L408J1009 Vaportsat

NY_Hammer

What setting to us for one pipe steam system?



I assume it's

16oz on MAIN

8 on differential?





Basically I want the system run at 1.5 PSI max and start again at 0.5 PSI.



Just having problem dealing with OZ per Inch instead of PSI





Thanks

JStar

Vaporstat

16oz = 1 pound



With a Vaporstat, you want to set the pressure as low as possible while still satisfying all radiators. You figure the length of the furthest radiator. You lose about 2oz per 100 feet of pipe. Double the length for fitting losses. Then double that again for safety.



Example...



75 feet of main. 25 feet to the furthest radiator off the main. That's 100 feet. So you need 2oz of pressure so far. Double that for fittings. 4oz. Double again for safety. 8oz operating pressure. Then set the differential somewhere slightly below that, say 6oz.

NY_Hammer

Are you sure

I was under impression that vaporstat is the same as pressuretrol but more sensitive.

So the actual setting should be the same.

So as I said what I want to achieve is cut off on pressure at 1.5 psi and cut in at 0.5 PSI





It just happened that I got one with OZ scale so all I want to know that should be my setting in OZ SI for MAIN and differential. So since 16oz SI= 1PSI I cant get 1.5 so I put MAIN to max at 16oz. Then 16-8=8oz = 0.5 PSI so the differential should be set to 8OZ.





Am I wrong?

MTC

A vaporstat is basically the same as a pressuretrol,

but far more accurate, and allows you to dial in much lower pressures.



A pressuretrol set at .5 pounds (8 oz) cut in may cut in at 6oz or 10oz, they're just not all that accurate. So if you had it set to 2oz cut it, it might never cut in at its accuracy level if the calibration was a bit off. There's really no point in trying for lower settings on it, its not capable of handling them well.



A vaporstat is capable of lower settings.



The issue I think you're running into is that the "standard" recommended setting for a pressuretrol is .5-1.5 pounds. This is generally a good plan for a pressuretrol. When you switch to a vaporstat, you want to go even lower. Basically, your steam system wants to run on as little pressure as is possible, while still filling the whole system.



This is what JStar was getting at. I like to set the cut-in at about the resistance of your piping, plus a little extra for good measure. That ensures than when the system fires up again after cutting out and depressurizing, the pressure where it kicks back on is enough to overcome all that resistance and get steam to the last radiators again as soon as it starts up.



I find a good starting point for most homes to be 10oz cut-out (the main on a vaporstat) with a 6oz differential (leaving you with 4oz cut in). In most homes this will be enough to handle all the piping and fittings, and leaves you enough differential to avoid very short cycles. See how this setting works for you, if you get heat to all radiators, etc, and adjust a bit from there as necessary.



But if you have a vaporstat, what you DON"T want to do is try to get back to your pressuretrol settings. You want to be a lot lower.