Hoffman Differential Loop air vent

GW

I'm just a one-piper, this is normal? The vent just needs to be replaced

Jamie Hall

First -- are you sure the vent needs to be replaced? What is it doing -- or not doing -- that it shouldn't -- or should?

But... you say you are a one-piper. Eh? Honestly, I've never seen a Hoffman Differential Loop on a one pipe system. Can you expand on that?

GW

Jamie The homeowner says it’s blowing steam up at the sheet rock.

Sorry for the confusion, I meant to say my experiences are on one pipe systems 

Jamie Hall

@GW -- then it needs to be replaced! I'd probably put a Gorton ##2 on there.

It shouldn't ever even see steam, however, Gary, if the system is running right. The way the differential loop operates is that the vent -- the only vent that should be anywhere on the system -- vents the dry returns (problem one: how are the traps on the radiators? How are the crossover traps out there in the wilderness?). The water in the loop balances the steam pressure against the dry return pressure and, if the pressure difference is over seven to eight ounces or so that water seal is blown and allows steam to hit the vent, which promptly closes (you hope) and allows the steam to pressurise the dry returns, keeping the pressure differential down. The idea is to keep the water in the boiler... and minimse the stress on the traps and all.

So... that system has to have a vapourstat to control it. I'd set the thing at 7 ounces cutout with a 3 ounce differential.

Vents anywhere else on the system defeat the operation of the loop and should be removed.

GW

Right on thanks Jamie. The guy sent a video. Maybe I’ll go myself and not my tech. 

Steamhead

A couple more things:

First, that vent is too small. It looks like a Vent-Rite convector vent. Since we have a Differential Loop, this is a Vapor system, and this cute little vent is (or should be) the only air vent in the entire system. I bet the system heats a lot slower than it should. First order of business is to replace that vent with a Gorton #2. This vent is rather tall, so you may need to cut a hole in the sheetrock above the vent. Do so.

Second, if steam is reaching the vent, as Jamie said it may be due to the action of the Loop (see Lost Art, chapter 15), or it may be the result of bad radiator traps. If the latter, rebuild the traps.

And what Jamie said about the Vaporstat.

GW

Muchos thanks I’ll check it out

EBEBRATT-Ed

@GW
I will bet you found this system in a big NHamp house LOL

GW

Ed it’s in Amherst- our other favorite stomping ground

Jamie Hall

Spent a good bit of time in Amhur$t about 40 years ago -- at UMess. Also the home of Hamster College... There are some really nice houses in that town.

GW

Easthampton Northampton Hadley Amherst, that’s my neighborhood

EBEBRATT-Ed

Not that this means anything just popped into my brain.

Didn't the Amherst Town Hall refuse to fly the American Flag for a while? I did some work in their once can't recall the whole story.

Did more work at U mass than I care to remember. All their old buildings are loaded with asbestos. No place to park=parking tickets...ahhh the memories. And they are -------to work for don't miss it at all.

GW

Oh bummer. My emotions are more favorable with Amherst, I just deal with homeowners. We seem to get along well. Never worked for the colleges. I’m a COD man😀

Jamie Hall

My stint at UMess was working on a graduate degree -- and if you think the business side of the colleges leaves something to be desired, working more or less directly with the faculty (as one must, as a student or sorts) really puts the fun in dysfunctional. The only lot I encountered which seemed to have some grasp of reality were some of the people at the Stockbridge School, which is sort of by not really part o UMess.

GW

never did the college route, but I’m getting by. 

Jamie Hall

Sometimes much better not to do the college route. At least in my humble opinion. It's good and rewarding for some people, yes. But so is really learning a trade, or working the land. All equally valuable at the end of the day. As someone said in another thread, if you are enjoying what you are doing, that's good and what counts!

GW

OK I didn't communicate myself extremely effectively, 'things are pretty good'. I think a portion of the college educated folks would gladly change places with me