IMI Marstair HLR 540 problem

[markj]

HI,

Visited a site today to investigate a problem with an Marstair HLR540 unit in a resturant kitchen. The unit was moved by another contractor last week who i am told has since vanished off the planet. The condensing unit is MCU +130 ( R22) with HP control. only having a short time to spend investigating today the problem of poor cooling.

The indoor fan coil is icing on the first 5 rows and the frost stat cuts out after a few mins. Upon investigation it appears the previous person has fitted a shiny new liquid dryer and sight glass after the restrictor??, could this be causing the problem. I did notice a capillary on the indoor as well ( i would guess it's for reverse alought a cooling only from memory some old marstairs use only a capillary on the indoor). Suction drops slowly and sits at 3 bar approx then eventually ice stat trips after a few mins. plenty of airflow over the evap and condensing HP controll running ok HP was at 24 bar which is high for a room that was not hot as kitchen not open.
I am told by the owner they came back once and re charged it ? the black pen on the side says 4kG with the date which i would gues is about right however i would have to recover and re charge to correct weight to confirm 100%. ( pipe run 8mtr max)
So the question is assuming the charge is ok could it be the fact they have fitted a liquid line tryer after the restrictor thats causing the probs? I know it should be befor the restrictor or TEV if required but an not sure of the effect of fitting after?

I am asking the question as i'm pressed for time next few a weeks and need to get in and out quick. obviously i can remove this and check the restrictor re charge etc but it would be nice to know if any one has come across this type of problem b4 and if it makes no difference to leave the glass and dryer in even though it will serve no function.

Any info will be usefull. Thanks in advance.

[frank]

Why would any one fit a SG and drier in the expansion line? total waste of time.

These items would not cause partial frosting of the evap though. SOG would.

[sean1]

the filter drier does cause a slight pressure drop as i understand.would this cause what symptoms you have-dunno but i am betting you get a reply that does-got me interested though pls post what you find as fault. would suggest removing and installing drier no matter what the result

[markj]

just been back to site this morning as i had an hour to spare. recovered almost 5 kg of gas from the unit. so i can now rule out that it's short of gas.

[marc5180]

Short of gas? You say you have taken out 5kg?
Dont you mean overcharged then?

the black pen on the side says 4kG with the date which i would gues is about right however i would have to recover and re charge to correct weight to confirm 100%.

[Andy AC]

As you mentioned earlier, a marstair hlr has capilary on indoor, so no need for restrictor on outdoor unit. Pump it down, do away with the restrictor assy, leaving a straight liquid line to the indoor unit.

Had your problem years ago, installed a marstair impact with, the restrictor on the outside unit, but the customer complained about the noise of the impact indoor unit so much that we changed it for a hi/lo or hlr.
We just connected it up without doing anything to the condenser - forgot to take restricor assy. out, which resulted in horrendous gas noise and crap performance.

Andy

[markj]

hi, no you are correct it's over charged, just downloaded manual from heronhill and the charge should be 3.97kg. it appears from the install guide that the capillary is if the unit is used in reverse cycle and the restrictor should be fitted?? there was little heat loadf in the room when i first looked and the hp was about 350 with poor suction and icing on the evap. I guess the restrictor could be blocked? I am goind back monday so i will remove the restrictor and inspect.
Tricky as this has been installed by monkeys ( see firts post).

[markj]

Andy... i will remove the restrictor orifice and leave the sg and dryer in situ as this will becone the liquid thus using the indoor capillary as the expansion as you suggest. i will let you know......

Thanks in advance.

[markj]

removed restrictor, weighed in correct amount of gas. All working fine.

Thanks

[Brian_UK]

Good news, thanks for the update.