Don't understand our new Daikin ducted Reverse-cycle system ... please help!

Hi Guys, I hope you can us help trying to understand whats going on with our new heating/cooling system. We've just had a Daikin ducted reverse-cycle system installed (RZYQ8/FDYQ200 : 20KW cool, 22.4 KW heat) into our single storey 160m2 house. With the weather being a bit cool here in Canberra (!) this w/e, we've had a chance to test the heating side of the system.. and Im not impressed. Two major problems that Im having trouble understanding.

Firstly the air flow out of the vents seems to be extremely strong and produce a loud and constant white noise sound which is driving me crazy! It does dim slightly when, presumably, it reaches the required temperature but it doesn't stay there long. The outside temp is about 13degs and the heat temp is set at 22degs - so not a huge difference. Also, at the same time the outdoor unit seems to be running at full whack - causing a noise the is noticeable through double-brick walls.

Is there some fundamental thing Im missing here about these systems, or is there some way I can change these easily. We used to have an old ducted gas system in outs place, and even with that we never had this level of continuous and heavy air flow, I would phone the company that installed it ...but its a w/e! Really hope you can help here guys...!

Unfortunately what you are describing is installation specific issues so the only people likely to be able to help are the installers, or at least someone who are on site and can touch/feel/experience your system.

However,
The outdoor unit will run it's fans at "full whack" when it is in heating mode.
If it is too noisy maybe some anti vibration mounts are missing or it needs attenuation?

The noise from the indoor vents is likely to be proportional to the velocity of the air going through them.
What fan speed is the system set at and can you lower it?

:cool:

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Many thanks Viking for the quick response. Excellent.

Yes I know what you mean about someone being here and I do intend to get the installer here asap. However before that i was hopeing to get some idea as so what might be thought of as normal operation with these systems so i am at least armed with some knowledge before i speak to him.

The fan speed is set at its lowest on the control panel, but it still seems to be shifting a huge amount of air - particularly when compared to our old gas ducted system - and its pretty much continuous. At least our old gas system would turn off completely for long periods. We've even had to turn the TV up in inorder to hear it over the noise! I understand that it is good to have the power of a system scaled so that it can comfortably do its job without having to work too hard, but i am worried that we might have one here that is well over the required spec for our (4bed 10ducts) house?

However,
The outdoor unit will run it's fans at "full whack" when it is in heating mode.
If it is too noisy maybe some anti vibration mounts are missing or it needs attenuation?
Ok, understood .. at least then i can assume that it wont get any louder once we get some proper cold weather here in Canberra? Do you know what kind of attenuation you might be thinking of ... eg. acoustic, mechanical?

Generally,
Vents get noisy when too much air is pushed through them...
20kW serving 160m2 gives 125 W/m2 so that looks about right, this leaves the question if there are enough vents of the right size.

For the outdoor unit it really depend on the installation.
Is it standing on the ground? If so it might need rubber feet on concrete slabs and some sort of noise enclosure.
Is it hanging on the wall? If so it might need different brackets.
Or it might be an imbalance of a fan that needs sorting.

:cool:

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Thanks again Viking - Ok thats good that the power looks about right and yes that makes sense - if we have more vents then the rate of air will be spread out and the noise through each should be less. Good, ill think about that. thank you.

The outdoor unit is on rubber pads sitting on a concrete path. When running, the centre of the fan rotates about its axis in a radius of about 5mm - I assume thats within spec but I'll ask them. If we do need one in the end, do you know what kind of enclosures are available commercially, or might there be some way i can do something myself reasonably easily?
Cheers.

The 200 unit is a big unit so will shift a lot of air. It would have been better (and dearer) to go with 2 100's

I would consider the night setting which will lower the noise

Does the fan go even faster when set to higher speeds? mybe its just stuck on highest setting.

If the unit is just sitting on your ceiling and not hung from the roof this could increase noise to.

the indoor fan will speed up as the coil temp rises. Is the return air ducted on to the unit

Quote:

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Originally Posted by r.bartlett

The 200 unit is a big unit so will shift a lot of air. It would have been better (and dearer) to go with 2 100's

I would consider the night setting which will lower the noise

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Yes thanks, I have seen references to quiet mode/ night setting on the net but I assume that has to be done by the installer, since there doesnt seem to any way of accessing that vis my controller?

If ducts in house are sized for heating with hot air from furnace, than it is possible that existing ducts and vents are not matched (too small of size) for that unit because it need to move much more air to make same heating performance with lower temperature of air which AC coil is capable. But, if old duct is sized correctly, than you probably have high pressure duct unit in place of normal pressure duct unit.

So, first what should be done, is to establish if ducts and duct unit are matched.

Give us full model name of indoor and outdoor unit.

Quote:

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Originally Posted by Simeonx1

Does the fan go even faster when set to higher speeds? mybe its just stuck on highest setting.

If the unit is just sitting on your ceiling and not hung from the roof this could increase noise to.

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yes, thanks, I have just two fan speeds i can control and it definitively gets louder when i put it to the higher fan speed. Yes, understood, since it is sitting on my ceiling it would be noisier.

Quote:

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Originally Posted by nike123

If ducts in house are sized for heating with hot air from furnace, than it is possible that existing ducts and vents are not matched (too small of size) for that unit because it need to move much more air to make same heating performance with lower temperature of air which AC coil is capable. But, if old duct is sized correctly, than you probably have high pressure duct unit in place of normal pressure duct unit.

