I have written an article in the past about building your own mash tun. You can find that article in the menu on the right. It has been a while since that article and I would now like to cover HLT(hot liquor tank). There is not as much building here as a comparison of a couple of different methods I have used.
When I first started all grain brewing I was using the same vessel, an old stainless 50l keg as both my hlt and kettle. So after mashing in I would heat up sparge water and transfer that to another vessel. I would then run the mash into the kettle/hlt. Once that was completed I would batch sparge with the hot water I had temporarily transferred to another container. That was a pretty ugly system, but it worked and got me started. Eventually I got a separate vessel for a kettle and stopped doing the hot water shuffle. Last year I upgraded this again by replacing the gas fired ex keg hlt with a 30l stainless electric urn with thermostat. This is still my hlt.
The gas fired option. This is a good easy and cheap way to get started. You may already have a burner and or a large pot lying around at home. This method allow for rapid heating of water. Faster than electric systems in my experience. However, the down side here is the lack of thermostatic control. A thermostat could be installed and used on a gas system but this would involve installing servos etc to control the gas. A project that is probably beyond most home brewers.
If you are willing to manually manage the temperature of the hot water either by manually dipping in a thermometer or perhaps fitting a gauge to the hlt it can be achieved easily. My gas fired hlt was the old keg with the top plasma cut off and a hole cut in the side near the base. If you have a look at this page you can see my original hlt. Through the hole near the bottom I put a piece of plumbers thread and attached a ball valve to it. To hold the thread in place I used some hand crafted rubber washers and standard size nuts. I never had any issues with leaks or degrading washers. On that page you can also see the burner used with the hlt.
That hlt served me well until Christmas a couple of years ago now when my partner presented me with a 30l electric urn, just like this one. I have the 30 litre model as anything larger is fitted with a 15 amp plug which would mean I would require a 15 amp socket to be installed at home. I generally do 20l batches so a 30l urn is fine.
The urn I have has a thermostat on it so I can dial in the strike temperature I want. My brew day starts with me filling it up, setting the temp and then I prepare everything else while the water heats. The markings on the dial are not entirely accurate but I have calibrated it using a accurate and calibrated thermometer. The control has been calibrated. I couldn’t say for certain how long it takes to get to temperature but by the time I’m ready to mash in the urn is ready to go. Once the mash is in the urn is refilled with the sparge water. I normally do a 60 minute mash and the sparge water is always ready to go by the time I need it. The urn also has a site gauge n it which I have marked volumes on so I can hit my volume as well as my temperatures accurately.
In summary if you can afford the extra cash I would recommend the electric urn style hlt. However, this will depend on your brewing area and the size batches you are doing. If you are regularly doing 50l batches it may get really expensive to go down the electric route. The only real down side for electric is cost and having electricity in a wet environment. The speed of heating ceases to be an issue if you plan your brew day.
All this said I used the gas fired hlt with a thermometer for years. You have to pay a little more attention to what you are doing but that isn’t always a bad thing. It’s a good way to get started but I would recommend an upgrade to electric when you can fit it into your brewery and your budget.