Venting Main...At the Radiator Inlet

AdmiralYoda

I have two mains. One is 2" and about 45' in length. I have a Barnes and Jones Big Mouth on it at the end.

The other main is a bit different. It has about 20' of 2" pipe, the it splits. One 1.5" pipe is 20' long and goes to a 1st story radiator (60EDR) and a 1.25" pipe that is about 15' long and goes to an upstairs radiator (20EDR). There is no vent on this main and no convenient place to add one.

I was thinking of replacing replacing each Right Angle radiator valve with an Ell with a 3/4" tapping and using an inline radiator valve to the radiator.

Then I'd install a main vent at the 3/4" tapping before the radiator valve on each radiator so the steam would get to them at roughly the same time.

Is this overkill? Or just install a main vent at the end of the 20ft of 2" main and let the radiator vents vent the 20' of 1.5" pipe and 15' of 1.25" pipe?

Thanks!

ethicalpaul

It might be a little over-kill but probably the only way to know for sure is to see how each room heats. Maybe you will actually have a better temperature match with a longer delay to heat for those ones.

Are they in service now? How is the comfort in those rooms?

But yes you can definitely put a vent just before a radiator to vent that supply faster. It's even described in The Lost Art

AdmiralYoda

Thanks Paul... the comfort is fine but they tend to take a little longer to get heat. They are part of a small addition off the side of our house. The first floor is in service and the second floor is going to be added on soon.

If they weren't so expensive I'd probably just put a Big Mouth before every radiator and never have to worry about the mains ever again.

ethicalpaul

Well that would get you a lot of humidity in your living space at least

JUGHNE

A 1/4" IPS will handle a Gorton #2

You could drill and tap even that 1 1/4", maybe just use a Gorton #1 on each.

AdmiralYoda

I think I've seen this... but is there a chart or something for how much vent you need for diameter vs length for main piping?

More is usually better but I've always been curious as to when a #1 would be okay vs a #2 or if multiple #2's are needed.

Waher

AdmiralYoda said:

I was thinking of replacing replacing each Right Angle radiator valve with an Ell with a 3/4" tapping and using an inline radiator valve to the radiator.

AdmiralYoda

@Waher thanks!  Pretty much I'll be doing.  Most likely a Gorton #2 or B&J Big Mouth right into the reducing Tee.

Steamhead

Waher said:

I was thinking of replacing replacing each Right Angle radiator valve with an Ell with a 3/4" tapping and using an inline radiator valve to the radiator.

That's one way to do it. But I'd drill and tap the 20' main in the basement near the tee, and install a Gorton #D. This would be a lot easier since you'd only need a 1/8" NPT hole.

ethicalpaul

IMO a #2 or big mouth would be wildly more vent and $ than would be useful there. I’m with Steamhead’s idea