City Multi - Hotel

[ronaldo9]

Hey guys,

I have searched the forums for this fault and found some helpful threads, however i have still
unable to solve the issue, mainly due to site visits being few and far between.

Its a hotel with 4 floors seperated into two sides, old and new.

On the NEW side i have 4 x PURY-P250YMF-C-BS outdoor units each with their own BC which is
connected to 10 wall mounted indoor units. Each indoor is controller by a PAC-SE51CRA.

On the OLD side i have 3 x PURY-P250YMF-C-BS outdoor units each with their own Bc which is
connected to 10 wall mounted indoor units. Each indoor is controller by a wireless remote
(PAR-FL31MA with a seperate receiver)

Each side has its own G50 which is in turn connected to PC based monitoring tool.The PC
has a daily schedule of 4 off times 00:00, 01:00, 11:00 and 12:00.

The problem is mainly with the new side on all floors, im constantly getting calls for
communication faults, 6607, 6608, 6603, 6600, duplucate addresses. Usually these faults have
disappeared by the time i visit the site and everything is running. Ive checked Mnet
voltage everywhere at its always above 29VDC. The indoors are not powered from the
occupancy contactor in the rooms.


So basically where do i go from here?
Thanks in advance.

[ronaldo9]

hey guys,

had an idea, the comm cable between the indoor unit and the remote is not screened. In most rooms there are light switches and in some cases fuse boards directly above the remotes. could this be causing interference on the mnet. this would account for the intermittent nature of the faults,

[Si@Airmaster]

It's good but I would doubt it, this is very uncommon. For the system to pick up noise the cable usually has to run with the power cable for a reasonable length to pick up enough noise to worry it. Plus mitsi's stuff had ferrite noise reducers coming out of it's ears!!

Did you assign the addresses manually or let the system do it. Maybe there's a faulty board or power supply that's making a unit drop in and out of the mnet randomly. The unit would be constantly reregistering itself with mnet and would have to go through addresses till it found an unused one.

Try setting all the addresses manually with the switches and I reckon this will stop.

This is all guess work though cause I'm not that up on the mnet control logic but had a similar problem with Sanyo stuff

[Thermatech]

The YMF-C outdoor units are about 10 years old now & the central controllers then were MJ103.
So i am wondering if the G50's were added later.

Q1/ Did all systems have ongoing nusance comms faults from day 1 or only after addition of G50's ?
Q2/ Does each G50 have a power pack power supply ?
Q3/ Is the Mnet comms cable correct specification & screen tagged to ground correctly ?
Q4/ From the G50 to the outdoor units does the Mnet comms run along side 3ph power cables.
Q5/ Does the G50 recorded fault history show any pattern like the same indoor unit or outdoor unit stopping on the same fault multiple times.

When a comms fault is recorded at the G50 it shows the address of the unit which is not sending correct data.
So you can use engineers mode to look at the last 64 faults recorded in the memory. Each one has date / time / unit address with fault / the fault code.

For instance
If the 3ph power is switched off to one outdoor unit
then
The G50 can no longer get data from that outdoor unit / BC / all indoor units / all remote controllers on that one system.
The G50 records 6607 for the outdoor unit / BC / all the indoor units / all the remote controllers.
In this case you might have a word with the site mainenance engineer to replace the power supply MCB & outside isolator as a precaution & double double check that the connected power supply is correct. Then padlock the outside isolator.
Ask the site maintenance engineer to keep a log of all MCB trips for the AC outdoor units.

Suggest use the G50 fault record to home in on any regular repeated faults.
For totaly random comms faults you really need to be looking at external EMF noise as the possible cause.

Sometimes it can be somthing really simple but hard to find.
I had one once where eventually we found the Mnet cable from the outdoor unit to the BC was jointed with a connector block half way between the outdoor unit & BC. It was inside a juction box but water was getting inside & the terminal block screws were corroded. No one knew this juction box existed as it was hiden underneath the refrigeration pipes.
The contractor installed a new cable from the outdoor unit to the BC & the problem was resolved.

[ronaldo9]

Hey guys,

Thanks for the replys, Airmaster all the addresses are assigned manually, the mnet cable between remote and indoor unit is
only a few metres so noise might be wishful thinking on my part.

Thermatech, the G50s could have been a late addition im not sure, the maintenance guy only started a year or so ago. To
answer your other questions.

1) These issues have been plaguing the hotel for at least 5 years which could be the same time the G50s were added as
some major building work took place at this time. We have only been called in on and off within the last year, cant
understand them allowing this to drag on.
2) The 2 G50s seem to be sharing the same power pack supply.
3) Wherever i can access, outdoors, indoors the screen is grounded correctly, some BC boxes are inaccessible.
4) Even without knowing the exact route i can almost guarantee that the Mnet is close to 3 phase power lines, with lift
shafts and a lot of services on the roof its a safe bet.
5) I did go through the history, i printed it out from the PC monitoring tool, however to reset some of the faults
one of the lads powered off some of the outdoors which threw up a load of faults.

