Build Your Own Brewery for Under £100 ! - STEP 2 - the Boiler




Introduction: Build Your Own Brewery for Under £100 ! - STEP 2 - the Boiler

About: i love what the comedien Danny Wallace refers to as "Boy Projects" which is pretty much what this site is about!

Here it is! The not so long awaited sequel to STEP 1 where I showed you how to make your very own mash tun for homebrewing purposes.

It was a fun project and involved a few slightly dangerous things. This step however involves more dangerous things and I mean more in both the qualitative and quantitative sense. There are the same drills and cutting tools used in the mash tun build, but now we have the added danger of drilling metal as well as plastic. We also have some electrical work... nothing too complex don't worry. If I could do it so can you.

When in use this vessel has to maintain a rolling boil of the liquid you got using your mash tun for up to 90mins (although most in the US only use 60 min boils). That's a LOT of VERY HOT water bubbling away in a plastic bucket fitted with some amateur short, its not a super safe procedure but with a little common sense it is safe enough.

If you read step one, here's the same disclaimer with a few additions.

This instructable requires sharp things, spinney things, cutty things, hot things and sparky things. Please be careful at all times. The 'golden rule' of homebrew - "always drink a homebrew when doing anything to do with homebrew" - should  NOT be observed if you are going to use any of the above mentioned spinney/sharp/cutty/sparky/hot things.

This boiler will only process non alcoholic malt extract so I'm fairly sure anyone can make it but adding yeast to ferment this would make alcohol. This is legal here in the UK if over 18 but if you're not sure, check your local laws. I take no responsibilities for any fingers, limbs, lives, marbles, virginities, sights, sanities or freedoms lost. Or anything else for that matter!

Step 1: What Does This Do Then?

What you collected from your mash tun is a malt extract known to brewers as 'wort' (pronounced wert). Some say its only wort after its been boiled but for the sake of simplicity lets ignore those people like we ignore the people that say beer is bad for you.

The next step in the brewing process after you have the Wort from your mash tun is to boil this liquid for 90 mins with the addition of hops cones for bittering, flavour and aroma. Traditionally this vessel is called the copper for obvious reasons but as 'the plastic' sounds pretty bad I'm just calling it a boiler. The criteria therefore for the boiler are:

-Must be able to heat approx 6 Gal (about 30L) of liquid.
-Must be able to maintain a rolling boil for 90 mins (without a lid. Important but wait till part 4 of the series to see why).
-Must be able to drain the resultant wort out of the vessel whilst leaving the hops behind and leaving as little wort behind as possible.

As well as using it for the boiling you will also use this vessel to heat up the water used for mashing but more on that later.

Step 2: Tools and Materials

- 33L Polypropylene bucket (this was enough to make the usual 5 gallon batch in)
- 2x Cheapo Kettles (£4.75 each)
- 2x Maplin hot condition sockets (£2.69 each)
- 1 x 15mm ball valve tap (£3.98)
- 1m long piece of 15mm copper pipe (leftover from Mash tun)
- 1 x 15mm tank connector (£0.99)
- 2 x 15mm -15mm compression elbow (£0.68 each)
- I used - Scrap of electrical tape (<£0.01?)
- An extra female to 15mm compression elbow but its not necessary. (£1.28)
- 1/2" food grade tubing (not essential but useful) (left over from mash tun)
- I'm thinking of adding leftover insulation as a removable jacket but I haven't got around to it yet.

       Total Cost £30.61 (£31.89 with extras)

                      With the Mash tun that makes £ 66.26

- Drill and/or rotary tool (I also borrowed a hole saw for this step)
- Screwdriver
- A pipe cutter
- A craft knife
- A marker pen
- A Measuring jug
- 2x adjustable spanners

Step 3: Kettle Hack!

In the US I hear it's more cost effective to heat a boiler with propane or similar but here in the UK it's generally cheaper to heat it with kettle elements. We also don't have easy access to cheap large stainless steel or aluminium pots as do our deep fried turkey enjoying cousins. For those reasons most starting homebrewers will make their first equipment from plastic buckets and Kettle elements.

