Main Venting

joe7

I’m  totally new to (steam) heating systems.  I have a 4 family house   - 2 floors and an unfinished basement.   I noticed that there are no vents on the main in basement.

 

The back main is aprox 25’ long.  the front one  is 50’.  Is this normal?

The main is 8”

Hap_Hazzard

8" mains?

In a residential system? That would be unusual. Are your mains really 8" (about 8 5/8" in diameter)? Or did you measure the circumference and find that to be about 8"? (That would make them 2" pipe.)

BobC

main vents

Your steam mains are probably 2.5" pipe if the circumference is 8" and they should have vents on them. Post pictures of the boiler, the piping around the boiler and the area around the ends of the steam mains.



Bob

Hap_Hazzard

I think it's 2" pipe.

The OD of 2" pipe is 2.375". 2.375" x π = 7.46". The circumference of 2 1/2" pipe is 9". Neither one is exactly 8", but I think it's easier to be over by a half inch than under by an inch. The thickness of the measuring tape and any paint or rust on the pipe would increase the measurement.

nicholas bonham-carter

No main vents!

Can you see any place where the vents would have been? I am supposing you have a parallel flow system where the mains start high, and after serving the risers return close to the boiler,at a slightly lower level., as a dry return, then dropping down to the floor, on it's way to the boiler as the wet return. Main vents are needed if you are interested in fuel economy, and comfort.--NBC

joe7

Clarification of original post

Thank you for all the replies.



1) The actual size of the main is: 2”

Sorry for the confusion



The size of the pipes that branch off the main an go up to the radiators vary between 1” and 1 ¼”



2) I have attached pictures of the ends of the main and the piping on the boiler



3) Yes, I’m ‘ interested in fuel economy, and comfort’.



4) I cannot find a spot where a vent has been in the past.



Your help is very much appreciated.

nicholas bonham-carter

Main vent location

In picture no. 1, the end riser may have been added later, using the vent tapping. The main vent could be mounted on an antler on the drop to the floor. This could be drilled and tapped for a 1/2 in nipple as part df the antler for both ends.--NBC

Hap_Hazzard

Nicholas is right.

It's not unusual to see extra radiators added on to where main vents should be, in the mistaken belief that venting through the radiators is good enough. He is also right about the likely location. They're usually at the ends of the mains, directly above the return drips.

nicholas bonham-carter

Pipe insulation

I forgot to mention that you also need fiberglass insulation on the supplies for added efficiency.--NBC

joe7

are these vents essential – very beneficial?

Is this system – as is - fine? or is it highly recommended to add vents to the main?  What noticeable/essential benefit will I see from adding them?  How much ‘energy efficiency’ will the vents add?

 

Thank you!

BobC

If your happy now leave it as is.

main vents will allow the steam to fill the mains with steam faster and that will shorten the time the boiler fires. How much it saves is not easy to tell without a close inspection and the payback could be a few years or more. The same goes for pipe insulation, it saves fuel but will take a few years to see payback.



If your happy with the way the system works now and you don't mind the fuel bills leave it the way it is now.



Bob

nicholas bonham-carter

Venting difference

Try this test:

When system is hot, turn off the boiler, and turn up the thermostat.

Remove the vent on the radiator on the last riser.

Turn on the boiler and time the arrival of steam out of the open hole. Turn the boiler off as soon as you see the steam.

Replace the vent and turn on the boiler, and once again time the arrival of steam.

The difference in runtime is a factor in paying the fuel company to forcibly remove the air in your system, instead of letting the air out with no resistance.

My guess is an extra 10%.--NBC

joe7

Even distribution

1)      The radiators near the boiler – on the 1st floor of the shorter 25’ main heat much faster and warmer than the ones on the longer 50’



2)      Some of the radiators don’t get fully warm, only the first sections heat up.

 

A side question:  does distributing heat evenly affect the cost of fuel?

 

If I choose to put vents on the main, what size vents should I use? Also what company is best? 

Also, where should the vents be installed?  On top of the main or on the drop/return.  (there isn’t too much space between the main and ceiling.    Thank you!

BobC

about a foot down

If ceiling height is a concern I would drill and tap a hole on the vertical drop at the end of the return, maybe a foot down. Put in a short nipple (3-4") and then a 90 with another nipple and a vent. You want the horizontal nipple to have a little slope towards the return so water can drain. The other option is to weld a thread o let onto the pipe but that would take a pro.



Your main lengths indicate you would start with a Gorton #2 on the long main and one or two Gorton #1's on the the short main. You might have to add more vents to insure complete venting in a short time.



Venting the mains should save fuel and balancing things out is more a matter of comfort.



Bob

Jamie Hall

In sort of direct answer...

1) The radiators near the boiler – on the 1st floor of the shorter 25’ main heat much faster and warmer than the ones on the longer 50’

This difference probably is due almost completely to the absence of main vents -- adding them will reduce the difference in time significantly, if not to nothing.



2) Some of the radiators don’t get fully warm, only the first sections heat up.



This may be normal, although it would be more normal if they all didn't get fully warm on any given heating cycle.  Once you have main vents installed, you can "tune" the various radiators to what is needed by adjusting their vents, if this is a one pipe system, or their valves, if it is a two pipe system.  Get it so the rooms heat up the way you want them to.



A side question: does distributing heat evenly affect the cost of fuel?



Probably -- particularly if you have some rooms warmer than they need to be just so other rooms are comfortable.



If I choose to put vents on the main, what size vents should I use? Also what company is best?



Gorton.  Probably No. 2 on the short main, and two no. 2 on the long main should do the job just dandy.



Also, where should the vents be installed? On top of the main or on the drop/return. (there isn’t too much space between the main and ceiling. Thank you!



You do have a bit of a height problem.  The best place, though, is on top of the main, six inches to a foot from the end.  I hesitate to suggest putting them on the side of the drop, although it might work.  Even if you may have to open a bit of a hole in the ceiling of the basement, that's preferable.



And furthermore.  If you are really interested in saving money and getting better heating at the same time, get some insulation on all the steam carrying pipes you can find, from the boiler right on out.  An inch of insulation is best, but a half inch will do if that's all you can squeeze in. 



Also, check your operating pressure -- the boiler should cut out at not more than 2 psi for most one pipe steam systems, and cut back in at about half a psi or so.