Service Manager

tghog

My Co Installed a 5 section Steam boiler in a previous customer home. All done IAW Manufactures specs. 2 21/2" risers swing joints, piped up two cust existing 3" header after both risers, Then dropped down to 2" on equalizer, Down to Hartford loop , 2" below water level with close nipple. Old boiler did not have a Hartford loop. We are within a 1/4 of a inch of old water level. At the end of the heating cycle we get a little banging near the differential loop. This is a two pipe system with traps on all radiators & 1 trap on each end of the basement that go from the main to the returns. Both of these where replaced recently & check OK. All radiators heat very well. There is a brand new #76 Hoffman vent on top of diff. loop around 4" high. Boiler risers are at least 24" from water level on boiler to bottom of header. Is there a set level of water that should be in that diff. loop. We cant figure out why that bangs for around 3 to 4 seconds at end of heating cycle.Also there is not a domestic water coil in this boiler, cust has electric water heater.

Jamie Hall

Hoffman equipped

system.  They are wonderful systems.  Sounds like you have pretty well covered all the bases, except one: what is your pressure?  The Hoffman Differential Loops were designed to trip at around 9 ounces per square inch -- no more.  Anything over that and they will trip, and that might be your banging -- although I wouldn't usually characterise it as a bang, more like a colossal flush, maybe.  But steam does hit the dry return and can slam it when they trip.



Can't think of anything else...  maybe someone else can, I hope.



Off topic thought: if someone should convince you that you need more main venting (which you really don't), any additional vents must be at the same location as your #76.  Don't put a vent anywhere else on a Hoffman system!

Steamhead

That #76

is likely the problem. With oil or gas firing, we often get vacuum too quickly, and this can cause water to get held up in the system. This is true of most vacuum-type systems.



Replace the #76 with a Gorton #2, that should help. And make sure all the traps are working properly.