I used a Tesco Value Kettle and followed the instructions of one Wetdog over on jims beer kit homebrew forum. Many thanks to him for the advice and for letting me use some of his pics! Just follow the pics and you'll be fine.

1 - Open the box and remove the kettle (keep the base for later).
2 - Turn the kettle upside down and remove the 2 screws on the bottom and remove loosened panel.
3 - Remove the screw inside the handle and remove loosened panel.
4 - Wiggle the LED out then undo the screw holding the switch in place.
5 - Undo the 3 screws holding the element in place but KEEP the screws and washers
Pic 6 shows all the bits you'll need to keep.
7 - Take the electrical guts and cut the 2 red wires where indicated and cut the LED wire making sure to keep the resistor (the bulgy bit under the plastic shrink wrap).
8 - Strip a bit off of the 2 main wires and twist them together.
9 - Strip a bit off the plastic covering the wire after the LED resistor and itroduce the wire into the already twisted ones.
10- Tape all the Wires back together. Heat shrink would be better!

Repeat all this with the second kettle. It sounds like a lot but its pretty quick to do. The reason for 2 elements is that it heats up 6 gallons of liquid a lot quicker and then one can be turned off and the other will maintain the rolling boil. Also if one cuts out mid-boil for some unknown reason you can just switch the other one on!

Step 4: Plug It Up.

The back of the hacked element has 3 pins on. You can attach to these, a Kettle lead...not a PC lead.

Leads from old PCs are often thought to be the same as kettle leads...they ain't! People have used them in boiler builds and ended up with molten plastic goo. PC leads aren't so great at high temperatures. You can tell a kettle lead by a characteristic notch.

This step will almost certainly differ from country to country but this is a British instructable. Ok you probably know how to do this but if not...Here Goes...

1 - Cut the cable close to the base of the kettle base and remove about 2 inches of outer insulation.
2 - Open your IEC socket by removing the screw in the middle.
3 - Remove the black collar and slide it over the cut cable. Loosen or remove the 2 screws holding the cable clamp in (the red bit). Loosen slightly the 3 screws where you will later connect the wires.
4 - Trim the wires so they are the right length. Strip a cm or so off the insulation, twist the wire and wrap them around the loosened screws. Tighten the screws. Make sure you get Live, Neutral and Earth wires in the correct place. Slide the black collar into place and clamp the thing down with the little red cable clamp you removed.
5 - If you're not very confident with wiring maybe get someone to check your work before you do yourself a mischief! If you're happy its all OK then close up the casing and see if it fits the back of your kettle element!

YAY IT DOES! (Well mine did)

Don't turn it on yet as the metal bit is meant to be fully submerged remember!

Step 5: What Can You Put in a Bucket to Make It Weigh Less?...HOLES!!!

You will need to make one 20mm hole for the tank connector like you did for the mash tun. You can have a siphon effect going so it doesn't have to be right at the bottom but likewise you don't need it right at the top. i did mine maybe 15cm up.

You will also need to make two holes for the elements. For my elements I made a 38mm hole using a borrowed hole saw. I positioned the element holes close together on the opposite side of the tank connector hole about 9cm from the bottom of the bucket to the middle of the hole. Neaten up the edges with a craft knife or similar.

The reason for the elements being on the same side is that then when heating the liquid convection currents should help to stir the liquid up ensuring even heating.


When you have boiled the wort and added all those bitter tasty smelly hops, you'll want to drain the liquid off and leave the hops 'leaves' behind. For this we need a simple piece of copper with a few holes.

Mine measures about 20cm long but it depends on your vessel. You only want holes on one side which will point down in the boiler.

1 - Using a marker pen and ruler mark out 3 rows of dots about 1cm apart leaving about 2cm on each end. Then clamp the pipe down and use a centre punch (or nail) and a hammer to make shallow dents on all the dots. this will stop the drill slipping later.

