Over the weekend I did the first proper test of the newly completed mash tun.

I wanted to see how well it held temperature, so filled it to about 10 litres with water from the hot tap (which I know will really only reach around 40 degrees C), put the lid and cover on, and left it alone.

About an hour later I went back to check it, and using the very scientific method of sticking my finger in the water, could tell that the temperature hadn’t dropped much at all, which I took to be a success. In fact, another hour-and-a-half later I emptied it and tested the tap at the same time, and it was still hot.

So not a terribly scientific test, but one I think was successful. It held a good temperature, which will only get better once the grain is in there acting as insulation too, and I had no leaks, not even a drip. I’ve now got a digital thermometer so I can do the test again and actually track the temperature as I go. I’m very pleased, and looking forward to getting the boiler even more now.

Update:

Armed with my new thermometer, I conducted another test last night. I wasn’t going for a specific temperature, but wanted to get it somewhere around what I need for mashing, just to see how it does. By the time I’d added around ten litres of water from the hot tap and boiling kettle, I had a starting temperature in the tun of 58 degrees. On went the lid, and an hour went on the timer.

A year ago I’d have spent the next hour twiddling my thumbs and resisting the urge to take a reading every few minutes, but having a six month-old meant the next hour was occupied with baths, washing bottles and having a last bit of play before he went to sleep.

After an hour I took the lid and cap off and put the probe in with a due sense of worry. What if it didn’t work? What if I’d wasted all that time and money (not that it cost a lot really) on something useless? I needn’t have worried. An hour later the temperature had dropped a paltry four degrees! Bearing in mind that I was just using water and didn’t have a grain bed to help hold the heat, I think that means I officially have something that I can make beer with!

I guess I’d better start reading more about which sparging technique I want to use.

Last night I grabbed an hour while RAR was asleep and managed to finish the mash tun build.

The first part was relatively easy; fitting the ball valve tap. Obviously I don’t want the wort just pouring out of the bottom of the tun, so I needed a way to keep it all in and control what comes out, and how fast it does. This is important for things like controlling first runnings to pour back through the grain bed. Using the same compression fittings I used to plumb the pipe through, I attached the 15mm ball valve tap I bought from B&Q. I do have a 15mm female compression elbow to fit at some point, to redirect the flow downwards, but at the moment when it’s fastened tight it points to the right – not ideal.

Ball valve tap attached with compression fittings.

After I finished insulating the body before, all I had to do was make sure the rest of it was properly insulated, so that when I start mashing grain it holds temperature as best it can. The first, easy part was adding more of the insulating wrap I’d used for the rest of the build to the lid.

It’s not the prettiest, but it’ll do the job.

On the original Instructable that I’ve been following for the most part, the author found that he had a few inches of the internal fermenting bin sticking out of the top once it was put inside the main tun. That meant he was able to wrap more insulation around that exposed area to minimise any heat loss, so I thought I’d do the same thing. Except there was a problem…

Very shallow overhang when the internal bin is in place.

As you can see from the photo above, when my mash tun is assembled, there’s very little overhang exposed. This is both good and bad at the same time. Good in the sense that it means heat loss is lower, but bad because it gives me much less to work with to insulate it. By the time I wrap insulation around it, there’s almost no room left to attach the tape. The other problem is that I wanted to keep the handle attached to make it easier to remove the grain and clean it afterwards.

After a quick think (aided by a bottle of London Pride) I came up with a plan for a basic thermal cap. Think of it as a woolly hat for my brew. It’s a bit rough-and-ready, but it’s a good size and fit, and can be put on without needing to remove the handle.

Shiny! My mash tun’s warm hat.

So there we go, it’s finished! I’ve done a couple of quick tests for leaks, which have all been good so far (no drips anywhere!), and once I get a decent thermometer I’ll do some tests for heat retention, but all being well, I’ve finished.

Completed mash tun

…and another picture of the completed tun.

It’s taken a couple of weeks to do what I could have done in a day or two if I didn’t have a little boy invading every corner of my life, but to be honest, I quite like the slow build. There’s no rush after all, and I don’t even have a boiler yet. The longer I wait, the more time I have to decide what I’m going to brew, and how to do it. That said, I can’t wait to taste the first pint.

I’ve managed to make some more progress on the mash tun. Over the past couple of nights I’ve grabbed half an hour when everyone else has gone to bed and started to insulate it.

My insulation of choice is aluminium-lined thermal wrap insulation, the sort of thing you can buy a big roll of from DIY shops to wrap up boilers and such. It’s not the worst job in the world, but it’s not the easiest either. Let’s just say if I were to give one as a present now, I’d definitely be tying a ribbon around it rather than wrapping it.

After a lot of frustration and furious cutting and sticking, I’ve now got it to the stage where I’d be happy to use it, although I think I’ll be adding one more layer just to make sure. The whole thing is taped up with overlapping pieces of duct tape which should mean it keeps a nice waterproof seal and stops yucky, sticky wort getting between the insulation and the bin.

Mast tun all wrapped up warm, one more layer to go on. the tap needs tidying-up too.

Once the last layer goes on I’m going to fit the tap and fill it with water to test for leaks again, and then I’ll half-fill it with hot water and do a test to see how well it holds temperature.

I’m getting there slowly.