Hot Condensate

Eric

Looked at building today.

Thermostatic traps on radiators and Big 5 gallon buck size F&T's at AHU's.

Two pipe, condensate reciever, But pumped discharge had condensate piping into a hardford loop?

Zone valves on all radiators and coils.

Reciever venting steam. Hard to tell how much. they just piped to roof.

On serveral radiators and baseboard. With steam valve closed. I could touch downsteam of control valve. The condensate was so hot couldnt touch it. My guess is there is a big bad trap somewhere. Could you heat condensate piping up enough (from return side) to keep thermostatic trap closed even with cool condensate above it? And feed radiators backwards.

BTW, It popped and banged when steam valves cycled open. IE water in radiators/baseboard. Also. Didnt see any vacuum breakers? Operating pressure 5 to 10 psig. 1.7 Million BTU.

Thoughts.

Woody

bad traps

that's your problem. note the thermostatic valve works on the room temperature while the thermostatic traps work on
the internal steam temperature. it doesn't make any difference where the steam temperature comes from(supply or return side). it is a thermostat that closes on temperature. why running up to 10 psi?

Bob_19

You Probably Have

flash steam in the return side.
As the condensate moves into the return it goes into a low/no pressure zone causing flashing. Being that condensate at the outlet is only typically 5 to 15 degrees below saturated steam temp it's going to be hot. If you run at 10psig your saturated temp will be 240 degrees less 15 would be 225 condensate at the outlet. Thermodynamics state that water at 14.7 psia(0psig) cannot hold anymore than 180 btu's, the rest will flash to steam.
But, usually this flash steam will not make it back to the receiver in any appreciable amount.
If the receiver shows steam release at the vent which appears to be under pressure you have steam trap problems.

Eric

Double Check

I Too beleive its a bad trap somewhere. Just Wanted confirmation. With Thermostatic traps (temperature operating) I shouldnt have too much flash steam (right)?


I was mainly curious if anyone has seen where the condensate system was actually hot enough to keep thermostatic traps closed.

Bob_19

If You

think your condensate is too hot you can use traps that will release at a subcooled temp, usually around 35 to 40 degress of saturated temp.

If there not opening at the discharge properly they are probably defective,ie: not opening, not opening enough to allow proper condensate evacuation.

I would think that if the condensate is keeping the trap closed due to high heat they are probably defective.

By having live steam in the return this will affect proper condensate discharge by keeping the pressure to hi on the line. This could cause to small of a delta P in your return line playing havoc on your elements.

Steamhead

Also check the pressure

do you REALLY need 7-10 pounds for this system to run? Condensate from good traps can flash when coming from this presure to atmospheric. Try turning it down and see what happens. Bet you get a lot less flash steam.

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