Problem with my Maxi 110 thermostat

[guypettigrew]

A few months ago I bought a 'reconditioned' Maxi 110 off ebay.

The temperature in the ice bath was about -0.4C when I got it. Today it's showing 2.5C. I haven't checked it for several weeks, so don't know when it started going wrong. 2.5C is OK for pulling the beer in the FV low enough to drop the yeast out before kegging, but there's clearly a problem. My guess is the thermostat isn't working properly.

Anyone know where I can get a replacement thermostat, and is it easy to fit?

A Google search hasn't yielded much, other than a main Cornelius distributor in Brighouse, Yorkshire. A service engineer close to me (Dorset) would be a real bonus.

Thanks in advance.

Guy

[Goosey]

Have you tried these?: https://www.btowstore.com/epages/Store2 ... Categories

[Fil]

an stc1000 or similar type controller is a pretty easy fit, cutting the hole in the steel box being the hardest bit

the compressor, cooling fan and recirc/agitator all run off 240v a/c so can all be controlled via the stc1000 cold relay

carefully remove the waterbath lid to check an icewall is forming before atempting a fix tho. the lid may well be bonded with a putty like substance so gently prize it off after removing any screws. it could be an agitator or recirc failure ?

[guypettigrew]

Thanks both of you.

I've found a local engineer who works on these. He thinks it's probably the thermostat. Looks like it'll be about £60 to test and repair it.

Guy

[Kev888]

Ouch, £60 is about the price of a used one

These thermostats do seem unreliable; most of the non-working coolers I've had over the years have been due to them. Occasionally though the compressor (or gas) has been on the way out, so it depends if the maxi is not trying to cool enough or can't cool enough. You can test this by bypassing the thermostat (and ending the test if/when it gets to normal temperatures).

As fil says, quite a lot of people replace the thermostat with an stc1000. It gives you more control than the standard fixed thermostat (which may be wanted for cooling fermenters and/or using polyethylene glycol). In fact its not impossible that someone on here may have a spare used original from doing this. Or else people do it because its a cheaper solution than buying a replacement thermostat for a broken one.

(Though this does of course involve mains electricity, so you would have to be comfortable dealing with such things).

EDIT: BTW its probably worth checking that the agitator/pump motor is spinning, if thats not already apparent. If not, warmer spots can occur in the cool bath even if the cooling coils are working fine.

[Fil]

EDIT: BTW its probably worth checking that the agitator/pump motor is spinning, if thats not already apparent. If not, warmer spots can occur in the cool bath even if the cooling coils are working fine.

this is what i was aiming at saying... my #1 ebay bargain chiller performed very poorly until i ripped it open to discover the agitator motor was not spinning. Easily fixed by simply bypassing its control board and powering directly from the mains input.

if nervous about the electrics, pop open the case and take a few snaps for guidance, there are only 3 devices running inside, the compressor, the agitator or recirc (one or the other), and the fan used to cool the refrigerant. if either the agitator/recirc or the cooling fan are not performing properly they can have a deleterious knock on effect to the chilling efficiency. and neither need an expensive engineer to fix...

odds are in your favour its a simple fix either the thermostat as you suggest or one of the ancillary components, however if your loosing coolant its time to start scouring ebay for local bargains.. i wouldnt bother buying a reconditioned model again, as about the only servicing you can do with these boxes is flush out the product coils and dust off the top.

[guypettigrew]

This is really embarrassing!

What's the first thing to do if you're not getting a reading you'd expect? Yup, that's right, check your measuring equipment. What was the real problem with my Maxi 110? The thermometer I used to measure the temperature of the ice bath.

Substituting it for another showed an ice bath temperature of -0.2 C, as did two others I then tried. How stupid can you get? Well, about that stupid!

The upside of this, though, was that I got to meet a really knowledgeable and friendly refrigeration engineer. We got chatting about the difficulties of keeping the beer in my King Kegs at the right temperature during the summer. He reckons he can put together a very small version of the coolers used in pub cellars--in effect an air conditioner which works down to about 10-12 C--to cool down a well insulated cupboard which my three kegs would fit comfortably into. It would have an internal and external unit like an air con unit, but these would be very much smaller than usual.

So, it's annoying there was no problem with the Maxi, but well worth it to meet up with the refrigeration engineer.

