Got the vent guide, still need reassurance calculating my rads air volume

Jeffrs

So I bought the venting steam ebooklet to figure out how big my radiator vents should be.

I've found charts on how to find EDR sqft. Based on height and sections, but a few questions.

1. My rads I believe are old column style. Based on info I've read off sites, it appears 2 sections = 1 column. So an 8 section radiator means 4 columns, is this correct?

2. My rads are all 7 or 9 columns, so how would I figure how many columns?

3. Finally, I attempted to calc one rad by measuring it, here's what I got:

9 sections, I went with 8, it's 11.5" deep and 26" high, according to this source:

<a href="http://www.heatinghelp.com/files/posts/16023/Boiler%20Sizing%20Chart.pdf">http://www.heatinghelp.com/files/posts/16023/Boiler%20Sizing%20Chart.pdf</a>

I get 5.00. I multiply this by number of sections, 8 and get 40 EDR sqft. I then divide this by .025 for column rad and get 1. Then divide this by 3 based on number of minutes to vent all air from radiator and get .33. Comparing this a D size vent would work.

Can anyone confirm if I'm doing this properly?

Thank you tons. Sorry if this is dumb questions.

nicholas bonham-carter

venting calculations

concentrate on the main venting first. add enough venting so the resistance to the air escaping is very low. if your radiators are very big, or at the end of a long riser, then put a hoffman 1a on, on others use the hoffman 40. do not follow the Gorton company advice blindly on vent selection.

what you are attempting to do is fill the mains with steam at low resistance, and then when those main vents close, the steam will start to rise into the rads simultaneously. the venting tables are useful, but the best result comes from trial and error using a 0-3 psi gauge which will show you the back-pressure of venting.--nbc 

Boiler Talk

Also

I second NBC about what is really happening.  Calculations are helpful for "proofing" your needs, but sometimes, as the booklet advises, radiators and pipes steal.  As you see there are three columns: 1 oz, 2 oz and 3 oz.  As I understand it you need to consider using the 2 oz column after your main venting is verified or maximized.  Unless you add vents to your risers, then you would use the 3rd column. 

Jeffrs

Yup just recently added main vents

I was looking to replace my rad vents because half of um are leaking under steam pressure, so I was looking to confirm whether the right sizes were at least somewhat close to radiator size.

In any case since we're on main vents, I had added 5 of them to the system. They seem to be helping, but I still am late to get heat in my kitchen as oppose to everywhere else. This is on the longest run so I put 2 on an antler for this run as oppose to 1 for each other. Doing the math based on pipe size and length it appears that I should have enough venting for the run. But it's slower to get to these main vents then the others. This radiator uses a two pipe system with the return, returning to the wet loop and 1.5" piping. The other main uses 2" with 1.5" branches.

Any suggestions?

Thank you guys

nicholas bonham-carter

leaking under pressure

something must be wrong if you have any vents leaking under pressure.

get a good low pressure gauge [0-3 psi], and get your pressure under control [1.5 psi max] before getting any new vents.--nbc

Jeffrs

No gauge yet

I havnt added the gauge yet. But watching my 0-30, (I know this isn't the most accurate) I only build pressure after a large set back or if its very cold out. When I do it shuts down at 2 the highest and cuts in at a half. Pressuretrol is set at lowest, at 1. So I don't know how much pressure I'm building at a normal cycle, but I can tell that my pressuretrol is cutting out fairly close to where it should be and cutting back in where it should. Also my new main vents do not leak. I would think if my rad vents were leaking due to pressure too high, they would be leaking as well.

nicholas bonham-carter

leaking main vents

what make of vent can leak at 2 psi?

are the radiator vents making any noise?

either the vents are defective, or the gauge and pressuretrol are suspect.--nbc