Guide on charging Danfoss fridge?

demonboy

demonboy

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I have a Danfoss compressor, a fridge gauge set, a can of 134a and Calder's bible. I sat down with a fridge specialist and learned how to charge the fridge but that was some time ago and my memory is rusty. Annoyingly Calder's guide doesn't really cover Danfoss and he refers to using both the high pressure and low pressure side of the gauge, yet I remember my fridge specialist using only the low pressure side. This is backed up by the very poor instructions that comes with my gauge kit.

I also remember him running the system with the refrigerant supply open in order the attain the right pressure. I have tried the same but can't seem to get it to stay at 70psi. Perhaps I have a leak but the problem is that I don't know how long to keep this open when the system is running, or even when the system is switched off.

This is a convoluted way of asking if anyone has a pdf or link to a guide on charging a Danfoss system with Schraeder fittings using a standard fridge gauge set.

Thanks in advance.
 
Well I'm not sure how much help this will will help as I bought my gear when I was in Yemen, but a friend of mine has just bought the same gear here in India so I'm guessing it's easy to find the refrigerator gauge set.

The gauge set looks something like this:

images


The low-pressure gauge is on the left (blue), the high on the right (red). If you are just charging then you only use the left. NEVER fit to the red side when charging. Purging requires the red side and I have not done this.

To charge a Schraeder, Danfoss only:

1. Turn off the fridge
2. Close all gauges
3. Connect your bottle of 134a to the central, yellow pipe.
4. Connect the blue pipe to the gauge set and the fridge. This is called the suction side (red side is high pressure, purge side). Ensure you have the pipe the right way round, with the valve in the pipe on the Schraeder fitting of the fridge. The pressure of gas from the bottle pushes the valve open, which in turn pushes the pin down on the fridge fitting.
5. Open the bottle of 134a.
6. Open the suction gauge.
7. Allow the gas from the bottle to go in to the fridge and the pressure should equalise somewhere between 60-70 psi.
8. Slowly close the 134a supply.
9. Close the suction gauge.

Your fridge should now be fully charged. However when I did all this I was experimenting and not quite sure what I was doing and so at one point I turned the fridge on with the supply open. I did this because I remember my fridge man in Yemen doing the same. However this is why I wanted a simple guide on the subject because bits like this are unclear. Whether running the fridge with the supply open helped charged the system I am unsure.

Hope this points you in the right direction. If there are any fridge experts out there who can confirm or correct my procedure I'd like to hear from them.
 
Last edited:
demonboy said:
Well I'm not sure how much help this will will help as I bought my gear when I was in Yemen, but a friend of mine has just bought the same gear here in India so I'm guessing it's easy to find the refrigerator gauge set.

The gauge set looks something like this:

images


The low-pressure gauge is on the left (blue), the high on the right (red). If you are just charging then you only use the left. NEVER fit to the red side when charging. Purging requires the red side and I have not done this.

To charge a Schraeder, Danfoss only:

1. Turn off the fridge
2. Close all gauges
3. Connect your bottle of 134a to the central, yellow pipe.
4. Connect the blue pipe to the gauge set and the fridge. This is called the suction side (red side is high pressure, purge side). Ensure you have the pipe the right way round, with the valve in the pipe on the Schraeder fitting of the fridge. The pressure of gas from the bottle pushes the valve open, which in turn pushes the pin down on the fridge fitting.
5. Open the bottle of 134a.
6. Open the suction gauge.
7. Allow the gas from the bottle to go in to the fridge and the pressure should equalise somewhere between 60-70 psi.
8. Slowly close the 134a supply.
9. Close the suction gauge.

Your fridge should now be fully charged. However when I did all this I was experimenting and not quite sure what I was doing and so at one point I turned the fridge on with the supply open. I did this because I remember my fridge man in Yemen doing the same. However this is why I wanted a simple guide on the subject because bits like this are unclear. Whether running the fridge with the supply open helped charged the system I am unsure.

