Thoughts on One Pipe Vents

Nick_C

I replaced my boiler in 2008 in connection with a major house renovation.  Some radiators were moved as part of the process.  Everything was eventually done correctly (in no small part due to the guidance from this board and from Dan's books).  I have gone through one full heating season and am more than half way through the second now.  When I redid the system, I had all the radiators sand blasted and refinished.  I also, of course, took the time to replace all the vents.



Total sq ft of rads is about 1300.  A total of 19 rads and 4 convectors.  As a bit of a test, I used a combination of VariValves, Hoffman 1A and straight Gorton D vents.  I used Hoffman 75s as the main vents -- I just trusted the design better than Gorton #2s.  The Hoffman 75s have been great.



So far, every single one of my VariValves has failed.  Almost all of them become stuck closed or mostly closed.  Even when working, they spit like a camel.  Note that I have very dry steam and run at 1 to 2 oz of pressure.  I have a vaporstat that kicks in at 5 ounces and it almost never kicks in as the t-stat is satisfied before I get much over 2 ounces unless coming back from a setback of more than 6 degrees (vacation).  The water simply didnt want to drain out of these VariValves.  All of the Hoffman 1As and Gorton Ds continue to work perfectly.  Haven't had a single one fail on me.



I have since replaced all of my VariValves with Hoffman 1As.  In a couple of cases, due to the size of the radiators, I tapped the rads and put in a second 1A vent to get similar venting capacity of a VariValve.

I really wanted the VariValves to work.  They are small and don't "clank" like the 1As do when shutting.  But, at least for my system (which runs great), they simply didn't work.



Just my thoughts.