Insulation question

[IanS]

The split system in the house I have just purchased is now working (see previous post, low gas)

However I have noticed that both refrigerant pipes are enclosed in the same insulation as they run from the outside unit to the inside.

Now I am not a refrigeration engineer but my basic physics says that this is wrong and they should be in separate insulation so there is no heat transfer between the two pipes. Heat transfer between the pipes is pure wasted energy.

Will someone who knows about these things please confirm or explain why not.

Thanks

[nike123]

Both pipes are part of evaporator/condenser and their Delta T is not high. In short distances they could be together (they are together in their factory insulation about 0,5long), but better is to separately isolate them after that.
In my earlier days, I have few installations where they are together for 5m and more without any problem to operation of unit.
How much of lost capacity is that, I really don't know.

[IanS]

Thanks Nike123.

You have made me realise that I was misunderstanding the functionality and was incorrectly thinking that the delta T was what gives the Heating/Cooling effect. Of course it is the pressure change which occurs in the room unit that does this.

Doh!

[nike123]

Thanks Nike123.

You have made me realise that I was misunderstanding the functionality and was incorrectly thinking that the delta T was what gives the Heating/Cooling effect. Of course it is the pressure change which occurs in the room unit that does this.

Doh!

In indoor unit, there is no pressure change. Pressure change is in outdoor unit where capillary has placed.
Then (in cooling mode)low pressure saturated liquid refrigerant ( goes in smaller pipe) mixed with some evaporated gas go to indoor unit where all liquid refrigerant evaporates and we have superheated low pressure gas (which now returns in bigger pipe). That evaporation (change of state) of refrigerant is what gives cooling efect. Mater needs heat to change state. That heat comes from air which goes thru indoor unit.
In heating mode there is also no pressure change in indoor unit.
Superheated high pressure refrigerant from compressor comes to indoor unit in biger pipe where heat from refrigerant is transfered to air, and then refrigerant change state from gas to liquid. Now we have subcooled high pressure liquid which returns thru smaller pipe.

[chemi-cool]

It is wrong to put them together.

Although there is no change of pressure, there is a big change in temperature, it will work fine but if the pipes are insulated separately, it will work better.