Btu ?

[325abn]

A gal of fuel oil has about 140K BTUs and I am using a 2Gal/hr nozzle (assuming 100% efficiency) I am putting about 280K BTUs to my pan. Is there a formula for how many BTUs a pan based on size can absorb?

I have no idea how to measure efficiency in my rig but I would be happy if it was 55 - 60%.

[bowhunter]

An easy way to do it is to measure how much you're boiling away per hour. So if your rig is boiling 10 gallons per hour, that's equivalent to about 80,000 BTU's per hour of heat absorbed by the pan. A gallon of water weighs 8.3 pounds and the heat of vaporization for water is about 900 BTU's pound. The efficiency would be 80,000 divided by 280,000 time 100, or about 30%. This is not precise, but good enough for your purpose. A flat pan is generally rated at 1 gallon per hour per square foot of pan. Some do a little better, and some a little worse.

[BreezyHill]

The easiest way, I have found, to increase efficiency is to clean the bottom of the pans. Day one this season our rig was nearly double the record last season. The carbon buildup on the bottom of the pan was thicker than I have ever seen it. A hard black layer that would not come off with a pressure washer even. to repair a pin hole in the flue I had to use my air grinder with a housing cleaner biscuit to clean off the black. We had to soak the air intake on our 6.0l diesel to clean the carbon out of it so I filled the upside down flue pan with water and let it soak...wow an over night soak loosened a good amount of the carbon. I have since repaired the flue brush door that was broken for the last 10 years and will be brushing the flues every day before firing up. boiled off the remainder of the sap and the rate was lower than the day before. There was a good amount of flake carbon on the flues and the finish pan.

I run wood so on oil it will have less of an affect but still will need cleaning to boost Eff.

Angle of gun will also affect efficiency.

Great question!

[325abn]

Good info Bowhunter. I have a old 2 x 4 Small Brothers Lightning raised flue.

I bought two new nozzles today 2gal/HR solid cone, one at 80` and one at 45`. Do to the way my rig was built I have a flame impingement issue on the bottom, with 2" blanket and 1" fire brick I only have 4" of clearance instead of the recommended 9 for the 80`. I am going to use the 45` to stretch out the flame and not get as much impingement. We'll see how it runs.

[325abn]

I am also need to clean the bottom of the pan.

[BAP]

A good way to clean the bottom of you pans in the off season is to leave them out in the rain bottom side up. It does a good job of taking a lot of the carbon off. Putting them under the eaves of a building so the rain water coming off the roof hits it works even better. In a rainy spring and summer you can get your pans to shine for free.