Airedale Ultima Chiller

[Grizzly]

Has anyone any idea how to disable the Free cooling facility on the above chiller.
We have had to isolate the free cooling water circuit through the condenser.
Due to freeze damage of the pipework.
However the valve and condenser fans are still operating as normal.
Creating excessive sub cooling.
I have tried disconnecting the ambient probe as suggested by Airedale.
Which resulted in a probe failure alarm.
Thanks Grizzly.

[sedgy]

hi grizzly, yes I worked on a few of these < in the old days < normaly on free cooling the glycol is pumped from the dry cooler through the indoor unit < as you have seen< fi more cooling is requiered the 3way valves in the indoor unit change , the unit is in full cooling the glycol now goes through the small condencer taking the heat to the outside drycooler, the comps and all the 3way valves are in the indoor units< not much room < well thats the basics of thr system of corce this is 20 years ago and the set up may have changed, all the best = sedgy,
just reread your post turn off the fans or turn off the glycol pumps

[monkey spanners]

Could you warm the probe up so it thinks its too warm for free cooling? Or fit a resistor of the correct rating.
There was a post about decade boxes the other day that would be a useful thing in this case.


Down on the farm the correct way to get the condensing pressure up is with some fertilizer sacks....

Jon

[Grizzly]

Not a stupid idea there Jon.
Within the pco 3 software.
There is a setting which looks for a minimum difference between the Sp and Ambient temperature.
This was set at 2 degrees, Logic says change it to 20c and the freecooling will stop.
No difference.
Why I do not know?
As previously mentioned Airedales advice was to disconnect the Ambient Probe.
Whether I would of had more success linking out the probe connections, I don't know.
Grizzly

[frank]

Not familiar with this model so I had a look on their web site.

Even the Technical Manual doesn't give any clues. It's more like a Sales Brochure

http://www.airedale.com/v2portal/pag...ontent_018.htm

[Grizzly]

Not familiar with this model so I had a look on their web site.

Even the Technical Manual doesn't give any clues. It's more like a Sales Brochure

http://www.airedale.com/v2portal/pag...ontent_018.htm

I agree Frank.
Hence the post, hoping someone in the know can help.
Grizzly

[Brian_UK]

Had a quick read of the install manual (doh), http://www.modine.com/web_server_con...C75-450_UK.pdf , and a couple of thoughts rose up slowly.

As the free cooling is triggered when the outside sir is 1°C below the return water temperature would pulling the water sensor be a better bet than pulling the ambient? Clip the two together then they both read the same or if you disconnect the water sensor does it default to a -°C ?

Secondly it seems that the favoured way of operation is the Variable Supply Temperature mode but the Constant Temperature mode seems to ignore water temperatures, or have I misread that?, might be something to try.

[sedgy]

hi grizzly, with all this confusion why dont you just go onto the controler and turn off the free cooling? entry code 1234, sedgy

[Grizzly]

Brian.
I forgot to mention the chiller is required to be kept running, so if the return water temp probe is removed.
We would loose control of the chilled water temp.

Secondly it seems that the favoured way of operation is the Variable Supply Temperature mode but the Constant Temperature mode seems to ignore water temperatures, or have I misread that?, might be something to try.

You just may have something there?
Sedgy.

hi grizzly, with all this confusion why dont you just go onto the controler and turn off the free cooling? entry code 1234, sedgy

If I knew which setting to use I would.
You are refring to accessing the Mk2 PCo by the way.
Thanks guys for your input.
Grizzly

[NoNickName]

IF it's an NTC, as per Carel standard, the higher the temperature, the lower the resistance. So, replace the NTC with a low value resistor until the free cooling no longer kicks in.

[Grizzly]

IF it's an NTC, as per Carel standard, the higher the temperature, the lower the resistance. So, replace the NTC with a low value resistor until the free cooling no longer kicks in.

Good idea, well worth a try.
Thank you.
As I say I raised the ambient to SP minimum diff.
But for some reason that did not work. If I am allowed to return to site.
I will post how I get on.
Grizzly