Pilot (intermittent) leaks in stand by mode

[maxime kudinov]

Hello,

I have crown boiler (natural gas ) AWR 175 (intermittent pilot) installed brand new. Works fine.
The pilot leaks when the gas valve switch is in ON position and furnace is in stand by mode.
There is 24 V across PV and PVMV when thermostat is disconnected (no call for heat) and switch is in OFF and ON position.
The control panel was replaced and nothing changed but there is still 24 V across PV and PVMV.

 

[Jadnashua]

Having voltage when measuring across a switch implies that the switch is open. A closed switch is functionally just a wire connecting two spots...so, putting your meter's probes on either side of a switch is the same as putting them on the same side when it is closed (which would indicate a closed switch), but when open, there would be a voltage potential.

When measuring things...it is important to understand what the reference point is.

So, if you can always measure voltage across a switch, it is open and not closing.

 

[Sponsor]

 

[maxime kudinov]

Having voltage when measuring across a switch implies that the switch is open. A closed switch is functionally just a wire connecting two spots...so, putting your meter's probes on either side of a switch is the same as putting them on the same side when it is closed (which would indicate a closed switch), but when open, there would be a voltage potential.

When measuring things...it is important to understand what the reference point is.

So, if you can always measure voltage across a switch, it is open and not closing.

Thank you for answering.
By switch I mean gas valve switch. When it is in ON position and no call for heat from thermostat (disconnected) the pilot valve must be closed that is no voltage between PV and MVPV.

 

[Dana]

In the HVAC world "furnace" refers to a heating appliance that distributed heat via ducted hot air. What you have is always called a "boiler" or "hydronic boiler".

That's a pretty huge boiler for a house, unless the house is 5000' or bigger,or 3300' with single pane windows (no-storms) and effectively no insulation. (It could theoretically keep my not-so-superinsulated 2400' house warm even at -250F outside.)

When you say the pilot "leaks", are you saying that it's leaking gas even when it's not trying to light up? That would almost surely an internal defect in the gas valve, not a control signal problem. Did you swap out the controls, or was it some boiler tech?

 

[Jadnashua]

A not very common problem could be the failure of a gas pressure regulator, allowing higher pressure than the system was designed for.