system flooding

Unknown

or all of it, if you like.

http://steamheating.googlepages.com/evaluatingasteamsystem

Jim_108

building system flooding?

Small apt (14 unit) steam. Can't figure out why the system keeps getting flooded. I changed the MM valve and strainer cause I though it was leaking... Wrong, Two days later flooded. I did notice when I was draining enough water to change the valve (system still hot) I had air sucking back into the boiler. It was in a vacumn for quite a while? What is causing this flooding every few days?
Thanks
Jim

Unknown

It sounds like a two pipe system with steam traps.

Steam traps that might not all be working.

Noel

Jim_108

Noel, thanks foe responding it is indeed a two pipe steam system with traps. Thermostic traps on the raditors and float/thermostic on the main returns. You think I should start taking the f/t traps apart? Can they be repaired by cleaning them? Floats stuck maybe?
thanks
Jim

Canadasteam

steam system flooding

Before you do anything may I suggest you install a vaccum breaker on the top of, any of the on boiler water level control pipe colume(s). System vacuum caused by various reasons will draw water from the makeup/returns tank, and if the city water feed is located on that tank the float mechanism will supply water to keep tank level correct, so lots of water available to flood into a system. A simple horizontal swing check valve 1/4" pipe size located down stream of a pigtail mounted at the top of the colume will break the vacuum by allowing air in into boiler, yet closes up when boiler pressure builds. Easy to do, might fix the problem without going into big trap maintenance procedure. Worth while experiment. Also if you have any remote condensate receivers located in the building check them for proper operation.

Good Luck

Jim_108

Noel, I read the artical but lets say the main traps are bad and allowing raw steam to flow past them I still don't understand how that would flood the system? it seems to me that steam would condense and just flow back to the boiler.Is it that the traps are "stuck " closed and the condensed water is trapped in the mains?
Thamks
Jim

Unknown

picture this:

There might be a trap half way up the return blowing hot steam into a return. That steam goes both directions in the return, as long as the pipe is cooler than the steam. That flow hits every trap it passes by until the return becomes as hot as the steam in it. Those traps are now closing from the steam on the wrong side of them, but the radiators are still condensing the steam entering the supply side of them, and nothing will stop that action.

You have a bunch of radiators condensing supply steam with traps that can't cool to open and let the water out. These radiators all are "storing" water up until the entire return cools enough to let the water out.

That won't happen until the boiler shuts off. Then the flood begins....

Noel

Jim_108

Noel, Thanks I understand now. I have aquired much info from you this afternoon. I do alot of hvac and much Ref. 35+ yr just not much steam. Hope I can help you sometime in the future. E-mail me anytime.
Thanks Agaim
Jim

Unknown

It's been a pleasure

Pass it on to someone else some day.

Pay it forward.

Noel

Steamhead (in transit)

Another possibility

If the main air vents on this system are designed to hold vacuum, they might be holding water up in the returns. This is the same type of action as when you put the end of a straw in a glass of water, close the other end with your finger, and lift the straw out of the glass. Some water remains in the straw as you lift it out, until you remove your finger.

Saw this happen a couple weeks ago on a Trane Orifice Vapor system. I replaced the vents and the problem was solved.

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