Condensate tank steam from vent.

Krum

Hi guys,
could you please suggest what I can do to stop flash steam coming out from the condensate tank vent? Condensate occurs on the ceiling and soon the structure will be compromised.
thank you in advance
K

EBEBRATT-Ed

Usually it is bad steam traps blowing steam. You should fix the traps and maybe re pipe the vent to outside the building or a location where steam won't be a problem.

What steam pressure are you running?

Krum

The steam trap is brand new. The steam pressure is around 1-1,5psi.
really difficult to pipe it outside, even impossible.
Maybe if we pipe it to the sanitary drain will have enough height for the steam to dissolve in the air before hitting the ceiling. The system is in Calgary Canada and here the RH during winter is around 15%, which may help.

Jamie Hall

The steam trap may be brand new -- but that doesn't mean it's working properly or installed properly. Nor that it is even needed at all. At the pressure you are running, you shouldn't be getting any flash steam to speak of out of the trap and condensate it releases.

You may need to look at the entire system and figure out why -- and if -- it is even needed (and, for that matter, why and if the condensate tank is even needed).

Routing the vent to somewhere else is putting a bandaid on the problem.

Krum

The steam trap works properly, but steam flashes in the condensate tank and rises through the vent. Probably the boiler is a bit oversized. Calgary is 3300 feet above sea level and water boils around 205°F that increases the steam flash amount.

Jamie Hall

Aye, I got that far. The question is, however, why is there condensate at steam temperature there at all, and what is the purpose of the trap and the tank?

Krum

Krum

this is the system I have.
the FT trap is sized properly and operates like a charm.
the flashing steam comes out of the tank. It is not a lot but...

Jamie Hall

How big is your system? Odds are that neither the tank nor the trap are needed at all, unless it is very big -- gravity will do the job for you.

Krum

70hp of boilers.
A wet return will do the job but I matched how was the old system.
the building is ~32000sq.ft. 6 floors

Jamie Hall

Umm. Well, that's big... and you may need the condensate tank for additional water storage (in which case I hope it's controlled as a boiler feed tank, not a condensate tank!). Let me think on this one.

JUGHNE

How much pipe is between the pump and the F&T; and is it insulated?

Do you have a test port on the discharge port of the F&T?

EBEBRATT-Ed

If your running 1-1.5 pounds and have 1 pipe steam like your drawing that trap is carrying all the condensate in the system both the radiation and the steam main.

If that is the way, it really is rip the trap out and pipe in a loop seal. Drop the main to the floor turn and rise back up and go in the return. The water seal will keep the steam out of the condensate tank. Your trap may not be the right size, it should be sized for the weight of the steam main including pipe, valves and fittings plus the radiation load dripping back into the main

The loop needs to be at least 4' high to prevent the steam from blowing the water out of the loop seal.

You can read about it in the LAOSH one of @DanHolohan 's books available on this site

Krum

my gut feeling is that I have oversized the boilers a little bit.
the existing system was built 1919 and there was no possible way to check all rads in the building. I had to match what was on installed (boilers) but veg information was only available. I have used the Mills 2-20-200 to double-check my selection. Had a pick-up factor of 1.5 (old building with tons of not insulated piping). Anyway, the building is heated now but the only outstanding item is to stop the steam of flashing in the condensate receiver. this receiver actually acts as a boiler feed tank, pumps are controlled by the boilers.

pedmec

Are you positive you don't have another return tied into the main return between the f&t and boiler feed tank? Someone could have added a two pipe set-up, like a unit heater, and have to tie-in after the f&T as the unit would have to connect to return after the f&t. Many systems out there with combination one and two pipe.

Krum

not a "hybrid" system as far as I know.

EBEBRATT-Ed

The Mills system in this day and age will result in an oversized boiler which matters not but may cause short cycling. But that is not what is causing the steam at the boiler feed tank if your pressure is low as you posted.

Getting rid of that trap and piping in a loop seal will guarantee no steam at the receiver and as long as your pressure is low enough to not break the seal you will have full condensate capacity of whatever your return pipe is.

If you don't solve this problem, you are losing water and the make-up water will kill the feed tank and boiler slowly and the first thing to go will be the feed pumps which will be replaced again and again.