Principal Amy

JUGHNE

Would like opinions or comments on adding main air vents on the outlet of F&T's.

One of these mains is about 200' from boiler to EOM F&T.

The dry return runs about the same distance along the floor, (inside corner of wall and floor).
It can not be seen as it is boxed in.
I have suspicion that the slope to drain may be compromised.

It is a dry return that may be a wet return in places from pipe sag.

There are 2, each one runs the length of the building and picks up all the radiation traps in addition to the EOM condensate.

If a dry return has water pockets then I assume the air is not venting, no steam pressure behind it for push.
(there is now with some traps blowing by into the transfer pump....which is why I am there.)

So how can these returns work? Is the steam entering the emitters compressing the air out until the trap closes? The air then bubbles thru standing cond water?
I am sure there are other situations in systems with the same issue.


I have done the venting in another schoolhouse with the same issue of dry returns becoming wet.
In that case the main vents were put on the steam line ahead of drip traps (this was an attic downfeed system) . This seemed to improve the operation and cond water return.
I used BJ BM's up on 4' risers and still had a little water blow out.

EBEBRATT-Ed

I guess in a perfect world these lines would be pitched back to the boiler feed or condensate tank and all the air vented out through the tanks vent. The steam has done it's work at this point it's just about the water being able to get back to the condensate or boiler feed tank. Since it's two pipe the only thing working for you is height so it can gravity drain

I would leave it as is, no banging or water hammer and the water comes back your fine. If the water backs up because the air wont let the water move then that is a different story. But your pushing toward an open vent on the tank doesn't take much pressure

JUGHNE

Thanks ED,

I am not worried about the cond water flowing back to the pump.
It is the air that may have the struggle to get there.

There are 4 2" mains with EOM F&T's. Mains are perhaps 200'--120'--120'--110' from boiler header, each 2" pipe. That seem like a lot of air to push thru F&T's and down into return that is handling about 3000 EDR already.
Also 5 drips and 5 convectors-- 1/2" traps (10) are only 6-10" above the return piping.
So gravity for them is little to push water/air.

Also there is one return under the floor that has obviously been replaced in the past.
It comes out in the pit wall and elbows up into the transfer pump. It may or not have slope to drain and have no sags.

This is a one shot repair/upgrade so air vents will be added to F&T's outlets.
Also an air vent where the (wet?) return drops under the floor.

Theoretically these vents should never see steam.
But they would be above the ceiling or in finished areas so it looks like Gorton #2's will be used.

JUGHNE

I made the trip there for a 3 day weekend.

Changed 4 EOM's F&T's, (2 were bucket traps).
Previous maint man had no idea where they were hiding for at least 20 years.
So just the time factor seemed to justify the upgrade.

Also new F&T on unit heater.

Changed out as many convector trap elements as possible...about 20.
7 remain to switch out....a few odd Trane B-1Traps and some short body Hoffman's which will not accept the B&J 3500 cage unit without the extended caps.
And all of these are directly under the convectors so impact socket will not work there. Will remove the convectors to get to them.

Most units had Ammark 72N or 76N TRV's in various states of disrepair.

Does anyone know of a source for "Ammark" parts???

The end result so far is:

No steam at the cond/transfer pump
The feeder tank is room temp
The dry returns are room temp
The boiler room is comfortable, no need to open the windows.
The pressure is max at 3 PSI now.
A 0-5 PSI gauge was added.
(Have a 0-4 HG vaporstat that might get installed)

Will return for "spring break" in the middle of march for more repairs.

Thanks to Principal Amy's family and maint man Joe's help for some heavy lifting.

Also, free lunch every day.

ethicalpaul

Wow, amazing, will you come to my wife's school in NJ? Their maintenance staff is completely without clue

retiredguy

You mentioned that some of the return lines run along the floor. Sometimes that is how it is done if the original return lines ran under the floor, began to leak but were not accessible. We had many of the very old school jobs that we piped this way. It was the best you could do under those circumstances. If it were possible, we would pipe the returns to an area under a pair of steps or in a cupboard to a small dump condensate pump and then pipe the pump discharge overhead to the condensate feed tank in the boiler room. It was not pretty but it worked. From reading your posts and answers you do a very good job and are well versed in your trade. Many thanks to you from a retired commercial/industrial steam guy for the work you do. God Bless.

