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Posted by HeatPro on December 09, 2007 at 11:28:02:
In Reply to: Re: 2 issues, possibly related... posted by Greg on December 09, 2007 at 00:44:14:
: OK. I read your page and it makes sense, but...
: The PRV is on the outlet of the boiler, and the circulator is on the return just before the boiler, so wouldn't the PRV see more from the high pressure side of the circulator and less from the low pressure side?
++ Yes. However, if there are air vents near the return, air can be sucked in when the pressure drops to cause water dumping from the relief. It is a possibility,
: So... everything I've heard about putting the circulators on the return side to increase their life expectancy by running cooler water through them is a myth?
++ At one time, about 100 years ago, it was practical, not practical since the Buna and other rubber-like seals that survive well over 205F.
or simply not worth it?
++ Not worth it. It is a 'get-away-with-it' idea that can not be done with stronger pumps in commercial at all.
: I'm guessing from some of your other posts that I should shut the valve between the PRV and the boiler output? And for info, the expansion tank is located right on the boiler output as well...
++ As in the drawings on the site, the circulator should pump away from the expansion tank, both on the supply. Then, the water feed can be anywhere, because the pressure remains positive to neutral throughout the system.