Anyone know the drop away pressure for Vari-Valves?

DanHolohan

drop-away pressure applies only to vents with floats.

Daniel_3

Right now my pressuretrol is set for a cut-out of 1.5 psig and I am thinking I could lower that even further but the Heat-Timer website doesn't have the technical info save for some comparison venting charts. I may get a vaporstat but not sure how the wiring will be with the pressuretrol.

In anycase all the vents are vari-valves except for two vent-rite no. 1's on two rads just above the boiler which with the vari-valves got waaaay too hot and waaaaay too quick hence the reason I switched them even though I had them on the closed setting. This worked very well. It would seem the drop away pressure for these vari-valves would be much lower than other adjustable vents such as the hoffman 1A, dole vari-vent, and vent-rite no.1.

gerry gill

i'm not sure it would have one,

because its basically designed as a baby steam trap i think.

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Daniel_3

Actually your right in essence since the poppet seals it shut like a trap so there's no flash of a liquid. It should still "drop away" after the pressure cycles lower to allow air back in.

Daniel_3

Hmmm. So if it works like a trap then the only reaction to steam contact is where the phosphor bronze bellows expand closing the o-ring seal?

Unless I cut one open its tough to tell how it actually works since the Heat-timer website has only 2 pages of literature on it not indicating the fine details of operation. I could call them I guess . . .

What is the life span of a common steam trap anyways and what would be the commonly known details of failure?

Thanks guys!

Daniel_3

This vent then must be of the mechanical form and close to that of the Bourdon type according to it's size if compared with a steam trap.

Because it vents air then it's really only similar to a trap in that it has bellows but it is very much in common with those vents of bi-metal design such as some of the old ones that had a piece of curved metal that would heat up and close the vent to atmosphere. Do those type of vents have a drop-away pressure since the metal does indeed move it's position? The vari-valve is stated to be a positive shut-off type so it couldn't be an expansion of metal that's happening but rather some reaction to a volatile liquid in the bellows.

I'm trying to get a clear handle on this but it's quite confusing

Kevin Gabelmann

vari-Valves

Daniel;
There is no drop away pressure involved in the Vari-Valve. When the bellows cools it will open the vent allowing steam or air to enter the radiator.
If you have any questions please call we are here to help.

Kevin