Cad Ohms

[options]

Burnham MPO 147, Beckett AFG, L1 Head, new primary R7284, new nozzle .85/60B, fuel pressure 150psi (strainer clean), Tiger Loop with new filter, flue pipe clear, boiler lightly sooted. Smoke pump missing from kit. Will check it later today and clean boiler.

Beckett OEM settings S7 / B1. At these settings Cad ohms are 1700
Closing the shutter to 3 brings it down to 1150.

Beckett says it should be 300 to 600 and to stay under 1600.

Any suggestions?

Thanks

[Rovert]

Did you measure resistance with a light (flashlight) directly on the cad cell?

If it responds correctly to that, you either have poor flame, which I assume you checked for, or something blocking light from making it back to the cad through the burner tube. Did you clean the retention head?

If it doesn't respond correctly to direct light, it is a bad cad. I've seen lots of bad/weak cad cells.

[STEVEusaPA]

Why would you put a flashlight on a cad cell to check resistance on a non Riello burner? It tells you almost nothing.
Could simple be your cad cell is dirty, or mis-aligned. Bad cad cell or bad cad cell wire. Your Z dimension could be off. Excessive heat could've hurt the cad cell eye, even though you have a 15 sec. post purge.
First I would run burner, check draft/set draft, then do smoke test to get true zero smoke. Then take your CO2 number and open air shutter (not band) to drop that 1%.
You can check the cad cell reading on the control, or put the wires on your meter and check them.
Although the threshold is 1500 ohms on the older controls, like a 8184G, the newer Honeywells and Beckett Genysis won't lock out until 2500 or more ohms, especially with a head like an L1.

I have an MPO 115 and never checked the ohms, just a combustion test. I wouldn't check ohms unless I had a problem.
Draft is super important as that unit wants 0 at the port in the rear, and overfire positive. If you don't have the draft right you could be impinging on the target wall, creating soot and thus the higher (dirtier flame) ohm reading.

[VTP99]

I agree on the Z dimension and the type of shroud utilized.
Also checking your electrode tip adjustment.
Heed the "WARNING"

[STEVEusaPA]

You got the wrong pic for z dimension on L1/L2 heads. Correct for electrodes, and important, but probably not the problem with the OP (next page)

I agree about the Z dimension. I check it every time I touch a burner for the first time. Then I outline it with a marker. I also work by myself so I know I'll never have to check it again.
But moving that nozzle assembly in even 3/8" (which is huge) can change it from perfect to a dirty fire that's producing over 1000ppms if CO.

[options]

Did you measure resistance with a light (flashlight) directly on the cad cell?

If it responds correctly to that, you either have poor flame, which I assume you checked for, or something blocking light from making it back to the cad through the burner tube. Did you clean the retention head?

If it doesn't respond correctly to direct light, it is a bad cad. I've seen lots of bad/weak cad cells.

Its my home and I rarely worked on oil. I'm retired and my wife is on blood thinners. She was none too happy to wake up to a cold house. Boiler was purchased from Famous Supply at their Cleveland Expo the year Burnham came out with the MPO and rather than piss around with it I installed a new transformer and cad assembly along with the new primary. Primary has a digital readout for the cad which is what I was going by.

Thoroughly cleaned the retention head with brake parts cleaner and a small brass brush, disassembled and cleaned the fan and housing,installed a new coupling and checked fuel pressure. Also installed new electrodes using a beckett gauge to set them up.

Beckett OEM specs call for 2" but in the note section said to use 1 3/4" for the conic which is where it was set when I bought the boiler. I know because I marked its location and yes I checked it as well.

I did open the draft damper to get it to fire better.

I have a very old bacharach kit and will be buying a combustion analyzer this week. Any suggestions? Local RE Michel has a UEI C85 kit that someone ordered then backed out. They're willing to take off a couple of hundred to get it out of there.

[VTP99]

You got the wrong pic for z dimension on L1/L2 heads. Correct for electrodes, and important, but probably not the problem with the OP (next page)

I agree about the Z dimension. I check it every time I touch a burner for the first time. Then I outline it with a marker. I also work by myself so I know I'll never have to check it again.
But moving that nozzle assembly in even 3/8" (which is huge) can change it from perfect to a dirty fire that's producing over 1000ppms if CO.

Yes let me post the correct one

[options]

Thanks but had those pics.

[options]

Had a friend who specialized in oil check this each year, but sadly cancer got him and when I called around, two said they set them up by eye, another said I knew more than he did and the rest didn't want to get their hands dirty. Told my wife last night that when the oil tank is empty I'm installing a heat pump.

[VTP99]

Yep, heat pumps are great especially the higher seer ones.
A friend has a Bryant Evolution 16 seer and it's good down to about 20°f before it kicks on the backup heat.

