Thermowell or no thermowell

[Pcpogo]

Folks,

I've nearly completed gathering parts for my HLT.

I have purchased a PID controller. My question is do I need a thermowell for the pt100 stainless steel sensor I've ordered or can I just fix the sensor striaight into the HLT?

 

[Vossy1]

It's up to you really P. I have 1 fixed in the HLT but using a compression fitting not thermowell, the theory being I didn't want the 'lag' albeit a small one of using a thermowell, it's not important really. I also have one I use as a 'roving' sensor which I use in the boiler/mash tun/hlt to double check everything's 'true'. If I had to do my system again and could only have one I'd use the roving option for flexibility.

 

[evanvine]

I have a "thermowell" in my HERMS, but is only used for pre-heating.
The main control of the HERMS is done by placing the PT100 in the outflow to the Mash Tun.



The pic shows the "Thermowell" in the HERMS unit and the PT100 in the pipe to the Mash Tun.

You cannot accurately control the output temp by controlling the HERMS temp.

I have another PID for controlling the HLT which has its own "Thermowell".

 

[Fil]

first thing to consider perhaps is do you want to use the pid for anything else with the same probe? in a rims or herms experement or even something non brewing?? if so a thermowell is a good idea.

if static then a thermowell isnt needed but some cheaper probes are not always sealed between the ss sheaf, And not all probes sold as SS have a SS threaded body.. so perhaps dont rely on just using a locknut to secure the probe unless you know its quality.
ive had both leaky and rusting body pt100 probes...

the safest way to mount would be thru a gland or compresion style fitting which seals against the probe sheaf if your at all unsure about the probe, the sensor is at the tip of the probe so as long as thats exposed :).. and ptfe tape can make up a mm or so

I also have had good results with a home made thermowell made from a 15mm compression tank connector a couple of inches of 15mm copper tube and a reducer to a short length of 10mm tube capped off, as long as the probe used in it makes good contact with the end cap i have confidence in the readings i get.

 

[Darcey]

I am afraid to say I am a dangler . Have not got round to fitting it permanently so I just dangle it in. I can confirm from this that my probe is SS but the cable guard is most definately not. I think when I get round to it I'll just use a compression fitting but for the moment I'll dangle.

I use a STC8000 temp controller for the mash and just again... dangle the probe in. Got a cheap waterproof one with a 3m cable its useful as V said for checking other temps around the place. Just make sure you calibrate them all!

d

 

[Pcpogo]

Folks,

First class replies as usual.

I think I'll go with the thermowell purely so that if required I can use the pid for other things. Just adds a bit of flexibility to the set up.

 

[Baldbrewer]

Another thing to be aware of is that not all pt100 probes are waterproof !
They may look solid to the naked eye but I have used one through a compression fitting only to find water leaking from the cable entry of the probe!

So unless you purchase quality probes a thermowell will stop this issue,just make sure you use heat transfer paste when installing probes in the thermowell to ensure good heat transfer and therefore accurate temp measurement. :

 

[Vossy1]

They may look solid to the naked eye but I have used one through a compression fitting only to find water leaking from the cable entry of the probe!

Not good B