Would noise between the G50 and outdoors cause faults in individual rooms, or would it just depend on which unit was
turned on at that time that the noise was encountered?

I was considering suggesting that we disconnect the G50 for a week or two and see if the faults stop. HOWEVER the big
drawback is that i would be relying on staff to record faults,

Any advice on what to do next, my big problem is that im only in there for a day here and there. Im trying to convince them
that i need time at this, and instead of ringing me on saturday night with a full house let me work on it from monday
morning when there is few guests. Its frustrating when your trying to do right by a customer when they make it so difficult.
Anyway rant over, problem is still there,

[Thermatech]

If the comms faults are completely random then I would suspect noise from 3 ph power cables as cause.

The indoor units are constantly sending & receiving data from RC , BC & outdoor unit & G50.
The outdoor unit is constantly sending & receiving data from BC, indoor units & remote controllers & G50.

So if any single Mnet circuit board in the system does not get a correct reply from another unit then a comms fault is recorded at the G50.

The one thing which is common to all units is the G50.
So its easier to trace & seperate this one daisey chain cable from any 3ph power cables & make sure screen is grounded in one place only normally at the Power pack or one outdoor unit.

Most contractors would install one power pack for each G50 although I seem to recall that it is ok to connect 2 G50's to each power pack.
It would be easy to connect the one power pack to only one G50 & see if that makes any difference.

[ronaldo9]

hey guys

havent been back to that site yet, will let you know how i get on with your recommendations when i do. cheers

[ronaldo9]

Hey guys,

Was back at this site today and will be there tomorrow, Have an entire floor empty instead of just a room here and there so should get a good go at it. Started by isolating the entire floor from G50, so its independent. I did find wot looked like some type of LONWORKs board near the BC, which was by passed so G50 could have replaced some old BMS, will let you know how i get on tomorrow. Also had gas problem, the dreaded 407c, added new charge, leak on flare on BC

[stufus]

Just a thought ,check the IP. address' on both g50's in the set up
to make sure they are not conflicting,
Go through the group set up in both g50's and keep an eye out for ghost controller address .
The g50 and g50a are good bits of kit ,the most common problem is lack of knowledge.
You mentioned a lonworks pack double check to see if a mitsu gateway is hidden away some where unused but still connected.

Cheers
Stu

[ronaldo9]

Cheers stufus, will check those out. I know the G50s are good and i have to admit to not been to any mitsu training on them anything i know i got from manuals,

[ronaldo9]

Hey guys,

As well as communication faults which has stopped now i have the floor isolated from G50 i think there might be a problem with capacities, the indoors are

6 x PKFY-P25VAM-A
4 X PKFY-P32VGM-A
1 X PKFY-P40VGM-A

The outdoor is a PURY-P250YMF-C-BS

I know that the indoor capacity can exceed the outdoors, but there are definite performance issues when all units are running together, which is often the case on this floor. Especially the four P32s suffer.

Getting between 28 to 36 degress coil temps on test heating and between 0- 6 degress on test cooling.

[marc5180]

Hey guys,

As well as communication faults which has stopped now i have the floor isolated from G50 i think there might be a problem with capacities, the indoors are

6 x PKFY-P25VAM-A
4 X PKFY-P32VGM-A
1 X PKFY-P40VGM-A

The outdoor is a PURY-P250YMF-C-BS

I know that the indoor capacity can exceed the outdoors, but there are definite performance issues when all units are running together, which is often the case on this floor. Especially the four P32s suffer.

Getting between 28 to 36 degress coil temps on test heating and between 0- 6 degress on test cooling.

Thats 127% Diversity. Most systems that i have come across are around 125% so that figure seems fine if i've worked it out right.

Do they only struggle if they are all on at once?

What happens if only half of them are on? Do they work better?

[stufus]

With those indoors models you should be ok capacity wise.
Have a look at this..
http://81.3.179.242/workdocs01/Guests/Mitsubishi_Electric/techcat/00000909_00040053.pdf
Do you have service tool ,IE laptop and converter?
Flat out whats your discharge temp?
Whats the p1-p3 diff at the BC?
Is this hotel in Dublin?
Cheers
Stu

[AbsoluteWDJ]

Hey guys,

As well as communication faults which has stopped now i have the floor isolated from G50 i think there might be a problem with capacities, the indoors are

6 x PKFY-P25VAM-A
4 X PKFY-P32VGM-A
1 X PKFY-P40VGM-A

The outdoor is a PURY-P250YMF-C-BS

I know that the indoor capacity can exceed the outdoors, but there are definite performance issues when all units are running together, which is often the case on this floor. Especially the four P32s suffer.

