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Seized / Locked Alpha Circulator Pumps
Adolfo2
Member Posts: 32
Turned on my hydronic heat yesterday for the first time this season and all three Alpha zone circulator pumps (four-years young) were seized (Display indicates “- -“ after about a minute of runtime). These pumps were last used in July or August and it’s now almost Thanksgiving.
Removed the pump cartridge from the cast-iron housing (everything was clean except for some black slime on the O-Rings) and manually turned the impeller. It made a “snap” sound and was then free to rotate. Reinstalled and repeated the procedure for the remaining two pumps and now everything works fine.
Operating Conditions:
• Soft city “ground” water (Suffolk County Water, Long Island, NY)
• No glycol or inhibitors
• Boiler water and strainers are clean
• No make-up water to speak of
• Piping is 99% copper w/couple feet of PEX
• High efficiency, condensing gas boiler
• System water temp is typically under 130 deg F
Is this considered normal behavior for some relatively expensive, high-quality pumps? Any suggestions other than exercising them more often during the off-season?
Removed the pump cartridge from the cast-iron housing (everything was clean except for some black slime on the O-Rings) and manually turned the impeller. It made a “snap” sound and was then free to rotate. Reinstalled and repeated the procedure for the remaining two pumps and now everything works fine.
Operating Conditions:
• Soft city “ground” water (Suffolk County Water, Long Island, NY)
• No glycol or inhibitors
• Boiler water and strainers are clean
• No make-up water to speak of
• Piping is 99% copper w/couple feet of PEX
• High efficiency, condensing gas boiler
• System water temp is typically under 130 deg F
Is this considered normal behavior for some relatively expensive, high-quality pumps? Any suggestions other than exercising them more often during the off-season?
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Comments
No black, inky sludge when you drain at a low point? That could indicate magnetite getting into the magnetic rotor.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
No evidence of black, inky sludge anywhere and except for about 10-feet of PEX the entire system is copper & brass. There was once a cast-iron gas boiler (4-years ago) but unfortunately, the system wasn’t chemically flushed prior to installation of a new Lochinvar Knight boiler.
The three Alpha zone circulators are wired to individual “TACO SR501-845RP Universal Replacement Relays” which don’t have an anti-seize function. The boiler does for all pumps, but it can only natively support one System Pump, not three zone circulators, hence the TACO’s.
I’m still not sure why the pumps are seizing but since the boiler has this feature, I must assume that it’s not an uncommon occurrence.
As a solution, I’m debating wiring up a system of “NO” isolated contact relays across each of the three TACO thermostat inputs. The 120V relay coil would be energized by the boiler whenever it runs the daily System Pump, anti-seize function thus cycling the pumps during the off-season.
My alpha is now 2.5yrs old and is not used during the summer either. I've had no problems with it locking up- and I believe it's due to the boiler (HTP UFT-80W) exercising the pump over the summer. I have witnessed it a couple of times- it only runs for a min or two, but I guess it's enough to stave off binding.
I have one CH pump and three zone valves, so when the boiler is exercising the CH pump it's actually deadheading the pump but I guess the rotor is still turning. This summer I left my zone valves open to prevent the deadheading.
a mag dirt separator just to eliminate that potential cause, rumor has it 70% of failed ECM is due to magnetite. You'd need to split the rotor from the can to know for sure.
Scratch EVERY circulator you disassemble from this day forward, see if the build up sticks to a magnet.
Also a pump exerciser is a simple second protection mechanism, be nice to see pump manufacturers include that in the onboard control.
If you are embracing ECM, which you should, and I applaud you for, magnets should be in your future.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Be sure it is a non ferrous separator, or you end up with particles stuck to the steel and know way to release them.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
From the manual:
It's a pretty simple system though... I have a tank type boiler, connected to a bunch of homerun, panel rads with TRVs. In heating season, I put the pump in AutoAdapt and it runs all winter. In late May I put it in summer mode. It's hardwired into my boiler circuit, my boiler stays powered too, but my controller goes into warm weather shutdown at some point.
There you go!
Be sure it is a non ferrous separator, or you end up with particles stuck to the steel and know way to release them.
Yes, it's a TACO copper unit w/drain at the bottom.