Heat up maple sap using a tankless water heater?

[GreatLife]

Hi folks, every spring I brew a Belgian Saison whose entire brewing water bill consists of freshly collected maple sap. We're talking overall about 1000-1500 gallons for strike and sparge water. I use two gas-fired tankless hot water heaters (THW) to supply strike and sparge city water for all my other brews; with the sap I have to do multiple rounds of heating in the boil kettle, then transferring and storing the hot sap in an open fermenter, and pumping it back to the mash tun for strike and sparge. A PITA, but the beer is worth it. This year I'm thinking of putting a T and valve on the cold water supply to the THW, and pumping the sap directly through the THW to feed my platform on brew day.

For anyone who might be familiar with THWs and how they work.... can you foresee any big problems in doing this, either problems with the THW or with the resultant brewing water? The sap is typically SG 1.008, stored at 38F and would be heated by the THW to 165-170F. Flow rate thru the THW is about 3-4 gpm per heater. Many thanks in advance.

Patrick Clancy
Great Life Brewing Company
Kingston, NY

[dick murton]

This isn't particularly high sugar content and I guess you are only doing one or two brews of this each year, so I wouldn't expect too many problems. BUT, the temperature differential between the sap and the flame is going to be very high, so you may get some caramelisation and fouling. Have you tried heating the sap up in a pan on an open flame and seeing what the results are like? If you already have hard water the you may get a combination of sugars caramelising and embeddding themselves in with the hard water scale, making it harder to clean. Assuming this heater is made of stainless, then there should be no problems if you want to give it a decent caustic and or acid wash. before and after the saison brew/s.

But am definitely not guaranteeing this as I have never heated a sugar solution like this - comments are based purely on what happens in wort kettles etc.

[UnFermentable]

Is your sap boiled down from the farm? Usually the sap is boiled down to 150-200 centiposes for a syrup consistency (30 weight oil). The viscosity may cause you to slow to a trickle. Remember, viscosity and SG are not directly related. Heat exchangers in the on demand systems are small.

I’d try using your primary HX if it is a possibility. Instead of running CLT water, flow with HLT or on demand source and pump the sap as you would the wort. You know that HX has better throughput.