Pentair 250M Minimax Heater

Jump to latest Follow Reply
B

BNighGrow

0
Apr 1, 2013
82
Suburbs of Chicago
Hello All,

Today I tied the PVC back into the heater in hopes of the heater would work. The heater is a Pentair MiniMax 250M Minivolt Heater. Well as I figured it wouldn't be as easy as turning on a switch because it does not want to kick on. I took the front panel off and turned the gas valve to Pilot and hit the ignition, and the pilot stays lit. Then after I have the water running through it and I turn the switch to Pool and have the temp knob to hot. The burners don't come on...?

Some questions:

1. As I am looking through the manual it says there should be a lit diagnostic board showing power, service needed, ect. Well I don't see anything lit up on the front.
2. Does this heater get its electricity from the water running through it? Because I don't see any signs of electric running to it.
3. Any test I can perform before having to call a service company in hopes of being able to do it myself.

Here are some pictures
[attachment=0:2pq3gc82]pool_heater_3.jpg[/attachment:2pq3gc82]
[attachment=1:2pq3gc82]pool_heater_2.jpg[/attachment:2pq3gc82]
[attachment=2:2pq3gc82]pool_heater_1.jpg[/attachment:2pq3gc82].

Thanks
 

Attachments

  • pool_heater_1.jpg
    pool_heater_1.jpg
    194.1 KB · Views: 255
  • pool_heater_2.jpg
    pool_heater_2.jpg
    205.2 KB · Views: 250
  • pool_heater_3.jpg
    pool_heater_3.jpg
    186.7 KB · Views: 247
BNighGrow said:
Hello All,

Today I tied the PVC back into the heater in hopes of the heater would work. The heater is a Pentair MiniMax 250M Minivolt Heater. Well as I figured it wouldn't be as easy as turning on a switch because it does not want to kick on. I took the front panel off and turned the gas valve to Pilot and hit the ignition, and the pilot stays lit. Then after I have the water running through it and I turn the switch to Pool and have the temp knob to hot. The burners don't come on...?
Click to expand...
Start simple. You turned it to Pilot and lit it and it stays lit. Did you then turn the knob to "On"
 
Can you see in where the pilot is lit? There should be a "probe", about 3/8" diameter, engulfed in the flame. This is the powerpile that supplies the millivolts to power the gas valve. It is possible that this is not putting out the proper amount of voltage for the valve to work. If you have a multimeter you can test for the voltage from this. Ideally it should be 750 Milivolts. They can work as low as 300-350 mv.
 
Start simple. You turned it to Pilot and lit it and it stays lit. Did you then turn the knob to "On"
Click to expand...

Ha sorry, Yes I turned it to Pilot for a minute or two, then turned it to "On" and it stayed lit.
Then I turned on the filter, then turned it to pool (also tried spa) with the Temp knob all the way to hot.
Nothing happen, no noise, and water was not any warmer, and got on my stomach and couldn't see the other burners on.

Can you see in where the pilot is lit? There should be a "probe", about 3/8" diameter, engulfed in the flame. This is the powerpile that supplies the millivolts to power the gas valve. It is possible that this is not putting out the proper amount of voltage for the valve to work. If you have a multimeter you can test for the voltage from this. Ideally it should be 750 Milivolts. They can work as low as 300-350 mv.
Click to expand...

I do have a multimeter, what exactly should I be contacting with the multimeter? I see the "probe" you speak of where the only flame is coming out.
 
In your last picture there is a wire (two conductors, red/white) hooked to the gas valve coming in from the right side. The white is hooked to the TH/PP terminal and the red is connected to the PP terminal. That is your powerpile wire. To test it, hook the leads of your meter to each of those. It can be done with them connected but it is better unconnected. Looking at the pictures again you may want to clean up all of the connections as any slight corrosion will cause resistance in the circuit and the voltage is very low on this type of system. If you find that the Milivolts is good then another test to try is to bypass the control circuit by hooking a jumper between the TH/PP terminal and the TH terminal. If you have a good powerpile and gas valve the burners should fire right up. If this happens then you have a bad sensor somewhere in the wire going out from the TH/PP terminal and back to the TH terminal.
In the image I posted the "D" terminal is the same as your TH/PP terminal, "E" is your PP term, and "F" is your TH term. Part 5a and 5c is your powerpile.
 
jrross said:
Any chance someone can recommend where to buy a replacement powerpile? my local pool shop thinks it will be $90 which seems steep....
perhaps in WNY as I am in Niagara.... :)
Click to expand...


I am about 70 miles south of you. Down here we have a couple of local HVAC supply houses that I can purchase from. I am sure you have them in your area too. Do you have a heating contractor that you have dealt with in the past? They can be a good source for these items. I agree, $90.00 is a bit steep, $30-$40 is more like it on the retail side and $15-$20 on the contractor side
 

Enjoying this content?

Support TFP with a donation.

Give Support
Wow!
I have the exact same unit and had the exact same problem ..........twice in 10 years.

In my case, the problem turned out to be a balky pressure switch. It's a $5 item that costs $29 at the local pool store. But it's easy to replace yourself if you're so inclined - two wires and and a small wrench.

For testing purposes, the switch can be bypassed by merely connecting the two wires together.
 
I have basically the same heater (I have the 150M model) and I have the same problem (pilot lit, but heater won't fire). I tested the voltage across the thermopile leads and only got 185 millivolts. Does this mean the thermopile needs replaced? Or might it just be that it needs cleaned or something?
 
After changing my Thermopolis without it helping... Changed out the thermostat module (3 inch square black box behind the knows panel and she fired right up...) hope there's no other issues.... Good luck guys.
 
codyt said:
I have basically the same heater (I have the 150M model) and I have the same problem (pilot lit, but heater won't fire). I tested the voltage across the thermopile leads and only got 185 millivolts. Does this mean the thermopile needs replaced? Or might it just be that it needs cleaned or something?
Click to expand...
That is a pretty low reading. Make sure the thermopile is in the pilot flame real good and you have a strong flame. Also make sure there is no corrosion on the leads which would give a low reading as well. If all that is good then I would suspect the powerpile to be weak. I have pulled them out before and tested them in the burner on my gas stove to be sure. Idealy you should see 750 Mv if it is good. They will range a bit above or below that number... 600-800 out of the box.
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply