main vent on return piping

alanm

i have oil steam heat...on the return pipe, there is a vent....what is this for? i thought the main vent(s) should be on the piping going to the radiators...not on the return. see photo...it is the green vent. how can i test/check to see if this is working? thanks Alan

KC_Jones

As long as the vent is at or after the last radiator the location is fine.  The only potential drawback is the return pipe now will slightly heat the basement.  I actually did this on purpose on my system because my basement is a workshop.

I’d also add that unless your main is extremely short, that’s most likely not enough venting.

To check it see if it vents air when the boiler fires, preferably after it’s been off for 10 or more minutes so the vent is definitely cool/cold.  It should vent air until steam arrives, then stop when it gets steam hot.

alanm

thanks...so this #75 hoffman vent which is at the end of the last radiator.....i have pipes out of the boiler, so this #75 is on return of the pipes that most of all the radiators. the other pipe coming out only goes to 3 radiators (not getting any heat on the 3rd or 2nd floor) from that line/pipe-- s

KC_Jones

If you have a main with radiators not heating and it’s also lacking main venting, then I’d suggest that is a place to start for that main, add the venting it needs.

SteamingatMohawk

What does the copper pipe serve?

alanm

two are coming out of boiler....one runs to all radiators on 1st, 2nd and 3rd floor- the other run just goes to one radiator on 1st, one on 2nd and one on 3rd....this is the run taht those 3 radiators dont seem to get hot...unless heat is set low and then i increase by about 3 degrees or more, then it seems to reach those radiators...

Jamie Hall

Well now, the question really is -- is this a one pipe system? In which case, technically that isn't a dry return but an extension of the steam main, and has been said so long as the main vent is after the last runout it makes very little difference where it is. On the other hand, if this is a two pipe system, that may be a dry return, correctly termed, and it absolutely HAS to have a vent on it, as otherwise the radiators have no vents at all. Some two pipe systems have main vents; some don't but use crossover traps instead.

So it really matters what that pipe really is.

alanm

thanks...it is a one pipe system.......so that main vent at the end of "the one extension" is fine....so my issues: with that one extension that only heats 3 radiators, why is that not getting hot unless the temperature is set high? the other extension services about 15 radiators and they all work nicely. how do i get those radiators on that "one run" work ? you would think, the piping is right off the boiler and has a shorter run than the other main extension. thanks alan

Jamie Hall

OK, two more questions (sorry!). Is there a main vent on that short run? And is it pitched adequately?

alanm

thanks...so, that "other main vent"...comes off the boiler , then shoots over to a radiator on the first floor and at the split, it then goes to the 2nd and 3rd floor. No main vent anywhere..what you see in that photo is it...is comes off boiler and thats all.

Jamie Hall

You may be able to get things a little happier if you vent the radiators on that problem line very agressively. Try a Gorton D on the last radiator in line.

alanm

thanks...will try.

alanm

thanks......question (see photos)..if the Gorton D does not work.. should i drill into radiator and add another Gorton so there are two vents in the radiator? or where pipe is coming out of the wall into radiator, do i add a main vent there?

Jamie Hall

The better place would be on the wall before it gets to the radiator. That way you could put a lot of venting there to speed things along and still not lose control over the radiator.

ethicalpaul

The Gorton D almost certainly works. Before you go drilling, start a call for heat with the Gorton D removed completely and see if steam ever appears out that hole. See if air even ever escapes out that hole. That will tell you if there is a pool of water blocking your steam.

Keep in mind a Gorton D is the same amount as venting as a Gorton #1 which is a huge amount of venting (compared to what a radiator should need)

alanm

thanks...yes, i have tried removing the vent i have on the radiator now alltogether...and steam comes out fast/hot!

ethicalpaul

Interesting. Can you blow gently through the vent (while it's off)?

alanm

yes.....just seems that even though just 3 radiators on this "run"...it takes longer to get hot compared to all the radiators on the other "main run"....now this morning....therm set at 67..moved it to 69...and those radiators on that "small run" just started to get warm, while other radiators were fully warm.

mattmia2

alanm said:

yes.....just seems that even though just 3 radiators on this "run"...it takes longer to get hot compared to all the radiators on the other "main run"....now this morning....therm set at 67..moved it to 69...and those radiators on that "small run" just started to get warm, while other radiators were fully warm.

That is because all of the air from the main is trying to get out the vent on those radiators. You dont have a fast vent on them now, right?

dabrakeman

Per @KCJones recommendation can you take a picture of the shorter main in your basement so can see if there is a good place to locate a main vent down there in the basement? If not then using the inlet of the first floor radiator would be the next best place.

alanm

will try and answer the questions...right now..i have hoffman adjustable vents on those 3 radiators- opened to fast.... see photo. you will see two pipes coming from boiler..the one on the left feeds all but 3 of the radiators /and they work well (from 1st floor to 3rd floor) and then the pipe on the right...you will see as it goes up, it splits to feed a radiator (it is the one insulated) on the 1st floor and then continues around and up thru the wall to feed a 2nd and then 3rd floor radiator. that pipe you see under neath that, is the return from the "piping" going to all of the other radiators.

neilc

so there's no vent on the "right" hand main?,
how does the right hand main return to the boiler?
can you show the end of that main

alanm

there is no return....that run leaves the boiler...splits off off to the 1st floor, and then where it splits it goes up to 2nd and 3rd-- ends there.

