F&T oddity
Hey folks. I'm currently rebuilding all traps in a 1900s commercial building, none of which have been touched in 50 years or more. Boiler is new, all pumped returns. I've done 6 of 8 F&Ts with no issues. All have been pretty clean. This 3/4" Sarco FT-30 however has been plumbed in an interesting way.
It seems like this was done just to avoid that piece of 2x4. The wacky thing is that the return is almost directly below the trap with no obstructions. Naturally the trap was full of water and at least an inch and a half of mud.
Can anyone theorize a legitimate reason for this?
Comments
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Tough to see the return line. You can lift condensate with a trap as long as you have enough steam pressure to overcome the rise in the return. Thats why they used a check valve to avoid backwards flow.
Seems like a lot of mud in the trap but if it has been 50 years I guess that is normal.
With the two unions you could easily remove the trap to flush and clean it.
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I was thinking the supply and return differential could lift the condensate but that is just a little beyond my understanding.
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Collum of water 28" tall is 1 psi. So, if you had to lift the condensate 1 foot you would need the steam pressure to be .42psi" higher than the return pressure (if any).
In reality you need a little more to open the check valve and overcome any trap resistance which is minor.
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Ed, the return rises over that 2x4 and immediately drops 8 feet to the floor where it works its way to a return tank beneath a cover in the floor. After the check valve there's a nipple and a 90 straight down. I can't imagine what was going to flow backwards up 8' of pipe. I get that adequate pressure will push condensate up and over but if they'd come out of the trap 2 45s and a nipple, they'd have easily gone under that 2x4. It seems like they took pains to avoid an obstacle that isn't in the way which is why I was wondering if there might be some better explanation. Some dead men's piping feature that I'm not aware of.
None of the other traps have had any sediment in them (this one was bushed down to 1/2" for some reason which might also explain some of the buildup) but being continuously full of water seems like it would exacerbate the issue.
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the fact that there is a condensate tank and pump is a pretty good clue in most cases that whoever did it didn't know what they are doing. sometime you need one, but there are a whole lot of systems that have one that doesn't need it.
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We've got 3 plus a feed tank. Things could be better organized to say the least. In the case of this main, however, it's serving about 10 rads that are at boiler level with no path to run a wet return. It's not ideal though. Before my time, the pump failed on this tank and nobody noticed for about 5 years. 5 years of hot condensate overflowing into the ground and continuous make up water. Killed the boiler.
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looks to me like it was done to support the pipe(s). With that being a condensate trap 100% of the time, how does the system vent the radiators in that part of the system ?
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
the same pressure differential that will push the condensate up will push the air through until steam hits he thermostatic element.
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Maybe… And only if that pressure differential actually exists (never happen in my system).
The condensate will drain by gravity, all the radiators are probably higher than that trap. I bet that trap is always full of condensate. Steam / Air may never even get to the trap. And since the other traps don't have that piping vertical offset this part of the system may vent poorly if at all. Maybe there is another vent somewhere to compensate for the odd piping.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
you have a 1 pipe system where the mains are connected to the returns. commercial 2 pipe systems are usually run at a couple psig to allow for things like lifting condensate and if everything is functioning correctly the returns should be at atmospheric pressure. the feed pump or condensate pump, whichever that system uses, allows the condensate to return to the boiler that is under pressure, it pushes it in under pressure. it can be done by gravity but it needs to be able to get enough water column height to overcome the boiler pressure.
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I was referring to the pressure in my system, which is never more than 2 inches of water column. That vertical offset looks more than 2 inches.
" I've done 6 of 8 F&Ts with no issues. All have been pretty clean. This 3/4" Sarco FT-30 however has been plumbed in an interesting way. "
Also having 7 of the 8 F&Ts draining normally the pressure differential needed to vent air would be much less, so the needed pressure to vent through that 1 odd F&T that is continuously flooded would be greater and may never be achieved especially at the beginning of the heating cycle when most air is normally vented.
If it were my system and there are any heating / venting issues, I would change it match the rest of the system. Apparently less cleaning would be needed too.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
systems like that usually are also zoned.
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Ha. You're probably right. As venting goes, you've hit the crux of the problem. In the coal days, there were no main vents and nobody has thought to add any 😓. That'll be Job for spring, unfortunately. Some rads have genetic single pipe vents, some don't. So if this F&T can't vent to the return tank effectively, there's not alot of heating happening downstream.
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Your venting is probably at the return / feed tanks. I would probably rework that F&T trap so the outlet side is like the others with 3/4" pipe and drains normally. Having the F&T trap filling with sludge isn't helping any either.
The pipe support situation should be easy to correct.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
With fuel consumption and comfort in mind it may be better to repair it sooner than later. If the system is running longer than it really needs to compensating for poorly heating radiators that may use more fuel.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0
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