Main Vents; Can't find them!

Tailored_Tea

Folks, I am a landlord that is new to steam heat. I have an 8 unit apartment building that is basically two row houses next to each other. They are both heated by the same natural gas boiler, and it is a two pipe system.



The left building is consistently about 5 to 7 degrees cooler than the right, and based on my limited knowledge I think it is because I have air trapped in the system. I have recently replaced most of the steam traps on the radiators in the left building and it did not help. However, I have noticed that the heat travels very slowly up the risers. It will take 20-30 seconds for it to travel ~ 2 feet. I have looked all over in my basement and have not been able to find my main air vents. As far as I can tell the only air vents in the system are two radiators that have air vents on them. Both of which consistently hiss while the boiler is firing.



Can anybody give me some hints on how to find my main air vents, or where they used to be? I have tried to trace my dry returns back up from the boiler thinking that I should find the main air vents somewhere on the dry returns.



Thanks for any tips and help!

nicholas bonham-carter

Pictures worth a thousand words

Post some pics of the boiler and radiators, so we can see what's what.

From your description, it does seem you are right in diagnosing a venting problem. However, there, some venting must have been on the system in the beginning.--NBC

gcp13

bad traps near boiler

check the returns in the basement

if you have steam traps on each radiator the air is vented out from the system

from the retuns in the basement. look for f&t traps or

larger steam traps then main air vents on returns near the boiler

clogged traps on the return at boiler can stop all steam





photo of return trap full of mud causing no heat to front of building

JStar

Vents

I have a sneaking suspicion that this two-pipe system had an Air Eliminator and Return Trap that was ditched during modern work. In that process, the system's means of air removal was lost.



You have air vents on some radiators? Are the radiators installed as 2-pipe or 1?

Tailored_Tea

Re: Vents

Is the Air Eliminator and Return Trap you speak of the same thing as a Float and Thermostatic Trap (F&T Trap)? I believe that I have found one F&T Trap, but I have not investigated whether it is clogged yet. I should have at least on more F&T trap since I have two mains coming from the boiler.



I have approximately 35 radiators in my system all of which are installed as 2 pipe radiators. Only 2 out of the 35 have air vents installed on them.



Thanks for your help. I will post some pictures when I have an opportunity.

Tailored_Tea

Pictures!

Folks I have obtained pictures of my system. I know that I have a lot of insulating of the pipes that I need to do, however in the short term I am trying to find my main vents (or where they used to be). Any help or tips would be greatly appreciated!

Unknown

mid

That's a mid 60's Weil Mclain boiler.. which take off riser goes to the cooler part of the building??

Tailored_Tea

Cooler Part

In tracing the mains, it seems to me like the cooler parts of the building are near the ends of each main. One main goes towards the front of the building and the other goes towards the rear. They both then turn and go towards the left half of the building which is the cooler side of the building.

Steamhead

Can you take some pics

of the ends of the steam mains, as well as a few radiators?

ChicagoCooperator

2-pipe system, right?

This is a two-pipe system, right? There should be an air vent on the return somewhere, possibly a pipe which is open at the top. 

vaporvac

White-Rodgers Vstat?

Is that a White-Rodgers Vaporstat I'm spying? I have one almost identical, but older. I've never seen another. If it is, then you most definitely have a vapor system and possibly a vaporvacuum system. Most of those had one central air eliminating point, as mentioned above. As Steamhead requested a few pics of the rads would help clarify.

Tailored_Tea

Pictures of Radiators and Mains

The name plate on the pressuretrol says: White Rodgers Electric Co. St. Louis Mo. Type 1204 Pressure Control No. 5.



Radiator pictures include one of the radiators that has an air vent on it (Dan says this is a no no on two pipe systems however it heats well).



Pictures of the mains start from where one main leaves the boiler room headed towards the front of the building and it enters my basement tenants apartment. Then the main turns to the right and enters the left building (when facing from the street) which is cooler. It then makes another right and heads back towards the boiler room. While tracing this main I found the nasty rusted F&T condensate trap (I think this is what it is) above a drop ceiling and some paneling. After the condensate trap the main takes another right and heads into the boiler room, I still don't see any main vents.



Thanks for everyone's help. I am guessing I need to replace the F&T Trap, however, I am still puzzled by the lack of air vents.

Steamhead

That trap may be part of the problem

but is there anything at all between the trap and the boiler room?



And what's on the other main?

vaporvac

Vaporstat...

hi,

My old WR Vstat is model #1202-4 style B2, 2-16oz, opens on rise. Check out your psi limits.. If it's low pressure like mine you have a vapor system as I don't think they always put them on back then, unless one needed them.

Tailored_Tea

Not a vapor system, and Main Vent Relic?

Folks,

I investigated my pressure limits on the pressurtrol. It is a White Rodgers Open on Rise with limits of 3/4 to 5 PSI. It is currently set at 2 1/2 PSI with 2 PSI differential, if I understand the settings correctly. I think this means that I don't have a vapor system but a more traditional two pipe system? Also, I think I finally found one location where a main vent used to be. How do I know what size to buy? Anything else I need to know if trying to put a vent back on here?