Where to stick it?

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Troutman47
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Where to stick it?

Post by Troutman47 » Thu Nov 09, 2017 6:46 pm

Hi Guys, just wondering where the best place to have the PT100 probe on the HERMS?
I’ve got hold of a couple of kegs and want to convert one in to a mash tun, so is it best to have the temp probe as the wort returns in to the mash tun or what if the probe was in a thermowell so it sits in the mash?

Thanks guys!

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Re: Where to stick it?

Post by GrizzlyBrews » Sun Dec 10, 2017 5:08 pm

I would say with HERMS that you are pretty safe placing the probe in a thermowell in the mash tun. As you're not applying heat directly to the wort.

In a RIMS system a lot of folks place the sensor in a T piece just before the wort re-enters the tun. This is because it will have the fastest thermal response and reduce the chance of scorching the wort.

If the sensor was in the grain bed the thermal response would be a lot slower, because of the large thermal mass of the grain bed. Theoretically this then causes the element to be going hell for leather, scorching your wort. Something that can't happen in a HERMS system.

Hope this helps.

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Re: Where to stick it?

Post by PeeBee » Sun Dec 10, 2017 6:10 pm

You can put temperature probes in the mash, in the wort outlet to the HERMS coil and in the wort inlet from the HERMS coil. But all these placements are only informational so you can check what's going on.

If the probe is controlling the temperature of the mash it MUST be in the HLT or whatever else is heating the water around the HERMS coil (some folk have a small pot for housing, and heating the water around, the HERMS coil so as to react more quickly - there's 101 ways to <harm> a cat and I don't hold with this "small pot" idea). Placing the probe anywhere else will react too slowly and cause wild fluctuations in mash temperature before it settles down.

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Re: Where to stick it?

Post by RobP » Sun Dec 10, 2017 7:40 pm

As ever there are people that differ from that view.

"You want to be able to take the temperatures of the water and wort as it flows. If you just stick it in the kettle you will only get a stratified temperature, in your mash if you don't have good flow you will get a miss reading of temperature and miss your target temperatures. It also helps you notice if your having flow problems with pumps of a stuck sparge by displaying temperature swings. Remember this system is designed to control the process/temperatures. This is a very important placement of the probes and should not be minimized. Keep them in the flow.

Castermmt"

http://www.theelectricbrewery.com/forum ... p?p=290893

It's one of those contentious questions that will never have definitive answer.

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Re: Where to stick it?

Post by PeeBee » Mon Dec 11, 2017 12:43 am

RobP wrote:
Sun Dec 10, 2017 7:40 pm
As ever there are people that differ from that view.
"... If you just stick it in the kettle you will only get a stratified temperature, ...Castermmt"
http://www.theelectricbrewery.com/forum ... p?p=290893...
That's probably true; it is easy for me to forget the water does not stay stationary in my HLT and I get none of that "stratified temperature" business, and that's probably very relevant.

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Re: Where to stick it?

Post by RobP » Mon Dec 11, 2017 11:40 am

PeeBee wrote:
Mon Dec 11, 2017 12:43 am
RobP wrote:
Sun Dec 10, 2017 7:40 pm
As ever there are people that differ from that view.
"... If you just stick it in the kettle you will only get a stratified temperature, ...Castermmt"
http://www.theelectricbrewery.com/forum ... p?p=290893...
That's probably true; it is easy for me to forget the water does not stay stationary in my HLT and I get none of that "stratified temperature" business, and that's probably very relevant.
I don't understand how "stratification" happens. I'd expect the heating from the element to make convection currents in the water. Hey-ho.

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Re: Where to stick it?

Post by jaroporter » Mon Dec 11, 2017 12:46 pm

it will create convection currents but it's not perfect. in a system where you need accuracy to within a degree or so a gradient spanning a few degrees i guess would be an issue. i don't use HERMS though, are you controlling the temperature of the HLT to control the wort?
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Re: Where to stick it?

Post by PeeBee » Mon Dec 11, 2017 2:21 pm

jaroporter wrote:
Mon Dec 11, 2017 12:46 pm
it will create convection currents but it's not perfect. in a system where you need accuracy to within a degree or so a gradient spanning a few degrees i guess would be an issue. i don't use HERMS though, are you controlling the temperature of the HLT to control the wort?
Yes the HLT (or special "small" vessel) is being heated in HERMS systems to indirectly heat the mash. Hence the temperature probe is in the HLT to control the HLT heater. The mash temperature is just following the temperature in the HLT via the HERMS coil.

My HLT is constantly pumped hence the temperature in the HLT is reasonably uniform.

It is important to agitate the HLT as you not only get the (doubtful) stratification of heat in the HLT but also a gradient of heat as you get further from the HERMS coil. (As my HERMS coil is outside the HLT, jacketed, and the HLT water continually pumped around the jacket I don't get that heat gradient either).

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Re: Where to stick it?

