Adding an air vent to rad

TomM

I have a two pipe air vent system.

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One of my radiators is really slow to heat.  Its the one farthest from the boiler in the horizontal direction.  I want to add an extra vent on the main next to the radiator. 

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Does it matter if the vent is before or after the radiator.?  It would be easier to place it after the radiator in the return.  The return then runs dry horizontally and then drops to a wet return. 

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It looks like my system used to have main vents at the end of the returns right before they dropped to the wet returns.  Where the main vents used to be, they are now plugged off.  I added one there, but it was devastated by water hammer, which is why they took them off in the first place. 

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Anyway, does it matter if I put the extra vent before the radiator or after the radiator on a two pipe air vent system?  I will be using a MaidOMist D from HD. ($9.95).

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Thanks!

Unknown

Main Vents

Hi Tom-  I'm a bit confused as to the configuration of your system. You say you have a  "two pipe air vent system".so you do have two pipes connected to each radiator?  Is there an air vent connected to each radiator?   You need  to have main vents on your system and those should be a lot bigger than a Maid O' Mist D. Tell us a little more about your system and we can tell you where to place the vents. Having decent main vents saves a lot on fuel. I've attached a picture of a typical 2 pipe system. There are variations of this so let us know how yours is different.

- Rod

TomM

two pipe air vent

Rod-

Two pipe air vent is a historical oddity.  It was a two pipe system before traps were invented, and used air vents like a one pipe system.  Some had some type of orifices in the return pipe which were early precursors of traps.  Mine is simply a one pipe system with two pipes.  I think that they only made these systems for a decade or so, and then traps were invented. 

Unknown

Main vents

Hi Tom - Thanks for the diagram as that helps a lot.  You need a main vent on the end of the steam main just before it drops down into the wet return. The idea being that this clears the air out of the steam main so that steam can then get to all your radiators faster.  Depending on the size of your mains I would think at least the capacity of a couple (or more) of Maid O Mist  "D"s would work well. More is better-You basically can't over vent your mains. If you give us the size and length of the mains we can calculate the venting capacity needed  for you.



You want the main vents to clear the air from the mains and the radiator vents to clear the air just from their individual radiator. Most people are using Gortons as main vents. One  Gorton #1 has about the same capacity of the Maid "D" and one Gorton #2 has 3+ times the capacity of a Gorton #1 (Pex Supply on the internet is a good source for Gortons)

I would also consider venting your return where it was located before.  Have you ever thought of updating the system and installing traps on your radiators?

- Rod