Heat Recovery Chiller Trouble

[Controlswiz]

I have two Daikin Air Cooled Heat Recovery Chillers (air cooled condensor) behaving in a similar way. The High Pressure Switch (manual reset) cuts off. Ambient temperature was 45degC in the shade and 50degC in the direct sun. I have checked all condensor fans - they are all working and in the right direction - blowing air upwards away from the chiller. The chiller is in the open air with no obstructions therefore the hot air does not get recirculated. I was told that Chillers are designed for this type of high ambient (high condensing temperature). The chiller has a facility to set and limit the capacity. Tried to limit capacity down to 50% but still doing the same. The screw compressor starts unloaded with the discharge pressure of 300psig and then reaches 350psig when it starts loading after about a couple of minutes. The pressure switch is factory set (cannot be adjusted) at 350psig cuts off the compressor. The chiller uses R407c gas.

Heat Recovery water side pump is working.

Am I missing something? I need help. Please give me all possible causes that I might have missed.

[AlexG]

Is the condensor surface clean? Is refrigerant charge correct? Not overcharged?

[install monkey]

is there head pressure control on the fans-can u lower the set temp( proportional control)

[chemi-cool]

And the water entering temp is?

Could somewhere after the condenser [I take it that there is no receiver] something might be partiality blocked?

[r.bartlett]

350 trip at those temps seems a tad low for the HP... ?

[chemi-cool]

350 trip at those temps seems a tad low for the HP... ?

Yes, at such ambient, it has to be set for at least 400psi.

[NH3_Sniffer]

HI,

I would complete a number of tests.
1. What is the water inlet temperature. If you are in high ambient conditions could the water be out of limits. if this is a regular occurrence the piping of the water system should be looked at. Maybe a bypass until water enters chillers envelope.
2. Any non condensables in the system? ie, system not evacuated upon commissioning.
3. All condenser fans/regulators operational
4. system not over charged. causing liquid to backup within the condenser coil and reduce THR
5. Screw compressor dichrage NRV. - with your manifold set check discharge pressure at compressor & after. is there a difference?
6. chiller supplied with standard spec

hope this helps.

[Genesia]

Heat recovery will ensure that part of hitherto wasted home energy is made use of for some useful purpose. One might find it hard to believe such wasted energy exist in his house. True it is more prevalent in industrial applications. But that does not mean your home is totally devoid of such wastage that can be reclaimed.

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