JUGHNE

Thank you Retired Guy.....BTY I am supposed to be retired myself, but this was an interesting challenge and will continue as such.

The returns here do run above the floor around most of the perimeter of the building by original design. Only a small portion of maybe 30' are under the floor.
There is evidence that that piping was replaced some time ago....floor cuts...newer tile etc. That comes into the side wall of the pit the transfer pump is installed in.
The other return lying on the floor goes to the same pump.

JUGHNE

Paul, I might consider your offer, however would need first class air fare, first class hotel room, cab fare, Jersey wages and enough money for a good divorce lawyer.

EBEBRATT-Ed

Good job @JUGHNE

A lot of fuel and equipment saved from distruction and no steam out the overflow will help save the boiler.

Every BTU lost out the condensate vent has to be replaced x 2 with having to heat up cold MU water.

In the big scheme of thing a little knowledge and a few parts is all it took. Except for all your hard work, driving and figuring out what was needed which is quite a bit of effort.

JUGHNE

Thermostat and TRV's.......

As mentioned above there is no tstat for the building, only timer.

The largest room is also the coolest one. It is the dining room/social room in the garden level basement (1/2 bsmt). Probably 75% of building floor area.

I was considering putting a indoor sensor in that room with tstat in boiler room.

And then remove the TRV control modules from the 5 convectors in that room.
The supply valves were originially straight inline valves.
Consequently the TRV valves are straight thru also. The control is mounted on the top of the valve and senses the heat of the valve and pipe it is mounted on.
I guess this explains why some of the valves are cocked 45 degrees into the room.

But then to protect the TRV tstat from PE balls etc there are wooden boxes over the top of the TRV's. More warmth in the compartment.

The 6 main class rooms on the first floor have TRV's on each convector.

The stairwells and halls have some TRV's also.

Any thoughts or advice for this plan??

ratio

I've seen wire cages that were ball-proof-looking, might be a better choice than a wooden box for protection.

In case no one's said it to you, thanks for all the work your doing for them. It's too far for me to go, & honestly you're going to do a better job of it than me, but I take care of my local parish church & school, & while everyone appreciates it they don't actually have much of an idea of what I do for them. I know what you do. Thank you.

PC7060

Can you use remote sensor heads for the TRV?  Even those would need protected I guess.  

I’d replace wood box with metal open mesh like expanded stuff used for small trailer gates. 

https://www.mcnichols.com/expanded-metal

Steamhead

Tekmar 279 is the outdoor control you want. Indoor room sensors are optional. Your Steam Established (a.k.a. "condensate") sensor should go on a steam pipe at the far end of the system, just before it reaches a radiator. Your outdoor sensor goes on the north side of the building where the sun won't hit it. Use shielded cable for all sensors and ground the shield at the control end, so things like cell phone signals won't mess up the sensor currents.

Simplified description of operating cycle is:

1- Boiler starts, system begins distributing steam;
2- When steam reaches Steam Established sensor, 279 counts down as the radiators are heating up. Length of this countdown is determined by outdoor temperature;
3- At end of countdown, 279 shuts boiler off;
4- 279 keeps boiler off until time to restart it. Time to restart is determined by outdoor temperature.

Obviously, the faster the steam distributes, the sooner the countdown in step 2 can begin. F&T outlets are good places to install vents- we've done this on several jobs. We've also piped Big Mouths between the inlets and outlets of F&Ts, to get around the limitations of the F&T thermostatic elements.

The indoor sensors used with the 279 are there to prevent overheating, not to start the cycle.

Steamhead

ethicalpaul said:

Wow, amazing, will you come to my wife's school in NJ? Their maintenance staff is completely without clue

Have them call @JohnNY , @EzzyT or one of the other Steam Guys in that area- those first-class plane tickets and hotels really add up

JUGHNE

You forgot to mention the divorce lawer.....and I forgot to mention licenseing issues.
My NE license (fishing) has expired.