Funny thing keeps happening on brew day

[hilljack13]

I use Brewfather and the Grainfather app to plan my brew day. I have found that my mash efficiency with the G40 is ~75%. I am only about 6 months into using this, or 6-8 brews that I can recall. So here is my dilemma. Today, my pre-boil SG was 1.054 (expected 1.051). Not too high, but on other occasions I have been 3-4 pts lower with the same settings. Here is where things get interesting. My post-boil SG was 1.068 (expected 1.059). This is a constant thing I am noticing. My boil rate is 1 gal/h and I have my FV at 5.5g. I am usually right on that 5.5g. Today I was 5.25g in the FV.

I did have a hicup on the G40 controller today where it stopped keeping time so I had to guestimate time elapsed once I found out it stopped.

So, what I am getting at, my pre-boil is usually close and my post-boil is always much higher than expected, but my FV volume is usually right on. What might I be missing to hit the numbers? I'm not opposed to a higher ABV, but the consistency just isn't where it should be. My gravity readings are from a refractometer. I have calibrated it twice and have had very very minor adjustments.

Just looking for insight and advice from more experienced if this has happened to you and how did you correct, if at all.

Thanks all!

 

[dbsmith]

Cheap way to rule out the refractometer is to buy a hydrometer and see of the readings are the same. Don't forget to adjust for temperature. Also, how accurate are your volume measurements?

 

[hilljack13]

I have used hydrometer as well. It reads 2 points high. For instance, at 60F I get 1.002 and that is consistent with the refractometer.

I have pre measured my FV and the G40 before I have ever used them. I have found the glass sight on the G40 is not accurate but is usually. 25 gal high after I put the measured water in it. The boil off rate is consistent even when using the glass sight. I think that is what you mean by volume measurements?

 

[Hoochin'Fool]

My gravity readings are from a refractometer. I have calibrated it twice and have had very very minor adjustments.

Are your sampling while the wort is still hot? I've personally found that using a spoon to take a sample of hot wort for the refractometer always reads a several points higher than it actually is. Collecting the hot sample in an eye-dropper - where any evaporating steam is contained - and letting it cool for a few minutes before placing on the refractometer is more accurate.

 

[hilljack13]

Are your sampling while the wort is still hot? I've personally found that using a spoon to take a sample of hot wort for the refractometer always reads a several points higher than it actually is. Collecting the hot sample in an eye-dropper - where any evaporating steam is contained - and letting it cool for a few minutes before placing on the refractometer is more accurate.

I do the latter. I use one of the plastic pipping things and add to a stainless shotglass, sit in the freezer to cool quick. I take a pH reading first so I always get the temp, then a few drops on the refractometer.

 

[homebeerbrewer]

As for the volume measurements, is it hot water or cold water that you’re going by? Water will expand as it gets hotter. It sounds like you’re measuring the cold water to start, and hot water at the end. You could have a higher boil off rate than what you think.

 

[hilljack13]

As for the volume measurements, is it hot water or cold water that you’re going by? Water will expand as it gets hotter. It sounds like you’re measuring the cold water to start, and hot water at the end. You could have a higher boil off rate than what you think.

Only water I measure is my RO water. Everything else I mention above was wort. I measure by cups because I have a 3 gal pot I fill and keep track of. It's tap temp. Anywhere between 68-72F depending on weather. For the boil off, the standard 4% expansion is what I use.

Edit: Are you suggesting I change from 1g/p/h to just under? I have only had one (the last) that was less than 5.5g target.

Edit 2: Also, I think my boil time must have been extended when the controller stopped keeping time and I tried to manually adjust. I must have undershot my estimate.

 

[marc1]

What are your pre and post boil wort volumes?

 

[hilljack13]

What are your pre and post boil wort volumes?

Pre boil is whatever is calculated from mash requirements in the app and post boil ~1gal less. The sight glass is inaccurate during initial water addition (5 gal might level at 5.25 +/- some) but after an hour of boil the level is down the 1 gal. I had an issue with this particular day because the controller froze and I have no idea how much time elapsed before I realized it. For this particular day I ended up not recording the numbers , I was already a bit flustered with the controller issue.

 

[mac_1103]

You can't create gravity points during the boil, so if your pre-boil gravity was 1.054 and your post-boil gravity was 1.068 and your post-boil volume was 5.25 gallons then your pre-boil volume had to be 6.61 gallons (68*5.25=357=54*6.61). Unless you meant 5.25 gallons into the fermenter and some unkown amount of kettle trub.

 

[hilljack13]

5.25 gallons into the fermenter

Yes