Understanding Airwell Chillers

[In-My-Van]

I am a service engineer with 15 years experience on commercial fridge and a/c. My a/c experience is only with split a/c systems upto 12.5kw with the odd dx packaged unit upto 50kw. The other day i did a sight survey and came across an airwell AQH35 chiller providing 8 room's chilled/hot water via 8 cealing concealed FCU's. Each of the room FCU's had its own airwell controller. I am trying to get my head around how the control side works. There does not appear to be any electrical control connections between the FCU's and the Chiller. I assume the controller regulates the valve on the FCU and the load detected by the two sensors on the flow and return on the chiller, control when the chiller runs . The controller has the usual modes, cool, heat, fan, auto etc but i dont understand how it gets the chiller to change over from heating to cooling without a signal. Does the chiller its self have to be set into summer or winter mode ie cool or heat?

[Mick13]

the chiller only chills, it doesnt heat. the fcu will have either a hot water coil hooked up to a boiler or an electric heater for heating. the chiller will generally cycle itself on chilled water temp.

[In-My-Van]

The Airwell AQH is cooling and heating as its fitted with a four way valve

[Nik BG]

Hi In-My-Van.
AQH does not have option to control FC units, at least the ones i have seen. I have put into service many AQH chillers brand WESPER, I quess it is the same.Actually i am sure. Some wesper units came with airwell control. The mode shoud be changed by the user. They control the return water temp. The FCU does not start unless there inlet water temp does not reach 30 degrees on heating or 12 degrees(+ or - ) on cooling.The right values are just a aguess, but this is the logic in general. If the FC is on cooling mode and you run the chiller on heating mode,it will never start i mean the FCU. It changes the thermostat polarity on changing over fr. heating to coooling mode and vice verse. Hope i help some how :-)))

[In-My-Van]

Thankyou, So your saying that if the AQH35 is in heating mode and the customer turns the indoor controller to cooling it will not change over unless its changed over directly at the the AQH35 by an engineer? Seems to be an inconvenience to the customer?

[frank]

Can't say that I've seen one of these Airewell thingies, but, as with a 2 pipe VRV/VRF, which can only heat or cool at any time (not simultaneously), one of the indoor units is designated a Master Control and this unit decides on Heat or Cool mode.

If one of the other indoor units wants cooling when the outdoor unit is in Heating, the request is ignored and the fan coil stays in Standby Mode until the outdoor changes to Heating Mode- via the 'Master Control'.

[In-My-Van]

Thanks Frank. Ive worked on VRF/VRV a few times. This is a air to water heat pump. I followed the water pipes to the indoor area and i could not see any interconecting comms cable hence my questions


9030

[Grizzly]

Hi Jason.
I have sent you a manual that should help explain things.
Yours is a chiller with heating or cooling mode. There are customer inputs as you will see in th electrical diagram.
But these are basic hot / cold. On / off inputs.

Basically you can select hot or cold water once it has left the chiller.
What is done with it has nothing to do with the chiller other than how much work it does dealing with the return temps!

I would of posted the manual via mediafire only at 7 meg the upload was too much for my snail mail.

Good luck Grizzly