# Dometic fridge freezer



## GMJ (Jun 24, 2014)

Hi

I have one of these in my Autotrail Comanche. Its an RMD 8505 model (or RMD 8405...the only difference being the width I believe...I haven't measured it). Anyway, whilst we were away on the Continent this summer in high ambient temperatures (mid to upper 30's) it was apparent that mains electricity wasn't 'man' enough to keep the thing cool so we switched to gas.

This did the job better...and even better when on position 4 rather than the top cooling position 5 on the setting.

After 2 weeks we noticed some fumey smells in the hab area presumably from the burning of the butane.

I arranged upon return to have the fridge checked, serviced and cleaned up plus have the Dometic fan fitted (as detailed in the Dometic handbook) and also have the rest of my gas appliances checked (cooker, water heater etc).

The chap who came replaced a jet and fitted the fan. His advice was that if used on gas the fridges should be checked,cleaned etc at least twice per year for similar issues as the one I had. He estimated that it had never been looked at (and I bet this goes for most of us MH folks too). The cynic could possibly suggest that he was touting for work but I don't think so. I plan to have it done at least once per year so that it remains efficient and safe.

In terms of the extra fan, it cuts in when ambient temps reach a certain level and draws cooler air in to run over the blades at the back of the fridge. I am awaiting some indication of what 'pull' this will have on the electricity but I don't envisage much. The engineer will come back to me on it.

NB Whilst away I spoke with a Dutch chap who had fitted the 2 x computer fan modification that some folks recommend and he didn't rate it at all: he claimed it made very little - if any - difference in his Hymer.

I'll report back on the fan once I have used it in anger (probably next summer now:frown2

The costs for the chap to come to my house to supply and fit the fan; replace the jet; and do all the service, inspection, test work etc was £172 including the dreaded VAT

Graham:smile2:


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## Mrplodd (Mar 4, 2008)

I have fitted the computer fan mod to a number of vehicles (inc current caravan) I have found it makes a huge difference? 

I sometimes wonder if some who complain they don't make a difference fit the fan to the BOTTOM rather than top vent and if they actually make sure the fan is blowing air out (rather than sucking it in!) Its very easy to wire it the wrong way round.

The only way it will work is for it to draw air IN through the lower vent and force it OUT via the top vent. Its no use if it's sucking air IN through the top or pushing it out through the bottom.

These fridges will always work better in high temperatures on gas. It's because they rely on a temperature differential to work,and a small flame will deliver a higher temperature that a small electric element.

You should NOT be able to smell anything when your fridge is operating on gas!!! It's should be sealed around the edge to prevent the possibility of combustion fumes entering the vehicle. Having said that on most MH' s there's a howling gale coming from around the edge of the fridge. Invest in a tube of silicon sealant and run a small bead around the edge. ALSO make sure you get a Carbon Monoxide ALARM (not a detector, you need an alarm ) to alert you in the event of CO. A smoke detector is NOT the same, you need both

Andy


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## powerplus (Oct 6, 2014)

hi andy
thanks for the advice on a fan i have recently fitted a 120mm fan 20mm thick is this what you have used or possibly the thicker more powerful 25mm fan

my fan is not very noisy but it does push air out of the grill

do you recommend 2 fans as i have only 1 at the moment

cheers

barry


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## cabby (May 14, 2005)

I must be lucky then, as we have just one inlet grill on the side and an outlet on the roof, I would imagine that this would enable the hot air to rise and escape quite quickly, so no need for a fan.I have had no problems with the fridge yet.

cabby


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## Jezport (Jun 19, 2008)

I have 2 80mm computer fans on a switch and have a thermometer with a wireless sensor in the freezer and in hot weather the temperature drops quickly once the fan is turned on


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## GMJ (Jun 24, 2014)

Mrplodd said:


> I have fitted the computer fan mod to a number of vehicles (inc current caravan) I have found it makes a huge difference?
> 
> I sometimes wonder if some who complain they don't make a difference fit the fan to the BOTTOM rather than top vent and if they actually make sure the fan is blowing air out (rather than sucking it in!) Its very easy to wire it the wrong way round.
> 
> The only way it will work is for it to draw air IN through the lower vent and force it OUT via the top vent. Its no use if it's sucking air IN through the top or pushing it out through the bottom.


