Location for #2 radiator vent

Luv'nsteam

I have added an additional radiator to the third floor, where none existed before.  I have calculated the venting needs of riser, radiator and run-out.  There is not enough space to place a tee on the riser and add a vent and then use a gate valve to the rad.  Also, the radiator itself has more venting needs then the riser, so venting the rad quickly is my primary goal. 



That said, the radiator I am using was setup and used for a hot water system.  The upper part of the end casting has a threaded hole for a bleeder and there is another threaded hole below that, that I presume is there for a steam vent.  I already expect to have to drill and re-tap the lower bung (reinforced & threaded hole) in order to install the new air vent. 



Now that I know a single vent (Gorton D) will not vent this radiator fast enough, I need to add a second vent, but where?  Will it vent correctly if I put an air vent in each of the bungs (this is the simplest way to add two vents that I can think of)? 



Or, if 1/8" pipe will vent .506 CFM, can I build I an antler to feed two vents?



Any ideas/suggestions/words of caution/etc, all greatly appreciated.



Thank you,

Mike

Paul Fredricks_3

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According to the venting capacity chart I have, 1/8" open pipe will vent 2.0 CFM @ 2oz.



A Gorton D will vent .54 @ 2 oz.  If the "D" is all you need then you are fine.



But you do need to vent this radiator from the lower tapping. It looks, in the picture, like there is one.

Luv'nsteam

One versus two radiator air vents

Paul,

Thanks for pointing out to me what I missed in the chart and the first listing to boot!  Oh well, I wasn't wearing my glasses and I'm sticking to that....



The radiator in question is two floors above the boiler and the second furthest away, as well.  The calculated number is below the venting of the Gorton D, but not by much.  With the calculated number combined with the geographical distance combined with being at the upper limit of vent capacity for the D, do you then think the D is still sufficient?  I wasn't sure, but with two holes to use or an antler with two vents, I thought using two would help.  I am not advocating waisting money either, I just don't want to cheap out and have performance suffer a bit because I was cheap or lazy.  Your thoughts?



Thank you,

Mike

crash2009

Tapp the riser

If you need a second D, tap the riser if possible.  A riser tapped D will get the steam up there quick, and then the radiator D will take over. 

Abracadabra

adding a second vent

Isn't there a spot for a vent on the valve side (opposite side from your picture) for a vent there?  the end sections for radiators are usually the same.  You can add another D to that valve side.  The benefit is that once the riser is vented and steam hits the first section, you close up that vent and vent the radiator just using the 1 D on the far side.

gerry gill

I would do...

what Abracadabra said.

Luv'nsteam

Considered thoughts

If I tap the riser and vent it, the short run-out to the rad plus the rad requires .473 CFM to vent.  At 2oz of system pressure, this is fine.  But what if I am able to run at a system pressure of only 1oz?  In that case, the Gorton D still does not cut it and frankly, if the system will work on 1oz, I prefer to run it at that pressure.



As for venting the input side of the radiator, I suppose that would work.  I will need to think about it from the point of steam, though.  The rad in the picture is a twin of the attic rad in question, but easier to photograph.  Does anyone know if venting from the upper tapping in conjunction with the lower is useless or worse, harmful?  Still not sure what way to go.  Great ideas, all.  Thanks!



Thank you,

Mike

Abracadabra

doubt it will work at 1 oz.

what type of a steam system is this? If it's 1-pipe, I seriously doubt it will work well at 1 oz. 

Paul Fredricks_3

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Yeah, you could use both tappings on the same end. It will get the steam to the top of the radiator quickly and then the lower vent will finish filling the radiator with steam.

Abracadabra

vent your radiators slow

"Vent mains and risers fast, vent radiators slow"







That is all.

Luv'nsteam

Great suggestions!

OK, so my system may not work at 1oz, I can deal with that, but was thinking about the 1oz pressure as it relates to venting.  But if it won't work, then that is pointless arithmetic and I digress from that system pressure as a variable.



I can vent the riser, should I wish to drill and tap it for the vent, but prefer not too.  This point becomes more prominent when I consider the radiator has more than ten times the volume of air than the riser and short run-out to the radiator.  Do you agree that venting the top of the riser is not a great benefit?



That leaves two other options:

Option #1) Place one vent at each end of the radiator in the factory location.  I am thinking that the vent closest to the supply valve will more or less vent the riser first, then some of the radiator before closing.  Then the second vent at the other end will vent the radiator as normal. 



Option #2) Place two vents on one end, opposite the supply valve.  One would be in the correct location and the other would be at the top, where currently is located the bleeder screw for hot water heat.



Which method is better? 

Does anyone have any experience with either setup?

If I go with option 1, do I use a radiator valve at each end?  Or, considering "vent mains and risers fast and radiators slow", would it be beneficial to use a main vent on the supply side of the radiator (if that's even possible?) and a rad vent at the other end? 



Thank you,



Mike

Abracadabra

venting

#1 - How big is this radiator?  Can we have a pic from the front?  Height? Width?







#2 - What is the size of the riser? If you are on the third floor, I'm guessing the riser is about 20-22 feet long.

#3 - Once steam hits the radiator, the condensing steam will create a vacuum that sucks more steam into the radiator. Don't worry about the volume of the radiator.  You won't know how it works till you try something.  You can always adjust a vent up or down.

I'd vent the riser with a Gorton or MOM "C" placed on the valve side of the radiator. I'd vent the radiator with a Gorton or MOM #5 to start and see how that works. Yes, use radiator vents.  No need to use a main vent on the riser.  Besides, main vents are 1/2" or 3/4".  Tapping on the radiator is 1/8"

Luv'nsteam

The numbers are..

Here are the numbers:

Riser to second floor: 10' @ 1 1/2" =          .140 CF

Second floor radiator:                                 .810 CF (Column, 3 verticals per section, 26” tall, 12 sections)

 

Riser from second floor to attic: 10' @ 1"    .100 CF

(no 1" pipe listed in chart, used volume for 1 1/4" pipe)

Run-out, riser to attic rad: 3' @ 1 1/4"         .030 CF

Attic radiator:                                               1.388 CF (Column, 3 verticals per section, 26” tall, 15 sections)

 

Initially, I wanted to vent the riser at the top and then each radiator, individually.  But because I do not have the space to add a tee and vent to the top of the riser, I decided to vent each radiator and its associated riser. 

 

Your thoughts?

 

Thank you,

Mike