Wet hissing

DeeJay3

Hi. I have a single pipe system and the rad furthest away from the boiler drips from the valve and has a wet hiss coming from the vent, which is fully open Hoffman.



Are these two situations related? Will repacking the valve stop the leak? Will it stanch the hiss?

nicholas bonham-carter

hissing and dripping vent

can you think of anything which has changed, lately to cause this or has it always done this?

1. check your pressure with an accurate low-pressure gauge [gaugestore .com 0-3 psi]. pressure over 1.5 psi might be to blame.  actually every ounce of pressure over 8 oz. is costing you extra money.

2.check your main air vents on the supplies. these should do all the work, otherwise the radiator vents will cause extra water to be pushed towards them, with wet result.

3.don't use an extreme nighttime setback, as the energy used for recovery negates any previous savings at the lower temperature, and can make the boiler run long enough to aggravate #2.

there are some books available in the shop here which are well worth having for your being able to diagnose/maintain your system:"greening steam", and "the lost art of steam heating"--nbc

DeeJay3

Response

Mr Bonham-Carter, I checked the vent off the boiler and I did not detect any escaping vapor while the system was boiling. Should that be always venting when the system is boiling?



The pressure gauge was at or awfully close to zero.



I corrected my nighttime setback last year. I think I'm at 68/66 or 68/65

nicholas bonham-carter

no steam from vent hole

if you remove the main vent, and fire the boiler, then steam should flow out from the vent hole, so if not, then could there be a low spot, with pooled water trapping the air before the steam gets to that location? be careful of steam as it burns deeply!

with a level, check all the lines  leading back to the steam main on the boiler, to see if you have a sag somewhere.

in addition, your gauge, while still showing close to zero, is not really accurate enough for steam systems such as mine which does its best work a little above 2 ounces. see if santa will stop by gaugestore.com on his way to your chimney, and leave you a 0-3 psi gauge, which must not replace, only sit along side the 0-30 psi gauge.--nbc

jpf321

i think ...

his concern is more with the dripping supply valve .. which can be repacked by getting some "graphite valve packing" from a plumbing supply store, loosen the top nut closest to the valve stem .. push up the nut, jam in some packing, tighten nut.



NBC's comments may have more relevance with regards to the hissing vent .. sounds to me that perhaps it's just not closing all the way...try boiling in vinegar, squirt a dab or two of WD-40 or replace vent with like kind. A hoffman should snap closed and not leak/hiss. Are you sure it's not the dripping valve that you hear hissing. Perhaps fix that first then attend to vent.