So, first what should be done, is to establish if ducts and duct unit are matched.

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Many thanks nike123, all the ducting and vents were newly installed with the system. However these new ones just replaced the 10 vent positions of the old gas system and are actually only slightly larger. Maybe we do just need more vents for this systems power?

not looking good:

We fitted a 250 system into an office and I was shocked at how loud the indoor unit was/is

http://www.productreview.com.au/p/daikin-fdyq200m.html

Quote:

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Originally Posted by nike123

If ducts in house are sized for heating with hot air from furnace, than it is possible that existing ducts and vents are not matched (too small of size) for that unit because it need to move much more air to make same heating performance with lower temperature of air which AC coil is capable. But, if old duct is sized correctly, than you probably have high pressure duct unit in place of normal pressure duct unit.

So, first what should be done, is to establish if ducts and duct unit are matched.

Give us full model name of indoor and outdoor unit.

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Thanks nike123, the indoor and outdoor unit no.s are FDYQ200PV1 & RZYQ8PY19 which fee 10x 200mm(8") square ceiling vents.

Sorry i meant "...which feed ten ceiling vents, each of which are 200mm(8") square."

Quote:

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Originally Posted by r.bartlett

not looking good:

We fitted a 250 system into an office and I was shocked at how loud the indoor unit was/is

http://www.productreview.com.au/p/daikin-fdyq200m.html

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Oops yep, doesnt look good! ...although ours is the FDYQ200PV1(indoor) & RZYQ8PY19(outdoor) so might be an improvement/later model ? (heres hopeing!)

OK.
IMHO, the indoor unit's fixing and noise levels doesn't come in to it.
The only complaint from the indoor side that I read about so far is the noise of the air exiting the grilles...

So,
0.2x0.2x10=0.4 having not seen the grilles I assume a free area of 80%. 0.4x0.8=0.32 m2 free area.
Your unit is rated 1200l/s or 1.2m3/s
1.2/0.32=3.75 m/s
Below is the velocity/noise chart for double deflection grilles from my "normal" supplier, the actual levels will vary from manufacturer to manufacturer as well as between grilles but I would say that 3.75 m/s is far too high in a domestic situation.

http://www.vikingphotography.co.uk/sound.jpg

So sorry, without attending site I'm afraid this is as close as finding the root of the problem as I can get.

When it comes to the outdoor unit, it is floor standing and blowing the air upwards?
If this is the case you might find that 4 wooden, fence type, walls slightly taller than the a/c unit and with an air gap at the bottom, placed 1/2 meter away from the unit will get rid of most of the noise from it.
But again, it needs site attendance to find the best solution.

:cool:

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BTW,

Out of interest, what did the installer say?

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Quote:

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Originally Posted by The Viking

OK.
IMHO, the indoor unit's fixing and noise levels doesn't come in to it.
The only complaint from the indoor side that I read about so far is the noise of the air exiting the grilles...

So,
0.2x0.2x10=0.4 having not seen the grilles I assume a free area of 80%. 0.4x0.8=0.32 m2 free area.
Your unit is rated 1200l/s or 1.2m3/s
1.2/0.32=3.75 m/s
Below is the velocity/noise chart for double deflection grilles from my "normal" supplier, the actual levels will vary from manufacturer to manufacturer as well as between grilles but I would say that 3.75 m/s is far too high in a domestic situation.

http://www.vikingphotography.co.uk/sound.jpg

So sorry, without attending site I'm afraid this is as close as finding the root of the problem as I can get.


When it comes to the outdoor unit, it is floor standing and blowing the air upwards?
If this is the case you might find that 4 wooden, fence type, walls slightly taller than the a/c unit and with an air gap at the bottom, placed 1/2 meter away from the unit will get rid of most of the noise from it.
But again, it needs site attendance to find the best solution.


:cool:

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Thats excellent Viking, very well explained. Much appreciated.

Ok so for example if we double the number of vents then the free area should be doubled and so the air speed should come down to around 1.9m/s. Therefore from your table (i like it!), the noise level should be reduced from around 38 to around 26 (dBs?) .... this perhaps might be a bit more reasonable for domestic use? The indoor unit is actually a bit loud also but it is at the end of a hallway so not such an issue as long as we dont have it on overnight (probably never) . However maybe in the in end we'll think about going with a combination of 'quiet mode' and extra vents ..... ?

I actually do like the idea of more vents so as to allow the incoming air to be spread around the house more efficiently.

For the outdoor unit this is just what I was after, thank you very much. Yes it is floor standing and it does blow upwards. I'll get onto this asap. ... do you think a 100mm air gap at the bottom would be about right?

I've got the installers coming over on Friday so I'll let you know how it goes.

Many thanks again Viking.

if its a brc hard wired controller then you can change the static duct pressure to low- in 13- 6 -from 01 to 03 in setting mode 41

In principle you are right, double the grilles=double the area=half the speed=reduced noise levels.

However, grille selection and vent design is an art all of it's own. And it is not just the grilles that needs altering, there are also the ducts feeding them.
Your best option is to get hold of the grille selection criteria for the grilles you got and get someone to redesign the system based on that data.

Too high velocity creates noise and drafts but too low velocity reduces the throw and might also create draft.

My suspicion is that you want to keep the velocity going through the grilles below 1.5m/s but that is just a guess.

:cool:

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Thats great Viking, many thanks for all your help .....

Thanks very much IM, I'll get them to have a look at that also ... excellent.