Post by RobP » Tue Dec 12, 2017 11:50 pm

jaroporter wrote:
Mon Dec 11, 2017 12:46 pm
it will create convection currents but it's not perfect. in a system where you need accuracy to within a degree or so a gradient spanning a few degrees i guess would be an issue. i don't use HERMS though, are you controlling the temperature of the HLT to control the wort?
I am, yes. It seems to work fine but I'll implement a way to agitate the water in the HLT. Shouldn't be hard.

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Re: Where to stick it?

Post by johnmac » Fri Feb 09, 2018 6:42 pm

Does it matter if you have uneven temps in the HLT? The wort will pick up an average HLT temp and if some of the HLT is above mash temp, some below - so what. The HLT is a heat source for warming your mash, just like the element in a RIMS, which is obviously much hotter than the mash.

Please tell me if I'm wrong - I'm still working on my first HERMS!

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Re: Where to stick it?

Post by johnmac » Sat Mar 17, 2018 8:40 pm

Thanks. I decided to use a cheap kettle as the heat source and I'm measuring the wort temperature as the flow re-enters the mash tun. Seems ok so far.

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Re: Where to stick it?

Post by PeeBee » Sun Mar 18, 2018 2:53 pm

johnmac wrote:
Sat Mar 17, 2018 8:40 pm
Thanks. I decided to use a cheap kettle as the heat source and I'm measuring the wort temperature as the flow re-enters the mash tun. Seems ok so far.
Yeap, seems an okay position. I've a probe both in the HLT (heat source) and in the wort flow as it re-enters the mash-tun (after a, unused, RIMS tube which is in-line with the HERMS coil) and both read identical. As you are using a small volume heat-source (kettle) it'll be fine, but if making a temperature step-up and you were using a fast heating HLT or an ineffective heat-exchanger the temperature of the HERMS coil wort outflow would start to lag behind the HLT temperature. So if the probe in the HERMS coil outflow (to mashtun) is controlling the HLT element the HLT (heat-source) will begin over-heating. Hence for a large volume heat source like the HLT the controlling probe must be in the HLT.

Has "EINBREW" considered that before coming to some very dodgy conclusions about where to place probes? If inefficiencies does mean the mashtun is constantly lower in temperature than the HLT, that difference needs noting and the HLT heated to a higher temperature that will compensate: Better the inefficiencies weren't there.

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Re: Where to stick it?

Post by Fil » Sun Mar 18, 2018 9:33 pm

what is the herms/rims solution heat intended for?

is it simply to replace the heat lost as a consiquence of the recirculation of liquor,

Or is it intended to also intended to replace heat lost due to insufficient insulation and/or effect changes in mash temp upwards.

if the former then you need only consider the temp of the return flow and ensuring that its at the optimum mash temp is job done.

However if you attemping to input heat to keep the mash at an optimum temp or raise the mash temp then a 2ndary temperature reading representing the grain bed temp will be useful..
ist update for months n months..
Fermnting: not a lot..
Conditioning: nowt
Maturing: Challenger smash, and a kit lager
Drinking: dry one minikeg left in the store
Coming Soon Lots planned for the near future nowt for the immediate :(

Fil
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Re: Where to stick it?

Post by Fil » Sun Mar 18, 2018 9:33 pm

what is the herms/rims solution heat intended for?

is it simply to replace the heat lost as a consiquence of the recirculation of liquor,

Or is it intended to also intended to replace heat lost due to insufficient insulation and/or effect changes in mash temp upwards.

if the former then you need only consider the temp of the return flow and ensuring that its at the optimum mash temp is job done.

However if you attemping to input heat to keep the mash at an optimum temp or raise the mash temp then a 2ndary temperature reading representing the grain bed temp will be useful..
ist update for months n months..
Fermnting: not a lot..
Conditioning: nowt
Maturing: Challenger smash, and a kit lager
Drinking: dry one minikeg left in the store
Coming Soon Lots planned for the near future nowt for the immediate :(

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Re: Where to stick it?

Post by PeeBee » Mon Mar 19, 2018 1:38 pm

Fil wrote:
Sun Mar 18, 2018 9:33 pm
what is the herms/rims solution heat intended for? ...
Hi Fil. The RIMS was originally because I couldn't make my mind up when building the brewery (RIMS or HERMS). But it was subsequently used for raising the temperature of water in the mash-tun to strike heat, independently of the HLT which could be kept at mash temperature. It was also employed (rarely) for rapid heating the mash-tun for temperature stepped mashes. It was sort of thumbing my nose at the "small vessel" HERMS technique.

I'm now working on another idea for very rapid steps in temperature. Using a fourth vessel for heating (or keeping cooler) a portion of HLT water "off-line" from the HLT (HERMS heat source) which when returned to the HLT causes a near instant change in temperature (there will still be a lag to mash temperature while the mash liquid repeatedly passes through the HERMS coil). That bit is still being built on to the existing setup. Relies on a computer to determine the resultant temperature of mixing two known volumes at different temperatures - I'm using a spreadsheet - hardly an issue as a computer is already used for logging, calculating strike temperature, etc.

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