I can only speak as I find: that is what he reckoned plus he did have them fitted in the correct manner (I checked).

"You pays your money and you takes your choice"...I guess!

I'm happy to have the official Dometic solution fitted anyhow so fingers crossed!

Graham:smile2:


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## Spacerunner (Mar 18, 2006)

Problems can be caused by the gap behind the fridge/freezer being to wide and not creating the desired chimney effect.
Also quite a few fridge vents are sited close to the habitation door so that with an 'on-door' breeze fumes will enter the van.
I have fitted a thermostatically controlled computer fan. It has to be turned on manually but it's speed is governed by the temperature at the top vent. Seems to work OK.
I learnt the hard way, in very high temperature in France, the cooling unit failed by overheating which resulted in a hole in the cooling unit.
Replacement was about £800!


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## sallylillian (Sep 26, 2011)

GMJ said:


> I can only speak as I find: that is what he reckoned plus he did have them fitted in the correct manner (I checked).
> 
> "You pays your money and you takes your choice"...I guess!
> 
> ...


Graham do you have details/link to the "official" Dometic cooling solution. I have a new Tec Tower and am having some concerns over its eratic cooling, I have fitted a popular 2 fan additional unit but that did not improve performance.
Michael


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## GMJ (Jun 24, 2014)

Hi Michael

It mentions it in the Dometic booklet/manual that came with the fridge freezer. If you have the same model it is on page 17, section 4.3.3, right at the bottom.

It says " For ambient temps exceeding +32C for a longer period of time, it is recommended installing Dometic additional fan (item no: 241 2985-00)"

As I say above I cannot vouch for its effectiveness yet but cannot see how it could be worse than the computer fan solution described here and elsewhere. 

Graham:smile2:


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## Mrplodd (Mar 4, 2008)

Barry

I have only ever fitted a single fan. I have no idea what the size is as I usually scrounge one of the chip cooling fans out of an old computer rather than the larger PSU fan. On each occasion I have fitted it directly to the inside of the top vent, (blowing out!) however it's important (I think) to make sure it's well away from the flue outlet as it needs to maximise the airflow over the cooling fins. It always amazes me how hot the air is that is blown out, even when the ambient temperature is high, that to me shows that the fan is a worthwhile addition as, by removing all of that hot air, the fridge can get cooler. 

I have never bothered with a thermostat, I simply wire it into the switched 12V supply and use a small rocker switch with a built in LED warning. I position the switch wherever is convenient above the sink etc so I can clearly see when it's on. The light is very unobtrusive BUT when you turn all of the lights off at night it's very easy to spot! I always turn it off at night as it's always cooler then anyway. 

Total cost is a few hours time (which I enjoy anyway) a few feet of wire, a switch and a bit of glue/small self tapping screws (to secure the fan to the grille) less than a fiver all in. 

The noise level when operating is very low indeed so it's not an issue. Also the power drain is so low I don't even consider it.

The fan doesn't shift vast amounts of air but it certainly does the job of augmenting the normal convection current that's present and, on every vehicle thus modified, I have found it makes an appreciable difference to the internal fridge temperature. 

Having said that if the external temperature is high it's vital to operate the fridge on gas rather than EHU!

I am sure the specific Dometic unit does the same job but I doubt it's as cheap as my DIY efforts.

If you are travelling to areas where it's going to be hot I would say it's a VITAL modification. 

Andy


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## Spacerunner (Mar 18, 2006)

It's quite easy to pick up a 12 volt feed from the top of the fridge behind the control panel, then mount the switch on the panel itself.
Much shorter wiring, to the switch h and fan and looks very neat.


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## GMJ (Jun 24, 2014)

Mrplodd said:


> I am sure the specific Dometic unit does the same job but I doubt it's as cheap as my DIY efforts.


You are right there Andy...£46 plus VAT fitted.

