Modine PA 105 Unit heater. Questions and/or manual.
I have an ancient PA 105 Unit heater with a bad limit switch. This switch is an odd design, combines both the temperature high limit with the fan cut-in. It appears to be a poor design which Modine changed in 1986. Two questions. Would anyone know where to find a manual for this thing? It's not on the Modine site. I'd also like to find the temperature cut-in/out numbers for the switch, and replace it with a more conventional setup, IE separate switches for the fan and gas valve. Put more simply, what's the high-limit temperature on these things?
Usually, not always, the temperatures are on the unit itself. They are not always evident, but can be "buried" in the information stamped or printed on it. Usually a fan control will have numbers like 175/30 or something of that nature. The 175 means it turns on at 175 and the 30 means a 30 degree differential (shuts off at 145).
I did a search of Modine's website and found a parts breakdown of the unit. Just depends on how you type the search into Google probably.
Thanks for the quick reply. I was able to find the parts breakdown, and even the original part number, on the site. What I haven't been able to find anywhere on the net are specs on the limit switch in question. I'll take a closer look at the numbers stamped on the old switch, maybe it'll have the temp ranges as you suggested.
I was looking at the side of the heater again, Modine must have known that it was a bad design from the start. The sheet metal already has the mounting holes (plugged) for a second limit switch.