setting for dual pressuretrols on a millivolt control circut

bob fopiano

Have a residential steam boiler, Burnham. Milli-volt control circut with primary and secondary pressuretrols, what should the primary and secondary be set? Well more like looking for the secondary control setting, and why !?

Adam_13

2 pressuretrols

Just a homeowner here, but to try and help on my boiler with the millivolt system one pressuretrol is the main operating pressuretrol which controls the normal operating pressure and the other pressuretrol is the "pilot safety" prressuretrol. The millivolt system uses a standing pilot and a thermopile to generate the power needed to run some or all of the controls. The pilot safety pressuretrol is a safety device that is there in case the pressure goes too high. If the main pressuretrols fails (or for some reason the pressure goes too high) the pilot safety pressuretrol cuts out the standing pilot flame and effectively shuts down and locks out the system. Again, I'm just a homeowner here, and this is how my system operates. I strongly recommend that you find a good gas control pro to take a look at your system and help you identify which pressuretrol is which (and properly set and test them, etc.). Hope this helps, -Adam

Adam_13

2 pressuretrols

Just a homeowner here, but to try and help on my boiler with the millivolt system one pressuretrol is the main operating pressuretrol which controls the normal operating pressure and the other pressuretrol is the "pilot safety" prressuretrol. The millivolt system uses a standing pilot and a thermopile to generate the power needed to run some or all of the controls. The pilot safety pressuretrol is a safety device that is there in case the pressure goes too high. If the main pressuretrols fails (or for some reason the pressure goes too high) the pilot safety pressuretrol cuts out the standing pilot flame and effectively shuts down and locks out the system. Again, I'm just a homeowner here, and this is how my system operates. I strongly recommend that you find a good gas control pro to take a look at your system and help you identify which pressuretrol is which (and properly set and test them, etc.). Hope this helps, -Adam

Unknown

The pressuretrol

wired into the valve coil circuit is the normal one used on all boilers it should be set 1.5 to 2 lbs off, .5 on. The other is as Adam so well explained to break the millivolt circuit and shut the entire valve down. It is usually wired right into the pilot generator feed to the vale or it may be connected to a junction block in tne generator wire. The safety pressure trol should be set for 14 lbs off and 9lbs on (set the cut in to 9 and the differential to 5).

This double pressuretrol was due to the requirement for boilers to have dual seated (redundant) gas valves. Powerpile valves are not able to be dual seated so hence the extra safety.