Low Starting OG on 3 of 4 LHBS-purchased partial mash kits

[jmill]

I'm sure this is one of the more common beginner brewer questions, but I'll ask it anyway.

I dove head first into home brewing about a month ago. I've done a brew every weekend since then, completing my 4th beer yesterday. For each I have used a recipe kit from my LHBS and have followed the directions as closely as possible. (I think my second mash got a little too high about mid way through, but not for too long.)

Each, except my first beer, has had a significantly lower starting OG than the recipe called for. (From most recent brew to first: 1.043 v. 1.051; 1.038 v. 1.058; 1.020 v. 1.042; 1.052 v. 1.050) (And if style matters, same order: 70 Shilling, Belgian Wit, Blonde, Kolsch)

My second beer, a blonde (1.020 v. 1.042), actually had an "alcohol booster" addition, which was supposed to drive up ABV, thus I was expecting a higher starting OG than what the recipe called for, 1.042.

I've been doing a bunch of research, but I feel like the results I'm getting are more what I'm looking for instead of what I actually need.


Here are some variables I know can have an effect:

Mash temp - Held within 5 degrees of what the recipe calls for. (usually 155 for 45 mins)

5 degrees seems like a big change, especially if it is going up, then down, and back up. This has me considering just getting a 10 gal drink cooler and doing all grain since I have all the other equipment.​

Thermometer issues - Using a Thermapen, so shouldn't be the issue.

Water pH - I've tested my water recently and it sits around 7-7.5 after running through a Brita filter, 7.8 without. I have some water additives on order for the next brew. (I also plan on getting a full water profile, but have yet to do that.)

I'm not too sad about this, since I will have some nice session beers for summer. (Can't complain if any of my first four beers are drinkable...the Kolsch in a keg seems to be getting there.) However, I want to dial in my technique so I'm producing a wort with sufficiently high efficiency so I can try some higher gravity beers.

Any advice? Variables to check and how to isolate them?

 

[kh54s10]

Are these partial mash kits with base malt grains, specialty grains and malt extract? Or is it an extract kit with steeping grains?

Are you adding top up water? If so I would say that you are just getting false readings due to uneven mixing of the wort and top up water (quite common as it does not mix easily).

An other thing to check is the calibration of your hydrometer. It should read 1.000 in distilled water at the temperature it is calibrated for.

 

[HopHeavy]

Sounds like you are mashing malted grains, not doing extract and steeping grains... If this is correct, fluctuations in mash temp will have a dramatic impact on your finished gravity, not so much on your starting gravity. I am going to lean toward a volume issue. Somehow getting diluted wort in the boil kettle, not boiling off enough, or both. This calculator can help with the dilution volumes kh54s10 spoke of <DILUTION CALCULATOR>
On another note... Did you happen to weigh your ingredients? You will find that even the LHBS is not beyond a mistake now and again. I have found myself short on some ingredients when I picked up a recipe once or twice.

 

[chickypad]

Are you adding top up water? If so I would say that you are just getting false readings due to uneven mixing of the wort and top up water (quite common as it does not mix easily).

Mixing/measurement errors are very common. I would take a reading on your mash runnings to see how you are doing there. Can you run through the details of your mash process - for example list a recipe, how much water you used, etc.

 

[Calder]

If you are using a booster, I suspect you are just steeping some specialty grains (usually about a lb), adding extract to the boil, and topping up with roughly 50% water at the end.

If that is the case, then you really can't go wrong, and will get what the recipe says you should get (........ I did see once a series of extract kits that advertised an OG that was impossible to get with the ingredients given; I can't remember whos it was, and is probably not the case here.

I suspect you didn't fully mix (a common problem) and took your gravity reading from the top.

Please provide one of the recipes (and volume) and someone will tell you what you should have gotten.

If you are steeping (vs. mashing), the temperature is not very important. All you are doing is dissolving the sugars that are already present on the grain. Mashing requires more accurate temperatures as you are converting starches to sugars, and the temperature affects the type of sugars created.

 

[boydster]

Easily the most common culprit for low OG in extract or partial mash brews is wort stratification, meaning you didn't get everything evenly mixed and got a false reading. And it's even more common if you also did a partial boil and then added top-off water. In the top-off water case, you can take an OG before you add the extra water and then calculate how much you diluted it to get an accurate OG.

It's not really a huge deal, because fermentation will take care of mixing everything and the yeast will certainly have no trouble finding the sugar. As long as the beer tasted good in the end, I think you'll find you care very little about a wonky OG reading

 

[jmill]

Thank you for all for your responses. Yes, I am doing a partial boil and topping off. I suspect poor mixing is the culprit.

Details of my last brew:

2 lb Golden Promise
.5 lb Cara Pils
.5 lb Eng Crystal
.25 lb Peated
2 oz Chocolate
2 oz Black Roasted Barley

Steeped at 155F for 50 mins; in 2 gals water at this point; rinsed with 2 qts @ 175F
Took reading - 1.080

5 lb Extra Pale Extract; added 1 gal water

1 oz Kent Golding - 60 mins

cooled and added remaining water, totaling 5.25 gal - shook bucket, took reading 1.043


We will see if they taste good in the end.

I just acquired a cooler which I may turn into a MLT, but I feel like I need to do another partial mash just to see if it was just not properly mixed.