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Problems with TACO Bumble Bee HEC-2
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?