Posted by Tony Conner, TBP Industrial Steam Systems on December 28, 1997 at 21:02:12:
In Reply to: Re: Re: Re: New boiler system over-pressure posted by Dale Van Aken on December 28, 1997 at 15:20:46:
: Tony: Thanks for the informative response. I should explain the piping: The main manifold is 1 1/2 copper. It feeds six zones (only 3 in use) - each 3/4 copper. I meant that when only one zone is calling, the pump (Taco 011) is driving the loop through a long run of 3/4. Seems like this would create resistance on the inlet side and a lower pressure near the make-up feed. Following is the piping: Outlet from boiler, make-up feed, T-fitting splits into 2 main loops. Hot water loop continues through indirect tank and rejoins the inlet. Hot water loop goes thru check valve, expansion tank, then supply manifold. Seem like a reasonable location for the make-up water? P.S. Where can I get a copy of the book to which you refer?
Dale: Dab Holohan has written a series of soft cover books on steam & hot water heating. They are cheap, easy to read, and you can buy them right off his web site: "www.danholohan.com". He has 2 specifically on hot water: "How Come?", which is a question & answer format, covering hot water heat from the end of the last century, until the present, and "Pumping Away", which is more focused on modern systems. They are both excellent, but if you're only getting one, get "Pumping Away". I'm still a little fuzzy on how your system is piped, but if the make-up water feeder isn't located on the short section of pipe that connects the air separator & the expansion tank, this could allow the feeder to be affected by the circ pump. Dan's books explain it much better than I can. To have things work the best: the circ pump(s) should be located on the boiler outlet ("pumping away"). Between the boiler and the circ pump should be the air separator. Off the air separator should be a short section of pipe the runs to the expansion tank (the point of no pressure change). The make-up connection is between the air separator and the expansion tank. It' not that other configurations won't keep your house warm, but if you hook it up like "Pumping Away", you can avoid a lot of annoying problems. Tony