Getting between 28 to 36 degress coil temps on test heating and between 0- 6 degress on test cooling.


You mentioned you had a leak on BC flare nut. Did you calculate the piping size, length, and charge accordingly?

[techguy]

Hi Ron,

You could try installing a 100 Ohm resistor accross the control terminals at each outdoor unit. This will usually eliminate spurious communication faults.
At least it does with SANYO and it did with Mitsu when I worked it in the past.

T

[ronaldo9]

With those indoors models you should be ok capacity wise.
Have a look at this..
http://81.3.179.242/workdocs01/Guests/Mitsubishi_Electric/techcat/00000909_00040053.pdf
Do you have service tool ,IE laptop and converter?
Flat out whats your discharge temp?
Whats the p1-p3 diff at the BC?
Is this hotel in Dublin?
Cheers
Stu

Thanks stu,
Sadily no service tool, just using Sw-1. The hotel is in wexford. Basically wots happening is im putting all indoors on test heating, some are heating well while others one room in particular are doing ok. The outdoor is ramping up to 70Hz with p1 =41 and p2 = 38.9 LP=4.5bar and HP 20bar. After a few minutes the compressor ramps down to 50Hz and just sits there.
I checked that the pressures are correct as i had a similiar problem with an inaccurate LP transducer.
As i said all indoors are heating ok but surely in test heating the compressor should be running flat out. One of the posts mentioned correct charge. The additional charge was written on the electrical box. If someone could help me calculate the correct charge id appreciate it.

Distances are;
Outdoor is located 2metres above the BC.

Outdoor to BC = 15 metres
Combined BC to 6 x PKFY-P25VAM-A = 60 metres
Combined BC to 4 X PKFY-P32VGM-A = 40metres
BC to 1 X PKFY-P40VGM-A = 5 metres


Thanks

[stufus]

Hey Ronaldo
Going from memory up model 40 is 1/4 liquid line so multiply by 0.024
And up model 71 is 3/8 liquid line so multiply by 0.06
And mains to BC is 3/4 liquid line so multiply by 0.16
and add 2kg for capacity correction
so it goes like this ! i think!
(15x0.16)+(100x0.024)+(5x0.06)+2
( 2.4 )+( 2.4 )+( .3 )+2 = 7.1kg
I think puryp-250ymf-c came with a factory charge of 12kg
So you're looking for a total charge of 19.1kg
Hopefully someone else can verify those calculations as i've said tha'ts from memory.
Is this hotel on the quay in wexford with BC controllers mounted on the roof???
You need to check the accumulator level and the discharge temp!!
if it's short on charge it wont ramp up .
Cheers
Stu

[marc5180]

The outdoor is ramping up to 70Hz with p1 =41 and p2 = 38.9 LP=4.5bar and HP 20bar. After a few minutes the compressor ramps down to 50Hz and just sits there.
I checked that the pressures are correct as i had a similiar problem with an inaccurate LP transducer.
As i said all indoors are heating ok but surely in test heating the compressor should be running flat out. One of the posts mentioned correct charge.

On heating the P1-P3 in the bc box should be 3-4 bar diff.

The P1 that you quoted can't be right..... If your HP is 20 bar then your P1 pressure should be close to this (unless that reading you gave is DegC).

In heating the compressor will ramp down if the compressor discharge becomes excessive 110/115DegC or if it oversoots the target condensing temp

Also check SC16 in the BC box as this is an indication of refrigerant charge should be 15-20DegC.

First thing i'd do would be to recover to verify the charge.

[Thermatech]

The control voltage is 30v dc & the control data is transmitted onto this.

Can any electronics expert explain why fitting a 100 ohm resistor across the + - terminals will help prevent external noise from corrupting the data signal ?
Is this a cheap noise filter ploy ?

[Thermatech]

For heating performance the 3 bar diff at the BC box is vital & also LEV3 as it is the only expansion valve for the liquid returning from the indoor units. LEV3 flashes off the liquid into the suction pipe so if its faulty & not opening up enough then low suction pressure & comp discharge temp high & compressor ramping down to protect windings from overheat.

Suggest carry out standing pressure test to ensure all pressure sensors at BC reading the same standing pressure as the 2 outdoor unit pressure sensor ( use your gauges at the outdoor unit to ensure the pressure equalize from high to low sides)
If the BC pressure sensors are out of calibration then the system backs itself into a corner & cant recover because of the incorrect pressure data the BC is unable to acheive the 3 bar diff.

If the system runs low suction pressure & compressor discharge contantly high with known correct refrigerant charge then consider replacing LEV3 valve head at the BC.

[ronaldo9]

Thanks guys for the replies.

