I have problems doing a stepped-mash starting at 40C with my coleman igloo based mash tun.
I like the 40C step as it gets rid of loads of gums that can cause a stuck mash.
My normal MT is about 47L, but its difficult to raise temp enough with hot water additions so alternative is a decoction which takes a long time.
I saw the LIDL jam maker on offer last weekend so I thought I'd give it a go. A mash tun that can raise temp of mash

Recipe is 35% Pilsner, 49% wheat and 9% Oats + other stuff (see below)
5750g total grain
9% Oats is odd I know but I love extra body and mouth-feel it gives.
Gyle Number: 54
Fermentable Colour lb: oz Grams Ratio
Bohemian Pilsner Malt 2.5 EBC 4 lbs. 6.5 oz 2000 grams 34.8%
Wheat Malt 3.5 EBC 3 lbs. 4.9 oz 1500 grams 26.1%
Flaked Wheat 0 EBC 2 lbs. 13.8 oz 1300 grams 22.6%
Oat Flakes 2.5 EBC 1 lbs. 1.6 oz 500 grams 8.7%
Cara Munich 120 120 EBC 0 lbs. 8.8 oz 250 grams 4.3%
Carabelge 300 EBC 0 lbs. 3.5 oz 100 grams 1.7%
Acid Malt 2.5 EBC 0 lbs. 3.5 oz 100 grams 1.7%
Hop Variety Type Alpha Time lb: oz grams Ratio
Tettnang Whole 4.3 % 85 mins 0 lbs. 1.1 oz 30 grams 100%
Final Volume: 23 Litres
Original Gravity: 1.055
Final Gravity: 1.013
Alcohol Content: 5.4% ABV
Total Liquor: 36.7 Litres
Mash Liquor: 14.4 Litres
Mash Efficiency: 75 %
Bitterness: 13.2 EBU
Colour: 23 EBC
Yeast
Schneider Weisse
The main reason for the post is to record how well (or not) the new LIDL jam-maker copes with doing a step mash, so please forgive focus on that part of the brew.
I didn't have time to make a new manifold so I just used parts of my existing one.
It's far from perfect, very small and I new I was really chancing a stuck mash but hay-ho.
I used a bit of 1/2" poly pipe in tap hole and pushed 15mm pipe through this gently.
I found in tests if you're too rough you can tear the poly (tap hole cuts it under pressure).
Anyway it fitted OK.


I added 15mm valve on downpipe to help siphon effect.

Initial step set for 40C. I added water from HLT and after a while temp rose higher than expected.
This triggered an 'over temp' warning on jam-maker (see LCD pic) , but didn't make it switch off.

40C

50C. I found heating mash much more difficult that test day before with water.
Low conductivity of mash encouraged hot-spots.
This took quite some time AND lots of stirring as quite a temp gradient when heating using jam-maker. I had digital thermometer and othe temp sensor in mash and often 3-5C difference unless stirring continuously.
Jam maker probe at base (near heating element), my other sensors nearer top.

Jam maker did settle down +-1C or so once you'd stopped asking it to increase temp. See here at longer 67C

Ready for first runnings..

Start of first runnings. I started slow but no probs.

After 2 batch sparges


Next day while cleaning jam-maker I noticed signs of caramalisation / scorching where wort was trapped between element and manifold. Poor circulation / stirring probable cause.
I tasted this and no scorch taste.
I must admit my main worry was localised hot spots extracting tannins but I didn't taste any in wort.

After hose-pipe spray see where element heated up wort.

Cleaned up OK.

Its not ideal, but it is cheap and it did the job. Ideally I'd recommend a false-bottom rather than a manifold and recirculation, but stirring, though hard work, did the job OK.
I boiled next day in my normal burco boiler (OG 1051 25L).
Its bubbling away nicely now.