Air purging woes in new hot water heat system

Dave_16

I recently had a new hot water boiler installed for our combination baseboard (2 zones, 2 levels) and under-floor radiant (3rd zone w/ cold return mixing) heating. At the same time the boiler was replaced, the zoning work was done and a new refill system was installed. There are air bleeder vent valves on each of the baseboard loops, but not individual bleeders on each sub-circuit loop (i.e one bleeder upstairs and one downstairs, but not one in each room). The refill system is a Watts kit with an air scoop, bladder expansion tank and float vent valve. Between the loop bleeders and float valve, it seemed like all the air was removed before start-up, but we're still getting lots of gurgling in at least one of the upper loops. We only notice it, though, in the morning when the upper zone first calls for heat (each zone is on a slightly different thermostat program). It's silent the rest of the day.
The PRV is set at "12-15 psi" according to the factory tag, and the expansion tank factory pressure is 12-psi (although I haven't checked this pressure myself). I calculated a required minimum system pressure of 11+psi based on the pressure head + an extra 5 psi.
I installed a saddle valve in one room to try to purge any trapped air out, but I only got a little air out and the problem in the morning persists.
I don't see any leaks, so I haven't tried a static pressure test now that it's up and running.

Any ideas?

Thanks,

Dave

Steve Eayrs

air in system

I would talk to the installer of your system first, and find out whats wrong. It could be you need to run the pressure a little higher, or the flow rate is to slow to keep air out of the system (i.e. too small pump), or other problems.
I do know that piping it right can make a big difference, but don't know from you description if it right or wrong.

Steve

al leone

air in sys

sound like you still have some air in that loop.
Have your installer come back and try purging the sys. agian

S Davis

Pumping Away

Is your system pumping away from the PONPC, or is the pump on the return?

S Davis


Apex Radiant Heating

Dave_16

The expansion tank/separator/float valve are between the boiler hot outlet and the main pump, so it seems to be in the right place. But there is not a long (18-in recommended?) horizontal run of pipe before the separator, which may be the problem? There's only a few inches due to space limitations. Also, the tank/separator/float are not exactly plumb; they're off by a couple degrees, which doesn't look too bad to me, but I'm not sure how sensitive that float valve is to being slightly off-level.