An unconventional fitting of a Dometic brand new RM 5310 3-way fridge.

[Happy Traveller]

Just after the first lockdown began in March 2020 our fridge cooling system leaked its fluid into the freezer compartment. Even for day trips we like to use the fridge. It was not then possible to book the van into a workshop for help so I took the decision to buy and fit a brand new fridge myself. The old one was 16 years old being the original when we bought our van new.

 

I’m posting this under modifications and enhancements because of the unconventional way I’ve fitted this new fridge. But first I must say that when the van has a new owner then they will be able to re-fit it as a normal 3-way absorption fridge.

 

I’ve now got a 2-way fridge which works 24/7 on a direct (switched and fused separately) 12v supply from my leisure batteries or directly from the mains when hooked up. Other than proving that it works on 230v I’ve only ever run it on its 12v supply. This I have done for weeks at a time because our daughter, her husband and 2 children have slept, cooked etc in the van when visiting us in order to comply with covid-19 precautions and rules. The leisure batteries were, of course, on charge all the time because the van was hooked up so that 230v electric radiators, hairdryers, kettles etc could be used when required.

 

In effect I’ve got all the advantages of a compressor fridge without the noise. Like its predecessor this new fridge is silent.

 

Dometic have deliberately kept the RM5310 fridge exactly as its classic forerunner so that people like me can easily buy and fit it. So very importantly it has identical external measurements which enabled me to slide it into the space vacated by the old fridge and re-seal it all-round at the back to cut out potential cold draughts. All I had to do was work through the vents’ openings to disconnect the gas supply to my old fridge – having first disconnected the gas cylinder and then turned off and locked off the gas supply tap to the fridge -, disconnect the 230v and 12v wires and then unscrew the screws holding the fridge in place. There was a small amount of resistance when pulling the old fridge out because it was well sealed in at the back.

 

Dometic now advise that the 230v supply should have an easily accessible fused switch. I fitted this in the cupboard to the right of the fridge where I could conveniently get at the existing 230v cable and feed it into my new switch. Dometic fitted a very long 230v cable to the new fridge which easily reached my switch making the task very straightforward.

 

For my 12v supply I’ve positioned my own on/off control switch in the side housing of the underseat locker where the leisure batteries are. My fuse for this switch is between it and the terminal on the battery. I placed it here to enable me to see if it’s on/off as I lock the side door. My preference is to have the down position for off because if it’s knocked it will be downwards and I would rather switch something off  than on were I to knock it without knowing, even though it’s only 12v.

 

Running the 12v wiring from this switch to the back of the fridge was a bit of a round the houses affair. From the leisure batteries locker my wire went tight under the sink, down the back of and then under the drawers and through the hatch underneath, out tight under the raised floor, up into the cupboards beside the fridge and then through to the back of the fridge.

 

I will say at this stage that I actually had to run 2 wires from the leisure batteries to the back of the fridge because Dometic advise that a negative wire should be connected directly from the battery into the fridge 12v circuit.

 

This new fridge achieves much colder temperatures (yes, even on 12v) than my old fridge. I don’t select the lowest temperature but never-the-less the freezer compartment maintains -13 degrees easily. This for me is a big improvement.

 

All I need now in these covid-19 times is to be able to get away for a few weeks!

 

Best wishes

 

Keith.

 

 

 

 

[gazdoubleu]

Hi Keith

<p style=”text-align: left;”>I dont really understand the logic of this. Why would you completely rewire? The existing wiring should have been good for well over 10 amps dc (which is the draw of my absorbtion fridge) as its protected by a 20 amp fuse.</p>
<p style=”text-align: left;”>It also gets a bit higher voltage than the leisure battery will deliver when the alternator is running direct via a relay inside the Elektroblock & controlled by a D+  alternator signal.</p>
My dometic absorbtion fridge allows me to run from the 12 volt leisure battery manually by throwing the switch on the front panel whether or not the alternator is running.

I did it once all night to test out the Lithium batteries but it pulled 80ah from them.

If you’re ever gonna run an absorbtion fridge without hook up or gas you probably need more solar than the Exsis roof can accomodate or a massive capacity deep cycle battery.

Compressor fridges are a different entity, they only pull about 1-2ah once chilled down.

Using the mains hook up to charge the battery while the fridge is drawing dc from it is also wasteful, especially with lead acid batteries which have a high internal resistance. The low voltage wiring will also waste more energy in heat than the 240 volt wiring.

If you’re on hook up all the time you may as well run the fridge from the 240 volt supply.

Do you have a worry over gas or was it just that 2 way (compressor) fridges seem to be popular these days so you thought that was the way forward?

Cheers,

Gary

 

 

 

 

 

 

 

[Happy Traveller]

Hello Gary

 

I ran fresh 12v wiring because I didn’t know how to make the existing wiring free of ignition control. It was relatively easy to do.

 

I am not bothered if there is an extra cost.

 

In the spring of 2020 lockdown prevented me from having a new fridge fitted by a professional.

 

I’ve found that I can have the new fridge on for 16 hours continuously on a hot day away from hook-up without a bother. Maybe my 2 x 80 amp/hr leisure batteries are the reason for this. I did the same with the old fridge. For me there is a joy to switching the fridge on and then not thinking about it for the day or whole holiday (weeks). It’s so easy.

 

There are several advantages to running an absorption fridge this way. I like these. For me it is better than having a compressor fridge.

 

I’m always looking for the lazy way to achieve what I want, I always have but I think it’s become more pronounced since I entered my eighties. That’s why I chose the name Happy Traveller.

 

Best wishes,

 

Keith

[Happy Traveller]

Hello Gary

 

My first reason for doing what I did was that no manufacturer offered a condensing fridge which would exactly fit in the space vacated by my old fridge; in fact there wasn’t even a close fit. So it became a no brainer to buy the latest version of the fridge originally fitted because this was an exact fit.

 

I should have started my first reply with this information. Of course a new owner can get a suitably qualified gas fitter to make my new fridge operate as designed as a 3 in 1.

 

Best wishes,

 

Keith.

[Happy Traveller]

Hi again – please read compressor for condensing in my first line above beginning – “My first reason for” Sorry for this piece of carelessness.

 

Keith

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