Awful gate valves in steam system

Brad White_159

They may well be globe valves, not to delve into semantics.

They may have been selected for appropriate control/authority. The disparity in size does seem large but I have seen similar before that worked fine.

Naturally it depends on the incoming pressure. Perhaps it is a hybrid system with one-pipe on one side and two-pipe on the other? I have run across them on occassion and the higher pressure ruled, hence the Cv's were rather low.

Maybe you keep it albeit at a larger size to compensate for actual pressure and downstream control. Does it control to pressure? Control to condensate side sensor for cycle-timing?

Anyway, just a thought or two!

ttekushan_3

Awful gate valves in steam system

Here's a new one. Or maybe not. Looked at a steam heating system where turning UP the pressure was the only way to get steam into this otherwise wonderful two-pipe system. At least in the short term.

Improvements (!) in the system long ago involved zoning the entire system with motorized gate valves. Now, I don't mind zoning steam, and as a matter of fact I'm a big fan of those old systems with pneumatic thermostats and actuators connected to a modulating or hi-low firing steamer.

But this is just wrong. 4" down to 1-1/4" and back to 4" to feed a LOT of column type cast iron radiators. This is one of several.

Ya think we should rectify this? Just have to convince the client...

-Terry

ttekushan_3

separation into zones

occurred later in the building's life. It otherwise looks and operates like a good mid 1930's low pressure steam system. The only heat source is a boiler in basement.

The valves respond to room thermostats. The boiler responds to the opening of any one of the valves. None of the radiators can saturate at all if pressures are kept low. Yet the boiler will short cycle endlessly as the thermostats call continuously for heat. Running the steam capacity numbers I have to have the boiler at about 5lbs for the possibility for saturation anywhere in the system beyond the valves. Turn it up, Voila- everything heats, no short cycling, and the main t-stat's satisfied.

I rather like the zoning idea; but I just wish the installers had sprung for a line-sized valve.

-Terry

Brad White_159

There is no real substitute

for an original intent that worked.... I can appreciate your desire to tread lightly. 5 PSI is so unacceptable a way to just make it "work", assuming valve authority is not required. Good luck on this one.

Brad

EBEBRATT-Ed

Line size valves would surely be way to large. The valves can't control properly without some pressure drop across them.

You have a system that was never intended to be zoned with zone valves installed. You can remove the zone valves and run lower pressure or run 5 psi and leave the valves in. If the valves are working correctly and the condensate returns ok I would leave it as is jmho.

Brad is correct those look like Honeywell globe valves.

ED

ttekushan_3

what's interesting here

is that the valves are either fully open or fully closed, yet the indicator on the side shows fractional graduations. I presume these are used only to set up the opening fraction for proportioning while all valves are open.

News flash:

The client says he never uses the t-stats (and some were inoperative) and doesn't need the zoning for his purposes. Looks like we'll be removing them in their entirety and putting the system back as it was originally constructed. One or two TRV's are all that may be desired. Ahhhh. Back to low pressure.

-Terry

PS Despite everything, I think those are very cool valves; well thought out and constructed. They will NOT go into the trash!

EBEBRATT-Ed

If you looka at the valve actuators they could be line or low volatge, modulating or two position. Motor series could be series 90, 80, 40,60 etc.

Mayy times someone will mistakenly replace a thermostat with the incorrect one and the valves will not operate properly.

ED

bob young

drip line

should not the supply side of modulating valve be dripped with a steam trap ? when the valve shuts what happens to the accumulated condensate ? ----next cycle --bang, no ?

ttekushan_3

They leak

when closed, so we'll never know for sure.

-Terry