FAQ's

How much extra refrigerant do I need for a given pipe run?

Additional R407C per metre

Expansion Line size grammes 3/8" 16 1/2" 30 5/8" 48 Example 1: System charged for 7.5m. Pipe run = 35m, which requires a 1/2" expansion line. 35 - 7.5 x 30 = 140g

Example 2: System requires 250g for 7.5m. Pipe run = 65m, which requires a 5/8" expansion line. 65 - 7.5 x 48 + 250 = 3010g

Click here for Table of Extra Refrigerant Charge.

What are the pipe connection sizes for my outdoor unit?

Please see downloadable file 'Pipe connection sizes for outdoor units' for detailed answer.

What is the correct restrictor for a given system?

Please see downloadable file Restrictors' for detailed answer.

What is the maximum pipe run available for my condensing unit?

Please see downloadable file 'Maximum pipe runs for condensing units' for detailed answer.

What is the maximum pipe run for my heat pump?

Please see downloadable file 'Maximum pipe runs for heat pumps' for detailed answer.

What is the correct cooling only pipe size for a given pipe run?

Please see downloadable file 'Cooling only pipe sizes' for detailed answer.

What are the electrical details of my outdoor unit?

Please see downloadable file 'Electrical details for outdoor units' for detailed answer.

What is the correct oil to use in my system?

Refrigerant R22 is compatible with both mineral and Ester (Polyolester) oil.

Refrigerant R407C on the other hand can only used in conjunction with Polyolester oil.

If you have a new system and you simply need to add oil (for a pipe run over 25 metres), the polyolester oil should be used regardless as to whether the refrigerant is R22 or R407C.

If you need to replace a compressor or replenish lost oil in an older system there are several possibilities, depending on the original equipment:

  • A reciprocating compressor using R22: Mineral oil must be used/contained in the replacement compressor.

  • A reciprocating compressor using R407C: Polyolester oil must be used/contained in the replacement compressor.

  • A rotary compressor using R22: Mineral oil must be used/contained in the replacement compressor.

  • A scroll compressor using either R22 or R407C: Polyolester oil must be used/contained in the replacement compressor.

Your refrigeration components supplier will be able to advise you of the relevant brands that they have available.

NOTE: Polyolester oil is Hygroscopic, precautions must be taken to prevent ingress of moisture. Always ensure the oil container is kept tightly sealed when not in use and left open to the atmosphere for the shortest possible time during the procedure of adding oil to the system. Always keep pipework sealed prior to making final connections and evacuate the system without delay.

Installation of the Filter Drier should not be necessary if evacuation is carried out correctly and there are no leaks in the system. If the Filter Drier is considered necessary, it MUST be installed between the service valve and the expansion device.

I have a fault code on the unit LED's (L units). What does it mean?

Please see downloadable file 'Fault codes for L units' for detailed answer.

My outdoor unit starts, then stops almost immediately yet the cooling signal is still present. What is the problem?

Check resistors R25 and R258 on the outdoor PCB.

These should be smaller in physical size than resistors R26, R27, R28, R268, R278 and R288. The body of resistors R25 and R258 should be beige in colour with bands of: Blue, Grey and Orange on one resistor and Yellow, Violet and Orange on the other. It is of no consequence which of these resistors is installed as R25 and which as R258.

Click here for Diagram of Resistors.

What are the pipe connection sizes on my outdoor unit?

See download file 'Outdoor Unit Pipe Connection Sizes' for detailed answer.

What is the correct heat pump pipe size for a given run?

Please see downloadable file 'Heat pump pipe sizes' for detailed answer.

What is the factory refrigerant charge in a given unit?

Please see downloadable file 'Factory refrigerant charges' for detailed answer.

What is the new equivalent for a given obsolete unit? I have a 'Marstair' unit but I don't know what model it is. Can you identify it?

Please see downloadable file 'New equivalents for obsolete units' for detailed answer.

What are the connections for a networked system?

Please see downloadable file 'Networked system connections' for detailed answer.

I have a fault code on the unit LED's (E units). What does it mean?

Please see downloadable file 'Fault codes for E units' for detailed answer.

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