Fast pressure drop

RyanC

I have my vaporstat set to shut the boiler off at 12oz.  The low pressure guage I have indicated it is cutting out at 13oz.  I can deal with the 1oz difference.  Once the burner shuts down the pressure drops pretty quickly.  It takes about 90 seconds for it to get back down to 4oz where the burner turns back on. Is that too fast? My main vents are new as are all of the radiator vents.  I can hear them all clanking open and shut; so I think they are working. 

jpf321

not unreasonable

based on what i've read, 90secs doesn't seem unreasonable .. there was some discussion a while back about timing the entire on2on cycle and then figuring out the percentage of time that it's off during that time. in theory, that number was supposed to be 1unit off for every 3units .. or off for 33% of the on2on cycle...let us know the timing that you have for on-time once pressure cycling begins... is it about 3mins on and 90sec off?

Jamie Hall

Quite reasonable

That's what it's supposed to do.  The rapid drop is from the steam condensing, which it will do pretty fast.  And jpf is right, too -- at least in theory, that the ratio should be about the same as whatever pickup factor was built into the system.  It rarely works out that way -- but then, the numbers which go into the pickup factor are rarely exact either, and are really valid for only one precise set of conditions anyway.  But it shouldn't be way off, either.

nicholas bonham-carter

my theory is......................

on the subject of speed of pressure-drop at burner shutdown, if you have unexpelled air in the pipes, the pressure will be slower in dropping, than if you have been able to allow all the air out. as we all know from a good quote here, "air is the enemy; to be chased away, like the raccoon from the garbage can".--nbc

RyanC

Thanks!

Thanks for the info!!

lutorm

Sounds reasonable

After all, if there was only air in the system, there would be no pressure drop...