Glass Door Fridge Users! Tell me Your Experiences Here.

[Fat Bastard]

Ok, so I got me a you beaut glass door fridge to put my fancy conical fermenter in. Looks fantastic, lights up at night so I can tame the yeasts when they're less stroppy etc. But jeez, it's a bit crap.

I've never seen it get lower than 1.7o and now that the weather is warming up, she's just gone over 4o . It's on full blast (according to the dial thing), STC set to 2o but it's struggling. Noting the pattern of operation, the fridge thermostat turned back on @ 6o so I'm sure it's got something to do with that, the glass door does not feel very cold, although it's got enough condensation on it to indicate that it's losing some coolth through there.

I'm personally thinking of cutting a bit of foam and velcroing it to the glass to see if that helps.

I'm also thinking about disabling the thermostat somehow on the fridge so it won't turn off until the STC decides it's time, but I have no idea about how to do that. It does have a thermocouple protruding into the bottom of the fridge, so it may be as simple as burying that in silicone or something.

Any tales of woe appreciated.

Cheers,

FB

 

[Moad]

Turn the light off and maybe put a towel over the front to test.

Seals all good?

Mine gets down to.5

 

[Fat Bastard]

Light is only on when I'm actively mucking about with something in there. Seals may be an issue. I can get a noticable difference when I remove the heat belt and don't have to have the cord going through the door seal.

The thing works well enough for ferment temps, and it cools much faster than my old fridge, which would take a day and a half to get to 4o tis thing will hit 4o in under a day, and 20 shortly thereafter, it just won't hold it on hot days. It's old and cost me nothing, so I'm fearing the compressor may be rooted. Although if it was rooted it probably wouldn't get there in the first place!

 

[tavas]

My brother is a fridgy and he tells me that glass door fridges are not particularly efficient compared to a conventional fridge. You'll probably be getting some heat through the glass door.

 

[Fat Bastard]

Yeah, I've just been watching the temp fall with the ambient temp drop. Or at least that's my excuse for staying up drinking beers on Sunday night!
might try to make a cover for the door glass out of some foam or something and see if that helps.

 

[Dae Tripper]

I found that the thermostat on mine has a very wide range, the STC says (being used for indication only) -2 to about 3.5 or more degrees from memory. As far as I know most have a fan that runs constantly to circulate air, this has tricked me to thinking the compressor was running before. You will need to bypass the thermostat on it to get lower and more consistent temps that the STC can deliver, but only if the thermostat is bypassed. I plan to disconnect the fan soon as it could cause some heating of the cool space.
Otherwise I FN love my glass door to death and I haven't had it all that long!

 

[Online Brewing Supplies]

I have used Styrofoam sheet but on the inside and outside of the doors.
Works better now and I removed the old thermo and use a digital unit.
Nev

 

[Moad]

It's old and cost me nothing, so I'm fearing the compressor may be rooted. Although if it was rooted it probably wouldn't get there in the first place!

Yeah if it just wasn't cooling I'd say more likely to be the refrigerant has leaked, according to my fridgey mate not much goes wrong with compressors themselves.

 

[Florian]

Just a guess, but as these commercial fridges are designed to often hold things like soft drinks and milk etc on display maybe they don't get down to zero so as to not freeze the product?

Also, I'm guessing you are measuring temp in the thermowell and not ambient?

Mine's sitting at 2.5 at the moment with a sight glass full of creamy yeast, as soon as I get around to removing that I will see how low mine goes.

 

[MHB]

They are more expensive to run, that's just the nature of the beast.
The up side of them is they are usually a lot more powerful than domestic fridges, so they cool faster
They are fan forced so they are homogeneous (same temp top to bottom)
The fan improves the rate of cooling of the ferment by breaking up boundary layers (like chill factor on a cool windy day)
Remember that a 25W fan is a 25W heater and in a well insulated (well reasonably well) box if the compressor is off it will act as a heater (my last fridge would get to 40oC just from fan heat) which in cold climates and when making some styles can be a real advantage.