2 - Use a drill with a 2mm HSS bit and drill them holes. It wont take long and you don't have to press down hard as copper is crazy soft.

3 - Now the holes are all done take the pipe and point it at some light then peep down the length. You'll see lots of burrs that I suppose you could leave but I just used a round file and took them off. Only took a minute.

4 - One side will fit to the pipe work later but the other side needs closing. Easiest way to do this is to loosely place one end in a vice or clamp. Hold the other end steady then....

5 - Tighten the clamp to pinch the end.

6 - Check it's all closed up! I ended up using a big ol' pair of pliers to pinch the ends closed but it wasn't really necessary.

Step 7: Plumbing Without the Pb

Did you know that the word plumbing comes from the Latin name for Lead, 'Plumbum', as pipes used to be made of this toxic metal? ...You did?! ... oh... fine.

I didn't take too many pics here I'm afraid but look at the STEP 1 to see how I did this for the mash tun as the principle is the same.

1 - Tank connector pointing in through 20mm hole with washer on the outside, tighten. Pass through a short piece of pipe and attach the tap onto the outside. Its all compression fitting so you'll need 2 spanners/wrenches to tighten all the bits up.

2 - Add tiny bit of copper pipe then a 15mm compression elbow to point down to the bottom of the bucket. Then add a bit of pipe to reach almost to the bottom of the boiler. Then add another elbow (i tried using a push-fit fitting in this pic but preferred compression fittings) and connect that to the hopstopper. The idea is to get the hopstopper running as close to the bottom of the bucket as possible to reduce dead space in the boiler.

3 - All connected up with a bit of copper on the outside of the tap to achieve a siphon effect. I tried this all out with water and it was water tight 1st time (unlike the mash tun)!

Notice that in Pic 2 I haven't drilled the element holes or finished the hopstopper. That's because I didn't really know what I was doing and made a lot of this up as I went along (with lots of help from forums and friends).

Step 8: Turn On, Tune in and Drop Out.

Reassemble the elements in their holes, not forgetting to put the silicone washer over the edges of the holes to keep it watertight. Screw it all together.

You're pretty much done now! Sweet!

Do a check to make sure it's all watertight. Make sure the taps closed!

Now plug in the elements and give them a try! Mine worked really well and the little LEDs are really useful in knowing when they're on. Not so much when just boiling/heating water as you can see them working but when it's full of dark beer you need to know that they're still pumping out the heat!

Step 9: Finishing Touches.

It will be important when making your beer that you know how much liquid you have in the boiler. For this reason I made a Measurement gradient by adding 2L water at a time and marking where it came up to with a marker pen. You might need to use a torch or something to help you see the level through the plastic.

Next add a bit of silicone tubing to the pipe leaving the boiler tap to create a good siphon effect and be able to direct your outcoming liquid more easily. Guys will know what I mean! To get the tubing on, its' best to put it in hot water for a minute to soften it up.

Now drain all that water you put in out. Eventually the siphon effect will stop and the water level should reach the bottom of your hopstopper. The reamaining volume is known as dead space. Mark it on the boiler like you marked the other levels and then pour it out and measure the volume. This is useful later on when making the beer.

THATS IT YOUR DONE!!!! I can almost taste that first beer already. Just one more piece of equipment to build and that ones a quickie and really satisfying!! 

On to step 3... The immersion cooler!

2 People Made This Project!


  • Cold Challenge

    Cold Challenge
  • Clocks Contest

    Clocks Contest
  • Block Code Contest

    Block Code Contest



6 years ago

Chard, i have followed your steps and built a boiler i think looks great, and doesn't leak :) a couple of questions

1) does the flow of water in your boiler actually empty all the way considering your tap is above the water line. does the contraflow work for you?

2)placing the holes facing downwards on the filter, does that work for you?


Reply 6 years ago

Looks good! I'm thinking of making one of these and maybe regulating the temperature using a raspberry pi. Which kettle did you use for the heating element? I think the Asda smart price one is out of production now. I don't want to buy one only to find I can't get it apart easily..


