noise and water line issue

sig

I have a 1 pipe system where the main runs around the basements and pitches back towards the boiler until it drops down into the return. Also there is a tee just below the elbow for the piping described above that pitches away from and feeds a single radiator. The radiator vent seems to hiss constantly (it's been replaced) and there's noise, giggling and some banging in that line. The water line in the boiler also pushes down to nearly the same level as the Hartford loop tee but returns to normal after shutdown. Other observations, there's a 15' section of the 1 pipe system line that is nearly level and possible back pitched for a bit (but there's no banging in that area), the equalizing leg is 2" and the installation instructions call for 1 1/4", the return is lower than the boiler but it can go 5" lower if needed, a new 14,000 btu radiator was recently installed which replaced a 8,000....it's working fine. Homeowner says the hissing and noisy radiator existed before the new radiator but the banging is new. Of course the contractor who installed the new radiator will not go back.

ethicalpaul

The tee that feeds the new radiator is on the vertical of the dry return? I think I'd love to see pictures of this to better understand, and probably others would also.

nicholas bonham-carter

That line probably replaced the main vent!
No doubt, high pressure and no main venting is to blame here.—NBC

sig

The tee is on the vertical supply just below the elbow that starts the one pipe system. I think the line feeding the single radiator would be considered counter flow piping. So there's a mix of the one pipe and the counter flow. The new radiator was a replacement of an existing on the one pipe system. The main vent is a an adjustable radiator vent on 1/2" and it looks like it's been that way for many many years.

ethicalpaul

Ahh OK from the way I read your description it sounded like the tee was on the dry return.

If it's a tee that's been put in the wrong place on the near-boiler piping, it could be picking up water or who knows what. Can you send a photo from a few feet away showing the piping near the boiler including this tee and its radiator line?

sig

Sure I'll send pics tomorrow. Thanks!