Radiator Valve/Trap Recommendation

Cyclone33 · September 30

I’m looking for advice on what radiator valve and steam trap I should install on one radiator in my house. I’m in eastern Iowa with a two‑pipe steam system, originally built as a Trane Vapor system.

All of my other radiators follow the same piping layout, and I’ve attached a picture showing how they’re set up. This one radiator is the oddball — at some point it had a different valve and trap installed, and neither were working correctly. Since original Trane Vapor components aren’t available anymore, I need modern parts that will behave correctly in a low‑pressure vapor system.

Thanks!

EBEBRATT-Ed · October 1

Traps are not used on a vapor system at the radiators. And you don't use air vents on the radiators either. You can use a standard radiator valve on the inlet but what is wrong with the valve you have. We need to know what the problem your having is to be able to fix it.

Do you have cross over traps in the basement? You need to keep the steam pressure really low. i can't tell if your pressure control is a vapor stat or not

Jamie Hall · October 1

Good question… what's wrong with the valve?

As to the trap — you can use a trap on a vapour system, but as @EBEBRATT-Ed said if the pressure is under good control you can also just close the valve a bit, until the radiator is mostly hot — just not hot all the way across. Now if you do want to use a trap, and good radiator trap will work just fine.

Cyclone33 · October 1

@EBEBRATT-Ed it’s a vaporstat.

How can I verify cross over traps? I am new to steam systems. Thanks!

Cyclone33 · October 1

the valve constantly needs repacked and when I had it apart thought I would just replace it if viable

mattmia2 · October 1

the vaporstat is set at about twice the pressure it should be on a vapor system.

if you doo a good job of repacking the valve it should last for decades. teflon string packing should be very durable. make sure the stem is smooth where the packing rides on it.

mepco makes metering radiator valves that can replace vapor valves but repairing your original valve will be easier.

if the pressure is getting to the vaporstat setting, steam will end up in the returns on radiators without functioning traps.

if any of the radiators are missing their vapor valves and don't have traps steam may end up in the returns.

the combination of controlling the pressure and the metering vapor valves regulates the amount of steam admitted to a radiator to a little less than the amount that the radiator can condense so all of the steam is condensed, it doesn't make it to the outlet of the radiator.

steam in the returns can prevent other radiators from venting and heating.

Cyclone33 · October 1

Thanks for info. I will try that packing. I had been using graphite.

@mattmia2 can you help me get my vaporstat set correctly? Is there a process?

Cyclone33 · October 1

it also looks like my radiator orfices are on the outlet at the bottom, the valve inlet is just wide open on radiator at the top. I read contradictory information on the vapor system. Is this set up correctly?

Jamie Hall · October 1

https://forum.heatinghelp.com/discussion/comment/1905149#Comment_1905149

Its more common to have the orifice — if used, many don't — at the inlet. But either way will work. Not all vapour systems were designed to have orifices at all. Rather they depended on correctly setting the inlet valve (Hoffman Equipped and Mouat are this way). It also wasn't at all unusual to have traps on the outlets — not that they did much, but as a backup in case the system pressure differential got out of line.

Cyclone33 · October 1

I check a few more valves , some do look like metering type with a small opening that changes with valve. Is there a rule of thumb on how far to open them? Based off how radiator is heating up?

Jamie Hall · October 1

Yes, based on two things. First, how far the radiator is heating up — if it's heating over 80 percent or more of its width, the valve is open enough. If the room s too warm, the valve is too far open. If the room is still cold… oops. Need a bigger radiator!

Radiator Valve/Trap Recommendation

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