Daikin chiller on the blink

[Frank Wubbolts]

We use Daikin chillers (EUWAP20KAZW) in our CO2 extraction systems.

We have a project in Pakistan, in quite a remote area.

There was not enough glycol in the first filling and the evaporator froze up a couple of times during installation and commissioning. No problem it seemed, in Pakistan it can get 45 C and all starts moving again after some 10 minutes. Drained it partially, added pure glycol, problem gone.

After 40 hours of flawless running FL error appeared. Circulation pump appears to work OK as seen from small changes in pressure during startup. Changed flowswitch, now also HI error appears, flashing atternating with FL. Ambient temperature about 25 C, so it is not really hot.

What could be wrong? I've read the manual and consulted Daikin. Can freezing of the coolant damage the evaporator / plate heat exchanger in such a way that first it runs fine and later stops ?

Please help me out, when I go to Pakistan to fix it I want to make sure that it works. Thanks a million !

[nike123]

Check that you done air purge properly and that is no air in circulation. Also check wiring diagram and manual if some other protection is not in series with flow switch. Also check that system brine pressure is high enough to avoid cavitation caused by pump suction action.
HI error is in connection with FL.

[Frank Wubbolts]

Thanks. Will check for air in circulation. Engineers on-site in Pakistan are really *nice* guys but not confident / experienced enough to open it up and start digging. Daikin rep. left Pakistan 25 years ago.

I was thinking that instead of FL we now get HI or some reason. When HI appears it shuts down and FL appears as well because of the shhutdown. It could be something as silly as loose NTC connector which gives HI and then ...

Do you think that freezing of teh brine could damage the evaporator to such an extent that it causses this kind of errors ?

[nike123]

Ignore, double post!

[nike123]

Thanks. Will check for air in circulation. Engineers on-site in Pakistan are really *nice* guys but not confident / experienced enough to open it up and start digging. Daikin rep. left Pakistan 25 years ago.

I was thinking that instead of FL we now get HI or some reason. When HI appears it shuts down and FL appears as well because of the shhutdown. It could be something as silly as loose NTC connector which gives HI and then ...

Do you think that freezing of teh brine could damage the evaporator to such an extent that it causses this kind of errors ?

If plates in evaporator are curved toward gas compartment, because of expansion of freezing brine, you could have lower flow of gases in evaporator and lower than normal suction pressure.
Hi pressure error is usually in connection with low air flow at condenser or air is circulating back from fan exhaust (short circuiting).

40 hours of flawless work could indicate that is noting wrong with that evaporator.

[frank]

The FL error message relates to a Flow problem.

Without the glycol in the system, the density of your cooling fluid was matched to the pump performance.

When you added glycol, you have increased the fluid density, thereby making the pump work harder to ensure circulation. The pump is now circulating slightly less fluid due to the increased density and greater total system resistance.

The flow switch now needs to be trimmed to reflect the lower circulating volume, or the pump needs to be upgraded if the flow rate is below the required amount for the chiller. This can be logged on the pump performance graph, but I would hazard a guess that the flow switch just needs a tweak. There is a small hole on the top where you can insert a tiny screwdriver to make the adjustment. (Jewellers screwdriver fits the bill quite nicely)