Quote Originally Posted by DFBrews View Post
Here is a PDF explaining head pressure in a closed loop system.

basically head pressure in a closed loop system is only friction flosses from fittings lines etc

i bet you got air locked on the circulation loop and it is now purged are there air bleeds anywhere in the system ?

http://www.michiganair.com/newslette...2/section4.pdf
Thanks for the info, I"ll check it out. The first part along with your statement makes it sound like head isn't an issue on the circ loop.

No air bleed but we have the bib just to the right of the 003, the boiler guy added the bib to help drain air and a check valve between the bib and 003 since it seemed that we were getting some cold water back into the system. With the check valve there I'm not sure opening the bib did anything to help the air lock if it was at the pump, but when we took the pump apart it fixed the problem.

Now that I somewhat understand what's going on, I don't see where that check valve on the input side of the 003 adds any value since the only way cold would be coming that direction is if the 003 wasn't functioning at all.

Any thoughts as to why we'd be getting ghost flow on the pipes to the zones? Even when the thermostat is off and a zone hasn't called for heat in days, both out and return are about 180. Same with all the zones that aren't physically shut off. Boiler guy said it would require a re-pipe to add priority for the hot water but I have no idea if that's correct. He didn't want to do a re-pipe so I don't feel like he was trying to up-charge me, he just said that was the only way to completely fix it. He just suggested keeping the thermostats lower than we want the temp to be and physically shutting down all the zones in the summer.

Thanks again for all the help!