Site Glass Calibration and Temperature

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rockytoptim

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I just got Bobby M's site glass installed and I need to calibrate it. Do you guys use mash temperature water to do initial calibration on the site glass or do you just use room temp. Or am i worrying too much about the volumetric change of water as the temp increases?
 
I use water out of my cold water tap as that is what I start every brew with.
 
The density difference between room temperature water and near-boiling water is about 3%, so you can use that as a guide to determine if your system is precise enough to warrant being concerned about temperature when measuring volume.

If you do decide it is important, then the next question is, When are you using the sight-glass markings to measure your volume? If you are using them exclusively to measure the cold water you pour in like BendBrewer, then use cold water. If you are using them exclusively when the water is hot, calibrate on hot water. If you are doing both, you'll have to get creative :D

I've never worried about it that much to be honest. There are always other, larger sources of error in my system.
 
I do kinda like the OP's thought process though. If putting a sight glass on an MLT, use 150ish degree water and near 180ish if putting it on the kettle.

I just measure my strike and sparge water and deal with the volumes that I get after that. I know about what 13 gallons looks like in the kettle.
 
Interesting question that I hadn't even thought of before. The reason I haven't thought of it is that beer tools pro, the software I use, compensates the water measurements due to temp expansion and contraction. I agree with Bendbrewer in that if this is your also your HLT that will receive the cold water, you'd want that measurement to be correct. If it doubles as your BK, just know that you're shooting for a final volume about 1 quart higher than your finished batch.
 
Wow I didn't know it varied by 3%. I still have to calibrate mine. I'm thinking I'll do ~70 degrees to be accurate with the water I initially add and then after chilling. That will keep my efficiency calculations accurate.
 
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