Stu
Without naming names the hotel is on the quay , some of the Bcs are on the roof but not this system. I take it you have had the misfortune of visiting this establishment. I put 20kg in so hopefully that’s ok.Thanks for your calculations. I thought about the discharge temp and it never exceeded 80 Deg. I read your post about the R22 compressor, hope your back is ok. Its no joke in this game.

Marc5180
I’ll have to check P1 again, make sure I have the correct dip switches and measurement, deg pr pressure. Ill check condensing temp and SC16

Thermatech
Ill check those standing pressures tomorrow, hopefully that’s it. Ive been give a second floor so I should be able to swap out LEV3 to test it.

Im on site tomorrow so ill let ye know how I get on.

[stufus]

:DYeah I was there a few years back for Mitsubishi as the original contractor had emm "problems".
There are junction boxes hidden in walls and transmission cables running under the carpet in the corridors:eek:
It's a mess.I still tell people about what i found down there and very few believe it.
I may still have a few photos of that place somewhere , if i can find them i'll post them on the wall of shame:p
I don't envy you getting lumbered with that site.
Better get yourself comfy you could be there for a while;)
The back is grand thanks.
Best of luck
Stu

[Gingerair]

Had a site once with similar symptoms, turned out that the M-Net cables were jointed here there & everywhere.
It especially tended to go into fault when it rained as there was plenty of these 'joints' outside on the roof.
Ended up replacing most of the M-Net cabling..
Maybe worth a look, check the cable between your oc's & bc's first..

Also check M-Net cable is correct spec, 1.5mm CY
:)

[ronaldo9]

Thanks Stu for the good news, im trying to get hold of an service tool but Mitsubishi tech said end of february,:( is the earliest due to software version update. Trying to use sw-1. I did a standing pressure test and outdoor sensors are ok, however BC ones are confusing. ie

Manual states;
P1 = 01110000100 which gives value of 41.0, doesnt say what though, Bar(obviously not) , psi, kg/cm2 or Deg.

P3 = 1110000100 giving 41 also.

How open should LEV3 be when in full heating the most ive seen it is 600 during initial start up, hovers around 250 then.

[Thermatech]

Sorry I forgot the PI P3 data displayed at the outdoor unit is pressure converted to deg C.:confused: On the service tool the pressure & temperature is displayed.

In heating only the BC is constantly aiming at 3 bar diff between P1 & P3 with the high pressure being P1.
So there should always be some temp drop between P1 data & P3 data depending on how close to the 3 bar target with the system running in heating only.

Typically expect to see LEV3 between 400 to 800 during heating only operation depending on indoor unit load.

[ronaldo9]

Thanks Thermtech for your time...im just trying to get my head around wots controlling the inverter, Tc, LP, HP, discharge temp, LEV 3 is only showing around 250 with the compressor hovering around 40Hz, discharge temp was a bit high today 95 Deg. The thing is the indoors will heat the rooms and im getting good air off temps, a couple of the P32, seem to loose a lot of heat at the first bend of the coil but will put some heat into the room. One unit in particular the furthest from the BC does very little when all indoors are running, the suction is red hot going into unit but as i say it looses any useful heat straight away, i loosened LEV to see if it was ****ed and not opening fully but it didnt make any difference, also reset LEV.,,,,the plot thickens, or am i just thick and not seeing the woods for the trees:o

[stufus]

If it becomes a major problem for yourself and the client give me a shout and ill arrange to meet you there with the service tool.
FOC of course;)
Unless i sort it then you can buy me a pint:D
It's a lot easier when its all on screen in front of you ,does away with guess work,and stops you chasing your tail.
I'll PM you my number
Cheers

Stu

[Thermatech]

If for some reason the liquid from the indoor units is not flashing off through LEV3 enough then the suction pressure will be low & the discharge temp & DSH will be high & the compressor will slow down.
The system backs itself into a corner & cannot recover.

Incorrect pressure sensor data at BC ?
Refrigerant bypass some place in the system like indoor unit LEV locked wide open making overshoot of 3 bar diff at BC & BC responding by closing down LEV3 ?
LEV 3 locked in small opening possition therefore unable to open up ?
LEV 3 locked open in large opening possition & flooding too much liquid back into the suction ?

To be realistic you can only get the LEV valves, pressure sensors , solenoid coils , temperature sensors & circuit board for the BC as spare parts off the shelf.

Last week I had one down in Kent & after changing the pressure sensors & LEV valve heads the heating performance was better but still not great but not a great deal more can be done.
The week before I had one Knightsbridge & a new LEV3 head resolved the problem & near perfect heating performance.
In December I had one in Birmingham which only needed a new P3 pressure sensor as it was about 4 bar out of calibration & that resolved the poor heating performance problem.
This week I was looking at one in Birmingham with a locked open LEV valve at one indoor unit making large refrigerant bypass liquid to suction & making poor heating performance at the other indoor units.

Most times I find you can find the cause & resolve.