Operation problems

[ozbound]

The system runs on 404a new install. 15hp C,U to 2 equal sized evaps low velocity(dual discharge).problem is a very high head pressure with low suction. T5 danfoss valves No1 orifice. Suction at evaps fluctuate 3.5 bar to 2.2bar continuosly head runs between 20 to 22bar. Changed one of the orifice to a No 2 because TEV seems to be restricting flow and I could also check diferance between the 2 but all it done was send the hp to 25 bar and trip. The suction main is 1 5/8 branch 1 1/8 Liquid main 7/8 branch 5/8.

With the 2 No1 orifice in the system runs with above pressures the liquid line sight glass always flashes. I can not seem to get the TEV to run any sence Temp just after tev runs between 3-11 degs c suction temp is 10 - 13 degs c. If i add more charge then head rises to much as soon as th suction goes above 4.2 bar head becomes to high.

Any ideas would be most helpful as this has confused the s*"t out of me, even the tech Guy is a bit stumped. Or if you want more info

[Peter_1]

Overcharged
Condenser too small (What condenser was instlled)
Non condensables in your system

What's your SH and SC? Two important reading in your case.
Air on over the condenser (air short cycling?)

[mad fridgie]

You have a vapour/liquid mix at the expansion valve(s).
Does you liquid line move up from your reciever outlet?
Remember thst this R404a, and has glide. hence the bubbles.
There are a number ways to fix but need very specific install details.
PI Drawings and photos would be could

[coolhibby1875]

has the system had a good vac? could be a bit air in the system!

[frederik79]

or dirty condenser ..
what is the temp of liquid line ....

[FEISTY]

Just a thought but how was the ***** charged ?? R404 is liquid charge only with can inverted. Can't count how many 2nd opinion calls I've one on where the ***** was charged wrong direction. Also I learned the hard way that as can empties and suction gauge shows drop in pressure loading..STOP. Change to full can. Found that vapor will cause unbalance in charge and you are pounding your head when system starts acting funny. Good luck !!

[ozbound]

Charged as liquid.
24 hour vac all valves open.
Air on CU 25 c
Liquid line temp 44c
Liquid line rises 100mm to dryer s/g drops 400mm to S/V then rises 4m to top of cold room.
Just changed orifices to No 2 made head rise 23 bar suction at 3 bar.
Makes no diferance when i adjust the valve. Open or closed.

[ozbound]

or dirty condenser ..
what is the temp of liquid line ....

New system clean as a whistle!!!!!!!!!!!!!!!!!!!!!!

[Bones]

coolroom or freezer room? both coils doing same room? (whats the TD of the coils and temp your trying to run the room at?)

sounds like condenser too small, are the condenser fans running? if they are running more important are they running in the right direction?

are you cycling any condenser fans with pressure controls or variable speed fans or are they all just on 100% when compressor runs?

[ozbound]

coolroom or freezer room? both coils doing same room? (whats the TD of the coils and temp your trying to run the room at?)

sounds like condenser too small, are the condenser fans running? if they are running more important are they running in the right direction?

are you cycling any condenser fans with pressure controls or variable speed fans or are they all just on 100% when compressor runs?

Running cool room for flowers.
Both coils doing same room.
room temp 6-8c running at 11c.
condenser fan control bypassed run 100%.
Both running right way.
15- 19c td over condenser.
3c td over evap.
flash gas at tev (both).
out of tev (danfoss tes 5 Nov 3 orrifice) 13c suction b4 oil trap 13c the expantion seems to be done at distributer. only part of coil is used.
Suction -7c 4.2 bar at compressor and -2c 4.8 bar at coil suction. liquid 20-21 bar.

[chemi-cool]

Is there a suction filter? If there is, take it out, do not replace it.

[Bones]

cant seem to find any reference to danfoss tes5 txv for oriface sizing... everytime you increase oriface size your increasing load on condensing set which isnt having a good time handling the heatload.

is it possible some valves were still shut like maybe liquid line valves etc? or possible any nitrogen from welding system still trapped in somewhere, my bet would be on non condensibles at this point.

reclaim gas out as liquid through a drier if you can into a bottle and do a temp/pressure test see if its giving 404a pressures for temp of bottle when it cools down after reclaim...

let us know what you have

[monkey spanners]

Are the txvs the right ones for the refrigerant? Is the equalising line conneceted ok? ( schreader valve left in connection to suction line)

[ozbound]

No, no suction filters

[ozbound]

cant seem to find any reference to danfoss tes5 txv for oriface sizing... everytime you increase oriface size your increasing load on condensing set which isnt having a good time handling the heatload.

is it possible some valves were still shut like maybe liquid line valves etc? or possible any nitrogen from welding system still trapped in somewhere, my bet would be on non condensibles at this point.

reclaim gas out as liquid through a drier if you can into a bottle and do a temp/pressure test see if its giving 404a pressures for temp of bottle when it cools down after reclaim...

let us know what you have

The only valve is the roter lock valve on reciever thats open.
Have reclaimed the gas and replaced with new made a little differance.
Did check pressure / temp relasion and did match.

[ozbound]

Are the txvs the right ones for the refrigerant? Is the equalising line conneceted ok? ( schreader valve left in connection to suction line)

Yes checked all this out.

At the end of my tether, No more ideas accept not condensing correct!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[fazzamouse]

with a head pressure at 20 bar the unit is either too small or installed in a poor vented area,it ain't condensing enough at those pressures

[monkey spanners]

Is the condenser and reciever piped correctly, have read of condensers being piped up wrong, so to get any liquid out they have to be nearly full up with liquid.
Are the condenser fans all running the correct way, have seen one running correctly and the other running backwards.