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WILLPLUMB4$
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Discussion Starter #1
Got a service call on a 75gal. NG Powervent heater.
Initial diognosis= jump out vacum switch = heater works = need new vacum switch.
new part comes in swap....= heater still won't fire. part looks different.
I had some time to kill so I started checking out the blower & vent. Vent was clean and free... Blower was full of lint. Barb coming of the back of blower, to vacum line was full of ??? Cleaned up blower, fittings and new vacum lines now old switch works.. New switch doesn't I'm guessing it's not getting enough vacum.

How or what is the best procedure for tearing apart and cleaning a vent?
It's got this tar stuff like nicotene bld up? any chemiclas I could spray in and let it soak? I'm guessing this stuff is from the caustic reaction residually left after each fire. Any suggestions are appreciated.
 

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I would probably start with the combustion air. Is it in an open basement or is it closed off in a tiny room with a clothes dryer, for instance. Combustion air contamination can cause problems with flue gas emissions. Also, if it is a PVC vent, there are some that say that the temperatures of the flue gas are too much for the PVC to handle.

An easy way to rule the vacuum switch is to stick a small, clean poly tube on the inlet of the switch. Attach an ohm meter to the terminals and set it for the continuity function. Apply a vacuum to the tube. If you hear an audible noise from the tester, your switch is good. If not, replace.

I've also install my draft gauge or Magnahelic gauge to the blower itself to check the vacuum. This can eliminate a lot of headaches as well.:thumbsup:
 

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WILLPLUMB4$
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Discussion Starter #3
I'm guessing that the switch(s) are ok, and that the blower needs to be cleaned. Was wondering if there were any shortcuts or advice on cleaning the blower to increase vacum.
 

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Shortcuts......not that I know of. You could remove the whole blower unit or the blower motor assembly to check the blower wheel. If it's covered with lint, dirt, etc... it will decrease vacuum without a doubt. The same thing goes for the air inlets around the blower unit.

You could also take an amp draw of the blower motor to make sure it isn't in the process of seizing up.

The only other thing that I can think of is to check the blower wheel at its connection to the shaft of the motor.If the lower wheel is partially stripped at its connection to the motor shaft, a significant decrease in vacuum can happen.
 

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WILLPLUMB4$
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Discussion Starter #5
The blower is "blowing" great, it is in a very harsh enviroment. Out on the production floor of a commercial laundry. I did notice several dryers with vent leaks, and there was lint built up on the blower and motor. I used a compressor to blow that all clean.
I'm schedualled to go back tomarrow to disect the blower motor, I'll let you guys know how it turns out.
When I said "shortcut" earlier, I was refering to either a technique or processe to clean every thing up with out hurting anything and completing the task in the most efficient manner.
I do everything flate rate, so since I've never done this before, I don't have a "upfront price" so I get a little nervous making one up, I want to be fair to both the costomer and myself.
 

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I'll almost bet that the blower is plugged with lint from the dryers. If it's any help at all (I don't know how your flat rate schedule works) I would calculate a 3-4 hour block of time to disassemble, clean, lubricate (if necessary) and perform a combustion analysis on the unit. If the blower is getting plugged up with lint, imagine what the burner is drawing in with the combustion air:)
 

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WILLPLUMB4$
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Discussion Starter #7
Nailed it all down today fellas thanks for the help... Used compressor to clean debri from squirrel cage, recleaned vent.. Batta Bing Like a MFer, new vacum switch works perfect, took about 1 hr....
 
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