Vent on dry return

acl10

Isthere any benefit in putting a vent on the dry return near where it comes down to join the wet return. Will it speed up the system. Will it waste steam because the return will fill with steam as the air vents? Will it affect the water level in the boiler?

Rod

Vent on the Dry Return

Hi- I'm not quite sure what location you are proposing. Any vent in this area on the dry return needs to stay high up as depending on the steam pressure, water backs up from the wet return quite a way. If there is one on the end of the main there is no need for one of the dry return unless of course this is a two pipe system.  If it is a parallel steam system and there is no vent on the end of the main then you would need one of the dry return.

- Rod

nicholas bonham-carter

where to put the vent

do i understand from your question that you have no main vent now?

a main vent is essential to proper operation, as it will allow the air in the pipes, and boiler steam chest to escape as the boiler is steaming. with no main vent, you are wasting fuel, pushing the air out the radiator vents, which are ill-equipped to handle the task.

if you have no main vent, then you must put one on now.--nbc

Jamie Hall

The only systems

where a vent is needed -- and perhaps required -- on the dry return at or very near the boiler are certain vapour systems (actually, the majority of vapour systems) and a very few two pipe systems which have some type of crossover trap at the ends of the steam mains which goes into the dry return at that location -- which parallels the steam main back to the boiler.  Those systems were meant to be vented that way; the crossover trap takes care of venting the steam main into the dry return, without allowing any steam to get into the dry return, and the main vent(s) on the dry return vented the whole system.



Otherwise, a vent on the dry return really isn't needed.  You need to figure out how the system was originally intended to operate...

acl10

Vent

My long main is now vented with two Gorton ds same as 1s. The short one is not vented because of space situatuions there fore I want to vent the dry return. Will this affect my system in anyway?

acl10

Will it help

What I would like to know is if venting the dry return on the pipe that gooes dow diagonaly into the wet return will aid in bringing back mor condensate into the boiler or hurt it because of steam pressure. Also will venting it take away steam from rising into the upstairs? thanks 

Mark N

Try It

Give it a try and see what happens. I would think it should speed things up. If it doesn't work put a plug in it and try something different. I have a friend with a similar set up. His short counterflow main was unvented. No place to put a proper main vent. He just put a large vent on the last rad on that main.

acl10

Hoffman

Will a vent on the dry return push the condensate into my boiler faster?

Can I use a Hoffman 40 for that vent?

Mark N

What?

Vents don't push they vent air. When the steam reaches them they close and they stop venting air. The weight of the water that stacks up in the return plus any remaining steam pressure forces the condensate back into the boiler.

acl10

Put it on

I put the Hoffman 40 on and its working great. Takes out the little air and the shuts when the return fills with water

acl10

Picture

The picture is of the new vent near the ceiling being blocked by a copper water pipe.

Dave in QCA

Do you really have a dry return?

A dry return is a line, on a 2 pipe system, that never has steam in it, (unless a trap has failed in the open position) and never is filled with water.  Both condensate and air flows through the dry return.  The pipes are pitched so that the condensate flows back toward the boiler or the condensate reciever.  If the dry return is connected to a condensate receiver, the receiver will have an open vent and do all of the venting for the dry return.  If the dry return connects back to the wet returns at the boiler, there must be some kind of a device to let the air out.  These may vary depending on the design of the system.  Dunham used the air eliminator, other systems had special air eliminating devices.  Others, simply used a main vent.  The idea here is that is a system trap failed and steam got into the dry return, the vent would close and prevent steam from blowing around the boiler room.  Also, most main vents have a float device in them as well, which would close if boiler pressure got high enough to cause the condensate to back up.



Many one -pipe systems have a steam main that circles back to the boiler.  It is usually ventend somewhere near the boiler where a drip leg drops to below the water line, where it becomse a wet return.  In this type of a setup, neither the end of the steam main nor the drip leg are considered to be a dry return.

A dry return is at atmospheric pressure, and thus must be vented by some means.

acl10

One pipe

I have one pipe. The reason I called it a dry return is because it is above the water level in the boiler. The other side long main has a wet return on the floor and they join up at the boiler. It seems that since I put in that vent on the dry return near the to of the pipe I dont have water hammer because the water is able to move in the pipe back to the boiler without being obstructed by air.