Running a Bushman Fridge as a multi-zone

Submitted: Sunday, Sep 05, 2021 at 17:47
ThreadID: 142524 Views:1193 Replies:6 FollowUps:7
I have a question specifically about the Bushman C35 Portable Expandable Fridge 35L-52L.

The Bushman publicity material outlines three zones when the fridge is expanded to 52L: -2C on the bottom, +2C in the middle and +6C on the top. It's not clear what the thermostat is set to for these temps, but I assume it's -2C.

However -2C isn't really a freezer temp. I have read reports (perhaps here - I've read a lot of fridge threads) that some people have placed items like plywood or insulating foam just above the bottom zone, which has enabled them to turn the temp of the lower zone down several degrees, while roughly maintaining the temps of the other zones. But these have only been references in passing. I was hoping for a clearer description of how successful this was. Anyone here tried this?

Please also note that (i) I haven't ruled out a proper dual-zone fridge; (ii) I I realise that turning down the temp increases battery usage; & (iii) I already use a vacuum sealer.
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Reply By: RMD - Sunday, Sep 05, 2021 at 19:55

Sunday, Sep 05, 2021 at 19:55
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I don't own a Bushman fridge but see value in having a couple, maybe three, digital fridge thermometers, sensor on lead, so you can read and verify the temps in each zone created. That way you then know the characteristics of it all. For instance, an Engel will run it's sensor site down to around 10C. below the set temp so there is a "quantity difference of COLD" to be absorbed into the contents. ie, at 4C setting most fridges will cool to around -6C (hysteresis) to provide that ability. Depending on contents absorption rate and loss through walls the reserve of cool ensures the fridge isn't starting and stopping every couple of minutes. You can't test an empty space if investigating, air has no/little thermal mass, so pre cooled bottles of water to around the desired temp should be inserted to each zone to stabilise it all and provide some ability to decide the temps and performance. This all takes time and needs to be done with fridge in similar ambient temp to proposed use, otherwise the equation/ situation is different. It takes a while to get it all in the mind.

Edit
Going from 35L to52L is a big ask and compromise will have to happen. Some fridges use a 12v computer style fan inside to move cool around more evenly so some areas are not starved of cool. 40%more volume will mean much longer run times too.
AnswerID: 637808

Follow Up By: Pepper - Monday, Sep 06, 2021 at 10:52

Monday, Sep 06, 2021 at 10:52
I have used one of these bushman fridge /freezers and found they operate as promised ..you have to set temp by trial and error to get the temp in the region you want remember you are relying on cold air from the cooling plates ..there is no circulation fans so this can take some time..

The one I had worked well..
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Reply By: Member - William B - Monday, Sep 06, 2021 at 13:13

Monday, Sep 06, 2021 at 13:13
Hi Briste,
I have that fridge and as Pepper has said it will do as you require but will rely on you adjusting it to achieve what you need.
William
Always planning the next trip. VKS-737 mobile 1619

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AnswerID: 637816

Reply By: Member - peter g28 - Monday, Sep 06, 2021 at 20:02

Monday, Sep 06, 2021 at 20:02
I have the Bushman 35 to 52 Ltr expandable fridge and have only used the 2 zone system.. the thermostat temp below -4...
Pre cool the fridge before loading for your camp..If you can..use 240v..all the better..saves a bit of wear on the AGM's..
So from the floor of the fridge to the first basket..all the frozen stuff..meat etc...then I placed in the bottom of the first basket a layer of Techi Ice sheets..(measured to fit)..then above that level all the foodstuffs and veg..and in the smaller basket..mainly the dairy / small goods.
The only issue I had was with the large bottles I had located at the side..I had to keep an eye on them so they would not freeze..especially the wine.
Anyway it worked reasonably well..when I had finished the frozen foodstuffs..I increased the thermostat to 0 , +1..and had very cold drinks and foodstuffs.
The Bushman portable fridge wasn't really popular when compared to the Engels / Waeco etc that were dominating the camping leisure market at the time..so the Bushman fridge was a steal at $750 with all the baskets/collars it came with when compared to a 45ltr Engel that was about $1100 at the time.
So even today with its flexibility..expandable from 35 to 52ltrs..and nearly at the same price as a 45ltr Engel..it is still good value..
I have had a Bushman since 2007...still going strong..I bought it with Kev 07's GFC money he sent out to people...
AnswerID: 637824

Reply By: Briste - Monday, Sep 06, 2021 at 22:29

Monday, Sep 06, 2021 at 22:29
Thanks for those replies. Yes, I'm sure that the Bushman works as advertised. One of the remarkable things about researching it is just how happy its owners seem to be, particularly the long term owners. Low power draw and outstanding support being among the reasons.

