Problems with TACO Bumble Bee HEC-2

Willis

This is a new residential boiler install with existing fin tube baseboard  3 zones.    ULTRA 155 CONDENSING BOILER WITH DHW & WMCR3 ZONE CIRCULATOR CONTROLLER.     Zones 1 thru 3 are left to right in the photo.    Each Bumble Bee HEC-2 with integral flow check. 

ZONE 1  36,000 BTU 150 LF (EST 9 FT HEAD)  SET UP FOR dT MODE 20F   

ZONE 2  51,000 BTU 200 LF (EST 12 FT HEAD) SET UP FOR dT MODE 20F   

ZONE 3  36,000 BTU 100 LF (EST 6 FT HEAD) SET UP FOR dT MODE 20F  

after 1 week circulator 1 was energized but no flow.  I replaced the circulator.    it checked out ok during a bench test.    after 2 weeks Zone 1 and Zone 2, same problem.    I removed the flow checks and now have flow to both zones.  (need flow checks for control)    Zone 3 has not been a problem.    I suspect with dT mode at lower speeds, not enough flow to overcome head loss and open the check valve?    No ideas from Taco or local rep.   any suggestions?

Rich_49

Information

What is the fluid in this system ? 100% water , is there glycol ?  Are the ball valves we see full port , are there lots of fittings ? What is the air side charge on the expansion tank , what is the average fluid temp ?  One thing that jumps out at me is the 51000 BTUh @ 12 ' , the HEC-2 will not perform that task , EVER .   

Joe Mattiello

Bumble Bee

Thanks for providing the pictures.  The pumps look good, and it looks like they are pumping upward, which is favorable to keep any air in the system moving upwards.  However, it's possible to have air bubbles floating through out the system get hung up at the check causing the volute to fill with air.  This is a condition that I have seen many times. Have you attempted to re-purge the loop after experiencing a no flow condition? 

The other hypothesis, because the check valves are not installed at the factory, and added to the box loose, is the valves were installed backwards. I would agree the latter would have a lower probability, but it's possible and worth investigating.  

The Bumble Bee uses an IFC valve with a 6” wc spring (.26 psi cracking pressure)   part # 194-2990, which converts to approximately .6 ft/hd which can be overcome with the pump operating at it's lowest speed.  The other problem with this theory, is the pump operated ok for a week or two, before the no flow event occurred.  Another consideration, is the BB starts on full speed and runs 100% speed for 3 minutes before slowing down.

Hopefully, this gives you enough information to successfully diagnose the problem.  I'm available if you want to call me too. 

Weezbo

Very nice reply ,

Willis,

go with Joe on this one ...: ))

Weezbo .

*~//:)