DAIKIN VRV 111 fault

Hi

just replaced 2 compressors on a REQ16P8 feeding 11 indoor units
run the system in heating and I’m getting liquid flooding back /low (0°C to 1°c) superheat on the suction line, this is coming back from the indoor units (suction line visibly freezing on the suction pipe within the roof space and at the suction service valves of the outdoor unit).
All the pipe work is not easily accessible.
in a couple of the rooms I can hear gas/liquid rushing through the indoor units even though they are switched off.

I have shut the system down as not happy leaving it running & risking the new compressors , I’m assuming the valves are leaking through in the BS boxes, could this be they are just not controlling and need resetting (how can I do this? Do I need to power down the indoor units and outdoor unit as well? or is it a common thing for these to leak by? I did power down the 2 BS boxes and turned them back

Thanks in advance
CB

Liquid floodback should not be a problem as there is a large suction accumulator in the circuit.

In Heating mode, even when indoor units are not 'On' or called for, the EEV passes a small amount of hot gas through the indoor fancoil to prevent liquid (and oil) accumulating - I assume that this is what you are hearing.

Frosting on the Suction line at the indoor fancoil in Heating mode is not right as this should be Hot Gas?

As with all VRV's (VRF's), they are a critical charge system, so if you are having issues with frost etc. where you normally wouldn't see it, I would be making sure that the charge was correct (de-gas and weigh) before checking for other issues (sensor calibration, strainer blockage, faulty vale etc.).

One other thing to look for if it is not a system that you have installed is that the pipework is installed within the maximum allowed lengths. If fancoils are outside of these limits, they tend to collect oil (low suction velocities) which then lead to compressor failures.

To reset the entire system to Factory condition is to press and hold the 'Reset' binary button on the Master outdoor for 20 seconds (IIRC).

I guess those indoor EEV's (they are inside the fan coil not BS box) are faulty.
You can power off/on the indoor unit to reset the valve but commonly on older units the gears wear in the head.
To change them they just unbolt, pretty easy.
General advice when replacing those compressors is to also replace the outdoor temperature probes and the 3 EEV's too.

Thanks Frank
the noise is like a waterfall not just a slight hissing.
when I did the compressors the refrigerant was weighed out and weighed back in to the correct amount.
rather than a hard re-set I just meant a reboot of the system, I know some manufacturers recommend powering back up in a specific order I.e. outdoor then bs boxes then indoors?
is there anyway of when I’m working on this I can block the controllers as people kept changing stuff while I was working, it on a ITM & I’m using a service tool

Hi, yes that makes sense, so is it normally just the head that needs changed or the body as well?
re the outdoor eev’s is that just the heads or the body’s as well?

Just the heads all round. 👍

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