vents?

JuliaV

Hello all.  A month or so ago I had a thread similar to many I see here... new boiler installed, all kinds of problems ... posted photos, got tons of great advice.

Since then, we had our boiler re-piped. Majority of noise stopped. Insulated most of the exposed pipes (need to dedicate a few more hours to finish it blech), and changed out all air vents on radiators.

Do I need both air vents on the radiators and main vents?

Jamie Hall

I don't recall..

Julia, I don't recall whether your system was a one pipe or two pipe system; I'm presuming one pipe since you have vents on the radiators.  It doesn't really matter, though -- yes, you should have main vents.  In a one pipe system they function to get more even distribution of steam, as they let most of the air out of the system so the radiator vents only have to cope with the individual radiators and not the whole system of mains!  Much easier to control, much more even distribution of heat.



Glad to hear, though, that most of the other issues have gotten resolved.

JuliaV

one pipe

Yep, one pipe. Well, weirdly enough, one radiator is a 2 pipe.

I asked our installer quite a few times about installing main vents... he kept telling me no, and that they weren't necessary. From what i understand, operationally, no. But for efficiency and quick heating, yes.

We have one radiator that is real sluggish. Of course its in my bedroom. Main vents would help.

I don't want to think of the bill to install since we don't have any existing at this time.

Rod

You need Main Vents

Hi Julia- You really need main vents. Since you apparently didn't have main vents on your system in the past, maybe this is why the installer thinks they aren't needed now. Most of these systems were originally coal fired and back then it took a long time for a coal fire to build and heat the water in the boiler which slowly made steam.  As the steam pressure built very slowly, the air exited very slowly, therefore the radiator vents were capable of handling both the air in the radiator and in the piping and main vents weren't really necessary. With the switch to an oil or gas burner, things changed. When the burner was turned on, full heat was applied to the boiler almost immediately and steam was produced very quickly which necessitated a quick exit of the air from the piping so that steam could enter the radiators and push out the air through the radiator vents. Main Vents should have been added when the switch over from coal was done.

On a counterflow  system the main vents should be installed on each main at  the far end away from the boiler. Ideally they are located anywhere after where the last radiator is connected to the main. It's preferred not to mount they right on the end of the main as water rushing up the main pushed by steam might slam into them.  It shouldn't be that expensive to install main vents as they can be tapped right into the main steam pipe.  Pex Supply on the internet has Gorton main vents.  Post pictures of the ends of your mains and maybe we can suggest something. Also post some  pictures of your re piped boiler. I'm happy to hear that has worked out for you.

- Rod

JuliaV

thanks

Hi Rod.  I will take some pics when I get home for sure.  haha I hope its right!

I understand your thinking and respect your knowledge. Think I'll have someone come out to quote us to install some.  Sounds like he just didn't want to do it. I'm sure once we install the upstairs radiator (and furthest from the boiler) will finally heat up consistently!!!

Charlie from wmass

Julia Main vents will help

The counterflow system you have often did not have provisions for them. Your system may benifit from having the vents tapped into the end of the mains as close to the end as one can get. They could also be added at the last radiator by replacing the radiator valve and installing a tee and a straight radiator valve. While not ideal it will make it easier for the steam to reach the end of the main. A third option is to replace the last elbow on the main with a tee and Install another tee after that one for the main vent.