I wish my HLT was double the size of my MT. For a 12 gallon batch of my beer I sometimes need as much as 16.75 gallons of water total. Kinda hard to do in a 15.5 gallon converted keg. I have to refill and reheat my HLT after dough in or first infusion.
I have a 12 gallon Mash tun cooler that is heated. I am building a heated HLT cooler and I went with a 9 gallon Coleman Max because the price was right and the drain is set up to almost completely drain the cooler. Though as I look at some of my 10 gallon recipes, I see I need more than 9 gallons of sparge water. I pre-heat my mash water in the MT but the recipe I want to do next calls for 9.5 gallons of sparge water.
Now you see my predicament. I wish I had a 20 gallon HLT for my 15 gallon system. I brew 12 gallons and blend them if I want 15 gallons end batch, but even this doesn't get me out of refilling and reheating my HLT water.
Question: On your HLT I notice you have silicone tubing touching the element. Why? Also, how do you stir your mash so it doesn't scorch on/around the element? I built something similar only steam injected for a friend. It is the Motorized mash mixer and tun in my signature.
I don't see a problem with refilling the HLT during the mash because I don't think I'd want to have 170F water sitting around getting cold for the 60-90 mash anyway. Besides, you get your brewday moving along much quicker if you only heat up just over the amount you need for strike (6 gallons heats faster than 18). Now while you're mashing, start heating your sparge at a moderate pace so it hits temp at 60 minutes. I think it saves gas this way.
Wortmonger, I know your situation is a bit different in that you have a temp-holding HLT using electric and plenty of insulation but I still think heating the sparge during mash makes sense.
Well, I am stuck with my system, and you are right about the holding water at temp for that long. I can't wait to see how my new system functions. The element being vertical is also a scare on my system so I am forced to refill after every dump below 7 gallons. This works out pretty good though and shouldn't give me much trouble, but I would love to have had a little bigger HLT anyway.
I used a short piece of vinyl tubing to allow the braid to get closer to the bottom of the cooler. The round coolers are the best shape for adding a heating element but the dead space below the outlet is way to much. As long as there is water in the cooler, the element doesn't get the tubing hot enough to melt. I guess it would be preferable to have the tubing not touch but it was never a problem. I have since sold this cooler and I am building another one.