Gas Rattle R410A Daikin Multi 3MXS52EVMA

[ausmartin1]

I have the above with a 2 heads only install.
Upon start of gas flow in Cooling the indoor units (both) operational and non operational exhibit a "quite but noticable" 1 to 2 second "rattle" as if there were small ball bearings in the heads flow curcuit.
Even when both are operational in cooling mode - as the units cycle with temp / gas flow start up rattle occurs in both units.

Both units Cool & Heat very efficiently ~ 27M in total pipe run.

Is this to do with the particular model that the "buzzes" the working AND Non working units EV's on start of the gas flow in cooling mode?

Older R22 Multisplits had Gas flow noise only in the non working units when in heating mode (-Not in cooling).

In comparison to a Single split Daikins R410A units don't exhibit this start up gas flow rattle.
Just normal gas flow noise.

Install was vacuumed and no additional refrigerant charge was added as it is the below the lenght pipe work maximum.
No detectable gas leaks - either bubble or electronic snifer.....Could the unit have been over or under charged from factory? - but the temperature drop -down or up is perfect ie: great.

Just wondering if this is "normal" without annoying Daikin themselves.

[brunstar]

in relation to this refrigerant noise, make sure that you have not cut the flares off the indoor units.
On the indoor units liquid line you will find a little liquid receiver, if this is removed then the you will get some noise.
Keep in mind when using the multi system you should have your largest units at the bottom as these flare connections are usually larger.
What size indoor units do you have?
These units are usually pre charge to 30 meters so make sure you are not over that otherwise it could also be running a bit short of refrigerant..

[ausmartin1]

Hi Brunstar,

Nothing was cut off the x2 indoor units which are both 2.5Kw (FTXS25GVMA)
Definetly under 30M, suspect maybe the outdoor unit it pulsing both units valves, even the non operational one in cooling mode?
Heating mode I understand it has to - run gas to both units even if one is not operationing otherwise the outdoor unit will not switch to heatmode in cases where only 1 indoor unit is connected to this multisplit.

Cheers