I think that the on-demand heaters need a minimum flow to activate the heat source. I don't know what that minimum flow is but there has to be a safety so a dripping faucet doesn't keep making hot water all day. As with all things, there are ways to bypass controls and make the unit do what you need. Of course, I would never do such a thing!Originally Posted by Cedar Eater
I took my old coffe maker apart. Under the warming platform is a horseshoe shaped (aluminum?) tube that consumes 600 watts. I bet that would preheat sap quite well. It's about the diameter of a pencil. It has its own thermostat, so over heat might not be an issue.
good info can be found on Heat Source Comparison including electric http://www.kegkits.com/heat_sources.htm
Prob would work well, but aside from the flow they require. cleaning would be limited to just flushing water or detergent through the system. They don't come apart..at least not the ones we have. You can replace parts, but can't really get into them to clean where the sap would flow.
Eric,
How many kw's actually used to evap 1 gallon of sap? A 4.5 kw unit @ 3414 btu kw should evap est. 7 gal hr with a 2'x2.5 surf area.
Thanks,
Dwight
His surface area is closer to 2 sqft, but I'm curious how you came up with that estimate for 5 sqft. The reason I ask is because mine will also be close to 2 sqft.
CE
44° 41′ 3″ N
2019 -- 44 Red Maples - My home and sugarbush are for sale.
2018 -- 48 Red Maples, 7 gallons
2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
2016 -- 55 Red Maples, 8 gallons
2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
An awning over my deck is my sugar shack.
An electrified kitchen sink and an electrified steam table pan are my evaporators.
Or I could kluge something that works much the same way, just thinking of a SS coil and a heating element that heats a trickler to 180-200 degF. Doesn't seem likely to be very expensive.
CE
44° 41′ 3″ N
2019 -- 44 Red Maples - My home and sugarbush are for sale.
2018 -- 48 Red Maples, 7 gallons
2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
2016 -- 55 Red Maples, 8 gallons
2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
An awning over my deck is my sugar shack.
An electrified kitchen sink and an electrified steam table pan are my evaporators.
That would be more along the lines of what I was thinking, except it would be SS and immersed in a small SS pipe so that cold sap would enter the pipe from the bottom, get heated and come out on the top at around 200 degrees.
CE
44° 41′ 3″ N
2019 -- 44 Red Maples - My home and sugarbush are for sale.
2018 -- 48 Red Maples, 7 gallons
2017 -- 84 Red Maples, 1 Sugar Maple, and 1 Silver Maple , 13 gallons
2016 -- 55 Red Maples, 8 gallons
2015 -- 15 Red Maples, 6 Birches - 3+ gallons maple syrup
An awning over my deck is my sugar shack.
An electrified kitchen sink and an electrified steam table pan are my evaporators.
Dwight,
Here's where I jump off the train. I have never calculated what it actually costs me to make syrup. My goal was to figure out a way to make the same product cheaper than using propane and easier than wood. My first calculations showed that the cost of electric versus propane was about the same per BTU. When I factored in the efficiency of the submersed heater it all went pear shaped and propane was beaten hands down. The surface area of my boiler is just over 2 ft² and I manage to evap 3-4 gph. Near the end when I stop adding sap the rate goes up. Dealing with such a small production rate the differences are pretty easy to measure. I have to pause Netflix and check the boiler more often as it gets closer to syrup.
Preheating
Here's my take on preheating sap. Unless I'm able to make use of free energy to bring the temp of the raw sap closer to the boiling point I don't see the benefit of preheating. Wrap a tube around the stack or use the steam from a back pan and it all makes perfect sense. I could arrange a preheating vessel and use the steam from my boiler but I'm not sure that covering that much of the pan would be beneficial. My evap rate goes up when I use a fan blowing across the top of the boiling sap. It's the surface area that makes the difference not the temp of the sap entering the pan. I'm going to use a given number of BTUs to evaporate a given quantity of water. Using a second source of energy to provide those BTUs just adds more equipment to the process. If I can't keep a good boil going as I add cold sap I need to increase the BTU available at the boiler. That being said, if time is a factor and you're looking for a quicker turn around then adding equipment and preheating might make more sense.
Now let's work on the solar preheater and really get a bang for our bucks!
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