Can you vent entire system via condensate pump?

mjk

I have a gas fired 2 pipe steam system. There are no vents on the main. The end of the main comes back and enters an F&T trap, the condensate lines join after F&T. All go to condensate pump. Should I have a vent on the main? System works pretty well. All mains are insulated. I get a bit of water hammer at start up but suspect secondary to a supply running through cold crawl space and no insulation. The largest and last radiator on the run is of course upstairs in a cold room over screened porch. It usually only gets partially warm unless long boiler run (below 0 day). Would adding a vent before F&T trap improve heating? Or do I need to add a vent after last riser on main? Pics below:

JUGHNE

So is the end of steam main drip on the right and goes thru the F&T? Then are the 2 pipes on the left, dry returns that go into the cond pump? And you have standard traps on each rad?

How far from F&T is last steam take off?

mjk

Yes, the end of the main is pipe on the right. The other 2 on left are dry returns. All lead to the condensate pump and only vent is the condensate pump vent.
The last take off is approximately 30 feet from F&T. There are standard traps on all radiators. All traps replaced 2 years ago.

JUGHNE

I am involved in a job right now where I would be adding venting before the F&T. In your case you could remove the top plug from the H design F&T and add venting there. The air venting passage in the F&T is pretty limited IMO. This would vent your steam main faster......you could just get the plug out and pipe up with a ball valve installed.......time the venting with the valve closed and then with the valve open to see what you might gain. Be prepared for the steam to arrive at the ball valve......I'm sure you know how hot this can get.

My case is unusual in that I have 2 dry returns with a check valve draining into the discharge of the cond pump which has other dry returns going directly into the pump. I don't know how any air gets out of my system.

mjk

The situation you are describing sounds quite odd. How can the returns with check valves drain when pump not running?

I have a single main supplying 13 radiators on 3 floors counting the basement. Has anyone seen a setup where the condensate vent is the only vent? Seems like it wouldn't be enough. I'd welcome any experts. Would love if anyone knows a good steam man in Indianapolis!

JUGHNE

My odd situation is that the returns have to open their swing check valve by gravity flow. When the pump runs that check valve is slammed shut and will supposedly open again by gravity flow when the pump shuts off. It was stuck partly open and creating problems with flooded mains & returns. This is a digression from your problem.

But your system set up is a very common method of air venting. However I believe that additional venting of the main would help. Again put in a test port and measure the difference, then consider how much money you want to spend on venting.

Steamhead

MJK, I would question whether that condensate pump is even necessary. The returning pipes do look low, but without seeing what's on the other side of that wall it's hard to tell for sure.

If it turns out you don't need the pump, yes, you'll need some air vents. If you do, you'll probably still need some vents.

If you can lose the pump and its associated traps, you'd get rid of a lot of moving parts. A Steam Man could tell you for sure. Where are you located?

mjk

Thank you all for your advice/input. I remain a novice. I'm afraid I can't get rid of the pump. My main end was re-routed under stairs in order to finish basement. Therefore the height is low as enters boiler room. The static pressure of the water will not be enough to overcome dimension B. That said where do you think is the best spot for a main vents? BTW I'm in Indianapolis. Thx!

JUGHNE

If by chance you have a capped tee near the last steam take off, that would be good. However the top plug of the trap itself is open to the steam main. This would vent the air at a closer point than the cond pump and allow you larger/faster air venting than the F&T thermostatic orifice offers going thru the cond pump vent pipe.

If you click on my name and read my last discussion, several steam people commented on this very subject. (just disregard the oddity of my system/project)

nicholas bonham-carter

The wet return can dip very low without any problems. Gravity return is always preferable to pumped return.
If you had a separate building fed with steam, and a wet return coming back from a distance, then you might need a pump. If you can ditch the pump, then do so, before it fails on a freezing cold Friday night.--NBC

mjk

Thanks Jughne. Read your discussion. I'll try venting off of F&T trap. Unfortunately can't vent near last supply as when basement was finished main was enclosed in bulk head.
NBC you are correct. I could get rid of pump. My lowest trap is on 8' ceiling in basement and I run .5 lb pressure. I may look into cost of re-piping in springtime.