Size of Main Vents

Pete123

I have three mains coming off my boiler. 2 are 30 feet with 2 1/2 inch mains and one is 25 feet with 2 1/2 inch mains. I have 1 Vent Rite 35 on each main. Does that sound correct?



Also, I have three very large radiators that sit under the floor, in the basement (that heat the first floor) and they appear to be two pipe radiators. Each of them has a very long, thin stem that leads to a vent that requires a 1/2" female connection. Any recommendations for those?



Attached are some pix of the undermounted radiators, the attached vents, and the boiler.



Thx!

nicholas bonham-carter

recessed radiators

ventrite 35's are very slow. i would start with a gorton 2 on each main, and be ready to add more on an antler as needed. if you time the arrival of steam to the end of the main, before and after new main vents, you will see some difference in the times. faster steam=shorter running times=less fuel burned. basically, you are trying to approach the speed with which steam would travel down the main, if there were empty holes, with no vents in them.

what vents are on the recessed radiators now? once the main vents are installed, the preexisting radiator vents may be fine, as long as they are not too fast. hoffman 40's are a good start for the radiators.

also, download the manual for your boiler, and compare the required pipe sizes for it, as it looks like  non-standard piping for that boiler. once you are satisfied with the piping, insulate them, so all the steam will get to the radiators, and not be condensed in the pipes.--nbc

Pete123

Gorton or Hoffman?

What would be the equivalent Hoffman Main for the Gorton Main? Which is better and why?



Also, for the vents on the radiators, they too need to be 1/2 inch female (not 1/8). I think the Hoffman 40's are 1/8. I think what is on there now is a Dole 3C and a Dole 1933



THX!

Rod

Main Vents

Hi- For a rough comparison at one ounce of pressure:

3 ea. Vent-Rite #35 vent   = 1 ea. Gorton #1

3ea. Gorton #1 = 1 ea. Gorton #2

2 ea. Hoffman #75 = 1 ea. Gorton #2



The above figures are based on Gerry Gill & Steve Pajek’s Venting book which is available as a downloadable “E-book” from the Shop section of this website. Here ‘s a link:

http://www.heatinghelp.com/products/Steam-Heating-Books/25/146/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-by-Gerry-Gill-and-Steve-Pajek

It’s an extremely useful book which I use constantly for reference. Gerry Gill is an extremely experienced Cleveland steam pro! You might also want to take a look at his website as he has a lot of  information on steam heating and especially on venting. Here is a link to his website:

http://www.gwgillplumbingandheating.com/



Both Hoffman and Gorton are good quality main vents. You can get them at you local heating supplier or at Pex Supply on the internet.



On the radiator vents-  Not sure what to tell you on this. The Dole 1933 is a very slow vent, It has about 1/3 the capacity of a VentRite #35. The attachment size isn't that important as you can use adapter fittings to get match the vent to the vent pipe.

There are several Hoffman vents which would be in the range of the Dole 1933..

- Rod