New HeatTimer VariValve vent leaking

DefinitelyNotAWizard

I just replaced some old hissing vents with HeatTimer VariValve vents. The new vents are leaking a very small amount - about one to two droplets of water per cycle (so little most of them are not even dripping). I used Teflon tape and ensured it is going in the proper direction. Is there a better sealant I should be using or something I’m overlooking? The old vents did not leak at all.

Dan_NJ

So the leak is coming from the threads where the vent screws into the radiator? What vent was on there previously? It might just need another turn to seal properly. From the picture It looks like that Varivent is fully open, or close to it. The vent rate on that is going to be very high - like 3 times that of a wide open Ventrite #1 or Hoffman #1a.

Gsmith

Try closing the vent all the way, these vents are almost always too fast for normal sized radiators

SteamingatMohawk

When Varivents are shut they still vent at an equivalent of a #5.

SteamingatMohawk

Go see the latest or nearly latest entry in "Why can't I get the two sides of my house heating at the same time?" Attached is a spreadsheet with a table and chart of vent valve capacities.

Pumpguy

Are you sure the threads on the old and new vents are the same?

Typically, these are 1/8" NPT, but I have seen reports of some vents having undersize taper threads, straight threads, or even a different thread altogether like BSPP, British Standard Parallel Pipe.

If threads are 1/8 NPT, it might be helpful to run a tap into the hole just to clean up the threads, and then re-install the vent. Just don't go too deep with the tap and make the tapped hole oversize.