Fridge question?

[Buckman]

If running the caravan fridge on gas, will it use more gas in the summer to keep cool or use less gas? Same for winter. If no covers on vents will the fridge use more or less gas. I am of the opinion that in summer you would use less gas and in winter more gas.
Currently our Dometic fridge uses an average of 380gm every 24 hours so our 7.5kg cylinder should last approximately 19 days if no other gas appliances are used. I would think that off grid in the summer using all gas appliances our 7.5kg bottle would last about 14 days if we BBQ a lot or eat cold meats and salads.

 

[Sam Vimes]

I'm just guessing but I'd say more gas in summer and less in winter. In summer time when hopefully it's warmer the outside of the fridge will get warmer and so it will have to work harder to keep the inside temperature down.

 

[otherclive]

I can’t think why it would use more in winter. That seems to defy thermodynamics.

 

[Jcloughie]

Gas is the energy used to cool. The more work it has to do, the more it will use. Therefore more gas in summer as more cooling to do. Getting rid of excess heat will improve efficiency. Therefore no vent covers in summer. I find that my thermostatically controlled fans to assist cooling the condenser improve the cooling and should therefore reduce fuel use.

Caravan manufacturers make a poor job of installing fridges. The gap behind is too big. It is recommended to be narrower behind the condenser to form a venturi effect so air flows faster offer the fins.

John

 

[Buckman]

Gas is the energy used to cool. The more work it has to do, the more it will use. Therefore more gas in summer as more cooling to do. Getting rid of excess heat will improve efficiency. Therefore no vent covers in summer. I find that my thermostatically controlled fans to assist cooling the condenser improve the cooling and should therefore reduce fuel use.

Caravan manufacturers make a poor job of installing fridges. The gap behind is too big. It is recommended to be narrower behind the condenser to form a venturi effect so air flows faster offer the fins.

John

It has not happened to us, but on a very hot day our friend's fridge almost froze up as it vented into the awning area.
At the moment as we only use sites with EHU, we only run the fridge on gas once or twice a year for a few hours each time however always been in the summer months. Never monitored usage.

 

[Jcloughie]

It has not happened to us, but on a very hoy our friend's fridge almost froze up as it vented into the awning area.
At the moment as we only use sites with EHU, we only run the fridge on gas once or twice a year for a few hours each time however always been in the summer months. Never monitored usage.

Most likely it froze up due to poor thermostatic control. I am not sure, but perhaps fridges are not thermostatially controlled when on gas. Or perhaps some are are some not.

John

 

[Miche Harris]

I have been advised by my engineer to remove the vent covers whenever the fridge is in operation as it is essential for the vents to be open for correct operation of the fridge. He also clears any dust and muck that's accumulated in the vents (which is what the vent covers try to avoid) as he says that debris in the vents is a common cause of poor air flow, causing the fridge to malfunction. Also overfilling doesn't help air flow and the camping fridges aren't usually as big as what we're used to at home. It's my first post, but felt moved to let people know about removing the vent covers as I was lead to believe it is actually dangerous to leave them on when the fridge is running on gas!

 

[Buckman]

I have been advised by my engineer to remove the vent covers whenever the fridge is in operation as it is essential for the vents to be open for correct operation of the fridge. He also clears any dust and muck that's accumulated in the vents (which is what the vent covers try to avoid) as he says that debris in the vents is a common cause of poor air flow, causing the fridge to malfunction. Also overfilling doesn't help air flow and the camping fridges aren't usually as big as what we're used to at home. It's my first post, but felt moved to let people know about removing the vent covers as I was lead to believe it is actually dangerous to leave them on when the fridge is running on gas!

However the manufacturer of the fridge advises to use vent covers in the colder months for the fridge to work more efficiently whether on 240v or gas. Ours is a tall fridge with a large freezer compartment. Not sure what you mean by "overfilling"?

 

[Miche Harris]

Oh, just a reference to the icing up issue mentioned. We tend to crush all our supplies up against the fridge walls at the back which I know isn't recommended. It's the number of drinks we cram in the front that push everything else to the back! Hopefully won't be so bad this year as the kids are doing their own thing.

 

[Dustydog]

This explains how and when to use fridge vent covers.
https://www.outdoorbits.com/blog/2019/08/motorhome-caravan-fridge-winter-vent-covers-guide/

 

[ProfJohnL]

How much gas a fridge uses depends on several factors factors.

Older designs of fridges used a constant burner which ran all the time whether the fridge needed cooling or not. More recent or up market models used a burner with a thermostatically controlled variable gas rate to modulate the flame size according to need. And the latest models use a closed loop electronic control system which turns the gas off or it reignites the gas when cooling is required.

Each iteration of control system is more economical than the previous version.

But another major factor is the external ambient temperature. Manufacturers' should specify the range of external ambient temperatures in which the fridge should operate normally. If the ambient is within the specified range then the fridge should be able to maintain its normal operating temperature. But even so the greater the temperature difference between the ambient and the desired internal temperature the harder the fridge has to work, and it will use more gas to do so. The ability to restrict (in cold weather) or increase air flow (in hot weather) over the condenser coil on the back of the fridge may expand the ambient working temperature range.

How full or empty a fridge should be was discussed recently. It actually makes no difference to the fridges ability to maintain a temperature, but another point has been raised and that is there should be enough space around the produce in the fridge to allow the chilled air to freely circulate within the fridge.

 

[Jcloughie]

Vent covers...

Always thought they are overpriced, available around £33 for mine. But I found this 'special offer'.



They are having a laugh!!

John

 

[otherclive]

Vent covers...

Always thought they are overpriced, available around £33 for mine. But I found this 'special offer'.

View attachment 3266

They are having a laugh!!

John

That’s ridiculous pricing for two plastic mouldings. Hope it doesn’t reignite the CMHC debate re benefits of membership 😂

 

[Dustydog]

All the caravans I have had came with them. One to look out for when buying from a dealer or private.
From what I know anything below 8 degs C the covers should be left in place.

 

[Buckman]

Our pair cost us £22 in 2016 and we were able to transfer them to the new caravan.

 

[Beachball]

We got a pair of vent covers for our caravan at £29 a couple years ago

 

[Gafferbill]

......it is very easy to make a blanking strip that fits behind the existing slatted vent covers.
Mine are made from old vinyl flooring offcuts....cost me nothing.
Important not to block the air flow completely and leave any gas vent clear.
I made mine to cover 75% of the fridge vent.