Daikin Coils

[chrisboy27]

Hi All,

We have been having some issues with RZQS125C7V1B condensers coils leaking on the passes. We have had three become faulty now. All have been changed under warranty. Daikin decided to look into this and sent out an engineer to investigate. I have attached his findings which I find very strange, they look to me like a cover up for the defect in there coil designs.

Daikin report

We attended site to investigate and check why the condenser coil has failed within 6 Months.
We arrived on site and checked the indoor unit. The indoor unit’s application is to maintain a comms room temperature of 19c and prevent the equipment from overheating. The room is small, measuring 4.5m by 3m. There is little IT equipment installed as shown in the photos below.
We monitored the temperature and the room was at set point. The unit would start and drop the coil temperature down to zero degrees Celsius for about 3 minutes then shut down. The unit would then stay off for a further 3 minutes and restart, and constantly repeats the same cycle.
The issue of the coil failing is due to the insufficient heat load in the room, causing the unit to short cycle. The constant short expansion and contraction of the coil outside in such a short space of time has led to the failure.
The outdoor and indoor capacity is too great for the load of the room and the potential for failure will remain unless addressed. We recommend reducing the size of unit as it is too large for the room and its heat load. If this is not addressed, then no warranty will be given to this system as future failures will occur due to the miss application of the system.


My questions are:

Has anyone heard of this before?

How long would you think a system should run for to make sure it does not cause damage?

Daikins case above therefor means every coil I have changed in the last couple of years is due to the system being oversized?

I know the system is about 1.5kw over sized due to the area being a server room and we want to allow for increased heat loadings.

Any advice would be great as our customer also had a copy of this report and is asking tough questions.

Cheers

[al]

Get a second opinion for a start, it sounds plausable and a load of **** at the same time. i've had commercial condensing units banging in and out repeatedly without the condenser failing. Doesn't their software stop a unit short cycling? Are we now not to use splits in comms rooms...certainly not Daikin by the sound of it.

alec

[monkey spanners]

I have a commercial cooling system i look after, its over thirty years old and they cycle the condenser fans to maintain head pressure, at certain air and product temps the fans can be on and off every few minutes, not as extreme as stoping the whole system but never the less there must be continual expansion ans contraction.

Sounds like the daikin equipment has been value engineered till it is only reliable when applied in optimum conditions.

Surely a system sized to cope with the hotest day of the year will spend some time of the year loaded to a similar degree as your server room system? Are they just not up to the job?

[Mick13]

out of curiousity, are the leaks at the start of the coil, where the superheated discharge gas is entering the coil? or are they leaking further along in the coil where the refrigerant is at condensing temperature?

[tristanspence]

over the last 2/3 years i have replace approximately 20 condenser coils on split systems, 18 of them were Daikin.....the larger double fan condensers appear to vibrate and leak on the ends where the pipes go in. also have changed coils on single fan units that the bottom pipe of the coil has failed half way along, i think this is due to ice build up in heating mode starts to crush the pipe. i know im not the only one that has had these sorts of problems with daikin, but they normally last 2-5 few years.

try ringing your daikin sales rep to price for a "new coms room" with the same size/heat load etc, say you want to over size it slightly blah blah see if they will sell you the same unit and say its suitable for your needs.

[frank]

Unless I could see the calculations made by the Daikin 'Engineers' to substantiate their claims that the equipment is oversized, I would not accept the statement.

Also, I would consider that the equipment should be sized on sensible cooling for a comms room, so may not be oversized at all.

An outdoor coil will be designed and built to cope with constant expansion and contraction, so the claim that it has done this too much in a short time is another misnomer. It's what it is built for. Can the manufacturer, i.e. Daikin Belgium, confirm that their outdoor coils can only expand and contract in a longer time scale?

Never heard or read such a load of un-technical tosh. Smells like a load of Bull Poo to me.

[DTLarca]

The larger Daikin RZQ outdoor units are notorious for their leaky coil return bends.

[yinmorrison]

It seems to me that if they are saying the unit is cycling every 3 mins why have they not looked at this further. Does it cycle every 3 mins 24/7 ? The system is inverter driven so it takes up to 2 mins to get to full speed assuming it even gets there so it is only possibly running for 1 min at full load , also it can go down to about 6Kw at min speed so is load less than this? A very wooly synopsis if you ask me. Maybe VRV111 can help.Maybe they could not see the wood for the tree's or as has been suggested looking for a get out clause.

[bigspee]

I have had a few units doing the same thing all daikin, (with enough load in the room also comms rooms) . But it was cooling for a few mins then the compressor would stop, then the condenser fan would stop for a few mins then start up again 24.7 but wasn't maintaining the set point temp. after a bit of head scratching it turned out the one example was about 0.5kg s.o.g. And then the unit would chug along nicely just for one example

[frank]

I think this one might be leaky as well :D

We fitted this in 2008. The green is leak dye. Before we added the dye, the leak was so small that we could not locate it. 3 weeks on, it seems like the leak is a little bigger!

http://i116.photobucket.com/albums/o38/frankyboy_01/20130429_170753.jpg

[Rob White]

.

No need for the UV lamp then :D

Rob

.

[still learning]

ive changed at least three.
only one under warrenty, all dakin.
sadly these units now almost collapse when removing the side , they are now flimsy , imho.
when checking any dakin twin fan of any age ,i always run a hand underneath to feel for the oil.
also there is a setting through the remote control for comms rooms , ive forgotten it but a better bloke than me will know this .
comms room can be very dry( low humidity)

[install monkey]

http://www.mediafire.com/view/?byj8q4dc4fdu3rz

[leegally1983]

in not uncertain terms its bull s**t we have had about 20 odd coils fail, even the ones we replaced are now going as well. Daikin are trying to avoid admitting to a fault to protect themselves but they leak in the same place every time and your not telling me every person on here is oversizing the comms room?? what makes me laugh is they say we going send out a daikin engineer and they are just subbies we had a visit from a engineer from Belgium and he told me there has been thousands returned so there is a obv fault with the design. needless to say we no longer install Daikin, Mitsi all the way from now on

[hyperion]

We have had similar problems with the double fan unit condenser coils. When we queried this with Daikin spares, we were asked the serial number of the condensing unit and then advised that there had been a recorded problem and that all units within a certain serial number range had been earmarked for the potential full 5 year warranty, and the coil would be replaced under warranty if requested. Whilst some of these applications were in comms rooms, not all of them were.