Riser takeoff

Abracadabra

I have a riser takeoff, piped by deadmen that tees off horizontally from the main. This is not correct is it?  I thought riser takeoffs from the main needed to pe piped so that the takeoff is at a 45 from horizontal.

gerry gill

its not a good way to do it,

but i've seen it too..always remember that there was usually a coal boiler present and that made the system behave differently..slow steam delivery, really only heavy initial start condensate load once in the season, since you can't really shut down the boiler.

crash2009

45

Yes, I just finished reading that chapter again.  Page 87 The Lost Art of Steam Heating.  I was in chapter 7 for the entire month of December.  I hate reading. 

Dan, When is the book coming to the big screen?

Abracadabra

...

Gerry,

What problems would I encounter now? Would this give me a problem of little to no steam coming out of that tee?  Any suggestions to get more steam coming out of there short of repiping the thing?  Right now I'm getting pretty much all of the steam thru the run of the tee and basically nothing out of the branch.  I'm thinking of tweaking the venting downstream of the tee so that some of the steam will take the branch.

If I have to repipe this, I don't have much headroom to pipe the tee up 45.  Can I use a wye, with the branch of the wye flat?  I'd think that would help direct some steam into the branch.  What do you think?

Thanks much!

Dave in QCA

Vent slow for balance

As BoilerPro reminds us, Vent your mains fast and your radiators slow but completely. 

Before I even thought about repiping, I would slow down the radiator venting.  Slow venting of the radiators can do wonders in correcting balance problems, even in cases where the piping is less than perfect

Abracadabra

slower venting of rads

Yeah, I'm beginning to see that slowing down the venting of the rads might be necessary.  Of course this flies in the face of what TLASH says (pg 111-113) regarding faster venting of rads and even doubling up vents instead of halving others.  I just went thru and revented all the rads on this building too. gah!!!

Dave in QCA

boilerpro's article on venting

You probably have already read this article, but if not, I am posting a link to it.  It explains his theory on venting.  http://www.heatinghelp.com/article/323/Boilers/1551/Taking-Another-Look-at-Steam-Boiler-Sizing-Methods-by-Dave-Boilerpro-Bunnell    



Also, there is some information in either Greening Steam, or The Lost Art of Steam Heating on the subject, "can you vent a radiator too fast?"  The author explains an interesting, if not mind boggling example where this was the case.

Abracadabra

venting slower

Heh.. yep, read both of those.  Always thought venting slower was crazy :-)  Now that's it's happened to me, I've changed my mind ;-)

crash2009

Horizontal takeoff

ChrisJ was having some trouble with one of his vents flooding, to the point of not venting anymore.  He followed the riser back down to the basement and found a near horizontal takeoff.  It was slightly pitched but nowhere near 45, not even 20.  Don't know if this would apply to your difficulty but his was the first takeoff from the boiler.  I don't think this is a common problem.  Is this related to LR1, LR2, LR3? from your other post

Abracadabra

..

yes.. both LR1 and DR1 are fed with runouts that come off the side of the main. There is very little to no headroom for the runout to be fed at a 45.  I'm thinking the 2nd and 3rd floor radiators are stealing steam from the 1st floor.

Mike Kusiak_2

Takeoff location

The horizontal takeoff might affect the return of condensate, but I can't see how it would prevent steam from getting to the first floor radiator unless it was pitched wrong and condensate was blocking the pipe. But if that were happening you would also have water hammer which you don't mention.



In your previous thread you mentioned that the first floor rad was heating quickly and all across, so why to you think that takeoff is not getting steam? Do LR1, LR2 and LR3 get equally hot at the same time? If they, don't then I would experiment with the venting before contemplating anything else.

Abracadabra

...

The radiators in the 1st thru 3rd floor living rooms are ok, most likely due to a 2-1/2" horizontal takeoff.  Even if the pipe has 3/4-1" of condensate running back against the steam, there's still 1-1/2" of room for the steam to sneak thru.  The radiator in the 1st floor dining room is the one that's giving me a problem. These are very large radiators. 18 section 3 column 32" high.  If my calculations are correct, we are talking about 81 EDR per radiator per floor. 243 EDR on each riser. Maximum EDR on a 2-1/2" takeoff (horizontal runout) is 260 EDR. so I'm right at the limit.  Any amount of condensate returning will reduce the amount of steam I can get going back up.  The dining room rads are a bit smaller. Total EDR on the dining room riser is 162, but the takeoff here is only 2" which is a max of a 165 EDR.  I've got an even smaller margin of error here and the takeoff has very little, if any pitch, so condensate returning is a bigger problem.  There's no hammering, so I'm not getting any pooling of water, it's more of a concern of the condensate returning while we're in a heating cycle.