Minimax Pressure Switch Troubleshooting

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Uavmx

0
Sep 5, 2016
91
Albuquerque, NM
Hello,

I have a REALLY OLD Purex minimax 250 that I've been working on getting running. It was known bad when we bought the place, so I've started from scratch as it's never run under my watch.

So far here's what I've done and I'm confused on one portion which is the flow pressure switch:

1) No POWER LED: Had 28vac coming to one side of the LED, not the other. Soldered in a new LED, fixed, got power to the rest of the board. See picture, it's so old there's a second circuit board on the potentiometer/power panel that was later integrated.
2) No pressure LED: With water flowing, ohmed out the switch, no continuity, figured bad switch. Jumped the wiring, pressure LED came on, spark started firing. I also confirmed water was flowing through the hardline to the switch. New switch ordered.
3) Spark is firing, no pilot being lit: Good voltage to PV and MV, tried lighting with a match. Pulled the line from the gas valve smelled for gas, none noticed. Verified gas coming into the unit. Gas valve likely bad, new valve coming.

Here's where I need help:

4)Received the new flow pressure switch and it's still not working. I know water is coming into the switch, I know the wiring is good, but the switch isn't closing when the flow is running. I'm thinking maybe enough pressure isn't coming into the switch? It looks like someone modified the unit. They created a hardline that runs from the manifold over to sit above the gas valve (for convenience I assume) See picture below, you can see it above the gas valve. Could this be it? Is there a need to calibrate/adjust the pressure switch? The switch is a "The Little General" MSPS-EE05-Q11.

Pretty confident once I get a new gas valve and figure out the pressure switch this unit will fire up! Some pictures belowIMG_0165.jpgIMG_0163.jpgIMG_0169.jpgIMG_0166.jpgIMG_0162.jpg
 
A few things, you're probably losing pressure thru that modification with the line, try to clean out the port of the switch with toothpicks or Q-tips it may be plugged, use a small screw driver to actuate the switch to make sure it is closing, remove the extra tube, and turn on your pump to push out any junk in the manifold, mount switch back on to the manifold and try it again.

Steve
 
Steve H said:
A few things, you're probably losing pressure thru that modification with the line, try to clean out the port of the switch with toothpicks or Q-tips it may be plugged, use a small screw driver to actuate the switch to make sure it is closing , remove the extra tube, and turn on your pump to push out any junk in the manifold, mount switch back on to the manifold and try it again.

Steve
Click to expand...

Yeah, my next thought was to hook it back up to it's original position. I'll make sure it's all clear and clean. I did remove the probe and run the pump before to ensure there was water coming through at a good rate and there was...what pressure is that switch made to work in? Is there a high limit as well?
 
Uavmx said:
Yeah, my next thought was to hook it back up to it's original position. I'll make sure it's all clear and clean. I did remove the probe and run the pump before to ensure there was water coming through at a good rate and there was...what pressure is that switch made to work in? Is there a high limit as well?
Click to expand...
keep us posted on your progress, I know how frustrating it is chasing sparks around the equipment. I've attached the pentair Minimax service manual which seems to be the successor of your Purex model, hopefully it will help.

http://www.pentairpool.com/pdfs/MiniMaxNTServiceManual.pdf


Steve
 
Steve H said:
keep us posted on your progress, I know how frustrating it is chasing sparks around the equipment. I've attached the pentair Minimax service manual which seems to be the successor of your Purex model, hopefully it will help.

http://www.pentairpool.com/pdfs/MiniMaxNTServiceManual.pdf


Steve
Click to expand...

I'm an aircraft mechanic, so this stuff is fun. Does the switch have a high limit? Like too much psi shuts it off?

Looks like there is a procedure in that manual to adjust the switch, I might try that too.


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Uavmx said:
I'm an aircraft mechanic, so this stuff is fun. Does the switch have a high limit? Like too much psi shuts it off?

Looks like there is a procedure in that manual to adjust the switch, I might try that too.


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Click to expand...

No need to adjust. The only time you need to adjust it is when the pool sits higher than the heater and the downward pressure from the water would cause the switch to allow the heater to fire. So unless the heater sits below the pool, leave it as it is set.
 

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Steve H said:
Any progress on the heater?

Steve
Click to expand...

Yeah... Got the new gas valve, hooked it up electrically and could feel the click of the valve, so the old one was truly bad. I could not for the life of me get one of the gas lines removed from the valve...i think they glued it!

So back onto the pressure sensor. Tested again, didn't work. Took it all apart, flushed it, all seemed flowing fine, didn't see any sediment. I couldn't hook up the sensor to the manifold because the hole is too large (see pic). I'm thinking this hard line was standard or someone stripped and then upsized the hole in the manifold and tapped it.

I put it all back together not making a change. Put the old switch in but removed the glue to make adjustments. Fired it all up, threaded the adjustment in and out while there was pressure and no joy. Removed the glue from the new switch, hooked it up fired it all up and it worked! I don't think I even made an adjustment so I have no idea what fixed it. But the old switch is bad, new one works.

I'm taking the old valve into work where we have more tools to get the gas line out. I'm pretty confident she will fire right up when it's all back together! IMG_0239.jpgIMG_0240.jpg


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I've come across a few that have the copper tubing with the pressure switch instead of the switch being installed on the actual header. Yes the new pressure switch would need a reducer in order to install it on the header.

What looks like glue is probably just thread sealant. Common to be used. In fact you need to make sure you use that when you put the new gas valve in. I usually wrap some teflon tape on the threads and then add the thread sealant. Make sure you get the thread sealant for gas.
 
ps0303 said:
I've come across a few that have the copper tubing with the pressure switch instead of the switch being installed on the actual header. Yes the new pressure switch would need a reducer in order to install it on the header.

What looks like glue is probably just thread sealant. Common to be used. In fact you need to make sure you use that when you put the new gas valve in. I usually wrap some teflon tape on the threads and then add the thread sealant. Make sure you get the thread sealant for gas.
Click to expand...

Yeah, I think it's loctite or JB weld that they put on there. Why would they do that? Why is it required?

Aware of the special tape for gasses, I have it.
 
It's aaalllliiiiiivvvvvveeeeee
98cb1e78d711e5f221f6948eaa342023.jpg



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