4 red lights flashing on robertshaw gas valve, pilot not lighting 4 flashes pres switch open? how to fix??

SOURCE: rheem model 41vrp40n power vent water heater won't

"Pres sw open" means there is insufficient air flow. either the vent if blocked, or the blower turns too slow/ or died.

Posted on Feb 12, 2010

Mike Butler

• 6674 Answers

SOURCE: I have a Rheem 50 gallon gas water heater and I

Use a wrench, proper size and remove thermocouple where it attaches to gas control valve. Take some fine steel wool, or emery cloth and clean rounded end of thermocouple where it makes contact down inside gas valve. Spray electrical cleaner in where that end came out of, or twirl up a piece of steel wool to a point small enough, but long enough to go in hole and by spinning it, you can clean surface in hole as well. After cleaning, blow out with compressed air if you can, now re-install it and tighten until good and snug, don't strip it. ( you can even used compressed air can for computer cleaning if you have one.) Now use emery cloth or steel wool, and rub end of thermocouple that sits over pilot flame. (make sure gas valve is off, and thermocouple end has had time to cool.) Now try it. If that doesn't cure it, I'd buy a new thermocouple, being I don't expect you have a thermocouple tester, and they are relatively cheap. Next step would be a new gas control valve, so lets try the cheap and easy first. Also make sure flame under thermocouple is good, and is burning close enough to thermocouple to allow it to do it's job as well. Keep me posted.

Posted on Oct 25, 2010