Lightest windproof method for boiling 2.5L of water

Lots of butane canister stoves would work

BRS 3000 weighs 1 ounce – favorite on this site but there have been reliability issues reported

I like the Soto Windmaster because it has piezo ignition, 3 ounces, Japanese engineering seems a little more reliable to me

You also need a windscreen – search for “canister windscreen” and you’ll get a zillion threads on this site that describe various options

I have heard of people doing the following.  They have used the Open Country 2 qt pot with the TD Cone for the 1.3 Evernew.  They flip the cone over when using the Kovea Spider.  Not perfect as a windscreen, but you have almost all of the hardware.  The Open Country pot is darn cheap.  My 2 cents.

This would be the lightest way to do it using this type of burner with stainless steel mesh pot support and lightweight titanium windscreen:

The Fancee Feest stove might be the choice for you:

Boils 12 cups of water in 29 min Rolling Boil, steam pumpin the lid up, using 3 ounces of denatured. Continued to boil an additional 5 min.

From OP –

“we had to boil twice and this was a bit cumbersome. Longer stops, colder kids… I’m trying to make it more efficient.”

IMHO “efficient” was a poor choice of words for a geeked-out UL forum.  I’ll go out on a limb and suggest the OP is looking for a Fast, Light, and Compact.

e.g. a light packable 10,000 BTU burner operable at -5° C, under a 2.5L pot, behind a UL windscreen.

Edit to Add: The trade off between white gas and an inverted canister?

Build a fire would be lighter : )

I think you keep your spider and get a bigger pot and maybe a bigger cone and you are all set.

Another possibility – not lighter, but more compact than the reactor and same level of high wind performance:

https://www.msrgear.com/stoves/stove-systems/windburner-group-system

My vote is for you to consider the Jetboil Sumo pot and its superb (if a bit heavy) stove burner. The pot is 1.8 liter capacity, and the burner allows one to do a very nice simmer if that is desired. For example, by using JB’s pot support (sold separately), you can simmer a smaller amount of, say, soup in a different pot or a bowl with handles. Also, Jetboil stoves/pots are renowned for their fuel efficiency and fast boils.

I differ from my buddies on their following suggestions:

(1) The BRS-3000T stove won’t properly support a pot with > 1.0 liter of water. That is too heavy for it. It will do a 2-cup boil fine, but over 3 cups would be a bit dicey.

(2) Any alcohol stove will take a long time to boil your water, and the total weight of the alcohol setup will be greater than the weight of your canister fuel/stove.

The most efficient suggestion would be the camp fire or wood burning stove approach. But of course that would complicate things if you just want to boil some water for a quick lunch on a cold day. Then there’s the business of protecting the contents of your pack from a sooty pot. Many times I have done just that, when we were staying at a winter base camp for a couple of days and we kept a campfire going nearly the whole time.

So yeah, you’ll get all sorts of opinions on these forums…

With 3 kids, I agree with @zia-grill-guy….go that route

Kids like campfires, fit in a campfire or two and hang a stainless steel Vargo Bot in amongst the coals for some hot chocolate for the kids.

If boiling that volume of water fast is the goal, you’re going to find the 2.5L Reactor system very hard to beat, in terms of fuel efficiency, boil time, and kit volume.

This is my choice for group trips during all times of year, for the sake of speed and fuel efficiency.

Packability is going to be limited by the size of your pot, not the stove system.

Greg….The wife and I have adventured with FOUR of our teenaged grand daughters for the last five years normally for 11 -13 days using Evernew 1.3L pot with FLAT CAT 1.3 L WINDSCREEN & KOVEA ISOPRO SPIDER STOVE and experienced NO ISSUES you have described.. We did Freezer Bag Cooking (FBC) & Baking and on two trips used a BANKS FRY-PAN 8″ dia, to fry our fish and morning cakes. I believe from my experience you have a great setup!

For those time you need to boil 2x  and to “cover your bases” to do your cooking a bit faster for the children’s wants…….go with a 2 qt pot and forget your windscreen. If it is going to be a regular 2x boil then invert the TD Ti-Tri as Jon has explained OR have Jon Fong (Flat Cat Gear) make a  FLAT CAT 1.3 L WINDSCREEN for you that would ft a 2 qt pot OR purchase a Flat Cat Gear Bobcat Universal Windscreen.

As I said I believe you already have a great set up…..