MFTCW and MFTHW - Error 20
Error 20 is a HARD LOCKOUT when the Condensate Switch is OPEN = Fault.
The Condensate Switch is a NORMALLY CLOSED switch connected via tubing from the condensate drain trap.
Flow Chart
FYI - THE NUMBERED BLUE BOXES BELOW CORRELATE TO A SPOT ON THE FLOW CHART ABOVE
(1) Explanation of Error 20
Error 20 occurs when the "Normally Closed" condensate switch "OPENS" during operation which equals a fault.
The cause of this fault (error) is usually due to the condensate trap , condensate piping or boiler flue collector, neutralizer being clogged as well as a condensate pump not operating , if applicable.
This can also occur if any portion of the condensate piping is exposed to freezing temperatures thus causing ice to form in the condensate piping.
Another cause can be a "Hard Piped" condensate drain line that was not installed with a means of a vent . The included flexible condensate hose has a "Y" vent integral in the hose connection.
Cross Contamination due to improperly installed combustion exhaust and intake DOES cause a "milky white " substance to form in the flue collector, condensate trap, neutralizer and associated piping.
(2) Blockages Causing the Condensate Switch to open during operation
- Check condensate hose, condensate piping for blockages.
- Check all condensate lines, neutralizers and pumps if applicable for proper installation and quality.
- Assure there is a proper "vent" if condensate is hard piped.
- Remove condensate trap from bottom of flue collector on boiler to clean and flush well.
(3) Condensate Switch Troubleshooting
- Disconnect the two wires connected at the condensate switch and with a multimeter check for resistance at the condensate switch , NOT THE WIRING (any resistance reading fine).
- If a "ZERO" resistance at the switch is found then replace the condensate switch.
(4) Condensate Troubleshooting and Condensate Trap Removal Video
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