Purex Minimax 150m Millivolt won't start

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G

gpklos

0
Aug 9, 2016
3
North Huntingdon
Hi,
I've been reading these threads for a an hour now because I have a similar problem. I think the answer is in some of what I already read, but I'm still a little confused on some things. Anyways I've had my heater for 5-6 years now. I bought it used and it worked decent. It always was hard to start. I would have to push the on/off button a few times and finally it would start. Anyways, it finally quit starting the other day. So the Pilot light is lit and stays on. So I read the thread and used my multi-meter to test the millivolts coming from the Powerpile. When the pilot is lit and the power button off, it reads around 260 MV, when I press the on button it reads somewhere around 230 MV. So according to what I've read that is too low to start the heater. So I did the bypass test by Jumping the terminals on the TH-PP and the TH. As soon as I did that the heater fired up. So my question is since it started does that mean my powerpile is ok and strong enough (something else is wrong then), or does it mean that it is bad? Also by jumping this way, is that bypassing all safety switches? I ask because even if my power switch is off and I jump it, it still starts. Not sure if that is normal or not.
Where should I go from here?
Thanks,

Gary
 
Start by cleaning all of the spade connectors.
If that doesn't improve things, you probably want to replace the thermocouple.
Yes, jumping those two terminals bypasses all the safety and control switches.
 
You should be getting 450+/- on that reading. 260 is way too low to actually get the system running. Is it a lazy flame or does it look real strong? If the flame looks strong then you just need a new thermopile. If it looks weak you probably should replace the entire pilot assembly.

What you did by bypassing just shows that the rest of the safety circuit is good.
 
Here is a basic schematic of a standing pilot pool heater circuit.



It does not show an OFF/ON switch but there would be one in the safety circuit. In this diagram the terminals you jumped are the E&F terminals on the Gas valve in the picture. As was said, you may need to clean all of the terminals in the safety circuit as any corrosion will add resistance and drop the current to the valve below what it takes to operate it. If that does not fix it, it may be time for a new powerpile. A good powerpile, enveloped in a strong flame, will put out ~750 MV. You can also try cleaning the powerpile as carbon will act as an insulator.
 
Thanks for all the quick replies. So even though the unit fires up when I jump it, it still may be the powerpile that is bad?? I'm going to clean the terminals as best first, then measure the mv to see if that changes anything. Out of curiousity, how do you test the on/off switch?

Outside of that I plan to replace powerpile, or maybe even the pilot, etc. We shall see.

This is a great forum!
Gary
 
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