neilc

so is that a counterflow main? pitching up away from the boiler ?
and that coupler with the short nipple to the left, should be a down facing tee, with a drip return to the boiler,
and you need a main vent there somewhere, like up top, 3rd floor, between wall and rad,

alanm

not sure what you are saying..i am not a steam heat/radiator guy! so that first "turn" of piping from the boiler that is going to the 1st floor....should have some return there? and up at the 3rd floor...before the radiator...i should put in a main vent?

neilc

from the header, I see copper, to a 90, to a short nipple, to a coupler, to a nipple, to a tee to a first rad(insulated),
I'm guessing that main pitches up, to its far end, making it a counterflow main,
you said there's no return, correct?
so all condensate is coming back to the header, and you don't want that,
if I'm correct about pitch, that 1st coupler between the 90, and the rad lateral, would be a down facing tee, that drains the main without draining to the header, it drains back to the boiler return,
that's the condensate,
now about the air,
yeah, you need a vent at the far end of that main to clear its air, then the rads vent themselves only,
Vent your mains fast, vent your rads slow,

oh, and you're a steam heat/radiator guy now,
xmas is coming,
https://heatinghelp.com/store/

https://heatinghelp.com/store/detail/we-got-steam-heat-a-homeowners-guide-to-peaceful-coexistence
is a great primer,

dabrakeman

I think it is critical to know what the pitch of that short main is or was supposed to be. The tie straps suggest it may have been mucked with. If it is parallel flow (meaning the condensate drains in the same direction as the steam travel) then the far end of the main should be lower than the near boiler end and a condensate return needs to come off the end of the main, loop back above the water line of the boiler and then drop down and tie into the other mains condensate return below the boiler water line. Without the condensate return at the end you would be collecting water at the end of the main and possibly limiting steam flow particularly to the 2nd and 3rd floor. If it is meant to be counterflow meaning the condensate runs back against the flow direction of the steam then the far end of the main would be higher than the boiler end of the main and a condensate return pipe should be put in as @nelic describes at teh first coupler. Can you take some of the insulation off the far end of the main and get an "as is" measurement of pitch? Take a picture of the far end of the main.

If it is set up as counterflow you may be able to temporarily get away helping the issue by just adding more main venting either at the end of the main or at the third floor radiator. Still want to add the condensate return later. If it is setup with parallel flow pitch then it really needs a main extension return since there would be nowhere to go for some amount of the condensate depending upon the degree of pitch. Condensate could be partially blocking the takeoffs to the radiators.

alanm

thanks for those recent comments...going thru them both! oh, dont worry...i have like 2 of dan's books.....but i am getting to know more than i wanted regarding steam heat! so one of the take aways..putting a gorton D vent on the 3rd floor radiator may not do the job...may need a main vent right before it gets to the radiator on the 3rd floor (see photo)-- i guess i will need someone to do that...i dont want to break any pipe going between plaster walls/between floors. do they drill into the pipe or cut a section out (not much room there) and put in a T with a main vent?

dabrakeman

Looking back up through your posts I see you did test with success with the radiator vent removed so you certainly have some confidence that you can remedy at least your immediate heating needs by just adding more venting, probably not a water blockage in the short main. If you show pictures of the end of your main along with the radiator photo you already provided I am sure the real pros here can suggest which location is better for you and provide you some instruction if you want to DIY or have someone do it for you.

alanm

ok...here are 3 more pictures/different views. anyway, the one main that comes off the header.. as you said......"see copper, to a 90, to a short nipple, to a coupler, to a nipple, to a tee to a first rad(insulated),."...that one off does pitch up to the 1st floor radiator (photo 4153). then, the piping (above the return of the other main )- photo 4154 ( is pitched up to around the "bend" and then up into the wall (photo 4155). So as you said, seems like when there is condensate, it flows back to the header.

neilc

try the Gorton D first, it's easy enough , , , right?

then after that,
do you have room to move that rad to the right about 6 inches?

a tee would go where the valve is now, with a vent to the left,
and to the right, a new straight valve would add about 6" to the rad,
or,
do away with the valve, and just a union to rad would save about 3 inch,
or,
add a second, faster rad vent to the rad, on the supply valve side

or,
maybe a vent in the basement at far end of that main

alanm

thanks....! i understand about the radiator and moving to the right.....regarding the "main" on that run in the basement...where would it go? right after the 90 degree and before it shoots off to the 1st floor radiator?

neilc

alanm said:

.....regarding the "main" on that run in the basement...where would it go? right after the 90 degree and before it shoots off to the 1st floor radiator?

no, it needs to go to the far end of that main, all the way to the right,
show us that far end of that main,
are there 2 separate take offs for the 2nd and 3rd floor,
or does the 2nd floor extend up to the 3rd?

neilc

I missed your last 3 pictures,
looks like 2 and 3 are on that last lateral,
try the Gorton on the 3rd floor rad

alanm

thanks...yes....the radiators on the 2nd and 3rd floor are on that lateral that then goes up into the wall...so what you see....the copper off the header...split off to first floor and then up thru the wall...that is all that you see and on that pipe....so not sure if i put in a main vent there...where? i will first try that gorton D on the 3rd floor radiator

dabrakeman

If want to do the main vent in the basement you would need to take the insulation off the circled end of that main and see what is there and whether there is any logical location to put a vent in.