How much venting would you recommend for a 2" X 74' main?

SwedishPimple

Hi all-

Given a one-pipe parallel flow steam setup with single main.

How much venting (number and type of vents) would you recommend for a 2" X 74' main?

I've currently have 2-Gorton #2 and 1-Gorton#1 in place on my antler... but I've never really done the maths.

I do know that my venting is worlds better than the single Hoffman 75 I had before... but

Is it enough?

Thanks!

S.P.

SwedishPimple

Thanks for the info! It sounds like I have my main venting needs covered.

Interestingly enough the steam still takes 3 min. 30 sec. to close those vents on a dead cold start... timed from the time steam first hits the header. But, I have a feeling that most of that can be chalked up to my need to insulate the mains and piping after the new boiler install.

Thoughts?

S.P.

gerry gill

The time lag is due to steam condensing in the cold pipe..the math can't take that into account.

SwedishPimple

Thanks guys... this is good info.

I don't feel bad for having extra venting on my mains. Not only does it give me backup capacity should a vent fail. But, I also did notice an improvement going from 1-Gorton #2 to 2 on my system. The same cold start to vent closing time went from 4 min. to the 3:30 I noted before. Maybe it was a flaw in my testing methods, but I did confirm my findings it with multiple measurements?

Anyway...

I will do the timings again after I have insulation back on the mains and the header. I am expecting to see a significant improvement.

I'll update this thread again once that testing is complete.

S.P.

SwedishPimple

Hi BC-

I agree completely with your points. In fact, the impetus for my original post, was an attempt to confirm that I had enough venting in place. Now that I have that settled, I can move on the improving efficiency in other areas of my steam system (insulation, etc.).

You're right, there is a point at which the gains aren't justified by the expense.... and those Gorton #2's certainly do add up quickly in price. Diminishing returns indeed!

S.P.

nicholas bonham-carter

The benefits of having enough venting lie not just in the reduction of time needed to get the steam to the end of the main as quickly as possible, but also in making sure that all radiators fill with steam at the same time. You are trying to achieve a balance of main vent low resistance with radiator vent resistance (slightly higher back-pressure).
If you put a counter on your boiler to record the number of times it starts up in a year, then I think that the shortened total running time would well compensate for the cost of the extra vents.--NBC