MFTCW and MFTHW - Error 20

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. 
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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

  1. Check condensate hose,  condensate piping for blockages.
  2. Check all condensate lines, neutralizers and pumps if applicable for proper installation and quality. 
  3. Assure there is a proper "vent" if condensate is hard piped. 
  4. Remove condensate trap from bottom of flue collector on boiler to clean and flush well. 

(3) Condensate Switch Troubleshooting 

  1. 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).
  2. 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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