Rheem 266A Heater Won't Start

[lhlsea]

Hi there, I tried to turn the heater on for the first time of the season yesterday and it wouldn't light up. No noise of any kind after turning the power switch to on.

It's a Rheem 266A (P-M266A-MN-C). It's the model without a digital display (and no lights that I can see) so I don't think it provides any diagnostic info. The heater is only about three years old and has had no issues the past couple years, so I'm hopeful it's something relatively straightforward. Here are some of the things I tried:

- opened up the front/side panels to make sure there wasn't anything obvious wrong or any critters nested in there
- cleaned out some of the leaves/debris that had made it's way inside (it wasn't too bad)
- cleaned the filter and pump basket
- made sure the pump is on high speed to make sure enough water is flowing through
- lit the pilot light (it lit easily and seems to stay on fine)

I'm only moderately handy and don't know heaters well (it was put in not long after we moved in and this is the first pool I've taken care of), though have done quite a bit of searching/reading here on the forum before posting to get a sense for things. I do have a multi-meter if that's helpful.

Thank you so much for any advice on what I might try next. I've learned a tremendous amount from this forum the past few years!

Lewis

 

[ajw22]

You have the Millivolt heater that gets power from the pilot light.

Your manual is here --> https://s3.amazonaws.com/AWSProd/sites/raypakcom/documents/241236.pdf

Follow the flow chart on page 41. You probably have one of the safety sensors open. The flow chart leads you through jumpering each sensor until you find the one that failed.

 

[swamprat69]

Since you have a multimeter I would check the powerpile/thermopile ( the 2 wire metallic encased wiring from the area of the pilot assembly ) output. It should read ~ 600-750 millivolts with no load, which will drop somewhat if the heater is asking for heat and thus powering the gas valve. At no point should it drop below 300 millivolts.

 

[lhlsea]

Thank you - this is very helpful. @ajw22 I read through the flow chart and understanding the concept that I'm jumpering around different parts to isolate which one may have failed, but I think I might need a tad more handholding if you don't mind to make sure I'm doing it properly. What do I use to do the actual jumpering? (i.e. do I need to buy some wire with clamps on the end?) And is there a diagram I should reference to make sure I'm placing the jumper cables in precisely the right spot for the parts the flow chart references (TH wires, the Pressure Switch, the Thermostat, etc.)?

I think I can probably figure this out if I stare at the manual and think a bit more, but anything to point me in the right direction would be really appreciated.

And thanks also @swamprat69 - I'll give that a try.

 

[ajw22]

I would use alligator clips on the ends of a piece of wire as a jumper.

Look at page 24 and you will see the various sensors that all must be closed for the heater to operate. Then there are various pictures around the manual like on page 33 of specific sensors.

You will find location of parts on the Illustrated Parts List beginning on page 45.

 

[lhlsea]

Thank you for the quick response. I'll give it a try!

 

[lhlsea]

Success! Thank you so much for the help.

I ran through the flowchart as you suggested and isolated the problem to the thermostat. Then, just out of curiosity, after putting everything back together, I tried rotating the thermostat knob back and forth several times just to see if I could notice anything. That did the trick - the heater now turns on normally. Probably should have tried that from the beginning .

Is it possible something just got stuck with the thermostat over the winter months, and a bit of jiggling was all it needed? Or would you suggest I replace the thermostat anyway just to be on the safe side?

Once again just wanted to say thank you @ajw22 and @swamprat69 for your help -- I *really* appreciate it (especially as my local pool company said they couldn't come out for 3-4 weeks!) and have now learned a whole bunch about my heater that will certainly help me in the future. Thanks again!

 

[ajw22]

The thermostat is probably a variable resistor that the knob sweeps a finger over to set the temperature set point. You may have got corrosion in the thermostat that jiggling it made a decent connection again.

I would replace it at your leisure as it is likely to happen again and leave you stuck.

 

[lhlsea]

Got it. Thanks!