Single pipe steam question about vent settings in mains versus in radiators.

Roddy

A while back when reading a thread, the comment was made that "I like to vent my mains as quickly as possible, but for my radiators I usually go with the smallest (lowest) settings, e.g. a setting of one or two depending on location of radiator." I think I've got all my vents extremely well vented (lots of venting on mains and large venting on radiators). Am I wrong? It's all working, but in milder winter weather I sometimes have to shut off some first floor radiators to get enough warmth to the second floor radiators. I'd appreciate your comments.

Jamie Hall

If it ain't broke… but in your particular situation, you might try slightly slower vents on the more ambitious first floor radiators and see if that helps.

The thing about venting on one pipe systems is that the main vents and the radiator vents really serve two very different purposes. The main vents exist to allow the air out of the steam mains as rapidly as possible. Now there is a very real upper limit on how fast that can be — since the main factors slowing the steam are both the air and having to heat the pipe — but other than cost it's really hard to overvent a main.

Radiator vents, on the other hand, are selected to control how fast a particular radiator heats. Now they do interact with each other, which is unkind of them, but the general rule is if one is faced with some radiators too warm and others too coll you slow down the warm ones (smaller vents).

Now one can get fancier — in some rather rare but not really uncommon situations, a long riser or runout may just plain be slow. In that situation, it is best to add a vent before the radiator which is nice and big, and still use the radiator's normal vent to control its heat output, rather than trying to make the regular vent do double duty.

EBEBRATT-Ed

@Roddy You do what works for you.

The first rule is to vent the mains as fast as possible. If you have multiple mains, try to get heat to the ends of all the mains about the same time to prevent balancing issues.

As far as the radiator vents go its a compromise. You want to vent them as fast as possible BUT you want them to be balanced and heat at the same time and slower venting will help if you have spitting and hissing issues. Slower venting the rads may make balancing easier but you want to avoid the lowest settings if at all possible.