Westinghouse Tankless Water Heater WGRTNG150

[tmfixit]

A couple issue have popped up with this Westinghouse WGRTNG150 Tankless water heater.  Unit has been installed for maybe 5-6 years as far as I can tell.  It ignites and heats the water but there is a slight popping sound from the exhaust port.  I've checked the errors as #11 and #73 which are 'failed to ignite' and 'incorrect dip switch settings', respectively.  Checked the DIP switch settings and they're OK.  I did cycle each switch and this error has not returned so far.  Checked and cleaned the intake filter.  The only thing I can find that doesn't look right are the upper and lower fan speed settings, both in the -10 area setting.  What do the fan speed settings do, exactly.  Any suggestions on what to look for regarding the somewhat muffled popping sound from the exhaust port?

Thanks,

tmfixit

[tmfixit]

Ok, here's what I've found about these Westinghouse tankless water heaters.  The installation manual indicates that the burner and gas flow are required to be adjusted on site using a CO meter to properly adjust the gas flow/mixture for a proper burn.  According the Westinghouse tech support, all the units come from the factory (or did before they discontinued the heaters) adjusted the same and NOT having any factory adjustment for altitude.  I'm at 7200 ft and this unit always had some issues.  At a high flame burn the exhaust made some popping sounds and a 'rough' burn much like a lean carburetor does to an engine.  Didn't sound right, but in order to check or adjust the natural gas mixture to the specs in the manual a CO meter is necessary, so I purchased one.  There is a port inside the machine that allows access to the exhaust stream that I suspect is to be used for the CO measurement.  The CO is checked for this heater at a low fire setting that requires a DIP switch (#7) to be ON.  Checking in this configuration for a CO reading <60 PPM showed a lean burn at 12 PPM CO.  The high fire setting should be <200 PPM with DIP switch #6 in the ON position, #7 OFF.  This reading was about 25 PPM, also very lean in my opinion and also precipitated the muffled popping sound as if the burners were trying to fire but doing a bad job of it.  Going back to low fire for adjustment, I boosted the CO mixture readings from about 12 PPM to 21-22 PPM, still well under the 60 PPM limit.  With the increased gas/air mixture adjusted the unit was switched to high fire and the burner was noted to smooth out with no unusual sounds, no errors and apparently now burning as it should.  High fire CO increased a bit to about 32-35, still well below the 200PPM upper limit.  Mixtures were checked several times over several days both at the exhaust 'test port' and at the exterior exhaust opening and all were in line with the adjustment procedure and specs.  It apparently only took some small adjustments, slightly more than a 1/4 turn of the adjustment screw, to get the thing to burn nicely.   One other piece of info from the manual is if a whistling type noise is heard at the exhaust, the the adjustment screw should be increased by 90 degrees, or a 1/4 turn.  This noise was initially present but gone after the adjustment procedure was completed.  I don't know who installed this tankless unit but I suspect that even with the setting in firmware done through the user panel to set the altitude to the 5000-7999 feet range the required CO adjustment procedure was not carried out.  Hope this helps.