But much less fun...:smile2:

Graham:smile2:


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## sallylillian (Sep 26, 2011)

Thanks Andy, I have a new unit (only 2 months old) and this is my first experience with these Dometic things. I have experienced erratic cooling, and it can literally take all night to get down from 11 degrees or so to 7 after Sally has loaded up with some fresh food. That is on Gas. The Freezer seems fine. I am in between 25 - 30 degrees max at the moment and overnight can be as low as 16. I have the double fan fitted which I have adjusted so it is on low speed more or less permanently. Whilst the Norcold in my RV was always a risk with its own longevity issues, the food was always very cold even on a number 2 (out of 9 coldest) setting. This Dometic is like having a delinquent child, you just don't know what it will do next! I have one of those £30 double fan packages from ebay with the external control panel. It is fitted right up against the inside of the top vent and is blowing out.
Frankly at the moment I think they are a pile of junk!


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## powerplus (Oct 6, 2014)

hi andy

thanks for the reply

i should be ok with my 120mm fan then the fridge worked fine early this year in the algarve but i like you have to play

i have gone techie overkill and used a 12v digital thermostat that i have set to come on at around 25c infact we are off to leeds tomorrow and i just remembered that i have the fridge switched on and on hook up so will go and look


barry


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## Mrplodd (Mar 4, 2008)

Michael

The fridges fitted in MH's are designed to KEEP food cool rather than to MAKE the food cold!! If you put a large amount of not so cold food into one you are asking a lot from it. You are meant to leave a fair bit of space around the food as well, otherwise you have a large single mass of "stuff" with a relatively small surface area. It gets cold by the air in the fridge absorbing the heat from the food. If there is an air gap around the food then there is a far greater surface area so it will cool quicker. If you ram it full of fresh produce it will struggle, especially if the ambient temperature is high.

It's always best to put your fridge on a day before any trip, also if you can put a couple of freezer packs out of your domestic freezer in it in order to pull the internal temperature down as much as possible BEFORE putting any food in it. 

I would also try winding the fan up a notch or three, the more air passing over the cooling fans the greater the cooling effect and in the temperatures you have the fridge needs all the help it can get!!

Graham

What exactly do you get for your £46? Is it thermostatically controlled or simply on all the time??

Andy


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## powerplus (Oct 6, 2014)

hi andy

i have just finished checking the temperatures this is today in ascot berkshire

ambient temp near ground with sun shining on the fridge outside panel 19.5c

temp inside grill before fan switched on 56c

fan switched on and thermostat cycling on at 40c off at 38c this is what the fan can handle if i set the off much lower it will run constantly at the moment till the ambient temp drops

so the fan definitely does make a difference , but will have to see what difference it is when i go to the algarve next month

to be continued

barry


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## GMJ (Jun 24, 2014)

Andy


The former: it cuts in at a certain temperature

Graham:smile2:


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## Mrplodd (Mar 4, 2008)

Barry

Try running the fan constantly for a couple of hours, (the power drain is minimal) I think you will find that the temperature behind you grille will drop a lot more!!! 

Remember these are absorption fridges and they rely solely on airflow over the cooling fins to chill the fridge, the lower the temperature of the air going over the fins the greater the cooling effect, so the greater the airflow the better.

Therefore if you can get the temperature behind the grilles down as low as possible your fridge will also get cooler. Give it a try!!

Thanks for posting your experience, you have certainly now PROVED to all the doubting Thomas's out there that the fan modification clearly has a beneficial effect!! Just need to do the same for the "Do you need heating or just decent ventilation to keep the inside of your MH damp free over the winter" debate now 

Andy


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## sallylillian (Sep 26, 2011)

Mrplodd said:


> Michael
> 
> The fridges fitted in MH's are designed to KEEP food cool rather than to MAKE the food cold!! If you put a large amount of not so cold food into one you are asking a lot from it. You are meant to leave a fair bit of space around the food as well, otherwise you have a large single mass of "stuff" with a relatively small surface area. It gets cold by the air in the fridge absorbing the heat from the food. If there is an air gap around the food then there is a far greater surface area so it will cool quicker. If you ram it full of fresh produce it will struggle, especially if the ambient temperature is high.
> 
> ...


