Maxi 310 thermostat

[edit1now]

I just got another chiller (Maxi 310 - single product coil and python loop) for 99p from eBay

The thermostat seems to have died, but the pump, fan and compressor are OK.

Will one of these work, or do I need one of these which are more expensive?

The capillary tube seems to be threaded through a loop of stainless tube into the water bath.

[edit1now]

Thanks Chris.

Just for into, here is the capillary tube going in and out of a loop of tubing:



Very pleased to report that with the thermostat bypassed, the water bath was down to 0.6C after about half an hour, so that's all that seems to be wrong

[edit1now]

I got the universal fridge thermostat from the nice man, and fitted it.

Pics in case this helps anyone else.

Here's the original thermostat, which is held on to the back wall of the Maxi 310 with a couple of screws. The capillary tube passes through a stainless U-tube into the ice pack (I think) and out again:


I thought the new one would be very difficult to thread through, so I tied a piece of braided nylon cord onto the small lump at the end, with a clove hitch, after straightening the bent end a bit:


Pulled-through without losing the string ( ):


The new thermostat comes like this:


I unwound it, and stripped-off the white vinyl covering to about the same length as the old one:


Pulled it through:


and wound-up the spare into a coil using a bit of 22mm copper tube as a former:


The fridge-style thermostat has an adjusting knob, which I thought I'd have on the outside (probably take it off when I've got the temperature right). Here is a hole about 9mm for the knob, staring from one of the old thermostat fixing holes and drilled-out with a Cone-Cut bit:


There is also a fixing bracket, which stops the whole lot rotating:


so I made another hole to screw one end on to the box:


Here's the back view as installed:


You can see the socket I added for the pump wiring - that's another post (now live).

I've had it running since about 12:30 this afternoon (5 hours), and the compressor hasn't shut-off yet, so I'm wondering whether the temperature range of this cheapo thermostat is completely out for this application (I've got it on it's warmest setting, next to Off) and I'll have to give in and get the £14 one from Harmony Hut. The water bath was down to 0.7C when I last looked.

[RabMaxwell]

Edit1now did you get it working yet That cooler is the exact model as my one i have just chucked out as it got a gas leak.Not sure if your thermostat probe goes all the way down & out the other end of that little tube.Mine just went down halfway into the ice bank it should however get down to 7oc faster than 5 hours.If you are still having problems i can send you the proper thermostat if you want.Cheers

[edit1now]

I did get it working at the weekend. I got a Ranco K14 Fixed Ice Thermostat from Paul at The Harmony Hut on eBay for £16.99 plus P&P. The probe is threaded through the U-tube like the previous one. When I fist tried it the RCD went, because I must have splashed water around, tipping the chiller up at some point. After 24 hours to dry out it was fine. The water in the tank went down to about 0.5C in about five hours, then (finally) the compressor and fan shut off, so the thermostat is working OK - I was using one of my Pt100 probes on a PID to check the temperature, and the metal probe kept freezing into the ice bank The compressor went on and off a few times during the afternoon to keep the temperature constant - maybe five minutes every couple of hours.

Still, that means I got a Maxi 310 for 99p, plus say £6 for petrol, plus £17 for the new thermostat, so £24...

From what Rab said I should use this chiller for my next lager, as it has a greater chilling capacity than my Maxi 110 (bigger ice bank and more powerful compressor), and I should be able to crash-chill to 5C or below at the end of the primary fermentation. I couldn't get the 110 to go below 5C with the water test setup.

Rab - don't chuck out all the bits of your dead chiller - the thermostat might be useful for someone, and the stainless coils ditto!

[RabMaxwell]

I never chuck out any of the bits .I have the Python pump if anyone needs it. edit1now whats the insulation like on your fermenter the better the insulation the lower the final crash cooling temperature

[edit1now]

Well the test just used the plastic boiler jacket made from two layers of camping mat:


...but I think I'll need to do something better. Options include loft fibreglass (yuk!), bubble-wrap, more camping mats if I can get them dirt cheap...Armaflex is a bit pricy.

I may have to put an extractor fan in the shed as I have the Maxi 310 on the top shelf at the other end, and the top of the shed is going to warm up!

[RabMaxwell]

Probably one of the best options is one of them stainless thermo box things on Ebay if they are still available.

[edit1now]

Just cleaned out Lidl in Wembley for camping mats with a shiny side. Wilco's are supposed to have plain ones but not today in Wembley. Wilco's are thicker - they must be 10mm not 10cm as it says on the website, but are fractionally dearer for the acreage. Lidl = £4.15/sq metre, Wilco's = £4.43/sq m. I'll report back on how many rolls it takes to do a Young's fermenter - probably get three layers on it.

[edit1now]

Mark One with gaffer-tape joins.