Munchkin - 8 flashes

tim smith

while flushing water through heat x? Recirc of flue gasses seems to be one culprit of failed fans we have found but heat x build up causes most probs we see if not serviced once a year religously. Good luck.

Alan(OnVacationInOregon)Forbes

Munchkin - 8 flashes

This is on an older 140M unit - pre-925 controller. The 8 flashes on the green light on the circuit board tells me it's the fan or the pressure switch, but both are fine.

Aside: this unit has had two replacement fans, the last one about 2 years ago; I tested for CO inside the enclosure and none was found.

The owners have to flip the disconnect every day or so when they have no hot water; it works for awhile and then slips into lockout.

Any ideas? Bad circuit board?

Paul Rohrs_4

Concentric Vent?

Alan, does this have a concentric vent on it? I had a similar experience with a "radiant rescue" call and the culprit was an improper concentric installation. High winds caused a lot of back pressure on the exhaust, not allowing the pressure switch to "make". Try disconnecting the intake for a short time to see if it will still go to the 8-pulse fault.

Nothing better than hydronic CSI in the summer.

Regards,

Paul

Jr_12

The pressure Switch could just be getting weak. I would suggest upgrading to the digital board though. The new board will have the longer post purge on the fan, which will help if there is a negative pressure issue in the building.

Wayco Wayne_2

New board

The new 926 board has a much longer post purge. The 140 has a problem that after it shuts off heat would rise from the HX and melt stuff in the flu blower. The new board runs a 90 second cool down so the HX cools enough so that wont happen. Upgrade both refractories while you're at it. It makes for a nice upgrade. The new board also raises the voltage to the flame sensor and makes the sparker a second flame sensor. Say goodbye to any F-09 problems.

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S Ebels_2

Had the same thing Alan

A 140 we installed in 02 IIRC. After troubleshooting everything, and I mean complete disassemble, cleaning, tuning,flame sensor, pressure switch we still had the lockout problem. Chuck told me that the cure would be a board update to the 926 and he was right. Installed it and the boiler runs fine. In fact better than it ever did. It lights off at a little higher fan speed/input and then modulates down to minimum which really makes a difference in reliable starting. Modulates better, steadier fan speed during operation, flame sense reading in the 12-14 UA range. Lights up and stays lit just like it should. It really wasn't all that expensive as boards go.

Alan(OnVacationInOregon)Forbes

New Board

I like that longer post-purge feature. And the refractory replacement makes sense. Thanks, guys.

Nice to see some of my old friends on the board.

Steve Ebels_3

It's actually

A full update kit with new sensors and other fun stuff along with the board.