Natural Gas Stove Top Evaporator

[jdircksen]

DRoseum - I'm looking at your burners trying to see if I can apply that to my setup.
Was it difficult to set up those Dante NG air/gas mixers? I found documentation that their mixer is rated for an input of 25,000 Btu. is that all you're getting out of your 3 burners? I was hoping for double that per burner.
Do you think I could make my own burner using pipe, a T, 2 elbows, and 2 caps? Not sure how I'd know how many and what diameter holes to drill in the pipe.

[DRoseum]

Setting those up was easy. NPT fittings and adjusting the air shutter is very simple. As for building your own, you definitely could. I was very close to doing exactly that, but for cost of materials, time drilling out all the holes, etc, I decided to go with the the stainless U-burners from Hearth Product Controls. They were about $37/burner for the 18" ones. Spotix online distributor sells them in a good variety of sizes and you can get an LP orifice if you prefer that. Hard to beat that price for stainless.

As for BTUs... the burners are rated for 90k BTU and the gas line I ran and manifold I built supplies enough for the full 270k (all 3 burners), but i am not sure how much that is getting throttled by the orifice in the air mixer. I saw the same documentation you did but went with them anyhow. A venturi mixer runs very expensive (hundreds of $) compared to these.

What I will say is that you can get a VERY clean burning blue flame with them, and nothing close to it without them. Blue flame is going to be significantly hotter than the yellow or orange, and your fuel efficiency will be far better. Also, no soot being deposited on the bottom of the pan. I also wanted as many BTU as I could possibly get, and while these might slightly limit it (doubt it's down to 25k BTU based on how quick it comes to a boil), the tradeoffs were worth it.

You could always try to ream out a very small amount of the orifice inside the mixer to increase flow rate but you have to be careful because these work on pressure differential. Probably would want to run some calcs on that first.

[DRoseum]

Thank you. It was a very fun project to design and build it (yeah I am a bit of an engineering nerd). But it was even more fun using it and enjoying the syrup it helped produce!

I will total up list of materials and costs at the end of the season and post it. Been meaning to do that anyways.

[Daveg]

"Sap foaming" and "syrup foaming nearing the finishing point" seem to be two different things. At times, I have to put defoamer in the flue pan (212°F), but rarely in the finishing pan (217°F, 218°F, 219°F). You mention turning the heat down when it foams at 217°F. What happens if you don't turn the heat down? Does it foam even more? If you put less sap in The Stove Top Evaporator you can have a lower sap volume to heat source ratio. What guage metal are your pans? The thicker the metal, the poorer the heat transfer. 20 and 22 guage are the most common in the industry.