new account, no heat

FRANK_24

A properly sized an installed steam boiler w/ two zone valves. One for the steam heating load of the church in whose basement the equipment is located, and the other load to a side-arm heat exchanger. This second load is also properly sized for a heating load of the rectory which is over 200 feet away. The copper supply and returns are burried between the two buildings and are sized properly. The arrangement is the return enters the boiler room , goes thru a spirovent first, then the circ. and then into the HX.
Pump is properly sized as to BTU and head. Once into the other building, there is a by-pass pump (probably installed to keep water circulating at least through the burried piping to prevent freezing.) Someone also installed another circ. on the supply line.
Here's the problem: of the 10 cast iron convectors on the third floor, three get hot, two slightly warm, and the rest no heat at all. A pressure reading of 5 PSI was obtained at three locations, and all the cold rads vented cold water only. Needless to say, whether it's a mono-flow or two pipe system cannot be determined due to completely concealed piping.
My idea is some of the individule branch piping is plugged (by rust?) I've never come across any hot water piping plug up. Steam, yes. Hot water ,no. Ideas, anyone?

Steamhead

Broken Valves?

Once in a while someone will shut off a supply valve and it will break when they try to re-open it. The handle will move but the shell in the valve won't.

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Weezbo

this is one of my more weird ideas...*~/:)

what about reversing the pump into the field?let it run about a half hour and go see whats up...if you have any valves that are lockedpresurre on the oppisite side of the valve no matter how slight might help them release....an then too if heat is coomming out of one pipe and that is true for all of them then perhaps what is happening is some of the rads are a bit more air bound than you previously thought...

EBEBRATT-Ed

I would check pressures on each side of the pumps and get a pump curve and see where your at. This would show if the pump is at the end of the curve weather it be caused by wrong pump, impeller, closed valves, plugged lines etc. Who knows--over the years the bearing assembly/impeller could have been changed and the wrong parts substituted--they put in what they had. Check motor amps-probably low if not moving enough water--this is sometimes an indicator.

In fact you can try closing a valve (discharge only) partially while checking motor amps. The amps should drop when you throttle the pump. If the amps don't change theres a good chance the pump is deadheaded.