Daikin refrigerant charge issue?

[terminator]

Guys,

Had to nip into a site today with just gauges and a spanner!

I have a RP71 (fixed speed scroll) which is intermittently icing the evap and going off on low evap temp. Suction was 45 psig.

This to me says a shortage of refrigerant (R407c).
Firstly, I had no info at the time of the pre charge length of pipe (what it's pre charged to) - base charge is 3.1kg. Secondly, no info on how much to add per m over the pre charge.

My questions are these;

1. Does anyone have the above info?

2. You'd have to see the building to believe it but, the pipework has been built around, hidden etc since installation and you cannot measure it accurately, at best the length would be a guess.

So, going back years ago, when charging an r22 split, we would often just add r22 until the evap frosted, add more until the frost went and the suction was cold and wet. Suction was often around 55-68 psig depending on conditions. Could this system be charged on a similar principle, bearing in mind it's half impossible to trace the pipe route and therefore it's length.??

Many thanks...

[r.bartlett]

are you f-gas registered?

[hyperion]

If the system is short of gas, you will need to reclaim the refrigerant, carry out a high pressure OFN test to locate the leak, then repair the leak, evacuate the system and then charge with the correct calculated amount of new R407C.
If you contact the Daikin helpdesk, they will be able to advise you on the correct base charge and the additional amount required per metre.

[install monkey]

additional charge is usually 30gram per metre