2 replies to this topic

[3rd party JKor]

This Saturday I'm going to try to keep my brew day as short as possible. I'm going to set up my rig the night before, pre-mill the grains, pre-weigh the hops/brewing salts and maybe preheat the water. I'm not looking to end up with my water at the perfect temp in the morning (though, that would be sweet). I just want it to be most of the way there, so I can transfer it back to the kettle and get it up to temp. I've heard you can affect the water chemistry by preboiling the water, if I heat it up to just below boiling, is this still an issue?I could just fill the kettle with cold water the night before, but it would be nice to save whatever time I can in the morning.

[chuck_d]

So I'm constantly trying to understand water chemistry better than I currently do. If you have any reference on the issues of preheating water affecting your chemistry I'd like to read up on it. My only guess is that it has to do with evaporation concentrating most things in it. To minimize this impact you would obviously cover the kettle, but I assume you were planning on doing this anyways in order to retain the thermal energy. Measured pH is different based upon temperature, but I don't have a firm grasp of that scale yet. I really want to get to the bottom of, or rather below the surface of much of this brewing water chemistry. I have a lot of work ahead of me in that case though.Edit: don't count on any kind of response from me before you brew on Saturday though

Edited by chuck_d, 23 September 2009 - 07:08 PM.

[3rd party JKor]

So I'm constantly trying to understand water chemistry better than I currently do. If you have any reference on the issues of preheating water affecting your chemistry I'd like to read up on it. My only guess is that it has to do with evaporation concentrating most things in it. To minimize this impact you would obviously cover the kettle, but I assume you were planning on doing this anyways in order to retain the thermal energy. Measured pH is different based upon temperature, but I don't have a firm grasp of that scale yet. I really want to get to the bottom of, or rather below the surface of much of this brewing water chemistry. I have a lot of work ahead of me in that case though.Edit: don't count on any kind of response from me before you brew on Saturday though

My main worry is precipitating CaCO3. I was just thumbing through the water chemistry section in How To Brew. Palmer explains the mechanism for the precipitation of CaCO3 via boiling and aeration. One key point of the discussion is that the limit of the precipitation is down to 50 ppm of Total Alkalinity as CaCO3. Since my water only has 42 ppm TA, I wouldn't have any CaCO3 precipitating in any case.My understanding is that the mechanism is mostly dependent on the temperature dependence of CO2 solubility. CO2/carbonic acid is on the precipitate side of the equation, so as you raise the temperature of the water, CO2 solubility decreases. This causes CaCO3 to precipitate to the point where the co2 concentration is in equilibrium with the temperature of the water. I'm assuming at 212F the CO2 equilibrium concentration is equivalent to about 50 ppm.