Pentair Minimax NT pool heater issue

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L

Lakeside Homeowner

New member
Jun 14, 2023
2
San Diego, California
I'm chasing this same issue and starting down the path of 'throwing parts' at it.
The squirrel cage had rusted and fallen apart. I cleaned up the blower box and replaced the fan.

Vacuum from fan:
With the fan running, I put the sensor end of the vacuum tube in water and it pulls the water level about 1.25".

Vacuum to switch:
Reattached tubing and applied (very light) vacuum to the top of the tube (about as much as to pull water the same amount) and then pinch the hose to hold that vacuum, then the switch closes, the led lights, and the heater ignites and stays lit for the heating cycle. shorting across the switch (bypassing) also starts and maintains the heating cycle.

Replaced the switch with OEM (violet) part, same result. Also replaced the starter capacitor (because it was cheap), but this was probably unnecessary.

I suspect the vacuum from the tubing is not enough to close the switch. I am considering taking the fan box apart and sealing it up with high-temp caulking, but I would rather not glue it up if I don't have to.

Moved from here.
 
Last edited by a moderator:
Thanks. Still getting the E04 error.
Was looking into a manometer to test the vacuum from the blower fan, but the correct threshold value is not in the service manual, so even if I had the tool, I have no way of knowing what 'correct' value is. I can see that the vacuum on the tube with the fan running will draw water exactly "some". The service manual only says 'apply vacuum to the switch to test it' and it closes fine and the heater operates in that state, so my only conclusion is the vacuum from the blower box is "not enough".
I have not opened up the blower box, beyond removing the fan. Also, the diagram in the service manual indicates a gasket, which I do not have, so I may RTV the box tighter next and see if that works. Shorting across (bypassing) the pressure switch will allow the heater to operate, but this is hardly a 'solution.'
So, I'm off to tear it down further.
 
Lakeside Homeowner said:
Thanks. Still getting the E04 error.
Was looking into a manometer to test the vacuum from the blower fan, but the correct threshold value is not in the service manual, so even if I had the tool, I have no way of knowing what 'correct' value is. I can see that the vacuum on the tube with the fan running will draw water exactly "some". The service manual only says 'apply vacuum to the switch to test it' and it closes fine and the heater operates in that state, so my only conclusion is the vacuum from the blower box is "not enough".
I have not opened up the blower box, beyond removing the fan. Also, the diagram in the service manual indicates a gasket, which I do not have, so I may RTV the box tighter next and see if that works. Shorting across (bypassing) the pressure switch will allow the heater to operate, but this is hardly a 'solution.'
So, I'm off to tear it down further.
Click to expand...
Be sure that there is nothing blocking the inlet to the blower. Rodents have been know to build nests in that area.
 
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