Natural Gas Stove Top Evaporator

[HowardR]

I tried out my home-made gas-stove-top evaporator today. I pour the sap into a 15 gallon pot with a spout at the bottom controlled by a float in a float pan. The float keeps the sap about 2" inches high in the float pan and in the next three connected pans, each on its own gas stove. I had near-syrup trickling out the end of the last pan into a stainless steel bucket. I can work inside on my computer and just go out and fill up the 15 gallon pot about once every hour or hour and a half.

Here is a picture of the evaporator as a whole:

StovePotEvaporator.jpg

Here is the sap entering the evaporator through the float pot which uses a stainless steel float valve that I bought on Ebay:

FloatPot.jpg

Here's the 1/2 inch stainless steel pipe, valve and union as the sap travels between a pair of pans:

ValveBetweenPans.jpg

Here is the near-syrup exiting the evaporator:

SapExitingEvaporator.jpg

My first estimate is that it boils off about 7 gallons of water if the sap entering the pot is already hot.

[maple flats]

Just be careful for foaming. You may not want to let it go unattended that long. As the sap is boiled down the likely hood of it foaming up increases big time. If it starts to foam up, it could quickly ruin a pan and the sap that is left in it. An hour is a long time unless you set up a automatic defoamer, otherwise it's a sure recipe for disaster.

[HowardR]

Dave,

Thanks for the tip. That is certainly something to worry about.

But I may already have that under control. I have a thermometer in the last pan and increase or decrease the trickle rate out, to keep the sap from getting too hot. (I'm not trying to get it all the way to syrup in the evaporator.) Also, I suspect that there is less danger of foaming in a stove-top evaporator, given that the heat under the pans is lower.

[Haynes Forest Products]

Neat set up I take it you have good gas pressure at the house? I didn't see the WiFi camera....................you do have one right.

[maple flats]

Foaming can start well under the 219-220 target temperature.

[HowardR]

Neat set up I take it you have good gas pressure at the house? I didn't see the WiFi camera....................you do have one right.

Yes. The pressure at the gas regulator that feeds my house and garage is set at 7 oz, which is a bit higher than normal. The typical gas stove requires 4 oz. of inlet pressure to operate with full-size flames. My evaporator would work at lower pressures, but it wouldn't boil as much sap away per hour.

I don't have a wifi camera. Never thought of using one. My most important hi-tech app is the countdown timer on my smart phone. My dog starts heading outside just before me as soon as it goes off.

[HowardR]

Foaming can start well under the 219-220 target temperature.

I'm aiming for just 2-4 degrees above boiling in the evaporator. Then after I've collected a day's worth of sap, I finish it off on the kitchen stove. I've got a batch boiling in my kitchen right now.

[HowardR]

Today, I showed my neighbor the sap that was boiling in each of the pans. When I had initially explained my plan to him last summer, he had supposed that since the three pans were connected by open pipes, the sugar density in all three pans would be the same. I explained to him that the sap would always be running in one direction -- from the float pan, to the first pan, to the second, to the third.

Today, I took a clear pitcher and dipped it into the three pans in turn. In the first the sap was perfectly clear. In the second it was golden. In the third it looked just like syrup. Seeing is believing!

[jdircksen]

I'm glad to see it worked for you. I've been thinking of getting a natural gas cooktop and putting a 2x2 pan on it. Maybe the boss will let me put a full size stove out there so I can warm up bottles in the oven.

[HowardR]

I'm glad to see it worked for you. I've been thinking of getting a natural gas cooktop and putting a 2x2 pan on it. Maybe the boss will let me put a full size stove out there so I can warm up bottles in the oven.

If the "boss" lets you, you can get can get a used stove cheap! People discard them because the oven igniters stop working. If you call your local appliance store, you might be able to buy a traded-in stove from them. Look for stoves with some big burners on top. A five burner stove (extra burner in the middle) is perfect.