Help trying to find air flow rate from my ac in the roof. Daiken FDYP125DLV1

[Apples]

Help trying to find air flow rate from my ac in the roof. Daiken FDYP125DLV1

Its a Daikin super inverter ducted outdoor unit is RZP125DV1

I did find similar but not exact number matches.



I need to know my air flow so I can then work out how many CFM it moves so I can re route and fix up the flex ducting.

Possibly this number is the package deal ie outdoor and indoor, FDYP125DL

This is an Australian model too by the way.

[frank]

From the data sheet it rated at 840 litres/sec

http://www.daikin.com.au/home-solutions/ducted-air-conditioning

[Apples]

That is not the exact model number that I have though.....

[frank]

The model numbers only differ by Country.

Your unit is a size 125, so the airflow will be the same.

[Apples]

ok thanks frank

[Apples]

How do I know if my air handler is able to blow out at 840l/sec.

I have the middle flex 400mm/16" and the one on the right that goes to the tee fitting where the smaller duct comes off. After that it is just a on/off damper.

When I just have the main room going ie for hot hot days, I don't know if the way it is set up will allow full airflow out of the 4 supply registers. I mean we have 2x 400mm coming in from return air, but on the supply air side I have the one 400mm then the other one that is chocked down to a 250mm outlet.

So then add in the twists and bends of the flex duct. I don't think the AC will work as best as possible like this?

See the picture.

[install monkey]

flexi ducting isnt as efficient as spiral (rigid duct)
you want to fit volume control dampers to the 2 other ducts to increase airflow to the main occuipied room
anemometer will give you airflow in m/sec
then do something with the diameter of the duct-not my field ;)

[frank]

As the Monkey said you need a measuring device called an Anemometer.
The basic hand held device will give you a reading of the Velocity of the air (speed) in m/s or fpm.
Once you have the velocity reading you multiply this figure by the area of the duct to give you a volume flow.
The formula is Volume = Area x Velocity

[Apples]

But what I am thinking is that if I know what my l/sec is, 840.

Then I guess I need to supply 840l/s to the main area of the house. How then do I calculate how many 250mm/10" flex ducts I need to supply that much air.

Obviously as I have 2 x 400mm return flex ducts, I could have 2 x 400mm supply ducts and then I would be right.

But as the system sits now I have 400m down to 350 down to 300 down to 250mm etc.

I need to find a friction chart for my flex ducts, but I do not know what brand ducting I have. I think it is similar to the Westaflex vflaex ducting. But I can't seem to find a air friction duct sizing chart for them.

So, I wonder with my current setup if the machine is actually passing through enough air, and that the bends in the ducts and fittings etc are not bottle necking the system.

[frank]

Doing pressure drop calculations is normally carried out during the design stage, but to do them after the system is installed you will still need to know your volume/velocity flow in each duct and for this, you will need some form of measuring device.
The Daikin ducted fan coil will have a fan curve chart that you can plot your actual readings against to find out if it is working within it's design envelope, and this is in the Service Manual, but without actual readings you won't be able to do this.

[Apples]

Doing pressure drop calculations is normally carried out during the design stage, but to do them after the system is installed you will still need to know your volume/velocity flow in each duct and for this, you will need some form of measuring device.
The Daikin ducted fan coil will have a fan curve chart that you can plot your actual readings against to find out if it is working within it's design envelope, and this is in the Service Manual, but without actual readings you won't be able to do this.


Ok, so I need to get an anemometer then?

[frank]

I guess so.
I don't know of any other way, but I'm up for learning

[Brian_UK]

You try and build your own ;)

.
https://diy.org/skills/windengineer/challenges/165/build-an-anemometer