Want to add vent to riser

ChrisJ

Thinking about adding a vent to one of my second floor risers.  1 1/4" pipe which goes to a valve and then through a 45 ell to the radiator.  Radiator is vented via a  Gorton 4 and a Danfoss TRV.  Reason for the slow venting is if I go any faster it seems like too much for the TRV to handle.  A Gorton 5 worked, but seemed too fast for this specific radiator and caused more overshoot than the 4.

 

I think by venting the riser with maybe a Gorton 6 straight vent which I have on hand, I may stablize temperatures even more especially on warmer days.  Or, on windy nights like last night where it couldn't keep up.



Does this sound like a good idea?  If so should I drill into that 45 deg ell, or try to adapt the valve for a vent?  I have an 1/8" pipe tap on hand as well as a 1/4" pipe tap.  I'm assuming whether I adapt the valve, or drill into the elbow I'm going to need to use oil with the tap? (ugh).



Please don't mind the dust, or the apparent strip of cardboard laying on the pipe.  Apparently I need to vacuum there.

Rod

Tap the 45

Hi Chris- I'd just tap into to top the 45 deg. elbow. If it doesn't work satisfactorily then you just close it with a pipe plug.

- Rod

Hap_Hazzard

I'd drill & tap the elbow.

Take the union apart and stick a rag in there to catch the chips and the cutting oil. Use the oil for both drilling and tapping.

ChrisJ

Ugh

So trying to avoid this I tried putting a Gorton 5 back on the TRV and this definitely seems to mess things up.  I think I have no option other than to drill and tap the elbow and install a Gorton 5 or 6.  This way I'll get the steam up to the radiator in a reasonable amount of time and then allow the radiator to vent slowly with a Gorton 4 giving the TRV time to react.





Does anyone feel this is a BAD idea and I shouldn't do it?  Am I going too far (as usual) or does this make complete sense?



Also according to what I see I need a size Q drill bit for an 1/8" NPT hole, is this correct?

Bio

Trial/Error

I think If you are already running at very low/no back pressure, by adding a riser vent may throw things off balance, this riser may steal steam from other risers/radiators, like said before you can always plug it back in

ChrisJ

stealing

Hi Bio,



Yea, that is a big concern of mine.  When I used a Gorton 6 on this radiator my bathroom radiator didn't get much steam.  I'm assuming by venting only the riser fast and the rad slow it should be ok.   Unfortunately I've been wrong before, actually, a lot.

cn30

drill size

According to the chart I have, you need an 'R' drill bit. I couldn't find one (I was also tapping an elbow) so I used an 11/32 bit. It's a little too big, but it allows the tap to go into the hole a bit before it starts cutting, which made it easier to keep the tap perpendicular to the pipe.

Rod

Tap Drill Sizes

Hi Chris- For a 1/8-27 pipe tap -  some charts recommend a "R" and others a "Q". I go with Mc Master Carr who recommends a "Q". Check the tap as sometimes the correct drill size for that tap is engraved on the tap. You could probably use either an "R" or a "Q" .   The 11/32 might be a bit on the sloppy side depending on how much play there is in the drill chuck.

- Rod

21/64  =  0.3281

"Q"      = 0.3320

"R"      = 0.3390

11/32  = 0.3438

ChrisJ

The dirty deed is done

I drilled and tapped with success. 

It came out really good the only problem was the letters cast into the elbow ended up being a highspot.  This spot tears teflon tape off of the vent before it even vents into the elbow.  So, rather than do the right thing and grind it off some I decided to use pipe dope, though I did so very spareingly but it seemed to go into the threads much better than the tape.  Perhaps this is why dope works better than tape someitmes.



FIred up the system with the TRV closed just to see how it works out, I'm hoping the radiator won't heat atall but will settle for very little.