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.