P68 draft/combustion blower voltages change while running?

[corkman]

in in the process of installing a p68 and before connecting to the vent i thought i wiuld run a few tests on it. I have a draft meter set up and also a harman diognostic to see what the stove is doing. So with the stove in test mode all motors run. However,i noticed something odd with the combustion blower. The needle on the draft meter didnt move as the motor was changing from high to low speed. It stayed on .8 while running at both high and low. So i connected the diognostic meter and saw that while the convection blower worked normal showing 57v on low and 119v on high the combustion blower gave me a steady reading of 97v and never changed even though the blower is supposed to run on high and then drop to low. Anyone know what might be going on here. This is a used stove and is 3yrs old. I have 120v at the outlet

 

[Harman Lover 007]

The combustion blower runs at a constant speed on a Harman. Only the the distribution blower changes speed. What you are seeing is normal operation.

 

[corkman]

in in the process of installing a p68 and before connecting to the vent i thought i wiuld run a few tests on it. I have a draft meter set up and also a harman diognostic to see what the stove is doing. So with the stove in test mode all motors run. However,i noticed something odd with the combustion blower. The needle on the draft meter didnt move as the motor was changing from high to low speed. It stayed on .8 while running at both high and low. So i connected the diognostic meter and saw that while the convection blower worked normal showing 57v on low and 119v on high the combustion blower gave me a steady reading of 97v and never changed even though the blower is supposed to run on high and then drop to low. Anyone know what might be going on here. This is a used stove and is 3yrs old. I have 120v at the outlet

The combustion blower runs at a constant speed on a Harman. Only the the distribution blower changes speed. What you are seeing is normal operation.

ty for your reply. Now i am confused. I have an advance in the basement that does the opposite. Attatched are a fee pics. The convection blower again runs at 119 v on high and 57 when it drops to low. However the combustion blower runs at 119v on high and 97 on low. The magna gauge also drops as the combustion blower voltage changes. So you think the p68 is fine?? What are the numbers on the advance indicating? Ty again Corkman

 

[Bioburner]

I am going to try and change thread title to attract others as I don't want to fire up a Harman to check.

 

[Golfeur]

I have a p68 and test the combustion blower changes from top to bottom has every minute. potensiometre tone adjustment should be maximum that's why the speed of the blower does not vary

 

[corkman]

I have a p68 and test the combustion blower changes from top to bottom has every minute. potensiometre tone adjustment should be maximum that's why the speed of the blower does not vary

not sure what you mesn by potensiometer tone adjustment

 

[Bioburner]

Draft fan adjustment pot switch.

 

[Harman Lover 007]

So there is some conflicting info above and I don't like to muddy the waters. My experience is the combustion fan should run at a constant voltage, the only adjustment of that voltage is when a draft test is being performed and an adjustment is being made via the small draft adjustment screw on the control board. Most of us can't do that unless you have the equipment the OP has above. As we all know, the distribution blower is variable speed because we can manually change it right on the stove.

Bio....you're gonna have to fire up that Harman and run a test to settle this

 

[Golfeur]

I have a draft tester when I'm testing high = 0.65'' H2O
and min = 0.35'' H2O and speed of the combustion blower has changed every minute high to low

 

[Bioburner]

Not to muddy things even more but values may change if the stove is running and not when the stove is cold as the ESP helps control things.

 

[Harman Lover 007]

I have a draft tester when I'm testing high = 0.65'' H2O
and min = 0.35'' H2O and speed of the combustion blower has changed every minute high to low

....yes but are you turning the draft adjustment screw to obtain those different readings?

 

[Golfeur]

I adjust the draft as the procedure in the manual
NOTE: Test mode alternates between top draw
and pulling down every 60 seconds. If you need
more time to adjust the draw, wait until
Next pull-down cycle

 

[corkman]

im back.so i had a chance today to go check out another p68.on this particular stove the combustion blower voltage changes just like my advance in the basement.while the combustion blower was on high and reading 119v the room blower was reading 57v while running on low.after a minute or so combustion blower dropped to 93v on low and room blower 119 while on high.
the combustion blower on my p68 never sees 119v.just a constant 97v.
i also noticed his board and dipswitch settings are different than mine.
his board #3-20-05374d with dip switches at 00000011
my board #3-20-05886e with dip switches at 10101111 with red esp wires

 

[bags]

Throw pellets in it and enjoy the heat. Try not to fix things that aren't broken. A guy last year was tinkering with a new perfectly running stove and fried his board because he forgot the unplug trick before "fixing" it.