# need help...



## plumb nutz (Jan 28, 2011)

First off.. long time no see, huh?

So I was asked to look at an oil fired boiler. Someone had come before me and replaced a bunch of parts, the control module and the blower motor some time earlier. Apparently, the boiler is really old and the control box wiring was kind of rigged. After adjusting some wires, the unit fired but the exhaust was very dark, as if I'm not getting a really clean burn and when the unit first fires up, backdrafts into the room.

So here's what I got:
Bryant/carrier model 238AAN003120AAAA
Serial number 2993V02357

Honeywell R7284 oil primary is the new module

After several Google searches, I cannot find any documents on this thing..

Could it be something as simple as a dirty chamber or bad ignition?

Seriously, this is completely alien to me, any help would be very much appreciated


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## OldSchool (Jan 30, 2010)

First off do you have a combustion analyzer?

You are more than likely going to have to adjust the air intake into the burner

If the system is carbon up then your air shutter is not open enough

Do you have a smoke test kit?

You need to bring the system to light smoke... Then open shutter just until it is clear then lock air shutter in place


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## OldSchool (Jan 30, 2010)

If it is lighting on ignition then every thing is working

All you got on that thing is

- pump
- motor
- transformer
- electrodes
- primary control
- blower wheel 
- drive coupling
- blast tube and turbulator
- cad cell
- nozzle

If it lights and goes out .... Then the cad cell can not see a flame
- this could a few causes, faulty transformer, air in fuel or water ,lack of fuel, pump pressure, bad electrodes, bad cad cell, nozzle, to much air at shutter

If it lights and stays lit and smoke
- fuel air mixture( adjust shutter more air)
- faulty transformer, dirty nozzle, fuel pump, motor rpm, drive coupling slipping, blower fan loose, electrodes, air in fuel or water

Very seldom is it the primary control unless it will not start at all

The primary gets a call for heat on the tt contacts and that activates the relays inside to start motor and transformer

From there cad cell either sees light or it doesn't .... If it sees light if holds the contacts closed to allow the operation of motor and transformer


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## RealLivePlumber (Jun 22, 2008)

OldSchool said:


> If it is lighting on ignition then every thing is working
> 
> All you got on that thing is
> 
> ...


 
Forgot one thing..............

A clean, properly sized, unobstructed chimney.:yes:


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## OldSchool (Jan 30, 2010)

RealLivePlumber said:


> Forgot one thing..............
> 
> A clean, properly sized, unobstructed chimney.:yes:


Yup missed that one.... But if anything it would come out of backdraft damper

Also it could be a plugged up heat exchanger.....

Just give me the address and I will go over and fix it

Lot easier than speculating .... LOL


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## plumb nutz (Jan 28, 2011)

Sure come on down to the old dominion, heck , when your done we'll try our luck with the herring and cats down at the river...

So, the cam unit was replaced (not by me) about 6 months ago... It does fire, but poorly? Chimney gets hot but cannot see a flame in the sight glass, along with the heavy smoke..

Other than what the fan takes in I didn't see any way to adjust the air going into the unit. 
I'm guessing the spark goes across both electrodes to ignite and do not work independently?
If its a clogged heat exchange, is it difficult to clean?


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## plumb nutz (Jan 28, 2011)

One other thing, no dampner on the chimney, but the unit has been working for 30 yrs without one (not saying that's right)


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## OldSchool (Jan 30, 2010)

plumb nutz said:


> Sure come on down to the old dominion, heck , when your done we'll try our luck with the herring and cats down at the river...
> 
> So, the cam unit was replaced (not by me) about 6 months ago... It does fire, but poorly? Chimney gets hot but cannot see a flame in the sight glass, along with the heavy smoke..
> 
> ...


The spark goes across the two electrodes at 10,000 to 6,000 volts depending on the transformer

The air shutter should be beside the fuel pump

However seeing there is a carbon problem this has to be addressed first

- the heat exchanger has to be cleaned out... I am taking that this is a boiler

The chimney has to be taken off the top of the boiler ... Then remove the top casing if the boiler 

Then remove access panel

Then the heat exchanger needs to be brushed out.... If this is a pin type boiler good luck as the pins are so tight together that a brush will not fit

At times u use a rod of silver solder to pass through the pins

And if the carbon is loaded with wet fuel then there is no choice to pressure wash the unit

It is apparent that ... It may be above your knowledge of characteristics of oil burners to make a proper cleaning and checks and balances

There should be no smoke or carbon what so ever


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## pilot light (Apr 21, 2012)

RealLivePlumber said:


> Forgot one thing..............
> 
> A clean, properly sized, unobstructed chimney.:yes:


 Good call


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## pilot light (Apr 21, 2012)

OldSchool said:


> First off do you have a combustion analyzer?
> 
> You are more than likely going to have to adjust the air intake into the burner
> 
> ...


 Also good call! pull assembly check nozzle and the glazing of the electrodes also look for cracks.Check the the transformer, the burner fan, pump pressure must be 100 psi or more and vac must be below 12 but preferabaly under 8, smoke spot @ under 2 and then combustion for air and co!


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