work. My theories include: 1) debris/blockage within the radiator or even in the vertical in the form of corrosion; 2) the lower radiators venting at the wrong rate, not allowing any pressure to build and vent this one in time; 3) a leak somewhere in between. My questions are: is there a vent that allows 100% flow so this might be able to void more quickly? Is there an easy way to check for blockage or leaks during the heating season?
I'm concerned that adjusting the vents on the lower units will make them less effective and throw off the balance in those rooms. 

TonKa

Balancing the radiators is... well... a balancing act.

If you can't get steam to the laggard by removing the vent completely, it is very possible the radiators tied in earlier on the riser are vented too quickly. Fortunately for you, it's the simplest thing to check. Put slow vents on those radiators and you'll have your answer about whether to take more drastic action with the laggard.

The next most likely reason is the radiator valve is kaput.

subaru400

Great - thanks! I'll slow the others down a bit. With all the left over vents I have, I'm sure I already have something that will work.

mattmia2

There is probably water trapped somewhere in the run out to that radiator. The steam won't progress past the water until it heats the water.

BobC

make sure that radiator is sloped to any water can find it's way out. Next try lifting the whole radiator up by 1/4 or 1/2 inch to add to the slope of any pipes you can't see, lever it up gently and don't force anything and hust shim up yje legs to hold it up - recheck the level to make sure it is still pitched correctly..

neilc

i'll bet on #2,

do all the other rads have adjustable vents ?
you could try shutting all the other vents down by a notch, or 2,

this might be enough to load that last radiator,

Steamhead

What about your main vents? How long is each main, and what vent is on it?

subaru400

Thanks for the replies. The mains are Legend Valve T-65 1/2" vents. It does appear that this radiator has minimal pitch, so adjusting that will probably help. Any tips on lifting the radiator safely so I don't mess up the valve joints or sections?

Steamhead

Those Legend vents are pretty slow- comparable to the Hoffman #4A. How long are the mains, and what pipe size?

subaru400

Well, one is 45' and the other 90'. The longer run serves the problem unit. 

Jamie Hall

That 90 foot main -- even it is small diameter -- is going to need at least one if not two Gorton #2 vents to vent properly. Is it counterflow (I hope not!). Also slope on such a long main -- counterflow or parallel -- is really important. That's a long way for the water to go... and I hope it's insulated.

ethicalpaul

mattmia2 said:

There is probably water trapped somewhere in the run out to that radiator. The steam won't progress past the water until it heats the water.

Matt has it, there is where I would bet my money. Do you hear any popping or gurgling sounds if you put your ear to this one's pipe at the beginning part of a heating cycle, especially after a decent time off?

Gsmith

Are the steam mains insulated? Having them insulated also helps with good steam distribution to the radiators.

SteamingatMohawk

What are you using for vents on the radiators (brand, size)? Rule of thumb is the closer to the boiler the smaller the vent.

BobC

To lift a radiator use about a 3ft 2x4 and a block to act as the fulcrum in the center of that radiator and slowly lift the radiator up. Lift it gently and don't force anything. You can slide shims under the radiator feet to hold one or both ends up. I find 1-1/2x 9" strips of plywood (1/2 or 3/4" thick) make good shims and you can stain them to match your floor if you want.

Bob

ethicalpaul

Lift it maybe 1/2" at a time and let it be for a few days in between liftings. In my case it helped (stopped some hammer I had, but gurgling and slow heating continued). I had to re-pipe mine because the sag was in the basement and in too tight an area to fix it, plus I wanted the riser out of the outside wall.