Steam valve (and system) identification

veteransteamhvac

Hello, homeowner here but I do own a copy of the Art of Steam Heating. 100 year old house, two pipe system.

I have a couple of valves that have started to leak. I have taken the guts out of one in an attempt to see if I can control that. The markings on the valve say: ISG Heat. Here are some pics:






Additionally, on one of the convectors heating is very slow which I'd like to cure. Other than the different hole sizes on the valves there doesn't seem to be any restrictor plates, orifices or traps. There are vents on the convectors. There is a loop seal at the end of the main that drops down and back up to the start of the dry return. The sole vent is at the end of the dry return main. Seems to be some type of vapor system and as such I keep the pressure as low as I can but I only have a pressuretrol.

Here is a picture of a return elbow on one of the convectors. There is no trap and I have not taken one off to see if there is some restriction in there.




Thanks for the help.

Jamie Hall

It is a vapour system, not sure what specific name is, and those valves should be adjusted to function in exactly the way an orifice would -- and then left alone. But you will sure need to keep the pressure lower -- it will be much happier running at less than 8 ounces, which means adding a vapourstat.

Are you sure that there never were any crossover traps at the ends of the mains? The would help performance and evenness if they were there. Without knowing what appliances are around the boiler -- other than the dry return main vents, which are absolutely necessary -- I hesitate to suggest adding main vents on the mains; they could do a good deal more harm than good.

veteransteamhvac

Here is the end of the main and return with the drop loop as mentioned. No crossover. I disassembled the bottom of the loop to make sure it wasn't clogged as I do occasionally get some hammer. I do suspect that the loop doesn't quite go low enough. There was obviously a coal conversion at some point but I don't think they reconfigured for the smaller gas boiler. An addition to the house was added in the 50's and those 2 convectors lead to a wet return. They have vents and heat fabulously.

Steamhead

This may be a new Vapor species, though the loop seal reminds me of a Tudor system. Let us know what, if anything, is in those return elbows.

Jamie Hall

Anything over 2 psi maybe less is gong to blow those loop seals and you'll get hammering -- and poor heat. Nothing to do with the coal to oil conversion or gas boiler or boiler water line -- just pure pressure difference.

veteransteamhvac

I pulled one of the 2nd floor convectors off, one that was heating poorly btw, to look at the return elbows. As suspected, 1/2" return elbows with no orifices. I have also fully disassembled the valve from the pictures above and gotten a good clue on how those operate. I will post a video soon that shows disassembly and operation.

Here are the pics of the return elbow:







Based on the movement of the return piping I can see that I'm going to have to raise the radiator up somewhat to make sure it is sloping back towards the downpipe.