Reply 1 year ago

Did you end up using a Raspberry Pi to regulate the temperature of the boiler? I'd be interested in giving this a try. Cheers


3 years ago

how did you get the copper pipe to feed all the way through the tank connector , my tank connector will only take the pipe half way through the fitting, I have checked others out and they are the same, can you post the model number of your fitting ,thanks


9 years ago on Step 4

Thanks for an awesome instructable, I have one problem.

I bought the same maplin hot condition plug as show however after use I can see signs of it melting. Any ideas what this might be due to or what I can do about it.

I would be grateful for any help or advise.


Reply 6 years ago

Unsure if you still need an answer but I will post here. The plug from maplins is rated 10a the fuse is 13a. Means the wire will fail before the fuse which is a big nono.

You need all items to be rated 13a or above or swap your fuse to a 10a but that will blow all the time.


7 years ago

I followed everything on here except i used a 30L HDPE blue plastic keg i got off Ebay and didnt include a hop strainer as im BIABing. tested it this afternoon with water for leaks and stuff works a treat Nice one bro. just gotta put a plastic box over exposed electrics. any ideas what will stick to outside of barrell specially when its boiling.


8 years ago

Chard, where is steps 3 and 4, we miss you!!


8 years ago on Introduction

Hi, Looks like some good instructions here and hoping to try soon. Been brewing small batch BIAB with decent results and looking at sizing up whilst keeping it as cheap as possible so this is ideal. Wondering how the trub is prevented from draining out post-boil using this setup as the holes in the pipe seem too large to prevent this getting through. Is this dealt with at the next stage?

When is the step 3 instructable due out!



8 years ago on Introduction

how do you attach the valve to the tank fitting?


10 years ago on Step 3

Hey Chard, amazing step by step for the whole mash tunn and boil kettle. In case any other peeps are thinking about doing the kettle hack, the asda smart price ones require NO rewiring at all. just take it apart and put it in the hole in your bucket. you don't even use any bits from the base.

kettle hack.jpg

Reply 8 years ago on Introduction

I picked up 2 smart price kettles today. Did you leave the switch mechanism in? I pulled one switch off and there was a little white rod that slipped out from under it, near the power plugs. Im not sure if it's necessary for that to be in, because I can't see any obvious way of turning power on and off without that bar.


Reply 9 years ago on Introduction

Reverb, apart from the resister I would imagine!

How big a hole did you use? Also do you think you could attach these to a metal version?


9 years ago

Chard, where do you go for your food grade plastic tubs? Do they come with lids and are they cheaper than the ones from wilkinsons?




10 years ago on Introduction

Hi Chard,

I am attempting this project with a very limited knowledge of electronics. I have got the wiring out of the kettle, and it's different to what's in your walk-through. Tesco appear to have changed the design since you posted this. I've attached a picture of what the wiring now looks like. Any idea how I apply the method to this new wiring configuration? It looks like there are now less wires...


Kettle wiring.JPG

10 years ago on Step 9

I know it's a while since you wrote this and the mash tun 'ible, but please can we have the immersion cooler? I've nearly done everything you've written so far, with no beer to show for it!
Thanks - great 'ibles, by the way!


10 years ago on Step 4

I just bought the power leads from here

£2.74 each, saves messing about too


11 years ago on Step 9

Hi Chard,
When will the instructable for Step 3-the immersion cooler be here?


11 years ago on Step 7

Hi Chad, superb stuff on the DIY brewing front. Quick question about point 3 on this page. What is the advantage of the extra elbow and piping on the outside of the tap? Could you connect rubber tubing direct to the tap end? I've not tried this yet but about to buy the tubing so interested in your experience. Cheers.


Reply 11 years ago on Introduction

the only reason was to direct the pipe down to make syphoning slightly easier but you are right its not necessary. so long as you get a good syphon effect you're good to go!