Mc Quay MNG 168.2 SE ST Loading probem (screw)

[stufus]

Hi Gent's

Have an issue with the above chiller , was looking at it with a work colleague.
One of the compressors was replaced;
Original - Mc Quay HSA3221QY11YB
Replacement - Halls HSA203Q511YA

We have checked this with Mcquay and were told the compressors are identical and the model numbers are different due to the manufacturer ,so that's fair enough.

The problem is this when we run the new compressor it runs sweet as a nut all the way up to 97% load.
The basic figures are this on R134A LWT set point of 7.5c . With microtech 2 controller.
@97% comp loading
LP= 2.1 bar / 1.3c
HP= 10.5 bar / 45c
Approach 12.4c

@100% comp loading
LP-1.3 bar / -6c
HP= 9.4 bar / 41c
Approach 15.5c

What appears to happen for want of a better description is that when the compressor stages from 97% to 100% it falls off a cliff and does not recover.

Is there a way to limit the loading on the compressor to 95% as it would be more than sufficient for the site.
But more to the point could the problem be with the spring tension acting on the slide not being up to the job.And the piston is traveling to far???

All and any suggestions welcome

Cheers

Stu

[install monkey]

stick more gas in

[stufus]

:pNow't wrong with the charge monkey.:p
I'd say thats your answer to everything
cheers
Stu

[install monkey]

have u tried turning it of and on again!:o

[stufus]

:confused:Just bumping Thread back to the top

[install monkey]

still think the only difference between 97 and 100% load is displacement, so if alls well at 97% try a bit more to increase ur suction pressure and oil pressure , you can always pull it out again if im wrong

[Noori]

plz refer to the compressor manual and Mcquau microtech2 manual so that u can controle the load to 95% if its enouhg.

[stufus]

Tried to limitthe load to varying degrees but thecompressor still loads up to 100% and goes tits up.Even tried adding gas ,no joy there. So took it back out.Any more suggestions??CheersStu

[Grizzly]

Hi Stu.
I may get back to you with further info!
Just got to refer to my archives first.
1 though has occurred to me, have you considered that the comp may be, being starved at full load?
IE. a partially blocked liquid line filter?
Just a thought.
Grizzly

[Grizzly]

Also what's the state of the suction strainer/
Grizzly

[Grizzly]

Back again Stu.
I am not familiar with the chiller you describe so bear with me, but if this unit uses the LVDT 0-2ma control.
Could not an ofset be programmed into the Microtech to fool the controls into thinking it is at 100% load?
Just a thought!
Only I have pages and pages to wade through!
Grizzly

[Grizzly]

Back yet again Stu!
Just how new is the comp?
Is it the type that come with a suction sock fitted?
Old fashioned I know but still applicable sometimes!
From memory they should be only left in place for about 100hrs runtime.
Grizzly

[stufus]

Cheers grizzly brand new comp straight out of the plastic. No suction sock . Tried altering just about every parameter available to no avail . We are no resigned to calling in Mc Quay as we think there is something a miss with the slide set up. Runs well until 100% load then jumps about 40amps and the suction goes through the floor. Tried all the usual stuff pulled the tev stripped it , put it back no issues , same result .
Cheers
Stu

[Grizzly]

As you suggest, it could be faulty from out of the packet!
It certainly sounds as if there is something more unusual afoot.

It will be interesting to find the cause of your issues. please keep us posted.
Good Luck.
Steve.

[stufus]

Will do mate .
You'll be the first to know.
Cheers
Stu