[pecmsg]

Had a friend who specialized in oil check this each year, but sadly cancer got him and when I called around, two said they set them up by eye, another said I knew more than he did and the rest didn't want to get their hands dirty. Told my wife last night that when the oil tank is empty I'm installing a heat pump.

Your still going to need the oil from time to time!

Try here:
Heating Help dot Com (The Wall)

https://www.myhomecomfort.org/find-a-contractor/

[STEVEusaPA]

I'd come out and help you but we couldn't be literally any farther from each other and still be in PA.
The old Bacharach kit isn't really ideal to use on modern equipment.
If you're not really doing oil anymore, maybe get a friend who has an analyzer, buy him lunch.
Seems like you thru a lot of parts at it. I assume it's running now?

[STEVEusaPA]

Your still going to need the oil from time to time!

Try here:
Heating Help dot Com (The Wall)

https://www.myhomecomfort.org/find-a-contractor/

He's already cross posted.

[options]

Your still going to need the oil from time to time!

Try here:
Heating Help dot Com (The Wall)

https://www.myhomecomfort.org/find-a-contractor/

Only for my tractor!

Once the heat pump is installed that oil tank is gone and my wife said the baseboard heaters WILL be gone too!

House is well insulated and we only burn about 350 gallon a year for 1900 sq. ft. sitting on top of a windy hill. Duct work is already there for the A/C and I'll drop a run down to the basement and add a few floor vents from it to even it out.

I'll need a backup heat source. We had a rice burner when oil went sky high and it kept the house a toasty 75F on a couple of tons, but it was messy. When I sold my sheet metal shop I moved my wood shop from the basement to the building it was in and thinking pellets or a wood stove now that I have the room to store inside.

[options]

It's only 300 miles!

It is running but I'll feel better when I get it set up properly. I put it off last year but will be buying an analyzer and new smoke pump this week. Any suggestions?

I definitely bought more parts than I needed, but everything is new and cost far less than a weekend service call.

Unfortunately the friend I trusted has cancer and I honestly don't know anyone else.

[options]

Oops posted same twice

[pacnw]

Only for my tractor!

Once the heat pump is installed that oil tank is gone and my wife said the baseboard heaters WILL be gone too!

House is well insulated and we only burn about 350 gallon a year for 1900 sq. ft. sitting on top of a windy hill. Duct work is already there for the A/C and I'll drop a run down to the basement and add a few floor vents from it to even it out.

I'll need a backup heat source. We had a rice burner when oil went sky high and it kept the house a toasty 75F on a couple of tons, but it was messy. When I sold my sheet metal shop I moved my wood shop from the basement to the building it was in and thinking pellets or a wood stove now that I have the room to store inside.

If you don't install a back up heat source in the furnace air handler portion(electric strip heat or fuel) than if you allow the heat pump to operate below the point it needs to go into defrost the air coming out of the vents will be damn cold and defrost will not be complete.

You can stop heat pump use above/at defrost temp and then run another heat source, but that entails some planning and thinking.

[options]

If you don't install a back up heat source in the furnace air handler portion(electric strip heat or fuel) than if you allow the heat pump to operate below the point it needs to go into defrost the air coming out of the vents will be damn cold and defrost will not be complete.

You can stop heat pump use above/at defrost temp and then run another heat source, but that entails some planning and thinking.

No kidding. I may be old but at 66 fairly sure my brain still works. If not I wasted $25K on my first cnc router a few months ago. Thank you for your concern though, but just in case I'll make several large notes and hopefully I'll still be able to comprehend those when I'm ready to install the heat pump!

[P.Hank]

What’s your static pressure aka draft across the chamber and up the smoke pipe? Too much or too little can really throw off things. You should be looking for around -.01 to -.02 at the chamber and -.02 to -.05 at the stack. Too much draft your wasting heat and too little your failing to completely burn the fuel. You didn’t say anything about that and I don’t believe anyone else did either. Apart from testing with a analyzer testing draft really should be the first thing when there’s a problem if nothing is obvious. You mentioned living on a hill which can throw things off.


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[STEVEusaPA]

What’s your static pressure aka draft across the chamber and up the smoke pipe? Too much or too little can really throw off things. You should be looking for around -.01 to -.02 at the chamber and -.02 to -.05 at the stack. Too much draft your wasting heat and too little your failing to completely burn the fuel. You didn’t say anything about that and I don’t believe anyone else did either. Apart from testing with a analyzer testing draft really should be the first thing when there’s a problem if nothing is obvious. You mentioned living on a hill which can throw things off.


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Read post 3.
Your draft numbers are wrong for that boiler/burner combo.