Frost Line method

[aaronh]

Evening all,

Not to sure if this is in the right section but hey will try anyway.
I hear a lot about Frost Line method of charging small refrigeration systems, can someone please explain to me what the hell this is and how it is done, because I have never ever come across this method?:confused:

[Brian_UK]

With reference to your other questions I would stay well clear of this sort of thing.

Concentrate on doing it right before trying the other ways.

[Goober]

Me thinks exam questions are being answered for this young fella.......

[lana]

Hi there,

In a small system with cap tube the amount of refrigerant is critical because cap tube can not do superheat control (like TEV) and therefore, liquid flood back is highly possible if overcharged.
So, if the service tech does not know how to charge the system or if he does not use refrigerant scale then he assumes that when refrigerant flood back occurs then it is overcharged. Now how can he know that there is a flood back : by frosted suction line!!! When he sees the frost at the end of the cycle, he reduces the refrigerant charge so that the frost line goes back to wards the evaporator.
This is common on the domestic refrigeration service techs.
This is not a correct way. If want to charge a system then I suggest you learn the proper way.
Cheers

[Tayters]

In a nutshell, charge system wait until suction line frosts back then let a bit of the charge out until the frost starts to disappear.

As has been noted NOT the correct way but that's how some people do it.

Tried it myself once then weighed out the charge to see what I ended up with.
Unit charge 800g, weighed out charge 850g. Not bad for a beginner I thought.;)

[Tesla]

So if your charging a domestic like I had to once (my own) my boss was a very experienced at it. Charge until you see the frost line when down to temp. Then remove/recover a little until the frost line disappears about two inches into the insulation. Do it a little at a time and observe over a few cycles.

[taz24]

The other way is to stop the evap fan from working .

Charge the system till flood back is evident and then start the evap fan. When the fan is working the frost line will disapear.

One reason why this method is not used is to do with ambient temps.

If you charge the system up by using the frost back method in the winter it will be under charged in the summer. If you use the method in the summer it could be over charged in the winter..


taz

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