main vents on one pipe syst.

Lurker_2

And the radiators hiss out air, then it will get hot. . . eventually.

Perhaps your thermostat regularly gets satisfied before this happens? The main vent will help speed up the heating rate on this short main; best to make sure you put it after the last of the 3 radiators.

Another thing to try (though you should be very careful in doing so) is just to remove the radiator vent completely to see if the radiator gets hot. Keep in mine that it will spew steam (and potentially other crud) and might hammer a little bit if you do this. You can just do it to see if the very start of the radiator starts to get hot, and then quickly put the vent back on.

-Michael

ck quinn

main vents on one pipe system

I have a one pipe system with two mains serving each end of the house. One main serves three radiators, it is a short run relatively. These radiators are not working. I have replaced all vents. The main gets hot and two of the risers get hot, but the radiators just hiss cold air out the vents and remain cold.It has no main vent, but never has had a main vent and has worked for previous owners. I will install a main vent, but not at end of line due to difficulty of piping--I assume this will help, but it can't be the problem. Thoughts?