Flat Glass Electric Range Question

[TheGreatCornholio]

I have a flat glass range on my stove. I know it is not ideal for brewing but it is what I have to work with at the moment. I have a 5 gal canning jar enamel pot that I brew with. I am brewing 3.67 gal partial boil extract batches and adding top off water to the fermenter.

My issue is this: I am unable to get the batch to come to a rolling boil after adding the extract and hops. I am able to get the temp up to 210 deg F which I hope is sufficient.

I have just completed brewing my 2nd batch this way (in the primary now). The first batch is bottled and came out fine. Should I do smaller partial boils (i.e. 2.5 gal) and use more top off water or am I worrying too much?

Thanks for any insight you can provide me with!

 

[prohl84]

I use a ceramic/ glass cooktop on my half- batches (3.5 gallons) and I have no problem bringing 4.25 gallons to a boil. I also use a 5 gallon enamel canning pot.

You don't need to boil liquid extract- throw that in when you kill the boil. A lot of folks will tell you NOT to boil LME because it will sink to the bottom of the kettle and scorch/ caramelize.

If you lose the boil you can put the lid back on until it starts boiling again and then take it off.

A rolling boil will yield better hop utilization- in all grain brewing it's important because it unravels proteins that can result in a cloudy beer.

 

[IslandLizard]

Some stoves just work better than others for large boils. There are lots of posts where some have the problem you're experiencing and others say they get a full rolling boil with 4-5 gallons in the pot.

I can do 7 gallon full (AG) boils on my (Samsung) glass top stove, but have to keep the lid on part way or part time to keep it rolling. I know my stove cycles the power off and back on preventing it from continuously outputting at max capacity. It maybe a safety issue, or just a conservative approach.

Also, the enameled graniteware pot has an uneven bottom, concentric ridges and valleys, so it doesn't give you optimal contact and heat transfer from the glass top to the pot. The glass top has temp sensors and temporarily shuts off the element or reduces power when it reaches a certain temp.

You could split the boil, using 2 pots, 2 burners at the same time. One boiling 2.5-3 gals the other 1-1.5 gallons. Check to see what the second (usually smaller) burner can boil. You could put some Reflectix (2 wraps) around your pot to reduce heat loss through the sides. Just be careful the plastic doesn't get too close to the bottom and melt to your stove. SWMBO will be unhappy with that. I'd keep it at least 1/2" above the stove.

As said before, put the lid on, but only partially (like half way or 2/3rd way so some steam can escape and take some DMS precursors with it. Although DMS is less of a concern with extract brewing.

Spread your boil additions (brewing salts, hops, spices, irish moss) proportionally over the 2 pots. Then combine at the end of the boil and add your LME or DME.

+1^ on adding the LME at the end. It really doesn't need to be boiled or has much benefit from it. Even all DME can be added toward the end, or at least should be split, like 1/3 at the beginning and the balance at flameout.

I'm not sure exactly why, but I've read you need to add at least some LME or DME at the beginning of the boil. But for risk of burning, scorching, or over-caramelization, never the whole amount. 1/3-1/2 is common, but you may be able to do even less.

Partial boils with steeping grains or partial mashes can create wonderful beers. There are some limits on how hoppy/bitter you can get it since you'll be diluting at the end, but unless you brew 100+ IBU beers that's not much of an issue.

 

[robertus]

If you lose the boil you can put the lid back on until it starts boiling again and then take it off.

Yep, that right there. I have a flat glass cooktop, and I need to keep the lid on it until the boil gets going. Every now and then, I'll need to throw the lid back on for a couple of minutes. Particularly after additions.

 

[prohl84]

I'm not sure exactly why, but I've read you need to add at least some LME or DME at the beginning of the boil. But for risk of burning, scorching, or over-caramelization, never the whole amount. 1/3-1/2 is common, but you may be able to do even less.

Possibly a (lower the) pH thing- maybe to prevent pulling tannins from hops in the kettle? There isn't a lot of tannin in hops say compared to grain husks but it's there. Just a guess really- no idea.

 

[TheGreatCornholio]

That's a good call on the bottom of the pot being uneven and the heat losses. The kettle is very thin. Also, I haven't tried putting the lid on the pot. Everything I have read thus far has contradicted doing so. I was under the impression that it would create a bitter aftertaste. I didn't know that it was alright to do just long enough to get a rolling boil. Also it probably makes sense to leave it on partially to allow some of the steam to escape.

I will also start to add the LME at the end to prevent scorching. Thanks for the tip! Hopefully it didn't bite me this time.

Good responses guys. I appreciate the feedback.

 

[pumpkinman2012]

I brew on a glass top stove as well, my 8 gallon Bayou Classic Kettle that I have which is taller and narrow heats up to a boil no problem, my other kettle which is also an 8 gallon kettle, but wader and shorter takes longer to bring to a boil, just another possibility on why it may not be heating to a rolling boil.