Hissing and Spitting

P Eddy

Thanks to all who responded to my earlier post about my hissing vents. I've boiled them in vinegar to try and clean them - they're no more than two years old. And I checked the pressuretrol settings. The main is at 2.0psi, and the differential at 1.5 psi. But I awoke again this morning to hissing vents (not fun at 4:30 a.m.).

The vents make noise every time the radiators kick on, but that's a very light hiss as the air is being pushed out of the pipes. But this morning's hiss is much louder, and happens when the radiators heat all the way across. So I'm sure it has to do with the vents not closing. But I've checked the pressuretrol settings and cleand the vents. Not sure what else to do.

I ran down to the basement this morning when I heard the hissing, and looked at the psi gauge. Didn't look like it was moving at all. Weird.

Side note: The vents are adjustable. Got them at Home Depot for about $6.00 apiece. Think they are manufatcured by the Durst Corporation. Maybe they just don't work well, and I should buy some of the Hoffman 1A's for the bedrooms.

I'm ready to give up at this point.

jack_4

Hiss

Crank that pressure down to .5 and the diff wheel to 1 for starters. If your post is correct you have the high end set to be 3.5 psig. This is higher than the drop out points for most vents.

The long hiss is likely the pressure drop as the radiator is cooling down and one vent has to open and allow all the air to suck back into the system as the last of the steam condenses back to water.

When the suck back happens you will not have pressure on the gauge.

Get those adjustable Home Depot vents off and go to a real plumbing store. I must pull 10 a week off systems. They are just trash.

chuck_6

Hissing and spitting

I agree about taking the adjustable Home Depot vents off. You should try Gorton vents. Their phone number is (908) 276-1323. Speak to Ken Kunz and he can go over which number/letter vent you need on each radiator and he can tell you where the nearest distributor is. The Gorton vents will help immensely.

Steve Todd

it's inhaling, not hissing

I have a similar HO situation. The scenario: early morning, house is cool. Thermostat kicks on, furnance goes on, makes steam, rads get hot, rad-valve hiss a bit. Temperture met and thermostat kicks off. One, two minutes pass. Then loud 'hiss' at a rad valve. Put one-sheet of tissue paper near valve's hole: see tissue paper sucked against valve hole. It's inhaling.

I'm half way through Dan's book but I thinking [a] I need a new main valve since I've never heard it exhale pre-steam air and it's the main-valve closest to the loud inhaling rad-valve, and [b] I need new rad-valves throughout this 1929 house (they hiss on-and-off even once the rad is fully hot).

What do you guys think? Thanks.

Steamhead

Inhaling

This is due to vacuum forming in the system as steam condenses after boiler shuts off. There are two things that will help. 1- crank the pressure down. It should cut out at 1-1/2 pounds max, back in at 1/2 pound- this will avoid compressing so much steam in the system. 2- Insulate all the steam pipes- this will eliminate steam condensing in the pipes.

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Steve Todd

thank you

Thank you Steamhead. The pressure is set to low (.5 / 1.5 lb) -- I'm assuming the inexpensive-looking Honeywell control is accurate. But I'll screw it down a little lower. Most all the pipes are insulated and the insulation has not been changed recently but -- ah! pipes to those loud rads do go through an extra-cool crawl space (especially with this colder-than-average weather). The weather has changed!