Compromised Pump?

Alan (California Radiant) Forbes

We installed this heating system 21 years ago and it's been working flawlessly until recently when the heat started struggling to keep thermostat setpoint even with moderately cold outdoor temperatures.

I played with the heating curve and shift and it improved slightly, but not close to where it used to be. Also checked the outdoor sensor and supply sensor which were fine.

And then I saw a 40° ΔT and checked the pump. It's a Taco 0012 which should draw 1.33 amps. My clamp meter read 1.7 amps. What does that tell you?

Jamie Hall

Bad pump. That has a replaceable cartridge, though, with all the moving bits, so unless the problem is in the motor windings (shorted -- but almost impossible to test for) you might try that first.

EdTheHeaterMan

Jamie Hall said:

Bad pump. That has a replaceable cartridge, though, with all the moving bits, so unless the problem is in the motor windings (shorted -- but almost impossible to test for) you might try that first.

The replacement cartridge sometimes is just as expensive as the complete pump. I have often replaced the cartridge and motor body on 00 series pumps by purchasing the complete pump and removing the housing that connects to the piping, Do the same with the replacement pump and put the new pump parts on the existing housing. Sometimes that is faster than unbolting the flanges. Sometimes not.

Alan (California Radiant) Forbes

I thought this might be a good chance to replace it with a ECM pump.

But in the meantime, I'd like to be able to further test the pump before I replace it. Maybe @SteveSan could tell me what the 0012 ohm reading should be. Thanks in advance.

SteveSan

Alan (California Radiant) Forbes said:

I thought this might be a good chance to replace it with a ECM pump.

But in the meantime, I'd like to be able to further test the pump before I replace it. Maybe @SteveSan could tell me what the 0012 ohm reading should be. Thanks in advance.

Morning Alan, the ohm readings for your 0012 should be between the y-r, between 12-14, y-b between 14-18, and r-b between 26-32.

The 1.7 amp reading is close to lock cartridge or possible air. Rule of thumb is any amp reading that is close to or more than 1.5 times the nameplate amps would suggest that.

Removing the cartridge, I would do a visual inspection on the winding to make sure no damage to them before replacing the cartridge.

Hope this helps, and enjoy your weekend.

SteveSan

https://www.tacocomfort.com/documents/FileLibrary/Taco_Circulator_Replacement_Guide.pdf

Alan, the link is a nice cross reference that we have on the website from standard a/c models to ECM.

leonz

Hello Alan,

Keep in mind that the ecm circulators will affect pacemakers and pacemaker defibrulators due to thier permanent magnets.