Boiler Piping

DrPepper

Years ago I found a similar situation with a 3-way valve cutting off flow to a B&G series 60. The owner (City of Elgin IL) replaced bearing assemblies (no suction flow does all sorts of things) and cussed the pump and crummy heat output but no one ever looked at the valve installation which had been wrong for years. I had a nice long talk with the director of maintenance, we traced pipes, sketched up how it should be piped .... and we never heard from them again. They also stopped buying bearing assemblies.

ddlong1286@yahoo.com

Boiler Piping

Hi all,

I may have posted this last year, but of course that was last year. I looked at the community college boiler system this week. They complained that when it was 0, the system was not maintaining temp in some of the class rooms.

The supply piping comes out of the boiler, goes thru a 3-way valve, to the air seperator, than the pump. After the pump there is a tee to the coil in the air handler for the auditorum and the main line to heat the library and class rooms.

Should not the 3-way valve be after the pump? I see no purpose except to keep the return water warmer to prevent condensation in the boiler till water temp is above 140 degrees. But the control system is not set up for that purpose.

Take a look at the pics and let me know what you think??
I will try to answer any questions.

Thank you
Don Long
Moberly Mo

Brad White_191

Function

If the goal is to mix (say boiler water with return water to get a variable temperature), the 3-way has to go on the suction side of the pump. Two ports in, one port out and that goes to the pump.

If on the other hand, that valve were on the discharge, it would be a diverting valve, one inlet, two outlets. That is all that valve can do.

No mixing would occur except perhaps after one of the out-ports and by then, Elvis has left the building.

That is what I see if I understand your question.

ddlong1286@yahoo.com

Boiler Piping

Sorry about my terminalogy. The valve in question opens and sends water to the radiators or the coil in the air handler. Closed it sends water to the return side of the piping and back to the boiler.

When the valve closes, I don't see how the pump can move any water? Would not the pump cavitate since the suction side is closed off?

It looks to me like the valve is to be used as a zone valve with the second outlet to allow the pump to stay on and send water to the coil in the air handler or when both valves close return water to the boiler.

I quess I do not see the point of the current position of this valve.

I will try to find out the control operation.

Thanks

Don Long

Moberly MO