Main vent location and vent whistling

Steve Garson_2

In my continuing quest to solve the case of the whistling vent, which occurs when the boiler shuts down. It never happened with the old steamer.

1. It was suggested that the feed pipe to the radiator might not be insulated. I just cut hole in my ceiling to reveal that the pipe is insulated.

2. I reduced the vent size and this changed the pitch of the whistle, but did not eliminate it.

3. The system originally had a main vent at the end of the dry return, where the pipe headed to the floor and wet return. Before installing the boiler, last year I installed Gorton vents at the end of the main. Might this be the problem? (I doubt it:) Today there are two Gortons at the end of the main and one at the end of the dry return.

If there is someway to get the Gortons to open when the steam cycle ends, I'm sure that would solve my problem. If I mounted them on and ended nipple, perhaps with an elbow or two, might that help it cool down quicker and allow air into the main?