Daikin multi split controls

[Houseman]

I have recently purchased a model 4MXS32GVJU outdoor unit and 2 CTX509GVJU and 1 FTXS15DVJU indoor units. I am very happy with the operation as a whole,however I am less than happy with the controls. Is there a way to operate one indoor unit on "heat" and another unit on "fan" or "dry"? It would seem to me that this makes sense and on A/C I am able to run a fan on one unit and A/C on another.Also,on A/C,the fan runs continuously,as I would like it to do on heat,rather that start and stop with the heat cycle. I have contacted my installer and he tells me that there is no way to do this. When I try to do this the louvers on the unit on heat or dry open but nothing happens.
Any thoughts please?

[airefresco]

The units don´t operate the fan all the time during heating to stop cold drafts and keep the coil temperature up. Every heat pump does this (or should) and it is a good thing.

You can´t have one unit on heat and one on dry because dry is basically cooling with a really slow fan (it´s a bit more complicated then that) and it is not possible for the system to heat and cool at the same time.

Not sure about the fan only thing, never tried to do that. I would think that it should be possible, I can´t see a reason why not.

[Houseman]

Thanks airefresco, what you say makes perfect sense, I didn't realize that dry was just kind of a slow cool,and it makes sense concerning the fan on continuously with the heat as well.
I appreciate your thought,thanks again.

[Slim R410a]

I have a 2MXS50G at my parents house and I'm 99% sure you can't have 1 fan coil on heat and the other on fan only as the hot gas still gets pumped around both indoors although the other indoor is switched off.

[back2space]

I have a 2MXS50G at my parents house and I'm 99% sure you can't have 1 fan coil on heat and the other on fan only as the hot gas still gets pumped around both indoors although the other indoor is switched off.

Yes & if fan continues to run on one unit that is at thermostat off it will remove heat from the system affecting the other unit that is still at thermostat on meaning reduced output.

[wozza]

I have a 2MXS50G at my parents house and I'm 99% sure you can't have 1 fan coil on heat and the other on fan only as the hot gas still gets pumped around both indoors although the other indoor is switched off.
You should be able to run one in heat and the other on fan only as you have seperate eev,s for each circuit.

[AndyHX]

It isnt possible to have fan mode on when another indoor is in heating, these units have common discharge header on outdoor before tee of to indoors .

[back2space]

It isnt possible to have fan mode on when another indoor is in heating, these units have common discharge header on outdoor before tee of to indoors .

My multisplit I can run fan modes on units that I dont want to run in heating but I get warm air blowing off if the outdoor unit is running.

[BradC]

It isnt possible to have fan mode on when another indoor is in heating, these units have common discharge header on outdoor before tee of to indoors .

Well the one I pulled apart today has individual EEV's for each head, so it is absolutely possible for it to run one head in fan only mode while another is heating or cooling. Whether the software is clever enough is another story, but the hardware is certainly capable.

[back2space]

Well the one I pulled apart today has individual EEV's for each head, so it is absolutely possible for it to run one head in fan only mode while another is heating or cooling. Whether the software is clever enough is another story, but the hardware is certainly capable.

As I state even with separate EEVS in heating mode units that are at thermo off or turned off will have a small ammount of refrigerant circulating to allow for oil return so to have one unit in fan mode you will get warm air blowing off if one other unit is at thermo on.

[wozza]

I am 100% positive that in cooling mode you can have one in fan only and the other in cool.
The fan only will not cool as the eev will shut down,
In heat mode what stops the unit from heating on thermo off if the compressor is still running for another circuit? The eev shuts down to stop the refigerant going though the coil otherwise you would never stop heating or cooling.

[back2space]

I am 100% positive that in cooling mode you can have one in fan only and the other in cool.
The fan only will not cool as the eev will shut down,
In heat mode what stops the unit from heating on thermo off if the compressor is still running for another circuit? The eev shuts down to stop the refigerant going though the coil otherwise you would never stop heating or cooling.

Thats correct in cooling the EEV shuts down completly so you can have units in fan mode or cooling mode but in heating any units that are thermo off or turned off will have the EEVs open approx 10% to assist with oil return back to the compressor.

So yes you are correct in cooling mode but in heating mode small ammount of refrigerant continues to circulate all units. Its upto the control logic to ensure that the fan does not run so as heating doesnt continue.

On my crappy LG system the fan cycles on and off periodically on the floor mounted units to clear build up of heat from the coil however due to poor control strategy the fan stays on too long and the room over heats!

My wall mounted units dont run the fan at all at thermo off even though the coil will still be warm due to circulating refrigerant.

[wozza]

Same logic as vrv then, as the eev,s stay open 10% in heatnig

[Houseman]

I've been away for a bit and not able to keep up with the forum. There is a wealth of information here, Thanks to all who responded. :)