Guy

[Kev888]

Hah hah, well these things happen.

The mini air-conditioner is very interesting. I've used full-sized ones in cupboards before but their size makes them (highly) inappropriately noisy and inefficient for the job. Altering the thermostat on one also allowed the cold-side radiator to ice up with condensation (potentially worse in a small/closed cupboard). And it takes a bodge to make the portable ones split their air flow so that they don't need to extract air from the cupboard.

BUT all these were problems to do with cheap/poor implementation, the actual cooling results themselves were a joy. A larger purpose-made and sized cupboard is so much more convenient than a cramped or inconveniently proportioned fridge, or having cooling pipes and gubbins attached to the keg. If it could be done properly/professionally, it could be great.

[Fil]

Good to hear your sorted, it seemed a bit rough to buy a reconditioned model only for it to develop faults after only a few short months.

btw while i had a simple fix with my ebay bargain chiller, i managed to overlook the actual fault until i had planned a complete strip down and only by chance decided to test the ice wall build up when i got the bath lid off. as it happened it built up nice n thick within an hour or so ?? only then did i notice the static agitator DOH!!

re minikeg chilling, the rather expensive minikeg chilling machines with built in chilling and regulated party tap use peltiers that draw less than 35w

I Know as i have one with a 35w dc powerbrick they do take 12hours or longer to chill down from conditioning temperatures, but ince cool manage to keep them cool with only a hollow plastic wall as insulation.

peltiers work best when making good positive contact with a flat surface, so i think it would involve base mounted peltiers with fans blowing off the heat from the hot side of the plates.

keep the engineer sweet and in beer he will be a useful source of materials such as SS tube and soft copper tube in imperial sizes too as well as a font of useful information

[Stewb]

Good to hear your sorted, it seemed a bit rough to buy a reconditioned model only for it to develop faults after only a few short months.

btw while i had a simple fix with my ebay bargain chiller, i managed to overlook the actual fault until i had planned a complete strip down and only by chance decided to test the ice wall build up when i got the bath lid off. as it happened it built up nice n thick within an hour or so ?? only then did i notice the static agitator DOH!!

re minikeg chilling, the rather expensive minikeg chilling machines with built in chilling and regulated party tap use peltiers that draw less than 35w

I Know as i have one with a 35w dc powerbrick they do take 12hours or longer to chill down from conditioning temperatures, but ince cool manage to keep them cool with only a hollow plastic wall as insulation.

peltiers work best when making good positive contact with a flat surface, so i think it would involve base mounted peltiers with fans blowing off the heat from the hot side of the plates.

keep the engineer sweet and in beer he will be a useful source of materials such as SS tube and soft copper tube in imperial sizes too as well as a font of useful information

Fil- i have an issue with my maxi 110- want to be using recirculation for temp control but recirculating pump/ agitator not working. Was thinking it may be broken pump but keen to explore if there is something simple i can do to get it going- what is it you did?

Sent from my Nexus 5X using Tapatalk

[Fil]

@StewB

easiest test is to get hold of a basic multimeter and set it to read a/c mains current. And test if current is reaching the pump. In my case it wasnt..

the power to the agitator in my case was fed via 3 position speed control knob/pcb, I simply bypassed this component and fed the agitator directly..

Later when wanting to do what your planning i replaced the agitator with a 2m head fountain pump dropping it into the agitator void within the confines of the product coils the fountain pump was £25 a maxi 2nd use ebay python pump was £40 ?? the fountain pump does warm the waterbath slightly, maxi pumps which sit atop the waterbath dont so much;)

[Stewb]

@StewB

easiest test is to get hold of a basic multimeter and set it to read a/c mains current. And test if current is reaching the pump. In my case it wasnt..

the power to the agitator in my case was fed via 3 position speed control knob/pcb, I simply bypassed this component and fed the agitator directly..

Later when wanting to do what your planning i replaced the agitator with a 2m head fountain pump dropping it into the agitator void within the confines of the product coils the fountain pump was £25 a maxi 2nd use ebay python pump was £40 ?? the fountain pump does warm the waterbath slightly, maxi pumps which sit atop the waterbath dont so much;)

Cheers Fil, I'll see if i can borrow one from someone at work and give it a go

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