boiler bypass and circulator

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Try this link. Ps piping is a wise method. it may, or may not provide adequate protection, however.

http://www.pmengineer.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2732,90176,00.html

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IIM

boiler bypass / circulator placement on conversion job

I'm working on my old Victorian house that has a gravity converted system with an oil burner (single zone; heat only, hot water is on separate gas burner). Due to a number of reasons I am doing some serious repiping (restoring the period radiators and replacing the "replacement" newer ones with period ones), including redoing the near-boiler piping (it is a mess; for starters, it had nothing for air elimination/venting, too small expansion tank, etc).

I have a question related to placement of the circulator and the boiler bypass. I will put the circulator on the supply line, and the air eliminator upstream of it, but where should the bypass to the return line go? If downstream of the circulator, it pushes into the return and works well to prevent low return temperatures to protect the boiler from condensation/thermal shock; if upstream of the circulator (as in the boiler diagram), it sucks from the return and works well to keep the system somewhat less hot while the boiler still is in optimal range. Both reasons seem appropriate given the oversized radiation and the large system/boiler mass ratio. Which should I be more concerned about? Thus where to put the bypass in relationship to the circulator? And also, to use or not to use a flow-check (that might depend on the decision of the bypass functionality)?

Any info would be appreciated.

Rich P.

primary/secondary

Hi
When I get the opurtunity to work on an old gravity system
I like to pipe the near boiler piping primary secondary for 2 reasons. Less likely to cause flue gas condensation and to even heat distribution. A basic way is to run the system circulator continous, and a call for heat would turn on the boiler pump, increasing the system loop temperature slowly. I think this is a simple way to avoid overheating of the radiators/ rooms. This is basic it could get way more interesting from this point on.
A system bypass is good, but even distribution is more what your after. Hope this helps
Rich P.

clammy

air seperator

Your air seperator should be on the suction side of your pump .You should have a flow check on the outlet of your pump or use a circulator pump with a internal flow check built into it also use a set of isolation flanges on the pump instead of having to drain the system to replace a pump . As for a bypass i would do a system by pass which means you are by pass the system and tempering your return water so you don't shock it also if it is oil use a triple aquastat with a low limit circ so when the boiler falls below your set low limit the burner will contiun to run but it cycles the pump depending on how large the system is a 3/4 by pass line should be fine if your using a triple aquastat.You should if you haven't read some of dans books to futher understand pumping away and gravity conversion also check out hot tech topics peace and good luck clammy