Enough main venting?

pcloadletter

I replaced the main vents on both of my mains last week with one Gorton #1 each. I did some rough calculations and I figure that the longer of the two mains may need an additional vent. Both mains have three radiators each.



Main 1

13' x 2"

8' x 1-3/4"



Main 2

15' x 2"

10' x 1-3/4"



Thoughts?

BobC

SB ok

The 15 ft main contains about 0.33 cu ft of air, the follow on pipe has 0.12 cu ft and the Gorton #1 is rated for 0.33 CFM so that main should be able to vent in a minute and change. If you had a low pressure gauge and could see what the pressure was while that main was venting you would like it to be 2 oz or less.



How long does it take the steam to get from the boiler to the main vent now? Are the pipes insulated? I wouldn't be concerned with adding more venting at this point unless you are getting more than a couple of oz of back pressure.



Bob

pcloadletter

Enough main venting?

The main vents are at the end of each main before it drops down to the Hartford loop. When I figure out the numbers, do I only need to worry about the piping from header to the last radiator tee, or do i need to include the return piping from the last radiator tee to the main vent located by the Hartford loop?



The pipes are insulated and it doesn't take very long for the steam to reach the main vent (I haven't timed it). I have a low-pressure gauge and it only rises from 1-2 oz. up to 1.5 lbs. at the end of a cycle when the radiator vents close and the thermostat or the pressuretrol is about to shut it off.



The radiator vents whistle after the boiler shuts off and the system pulls a vacuum. Shouldn't the Gorton's open up after the cycle to vent air back into the mains?

BobC

Only to the last radiator takeoff on the main.

You want to get the air out of the mains fast so the radiator takeoffs can start filling with steam, any piping beyond the last radiator takeoff really doesn't count as far as mains venting is concerned. The Gortons will open when they cool down a bit, what kinds of vents are you using on the radiators?



Bob

pcloadletter

Enough main venting?

New Hoffman 1A's on all six radiators.