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Peerless Pinnacle PI 199LP Error Code F02

We own a Peerless PI 199 LP boiler (S/N 199LPK01I) with an upgraded PI617 926 control board and read-out pendant. This morning we awoke to lukewarm water. Water pressure is 20psi (low pressure threshold = 10psi) and LP tank at 50%. Failure code: Pro: open water pressure switch. No big deal, jump the leads until I get a new switch installed. After shorting the leads together, I turned power back on and now have error code F02 (interrupted or shorted supply thermistor.) Unfortunately, not so readily jumpered out. I called Peerless and ordered the two parts, water pressure switch and a thermistor (same part for supply and return) and drove to Bally, PA to pick them up as we live only 30 minutes away.

Upon returning home, I secured power, shut off supply / return water valves, bled pressure, and installed water pressure switch and supply thermistor. Resumed water flow, bled system, turned power on and same error code, F02. As it turns out, I had an additional brand-new spare thermistor that I had forgotten about, so I replaced the new thermistor with this newly found spare, to no avail. I then replaced the return thermistor, so at this point I had both new thermistors installed, again to no avail. Cleaned all leads, replaced spade connectors, to no avail. I reversed the leads, connecting the supply thermistor to the return leads and vice-versa, expecting error code F03 (interrupted or shorted return thermistor) if the supply thermistor itself was compromised. Still F02 error code. At this point I am starting to believe the six-month-old control board has failed. Passes visual inspection, no corrosion, burnt spots, moisture, etc.

Is there a course of action I can take to determine the failure? I scoured the existing posts and found nothing remotely similar to this issue.

Thank you.


  • Tim McElwainTim McElwain Posts: 4,227Member
    Get in touch with the folks from Heat Transfer Products. I am assuming you pushed the S4 manual reset button?
  • Gary_KahudicGary_Kahudic Posts: 2Member
    Yes, pressing the reset had no effect. Board failed while under warranty, replaced board but still had to pay for it, then wait to be reimbursed upon verification by the factory.
  • Tim McElwainTim McElwain Posts: 4,227Member
    I have expanded diagnosis on this unit which by the way was originally the Munchkin produced by Heat Transfer Products. The expanded diagnosis is not in my office but at my training center. I will get it for you when I go to the center.
  • Tim McElwainTim McElwain Posts: 4,227Member
    The other thing I found with this F02 code was the Molex connector being faulty. Check both the supply (usually yellow wires)and return (usually blue wires). Make sure the wires are firmly inserted into the Molex connectors on both ends. Shake the wires and if loose they will keep going back to the F02 code.
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