outside fan control from liquid line ?!

[Yuri B.]

Hello
I have seen a cool-only split (outsid unit) today which has a 3-way adapter added on its liquid line with connected presostat for fan control. The setpoint was 9 Bar, but what refigerant, I forgot to notice.

I am not sure, maybe the A/C contains an expansion device in the inside unit, although I doubt it. Then, such seemingly condensation P "regulation" is not wise on my view. If it is for a server room, what happens at low outside and high air room T ? The presostat will not stop the fan - so, no effect of it. Or at high outside T there is imaginable an intermediate P in the liquid line which would stop the fan untimely.

Probably lazy (or "economical" for the client) installers did not want to bother opening the system, brazing, vaccuming, etc. Or maybe the presostat is there for an other reason?

[chillerman2006]

Hello Yuri

I am thinking the same as you - no use

maybe a friday condensing unit & fitted to the wrong side of condensor

could understand if it was to bypass condensor on cold day

maybe someone else has a answer/theory

Regards chillerman

[al]

Yuri

i'd say you're right, fitted aftermarket to allow the unit run in low ambient, used to plenty of York units done like this, so long as expansion device is indoors it's ok but not great, i agree with you that ideally it could control off the discharge.

al

[paul_h]

I'd say expansion device is in the outdoor. It's the usual set up and 9 bar is too low to set a fan on a proper liquid line.
Rough guess, the PCB failed and doesn't run the outdoor fan anymore, hence bodged pressure control on outside condensing unit (because they couldn't or didn't want to replace PCBs).

[al]

Paul

you may have hit the nail on the head!! is it time for bodger watch yet?:)

al

[paul_h]

Maaaaate, I've seen it all!
It stops me from going to sleep at night :(

edit: If it's a new conventional fixed speed compressor split system with only an indoor PCB and mains power going to indoor not outdoor, odds are the only problem is the installers crossed active and neutral between indoor terminals and outdoor. In that case the compressor runs unhappily, but the condenser fan does not, as it gets two actives, mains power and PCB relay from indoor power switched to CF fan run)
I have seen that a lot too :(

[al]

That maaaate is how a NZ mate of mine used to explain bodges we had to fix, he's just point and go maaaaaate and shake his head!!

al

[paul_h]

Yeah, I have to do that a lot unfortunately :)

I mean in this case, why not fix the problem (wiring or solder in a new relay if the PCB is too expensive or impossible to get)
Why maaaate why? *shakes head*

[al]

I know mate i know, come on lets put the kettle on!!

al

[chillerman2006]

Nice one Paul (again)

been scratching me head for a whole day with this one

could not make head/tail of it


Regards Chillerman (http://www.refrigeration-engineer.com/forums/member.php?4978-chillerman2006)

[al]

Here CM how are do you hyperlink your name?

(Is it a ninja/jedi thing?)