How to get my keg MLT to hold temp?

so i did a 90 minute mash and lost quite a bit of temp (5 degrees). i've decided i need some way to keep a better temperature. here's what i've come up with, please let me know if i missed anything or sound off on your favorite:

(in order of my current preference)

1) insulate keg: it has 1 layer of silver bubble wrap reflectix stuff, should i add a couple more and make a custom lid? rubber membrane wrap?

2) HERMS: i have 3 kegs, so i could heat water in the HLT and circ it through a coil on the HLT to keep temp... i'm wondering if i could maybe even do this with a decent sized Immersion Chiller and have it work double duty? HERMS coil during mash and IC post boil?

3) direct fire: can i do this safely without scortching the grain/wort? do i need a false bottom?

4) RIMS: not really sure i want to build a RIMS tube, but it's a posibility i guess especially if i can get away with a 110v one.

5) give up and build a cooler MLT: they'll hold temp better, but i already spent all this cash building a keg MLT...

There are a lot of guys here that have HERMS setups and from what I can tell they wrap insulation around their mash tun. I use a round beverage cooler MLT. You might search around the pics and find a member with the HERMS and then send them a PM? I know Bobby_M has the shiniest system you will ever see!

a couple layers of reflectix should do the trick.

i'll give it another wrap or 2 of reflectix and give that a go... i guess 10 gallon batches would help improve thermal mass

Walker is my official support guru today, thanks for all the help!

1. A lot of the heat is escaping through the top. Be sure to provide some insulation there as well as on the sides of the keg. You will need to use a ton of insulation if you are brewing outdoors in cold weather.
2. Yes, a HERMS can be done, but there's more to it than meets the eye. Same for a RIMS whether direct fired or equipped with an electric heat exchanger.
3. You can safely direct fire, but again, it's not as easy to perfect this technique as you might think. I have a direct fired RIMS and it works well, but it took me a long time to get it to operate the way I wanted it to. Check out the Brutus builds for more info on those.
4. I don't know enough about an electric RIMs to advise. You could probably maintain mash temps with 110 v power, but that might not be enough for ramping up temps in a reasonable amount of time. I'm guessing here, so YMMV.
5. A lot of people use a cooler MT with great success and minimal hassle. It's probably the smartest and most cost effective way to go. Cooler MT's are less suitable for step mashing and such, but only you can decide how you want your brewery to operate. Go to a group brew sometime. It always amazes me to see that there are very seldom two systems set up exactly the same way. That's part of what makes this stuff so much fun.

Catt22 said:

Go to a group brew sometime. It always amazes me to see that there are very seldom two systems set up exactly the same way. That's part of what makes this stuff so much fun.

Click to expand...

And makes it so confusing to new people!

I've experienced the "deer in headlight" syndrome several times at our club brew days.

The times I did brew in the bag drew the new people like moths to a flame because it looked so familiar to them.

To stay on topic, I agree that the issue with heat loss is going to be mostly from the top of the keg and any exposed metal.

I would say, that a 5 degree loss for a 90 minute mash is negligible. The 5 wouldn't bother me in the slightest. I use a burner under my tun if I need to kick up the mash temp. The grain and the keg seem to hold temps very well.

I wrapped mine with fiberglass insulation and then sealed it up with insulation tape. I use a piece of Reflectix for the lid and I lose about 2 degrees in an hour. All found in the water heater section of Lowes.