Drill/taping second vent to hard to heat hot water (steam) rad

scottie_2

Dear All,
I need some advise on adding a second air vent on a hard to heat hot-water type steam radiator. It is a Weil-McLain Cameo three tube 60 sq ft ERD radiator. I would like to drill and tap another hole for an additional vent. I bought another tap 1/8" NPT because my automotive tap collection is useless in this application. I have drilled and tapped cast iron before, but wanted to check with experienced people before ruining a good radiator in the middle of winter.

My question is, where would be the best place to drill and tap this additional vent? I noticed the original vent has a raised boss where it screws into. That suggests to me that the rad is thin in that area? I attached pics of the rad. I was thinking of drilling where the tubes intersect each other in the middle of the rad, above the original vent. I also noticed the boss where the hot-water air vent would go at the very top of the radiator, could I just remove the plug and put the new vent in there?
Any suggestions as to where you would put it would be greatly appreciated.

kevin coppinger_4

before you ...

do that why not try a Gorton D vent to turn up the venting rate? the one you have is smallish....kpc

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Norm Harvey

No No No!!!!

Dont tap that top tapping!!!!!!


Instead try a larger vent or tee off the current vent to accomodate a second one. Your undergoing a risky procedure when all you need is an 1/8 tee, elbow, and some nipples

Unknown

scottie

This rad may be slow to heat because of its location along the main,,is the main vented at all?

scottie_2

yes the main is vented. Im in the process of repiping the near boiler piping, thats why I haven't changed any rad vents yet. Figured Id wait until that is finished until I tackle the uneven heating. I read so much about double venting big rads and wanted to know more about it. Dan talks about it in his book, but gives no details about actually doing it. I looked on the wall, and did not find much about tapping the rad for the extra vent.
Thanks for the help.

Norm Harvey

no need to double tap,... remove the current vent and come off the rad with a 1/8 nipple into the branch on a tee. then install a vent in each of the runs of that tee.

scottie_2

Thanks norm
Not do beat this to death, but would you ever need to drill/tap a radiator? Maybe Dan was referring to the old large column type steam radiators?
thanks again

Norm Harvey

The only time you would have to drill and tap is if you were converting a hot water radiator and needed to install a vent lower for steam.

Thats my opinion anyways. Limit the risks.