I fitted an STC to mine, powered it with a cord and took the two wires off the analogue controller and put them across the switching contacts on the STC, set it up (remember to check the calibration against good thermometer) and to set the compressor delay for long enough to prevent the evaporator from icing up (a bit of trial and error, but watch for ice build-up) than can make them run very badly and make them not cool well.
As mentioned above get the gas checked, that's about the main service requirement - except for keeping the condenser clean, I blow mine out with a CO2 bottle, keeping dust build-up to a minimum makes them work better and cost les to run.
Mark

 

[Fat Bastard]

Cheers for the replies. It looks like the stock thermostat has a very broad range of hysteresis. Like around 4 degrees. Seems to shut down at 2 degrees ambient and fire up again at 6. This takes a vey long time due to the thermal mass of the fermenter. I guess I'll have to do some research on bypassing it. In the mean time I've chucked a bunch of ice bricks in there to see if that keeps the fermenter cooler for longer.

 

[Mardoo]

There's a thread on here somewhere about bypassing commercial thermostats on fridges. I can't find the link to the detailed one at the moment but here's a (very, very) basic explanation:
http://aussiehomebrewer.com/topic/25423-bypassing-the-fridge-thermostat-how/

 

[Fat Bastard]

Cheers Mardoo! Sounds simple. In theory anyway! Will talk to the bright sparks at work about it.

 

[Mardoo]

Yep. Just a switch, from the wiring perspective. I replaced our furnace thermostat with zero issues, and I'm no genius.

 

[Ducatiboy stu]

Proper glass fridge doors should have 2 panes of glass with a vacuum between them. It is normal for the outside glass to be warm. Good seal are important on them. Also check that all your cooling fins are clean and dust free. - Advice also form a fridgie mate

 

[Feldon]

With conventional fridges you are only dealing with convection and conduction issues.

But with glass fridges radiation comes in to play as well. Glass can let radiant heat in.

Eg. if you have the fridge in a shed with a warm roof or walls these surfaces will radiate infra red heat which can heat the glass and/or the fermentor inside. This happens no matter how cool the ambient air is (think of the sun's radiant heat travelling to earth through the cold vacuum of space, and the cold upper layers of the atmosphere).

If you suspect this is the case, experiment by placing old cardboard box pieces near the sides and above top of the fridge to 'shadow' the fridge. See if it makes a difference.

... the glass door does not feel very cold, although it's got enough condensation on it to indicate that it's losing some coolth through there.

This is the wrong way to think about it. You've got to get your head around the fundamentals of heat transfer. There are only three ways - convection, conduction and radiation.

'Cool' doesn't transfer anywhere because cool doesn't exist. Only heat exists, and here we are talking about the relative differences in heat between the inside and outside of the fridge. The glass gets condensation on it because heat has been extracted from the glass which causes moisture in the air to condense on it.

 

[J.T]

Cheers for the replies. It looks like the stock thermostat has a very broad range of hysteresis. Like around 4 degrees. Seems to shut down at 2 degrees ambient and fire up again at 6. This takes a vey long time due to the thermal mass of the fermenter. I guess I'll have to do some research on bypassing it. In the mean time I've chucked a bunch of ice bricks in there to see if that keeps the fermenter cooler for longer.

A 4c differential is about what you want. In at 6c out at 2c, will average out to around 3-4c. The compressor needs a decent amount of off time, cutting in and out all day due to a small differential is no good.

Just a few quick comments on a couple points that i read while skimming through this...

The glass doors are double glazed to reduce the transfer of heat through the door, although they wouldn't be as efficient as a solid door, they aren't too bad. I would only stuff around with covering the door up when the ambient temp is high.

Glass door fridges are a commercial product with a lot more cooling capacity (and running costs) than domestic fridges, it should easily be able to cool a fermenter to 2c and fast. My guess is that its low on gas. By all means, switch over the thermostat for better control and adjustment, but it wont make it work any better. You should be able to adjustments to the existing thermostat if you are handy. A properly working setup would be able to get well zero if required.

Cool = lack of heat!

 

[Fat Bastard]

Looks like the thermostat may be the main culprit (although the gas might be exacerbating the issue) I just caught the fridge turning back on at 2.5. The STC should have had it running then. It certainly cools faster than my old one. I've got a gap in my brew schedule next week, so I'll have a crack at bridging out the fridge thermostat.

Cheers!