pri/sec piping question

chuck shaw

what will a ball valve (open, used for purging) do to the pressure drop, and how will it affect the boiler loop.

thanks,

chuck

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It's a problem, Chuck

depending on the ball valve, of course. You want that pressure drop between the tees as small as possible. Even a full port ball valve presents SOME drop. I like to get the tees, or better yet T-Drill take offs as close as possible. Less than 4" if possible.

Plenty of ways to install purge ports after the primary loop take offs.

Here is a job we rebuilt a month or so ago. For 8 years this job has been plagued with overheating zones. The 3 way valve take offs from the primary loop are way too wide. But worse were the 1-1/4" reduced port ball valves! The hole in the valve was about the diameter of a dime! It was acting more like a monoflo tee

The second pic shows the method I like for purging secondary loops. I install a Watts purge cock valve on every take off, return side. This allows easy and complete purging of indivual zones. With ball valves on the radiant manifolds you can actually purge loop by loop if desired. Not much more money than a ball valve between the takoffs on the primary loop and eliminates two potential problems.

Notice the T drilled secondary take offs closely spaced and going two directions from the primary loop.

hot rod

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