Hello! First time poster here.
My Pentair pool filtration system is comprised of an Intelliflo VS pump, a 4000 series DE filter, and the oldest component, a 400K BTU MiniMax NT heater. For a few years now, the MiniMax has sat idle, refusing to fire up. I don’t really need a pool heater that badly, living in Southern California, so I wasn’t in a rush to spend a pile of money on repair or replacement.
This spring, my neighbor, who had the exact same heater model, decided to replace his. Since I’m now retired and have some time on my hands, I accepted his offer of his old heater and stripped it for parts, to see if I could get my MiniMax running again.
At this point, I want to thank the folks who support this group. By researching old posts in this group with excellent advice from some folks who really know their stuff, I was able to knock off problem after problem, to the point that I only have one issue left, which I’m struggling to solve. I’ve replaced a bad 24VAC transformer, bad blower motor capacitor, bad thermostat, bad flow valve, fixed a poor ground on the igniter, as well as a few other issues that have escaped me right now.
The last issue I can’t seem to get past is a low pressure problem in the water inlet/outlet port. My port was relocated to the left side of the heater when it was installed in 2007; the unit did work for a good number of years in this configuration. The 2 temperature switches and the thermostat appear to work normally, but the pressure switch contacts never close. I’ve tried 3 different switches - my original switch, and two new replacement switches. I even tried adjusting the old switch and one of the new ones; over the full adjustment range, I could never get the pressure switch to close.
I’ve cleaned the sensor port, and water does flow freely out of the sensor port if I run the pump with the sensor removed. I did notice however that if I place my thumb to close the port, I can easily stop the water flow and I don’t feel any real pressure or force from the port.
My filter pressure gauge is indicating about 20 psi with the pump operating at max RPM, and I’ve got plenty of suction to pull the Kreepy Krawler around the pool.
If I jumper the pressure switch, the pressure LED lights on the DDTC, and the MiniMax will then fire up and work normally. I've heated the pool up a few degrees and the spa to 95. I’ve run it through several hours-long heating cycles without issue. But I won’t leave it to operate on its own without a working pressure sensor safety.
I’m assuming the issue is somewhere between the filter outlet and the heater port, although I guess there could be a problem anywhere in the heat exchanger. I have looked at the flow valve and did replace the power element as the old one was pretty cruddy and stuck quite a bit when running it under hot water - a new power element did not help the issue. I’ve since bought a brand new flow valve, and installing it still does not resolve the problem.
I’m looking for advice and ideas at this point.
Thank you in advance for your help.
My Pentair pool filtration system is comprised of an Intelliflo VS pump, a 4000 series DE filter, and the oldest component, a 400K BTU MiniMax NT heater. For a few years now, the MiniMax has sat idle, refusing to fire up. I don’t really need a pool heater that badly, living in Southern California, so I wasn’t in a rush to spend a pile of money on repair or replacement.
This spring, my neighbor, who had the exact same heater model, decided to replace his. Since I’m now retired and have some time on my hands, I accepted his offer of his old heater and stripped it for parts, to see if I could get my MiniMax running again.
At this point, I want to thank the folks who support this group. By researching old posts in this group with excellent advice from some folks who really know their stuff, I was able to knock off problem after problem, to the point that I only have one issue left, which I’m struggling to solve. I’ve replaced a bad 24VAC transformer, bad blower motor capacitor, bad thermostat, bad flow valve, fixed a poor ground on the igniter, as well as a few other issues that have escaped me right now.
The last issue I can’t seem to get past is a low pressure problem in the water inlet/outlet port. My port was relocated to the left side of the heater when it was installed in 2007; the unit did work for a good number of years in this configuration. The 2 temperature switches and the thermostat appear to work normally, but the pressure switch contacts never close. I’ve tried 3 different switches - my original switch, and two new replacement switches. I even tried adjusting the old switch and one of the new ones; over the full adjustment range, I could never get the pressure switch to close.
I’ve cleaned the sensor port, and water does flow freely out of the sensor port if I run the pump with the sensor removed. I did notice however that if I place my thumb to close the port, I can easily stop the water flow and I don’t feel any real pressure or force from the port.
My filter pressure gauge is indicating about 20 psi with the pump operating at max RPM, and I’ve got plenty of suction to pull the Kreepy Krawler around the pool.
If I jumper the pressure switch, the pressure LED lights on the DDTC, and the MiniMax will then fire up and work normally. I've heated the pool up a few degrees and the spa to 95. I’ve run it through several hours-long heating cycles without issue. But I won’t leave it to operate on its own without a working pressure sensor safety.
I’m assuming the issue is somewhere between the filter outlet and the heater port, although I guess there could be a problem anywhere in the heat exchanger. I have looked at the flow valve and did replace the power element as the old one was pretty cruddy and stuck quite a bit when running it under hot water - a new power element did not help the issue. I’ve since bought a brand new flow valve, and installing it still does not resolve the problem.
I’m looking for advice and ideas at this point.
Thank you in advance for your help.
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