Boiler Pressure

Jim Chamberlain

At my church, I had just had installed a new Weil McLain LGB6 for a three zone two pipe system (the two pipe system, however, branches off into a single pipe system of pipes going to radiators and convectors with vents).

The two Honeywell controls that come with the unit appear to be set at .5 and 2 PSI, but I keep watching the gauge go up to 5-6 PSI before shutting off. At first, I thought this was only happening when only one zone was open, but I have also seen it when all three zones are on and the thermostats from each zone are calling for heat.

How can this be?

And if I finally get the controls set so the pressure never goes over 2 PSI, won't the boiler shut off quicker and start to rapid cycle?

Jim

Patrick Linhardt, \"Linhardt's Field Guide to Ste

check the wiring

Hi Jim,

That sounds like a system out of control.

1) Check to make sure it is wired correctly. If the controls are set as you state, then the burner should shut off at the .5 plus the differential setting on the inside of the control. This should be set at 1, however if it is set to 5, then it would be working as adjusted.

2) Most systems work best at low pressures, usually under 2 pounds. It costs more to run at higher pressures and they can lead to other problems, like hammering or flooding.

3) On a multi zone steam system, since the boiler is producing way more steam than the system can handle with only one zone calling, it is possible to have "short cycling". To minimize this condition, make sure you have more than needed venting capacity from the ends of the steam mains.

4) Has the installing contractor been back to take a look at this? What is his response been to your concerns?

Best regards, Pat