Peter's use sounds pretty similar to what I had in mind. Peter - what was your thinking about the Techni Ice sheets as a layer between the bottom and middle zones? You're talking about "Techni Ice Reusable Dry Ice Packs / Gel Packs", aren't you? Are you using them as an insulating layer? Or .... ?

I dug around and found the Youtube reviewers who used other materials.This reviewer (at 7:20) mentions insulation foam, and as a user for nine years who has done a reasonably comprehensive review his suggestion has some credibility.

This other reviewer (at 1:40) mentions using plywood, but it's more of a offhand, bored lockdown evening review, and so is less convincing. I'd have more confidence in insulation foam, or perhaps Techni.

RMD's observation that you really need to test and measure in a loaded fridge is valid, but can only be one once I've finally decided and have purchased one.
AnswerID: 637825

Follow Up By: RMD - Tuesday, Sep 07, 2021 at 13:20

Tuesday, Sep 07, 2021 at 13:20
Briste.
I understand you cannot test what you haven't got, only suggesting ways to monitor any fridge so you know what it is doing, not what the temp setting says, as it is usually wrong. Engel state not to use the reading as the indicator because it varies so much.
The Tehni Ice if absorbed water in pocket bags is simply a means of transferring heat or cold energy to another section. If wanting a frozen section and a fridge section, Polystyrene foam will reduce the transfer of temps far more efficiently.
Once sorted then you really don't have to worry about it as you know it is working.

A fridge usually has an entry to the evaporator section which is the coldest and a return side where it warmer. Using foam sheet vertically from between the cold entry and the exit of gas, to the side of cabinet, ie, straight or L shaped divider, will see one side get frozen and the other exit side compartment as a fridge. Have to play around with it to know it works, then use it.
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FollowupID: 915966

Reply By: maurice b - Tuesday, Sep 07, 2021 at 10:31

Tuesday, Sep 07, 2021 at 10:31
Bushman power consumption test against a 50 litre Waeco .https://youtu.be/o3V7JAOsIJM
AnswerID: 637826

Follow Up By: RMD - Tuesday, Sep 07, 2021 at 13:06

Tuesday, Sep 07, 2021 at 13:06
Maurice.
Just an observation. the Bushman, which he calls Busman, is in a different vehicle in different shade. The Waeco he says uses less is in a vehicle with a great big sun shade over the side so the applied heat to the vehicle and fridge run time and heat applied will be way less. Nothing scientific about it!Seat of pants measuring. Just because it is on U tube means?????
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FollowupID: 915965

Follow Up By: AlbyNSW - Tuesday, Sep 07, 2021 at 16:44

Tuesday, Sep 07, 2021 at 16:44
I have seen other controlled environment tests and the Bushman have come out on top in the efficiency stakes but lost out for overall winner as they didn’t like the latches on the lid which I admit are a bit flimsy

The one thing that is refreshing with the company is you can ring them up and talk direct to a technician for advice.
I had to do that when on a trip last year, it turned out to be a battery issue but they were very good at running through my system over the phone to help fault find the issue
Hard to find that sort of service these days
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FollowupID: 915968

Follow Up By: RMD - Tuesday, Sep 07, 2021 at 19:17

Tuesday, Sep 07, 2021 at 19:17
Alby.
I think Bushman are a great product and sad to see reviewers cannot look past what they don't like and refuse to see the value. Remember, cash for comment still happens.
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FollowupID: 915971

Reply By: Allan B (Sunshine Coast) - Tuesday, Sep 07, 2021 at 11:01

Tuesday, Sep 07, 2021 at 11:01
.
Blimey, what a lot of trouble some of you blokes go to in managing your fridges!
Techni Ice panels, plywood, foam etc.
Did you ever get time to admire the sunset?

My old Waeco also had a temperature gradient but we just put the meat in the bottom and butter at the top, with beer in the middle.
Oh, there was a lift-out basket that eased rummaging but that's all.
The potentiometer that set the temperature failed years ago so I modified it to a switch for freezer/chiller operation. It just worked and I just relaxed.

Cheers
Allan

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AnswerID: 637827

Follow Up By: AlbyNSW - Tuesday, Sep 07, 2021 at 12:50

Tuesday, Sep 07, 2021 at 12:50
Stop making things so simple Alan, this is meant to be complicated stuff
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FollowupID: 915964

Follow Up By: RMD - Tuesday, Sep 07, 2021 at 19:11

Tuesday, Sep 07, 2021 at 19:11
Alby.
It isn't simple. I once trusted my Engel to freeze and found it wouldn't get below -1 in back of LC wagon and constantly running. Even had it tested in Alice and found to be correct under test. No good in 30c day in Alice though. Since then I insulate and monitor any fridge so I know what is happening. Even fitted a computer fan long before Engel did. To not do that risks loss of food when you need it most. Complicated NO, but some realization is required of the process to achieve a result.
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FollowupID: 915970

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