[Wanderman]

Today, when i went to test the diesel side of the Aquahot (I am running on electic in the winter to maintain 55 deg temps, which is working great!) I heard the main motor on the AH spin slowly at first, then speed up to normal. I saw some fuel coming out the bottom near the entry to the combustion chamber. It lit off...bunch of smoke... kept running, put sounded like it was going out and lighting up again. Each time a small puff of white smoke. Obviously, there is unburnt fuel at the bottom of the combustion chamber. The question is, what to do next? Keep running until clear? Remove assembly and clean? Somthing else?

Thanks!

[Trainer]

Motor spinning up slowly is not good. Pulling the burner, removing the black case, remove the motor and spin the clutch on the motor and then the clutch on the blower shaft is needed. Any side play or noise from the bearings is reason to replace the part, motor and/or bearings.

If there is fuel on the back side of the round plate the nozzle tower is mounted on, that is a leaky fuel pump seal, replace the fuel pump.

Wtih burner out, remove and clean combustion chamber and U-channel chamber. Replace the nozzle, clean the flame sensor and check the ignitor point position.

Re-assemble the burner, install into heater and turn on. Quick high wine for 30 seconds followed by igniton should result. The exhaust should be clean and clear. If unburned fuel is present in the system, the heat of the fire will cook it off as white smoke. That will clear over time normally clearing during the first heating cycle.

Not being there, my guess is the bearings need replacing. Do not run till solving the slow spin up and smoking problem.

[Wanderman]

Rudy,
As I said, the slow startup only happened once. Turing the unit on subsequent times including after a day of cold soak resulted in a normal high speed motor run. I was just concerned with the unburnt fuel at the bottom and that leaked into the tray.

Also, the on/off nature of the white puffs while it was first running again.. Will that continue until all unburnt fuelis gone??

[Trainer]

If you have a quick high whine on start up, the bearings and motor are okay. A puff on firing start is present in some burners but not in others. It is a puff and runs clean and clear till cycling off.

Repeated smoking while burning (not a puff), especially black smoke needs attention.

[Wanderman]

Rudy,
How long will the on off puffs continue usually? The system doesnt shut off.. so flame sensor sees a flame.

[Trainer]

If the burner puffs on start up, it puffs once. If there are continued puffs, you have a problem. An air leak into the supply fuel line will cause a white smoke problem. But that leak is usually continous, not puffy.

[Richard]

Here is another scenario that requires investigation.

You have clearly said, you hear it giving out and relighting. It can and will do that, the brain does not immediately shut the unit down if the flame sensor does not produce the correct resistance. The brain will fire the coil a couple of times before it shuts down.

You have to listen carefully to the “roar” to see if this is happening. If the roar disappears and almost instantly resumes, the unit is relighting. This is a tough problem to definitively diagnose.

First things first, have you cleaned the combustion chamber and installed a new nozzle ? That is not the same as I put a new one in some months ago, and it hasn’t run on diesel. Small drops of diesel harden on the nozzle when the unit is run on electric for long periods and no diesel use

[Trainer]

As Richard suggests, burner service which includes cleaning things up cures a bunch of firing issues. Not running the burner once per month, every month, year round, no excuses, causes a lot of firing issues.

[Wanderman]

I am sure it's the nozzle again. I was running it more than once a month, but got a bit lax.

I ordered a couple of nozzles and will replace when i get a decent day.