Why no float switches?

[kal]

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I get asked all the time why I don't use float switches in my boil kettle and hot liquor tank (HLT) to avoid firing the heating elements by accident if the water or wort level drops.

My answer:

I purposely do not use float switches in my design as they are not required as the water or wort level is never dropping as the heat is on. This is done on purpose as it's part of the design. It keeps the design simpler, which means there are less wires to get in the way, less wires to disconnect, less parts to clean, less expense, less complexity.

If you follow our brewing process (see our BREW DAY STEP BY STEP article) you'll note that we purposely turn off the HLT element at the start of sparging. The sparge water starts at 168F and slowly cools throughout the 60-90 minute sparging process while it rinses the sugars from the grain. By the end of the sparge the mash will be about 20 degrees cooler. This is completely intentional. A lower temperature near the end of the sparge helps minimize tannin extraction from the grain husks as it is most likely to occur when the mash has low sugar and higher pH. By the end of sparging the mash has very little sugar left so the drop in heat does not affect the flow (the primary reason for using hotter water to sparge).

Turning off the HLT element during sparging also has the added advantage that you do not need to worry about having the HLT element fire once the water level drops and exposes it to air. Firing heating elements "dry" can break them. Our process therefore does not need any sort of float switch or other safety device to ensure that the HLT element doesn't fire dry.

Same goes for the boil kettle: We are never firing the element as the level of wort is dropping.

One of the reasons I wanted to stay away from float switches too was that there are basically no good ones available for under $100-200. The cheap $10-40 ones get gummed up, stick, etc. You need to take them out after every brew and give them a good cleaning to ensure they don’t stick because they’re completely mechanical. They’re (IMHO) a pain.

Design your brewing equipment to match your brewing process. Process comes first. Don't look for missing "features" and assume that adding them will actually improve your brewing. There are times when adding something just makes everything more complicated instead of simpler.

Less equipment means lower cost, less wires to get in the way, less complexity, less time spent cleaning.

If you do decide you want float switches for the boil kettle and HLT, implementing them is very straight forward: The float switch is a simply on/off switch that should be wired in series with the BOIL RELAY and HLT RELAY coils. If the liquid level isn't high enough, the relays would not be allowed to close and current would not flow to the heating elements even if the PID/SSR are telling the element to fire. The user would know something is up the moment they turn the ELEMENT SELECT switch to either BOIL or HLT as the relays would not make that 'clunk' noise to indicate that the circuit is closed. I would use male XLR connectors on the control panel and female XLR connectors on a cable built the same way as as is done with the temperature probes. One of the three wires would simply remain unused.

Cheers,

Kal

[kal]

Register to remove this ad. It's free!

I get asked all the time why I don't use float switches in my boil kettle and hot liquor tank (HLT) to avoid firing the heating elements by accident if the water or wort level drops.

My answer:

I purposely do not use float switches in my design as they are not required as the water or wort level is never dropping as the heat is on. This is done on purpose as it's part of the design. It keeps the design simpler, which means there are less wires to get in the way, less wires to disconnect, less parts to clean, less expense, less complexity.

If you follow our brewing process (see our BREW DAY STEP BY STEP article) you'll note that we purposely turn off the HLT element at the start of sparging. The sparge water starts at 168F and slowly cools throughout the 60-90 minute sparging process while it rinses the sugars from the grain. By the end of the sparge the mash will be about 20 degrees cooler. This is completely intentional. A lower temperature near the end of the sparge helps minimize tannin extraction from the grain husks as it is most likely to occur when the mash has low sugar and higher pH. By the end of sparging the mash has very little sugar left so the drop in heat does not affect the flow (the primary reason for using hotter water to sparge).

Turning off the HLT element during sparging also has the added advantage that you do not need to worry about having the HLT element fire once the water level drops and exposes it to air. Firing heating elements "dry" can break them. Our process therefore does not need any sort of float switch or other safety device to ensure that the HLT element doesn't fire dry.

Same goes for the boil kettle: We are never firing the element as the level of wort is dropping.

One of the reasons I wanted to stay away from float switches too was that there are basically no good ones available for under $100-200. The cheap $10-40 ones get gummed up, stick, etc. You need to take them out after every brew and give them a good cleaning to ensure they don’t stick because they’re completely mechanical. They’re (IMHO) a pain.

Design your brewing equipment to match your brewing process. Process comes first. Don't look for missing "features" and assume that adding them will actually improve your brewing. There are times when adding something just makes everything more complicated instead of simpler.

Less equipment means lower cost, less wires to get in the way, less complexity, less time spent cleaning.

If you do decide you want float switches for the boil kettle and HLT, implementing them is very straight forward: The float switch is a simply on/off switch that should be wired in series with the BOIL RELAY and HLT RELAY coils. If the liquid level isn't high enough, the relays would not be allowed to close and current would not flow to the heating elements even if the PID/SSR are telling the element to fire. The user would know something is up the moment they turn the ELEMENT SELECT switch to either BOIL or HLT as the relays would not make that 'clunk' noise to indicate that the circuit is closed. I would use male XLR connectors on the control panel and female XLR connectors on a cable built the same way as as is done with the temperature probes. One of the three wires would simply remain unused.

Cheers,

Kal

[Crazy Brewer]

Thanks Kal, appreciate the clarification.

[foomench]

The one area where I've though of adding a float switch is the mash tun, to maintain the water level for fly sparging. But you really need to dial that in. A float switch just might end up pumping too much water through too quickly, resulting in a sparge completed too quickly and lower efficiency.