Harman P61a - 2 blink vacuum status light error??

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Minister of Fire
Feb 1, 2010
Salem NH
I am working on a Harman P61a about 5-6 years old. It is a newer stove so No micro switch. The updated circuit board has this as a vacuum error now.
The vacuum hose connects into the stove above the auger and gets air from the auger tube on the stove? The stove blinks and sometimes stops and sometimes goes back to running. Very strange!
I replaced the fire door ash door gaskets and the vacuum switch and still the same problem.
Here is a thread with the same issue but no answer! Does anyone have an answer?
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Also where the vacuum tube attaches to the stove make sure there are no air leaks…I’ve added more silicone to a couple
Thanks for your suggestions
Looks like there was one more twist to the cure.
Replacing the gaskets did help a lot that is why the short 2 blinks and then it kept running and now dying out.
The venting install seemed to have added something to the issue. The venting is 4” with a cleanout T inside with a 90 degree right on top of it and then goes straight outside with a termination cap with a coil wire to prevent any birds or critters. The cap is adjustable and had about a 45 Deg bend away from the direction the wind blows. So there is about 3-4 feet of straight pipe to keep smoke away from the siding. After replacing the gaskets and vac switch we cleaned the Cleanout T and the vertical chamber inside the stove where the ESP probe is. However Due to this longer horizontal length than the normal install there was a built up of ash in the outside section so after the stove ran for a couple hours the 2 blinks came and went. After cleaning this outside section the stove has been running fine! Whew!! LOL
Also there is a 3” outside air kit into the stove for plenty of fresh air.
In summary, it looks like after Harman moved the air intake from the air inlet tube to over the auger and into the auger tube the stove is more sensitive to low vacuum conditions than the older stoves. It does have a nice brass spigot there so the vacuum hose is attached more securely and less likely to leak but if you have one of these stoves, make sure your venting is kept clean and the door gaskets are more up to date so they are not brittle and spongy like new brakes in a car to make the best seal. :)
Here is a great way to test the Harman vacuum switch with upsizing the hose to the Harbor Freight brake bleeder tool and pumping in about 5 PSI to see if the bladder is brittle and leaking.
This one had a slight leak so I replace it. :)
Also not having a 3 foot rise in the venting cuts down on the natural draft that creates the air pressure in the stove. The fire codes do not specify a good 3’ vertical rise but it is better for this case and if there is an abrupt power loss.
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