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System Upgrades Completed on  RIMS, which is now a HERMS
FOR IMMEDIATE RELEASE
HERMS Has Better Temperature Control for Better Beer
02/26/2008 -- Just in time for summer, this year BottleTreeTM
has upgraded its brewery taking out the filter, and adding a new pump to the
recirculation system. Additionally, the wort chiller has been adopted to also
serve as a wort heater by placing the heat exchanger in the hot liquor tank.
This will make up for any heat losses during recirculation, and also serve as a
precise temperature control mechanism. The
mash-tun, has now be insulated (laugh all you want, it is removable), since it no longer has to withstand direct
heat, and now we are trying to keep as much heat in. Lastly, a false bottom was added to the
mash-tun, which is going to minimize scorching. These changes have been made in
order to get back into competition for the 2008 season.
Insulated HERMS
Mash-Tun Temperature for Varying Ambient (5 Gallon Batch)
Advantages of HERMS over RIMS:
1. No scorching the grain in the mash tun. No more direct heat.
2. Reduced stratification.
3. Precise temperature control, due to large thermal mass of the HLT.
4. Virtually no temp drop from the once through heat exchanger and the return to
the mash tun.
5. Whatever losses you have from recirculating are made up in the HLT, which is
the last thing the wort passes through before coming back to the mash tun.
6. Overheating the wort isn't possible as there is no heater, the heat source is
the water in the HLT, which you control.
7. If you don't want a bunch of wort hanging out in the recirc line when you are
done recircing, then add a C02 purge. I use C02, to put the wort back into the
mash tun, and out of the recirc piping. Hot wort, and air don't mix.
8. The same wort heat exchanger, can also cool the wort in the copper later in
the process, by placing in the copper, and changing some valve positions, to get
water on the inside, instead of wort. If designed properly, you won't have to
swap any hoses.
9. Because you are no longer applying direct heat to your mash tun, you can now
insulate that, to minimize heat loss.
10. Most importantly, make sure your system can run on pure gravity. See
disadvantage below.
11. A system like this makes it a lot easier to do all your rests, should you
need to...acid rest..protein rests..and step to any temperature that you want
to. And in a complicated mix of various grains, this might be a must.
Disadvantage:
1. If you lose your pump, well, you are back to a gravity feed system, and will
either need to rely on single infusion mashing, OR, some direct heat to the mash
tun, and probably a little bit of both. A properly designed system can operate
w/o the pump, but would lose some flexibility.
Tips:
1. There is a small difference in temperature between where you shutdown the
whole starch conversion process and where you are trying to soak. You need to
consider this in your heat exchanger. If you are not efficient, or have too much
tubing after the heat exchanger, then the max temp leaving the heat exchanger
might exceed say 168F. You don't want your wort leaving your heat exchanger at
172F, lets say, to heat up your mash-tun. So, your heat exchanger shouldn't have
a discharge greater than 168F, and if you are heating a mash to 158F, you can
see the point I am making. You increase the heat transfer with mass flow and
delta T. Since the max T has already been defined, and since you know the temp
that you are trying to achieve, you have mass flow to play with. Well, your pump
is going to more or less put out a constant flow. So, the only thing you can
play with is keeping your HLT temp below, the max you want your wort to see, and
the efficiency of the heat transfer and the losses in your piping and your mash
tun.
2. Minimize the time your wort is recirculating. Therefore, while the mash is
resting, get your HLT up to the max temp you want for your next rest first, then
turn on the recirc (maximize delta-T). Raising the temp of the HLT at the same
time you are recirculating to raise the temp of the mash tun, will insure that
you are recirculating longer. This isn't obvious, but true.
3. Take data on your system. That is the only way to know for sure. Otherwise
you are simply guessing. Precise temperature control is the key to good beer,
but also consistent results.
4. Your system, you can do what you want--isn't that one of the things that drew
us to this craft, in the first place?
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