Self adjusting air valve

dalton

Can someone tell me (1)how these valves work (2)I was told they where only put in certain parts of the house (3)How do i know if its working or not.

michael_15

interesting

I've never heard of these. Unless you're talking about a thermostatic radiator valve (TRV), which probably does what you're thinking.

A normal air vent closes on contact with steam. There are some details about alcohol and floats and stuff which I won't get into. The basic idea: no steam = open, steam = closed. Using air vents, radiators get hot all the way across so long as the thermostat is calling for heat.

However, if the radiator brings a given room to temperature and it's only half-heated, then you might be in for some trouble because steam won't hit the air vent to close it until the radiator is fully hot, and by then, you've opened the window. You need something to shut off the venting based on the room temperature, not based on whether steam has reached the end of the radiator.

A TRV does this for you. When the ambient temperature hits the TRV's setting (say, 70 degrees), the TRV senses it and closes off the air outlet. Hence, the radiator stops venting air and thus prevents you from overheating the room. For the radiator to vent anything, it must "pass" both tests: the "no steam allowed" test supplied by the air vent as well as the "no air if the room is warm enough" test supplied by the TRV.

You can't put it in the room with the thermostat, because then you've basically got two thermostats in the same room. If your TRV is set to close at 68 degrees and your thermostat is at 71, then your thermostat will call for heat forever and your boiler likely end up cycling on and off on pressure all day long.

Hope that helps,

-Michael