Hi Andy,

Sorry for delay but just moved on today and have not checked emails for couple of days. My experience is with the Norcold in my US RV, whilst it had its longevity risks it was the same 3 fuel operation and was brilliant in any hot climes and we just did not think about it. I am on a steep learning curve with this toy, firstly I now understand they target 7c plus or minus 2c. What a joke, recommended fridge temperatures are circa 5c. I have now read that they say put cool foods in the fridge as you advised, so I shall have to ask the supermarket to chill my fresh fruit at the checkout. We are currently in 25c yet I have no chance with EHU, I have to use gas and have the cooling fans running 24/7 just to maintain 7c, but as soon as we open the door to get some food out, bang up to 10 or 11 and then hours before it comes down. As the unit is brand new I assumed it must be faulty, not enough refrigerant or some other issue, but from what you say that is not the case. On odd occasions it will get down to 5c, but like I said erratic.
We do have our food stored in separate open baskets with plenty of space around. I thank you for your input.


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## Mrplodd (Mar 4, 2008)

Michael

By the sounds of it you are putting things in the fridge that don't actually NEED to be refrigerated, such as fresh fruit ???

I always work on the theory that if its NOT kept refrigerated by the seller then there is no need for me to do so !! So meat fish milk etc are put in the fridge, fruit and veg most definitely not. 

I suspect that the fridge in your previous RV was a compressor fridge (same as in a domestic unit) they are VASTLY more efficient than the absorption variety, however they are also VASTLY more energy hungry. 

Andy


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## sallylillian (Sep 26, 2011)

Hi Andy,

I suppose we all choose our way of living, I like chilled fruit, and for the record collected some chilled fruit from the local supermarket today. But that debate takes us down an unnecessary path.
My RV fridge was not a compressor fridge, it was a 3 fuel, Gas, AC and DC gas absorption fridge Norcold model 1210. Again not helpful but to provide some understanding of my expectations, AND cheaper to buy than this Dometic thing!
But it does seem that these are not refrigerators, they do not operate at accepted cooling temperatures 5-6c, cannot handle food chilling, and unless it is packed in a "special way" will be mostly useless, needs third party fans to even come close to surviving in European weathers, so all in all, as I said in a previous post, a pile of junk. IMO
However I do appreciate your insights they have enabled me to focus on the fact that it is junk rather than mine having some fault from new needing attention under warranty. So thank you.
But if I wanted a better one what are my choices in the same space?


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## Mrplodd (Mar 4, 2008)

Hi Michael

Please don't think I was trying to lecture you or be a smart arse. 

Many are unaware of the limitations of fridges fitted to leisure vehicles. So what I wrote was partly for their benefit as well.

By the sounds of it I would be inclined to speak directly with Dometic to get some form of performance figures from them. It seem to me that maybe yours isn't working as well as it should. If the freezer part IS doing what it should then MAYBE there is a fault with the fridge section?

Worth an email anyway?

Andy


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## GMJ (Jun 24, 2014)

powerplus said:


> ...but will have to see what difference it is when i go to the algarve next month...


I suppose that is the key to both these modifications...

...although the higher heat of summer would be a truer test.

Graham:smile2:


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## sallylillian (Sep 26, 2011)

Andy, I did not think you a smart arse, I do/did appreciate your insights. I have already spoken to Dometic and they suggested I contact one of their agents here in Spain. I was concerned after having been to one place and saw a newish TecTower standing in their yard covered in dust, "awaiting parts", that I decided that as I can survive I will await my return to the UK. However I do have temperatures here which cannot be replicated in the UK in November so I shall see how things go and make a list. The temperature has not exceeded 29 here over the last few days and Dometic say its should hold 7 in ambient s up to 32 on setting 3. I am on 4 at the moment, on gas, and its only holding 9ish. Dual fans running constantly on low speed, rising to high speed by the afternoon. Anyway clearly a debate to be had when I return.


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