Varivalve Quick Vents & Hissing

cleocleo

Just replaced the vents on all of my steam radiators with varivalve quick vents. Overall, the system is working well and all radiators are heating up evenly. However, I've noticed a few times per day one of the valves releases a very loud hiss for 2 seconds and then stops (can hear it from another room). Seems like the pressure has built up and the first valve the cool off makes the sound. Is this normal?

BobC

What kind of vent are using on the steam mains in the cellar? It sounds like that radiator valve might be doing more work than it can.

Varivalves are very fast and they can cause problems if they are used without careful thought. How far ioen are they? Check the radiators and make sure they aren't just hot across the top. If you vent a radiator too fast the steam can just shoot across without filling the radiator with steam, then the vent closes and you don't get all the geat you should out of that radiator.

Bob

Dan_NJ

I had similar result with a medium sized radiator closer to the boiler in that it would open first after a heating cycle ended and relieve the vacuum that was present from the collapsed steam. I've since replaced with Hoffman 1a's and they are working without the big hiss.

Fred

It sounds like that vent opens before the Main vents do and you are hearing air being sucked back into the system to break a vacuum. What type main vents do you have and do you have enough main venting? I don't like the Varivalves on radiators. They tend to vent too aggressively.

cleocleo

Just checked and don't see any main vents in the basement. Heating a 1st floor condo (1000sqft). If the system is small enough are no main vents used?

BobC

The lack of main vents is serious, without them balancing the sysrem becomes very difficult. Are there any spots towards the enf of the steam main where a main vent might have been changed to a plug?

Bob