double-venting a radiator

michael_15

I have second-floor radiators. All of the main vents are in the basement, which means there's a whole lot of pipe (vertical and horizontal) after the supply main and before the radiators.

Would it be recommended to have someone put a tapping and a nice big air vent on the supply side of the radiator to act as a "riser vent" to fill these pipes with steam quickly? Since the horizontal components of the riser are counterflow pipes, I don't know if I should restrain myself on the speed of air venting which I allow.

Thanks,

-Michael

Steamhead

On second-floor radiators

I usually just install a slightly larger vent on the radiator.

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David Efflandt

I have that problem

My end radiators on 2nd floor seem to have marginally sized risers (1.25 & 1.5"). Faster venting at normal location (far end of radiator) causes rapid condensation when steam hits a cold radiator, sloshing, gurgling, and eventually plugged vent. Slower venting allows sections to heat gradually with less condensate fighting the steam, and vents last for years without plugging. But in mild weather when the system runs for short periods of time, hours apart, those radiators do not fully heat.

I have seen pictures of staggered vents. But I think in my case, adding a vent on inlet side might allow steam to get to radiator faster and heat riser faster, but still allow radiator to fill at a controlled rate, without the slug of condensate from rapidly steaming a cold radiator.

You do not want to put a vent where is is going to get hit by a lot of condensate.

Steamhead

Are your main vents

properly sized? If not, the steam won't reach the risers quickly enough to get steam to those radiators before the boiler shuts off.

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Boiler Guy

Steamhead

I have a similar problem. My mains are well vented but due to numerous rads having been removed over the years, and the riser serving the third floor only having 2 working rads(1st flr seldom used), the top floor rad is very slow to heat. I was thinking of installing staggered vents on the top floor rad. What are your thoughts?

steve_6

gorton \"D's\"

On radiators furthest from the boilerthat are slow venters, and bad piping isn't the issue we hace had great success with the Gorton D. it vents as much and more than most main vents do.

Steamhead

This would be a good place

for a dedicated riser vent. You can drill and tap a 1/8" hole in the riser below the second floor ceiling if it's accessible, or replace the third floor angle rad valve with a tee and a straight gate valve and put the vent in the top of the tee, as shown on page 118 of Lost Art.

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Boiler Guy

Thanks guys

Actually these are all of the three things I was mulling over. I believe the riser is accessible. However, this might be a tough sell as most owners do not want additional vents in their living space due to historical problems with spitting vents. THAT is a whole other story which I have corrected by 98% already. I think I might try the Gorton first though. Thanks again