Hope this points you in the right direction. If there are any fridge experts out there who can confirm or correct my procedure I'd like to hear from them.
Click to expand...

--------------------------------

Guages here.

http://www.ryanairconspares.com/refco-m-10.html

Trust theirs no connection with the other mob!
 
Hi I will compile a quick guide to filling Danfoss refrigeration systems shortly as if you use this method it does not guarantee a completely full system. I usually start with the gas pressure equalised as you have described however they usually require more refrigerant than this in the system and you may find that the fridge still is not 100% efficient although it will probably run ok. A well charged system should have all of the cooling plate freezing and a bit of the return pipe towards the compressor sweating. This is when the fridge temperature is close to the required temperature but the compressor is still running. If the plate has an area that is not totally freezing then you may need to allow some more gas in ( with the bottle upright if it is a bottle with no dip tube inside). simply open the valve while the compressor is running and the gas will be sucked in by the compressor. do this in short busts of say 5 seconds then allow a minute or 2 for the system to stabilise. If you put in too much you will find that the suction pipe to the compressor will freeze up in this case it will be necessary to remove this refrigerant. I will add a disclaimer that you should hold a refrigerant handling qualification to carry out this work and recommend that if you are unsure how to charge a system you should contact a professional. Refrigerant removal should be done with a reclaim unit as gasses cannot be discharged to atmosphere. I can't tell you how many times I have attended systems that have been so overfilled that I could not believe it was possible to hold that much refrigerant. As a general rule refrigeration systems do not lose gas unless there is a leak so topping up is probably not the solution without repairing the leak first.
 
Thanks, Owen. A simple guide (bullet point like mine) would be really useful. As it was I did as you say, adding a bit at a time in short bursts. More out of fear than knowing what I was doing, mind!

Please keep us posted with the guide.
 
Apologies. It was the correct fitting.
I just hadn't realised you had to remove the Schrader valve on the existing fitting.
It does mean that you can't top up as such. You have to release the pressure in the existing set up and refill.
 
Talulah said:
Apologies. It was the correct fitting.
I just hadn't realised you had to remove the Schrader valve on the existing fitting.
It does mean that you can't top up as such. You have to release the pressure in the existing set up and refill.
Click to expand...

Sorry about that I have not actually used one of those fittings I have always used standard refrigeration gauges as I have them already. I would recommend that if you are removing the schaeder valve and refilling you should really vac out the system with a vac pump but if it runs ok down to the temperature of cutting off on the thermostat you have probably got away with it. If you have any problems you can give me a call I have a vac pump you could borrow if needed as I see you are local.
 
Many thanks.
You'll have to explain the use of the vac pump in the guide. I think there will be a lot of forumites who are looking forward to reading it.

I presume the vac pump is to help get the coolant into the system.
 
Here is the long awaited link for the recharging instructions. I have kept these very basic for emergency recharging but will also work on a more in depth document for those with all the correct tools. I do not cover the use of a vacuum pump and so this is not suitable for a completely empty system or a system with moisture in the refrigerant circuit. If anyone is unsure please contact me via PM.

http://coxengineering.co.uk/Documents/Recharging%20a%20simple%20R134a.pdf
 
owen-cox said:
Sorry about that I have not actually used one of those fittings I have always used standard refrigeration gauges as I have them already. I would recommend that if you are removing the schaeder valve and refilling you should really vac out the system with a vac pump but if it runs ok down to the temperature of cutting off on the thermostat you have probably got away with it. If you have any problems you can give me a call I have a vac pump you could borrow if needed as I see you are local.
Click to expand...

I purchased same fitting and am having same problem in that it doesn't reach the thread. I would prefer not to take off the whole fitting and have to vac out the system. Unfortunately no fridge engineers around where I am. I wonder is there another fitting that would do the trick?

By the way - thanks a million for the guide!
 
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