Mistubishi 2 x Splits with 1 x PAR-F27 Controller Temp Wrong

[funklet]

Hi,


I am a refrigeration engineer for drinks systems / milkshake machines etc. but now work in the office on IT and technical.

About 2 years ago we had 2 split ceiling grid mounted air source heat pumps fitted with a PAR-F27 or similar controller. I don't have the exact model of controller handy but I can get it if required.

Despite calling the installer back they seem unable to solve a problem. It had been a bit tricky to understand but I have the hang of it now.

The temperature in Heat or Auto doesn't read the correct value. When you come in in the morning it will read ok, e.g. 15C. You put it in Auto / Heat and it will heat. Then later on in the day e.g. 11am the office will be too warm. At that point the controller is reading the set point and still heating, e.g. 22C. If you then put it into Cool then then after about 5 seconds the controller then reads the actual room temperature, e.g. 26C and starts to cool spectacularly!
Strangely if you put it back into Heat or Auto it will then read 22C again and start to heat again. The installer was challenged about this but they couldn't really understand the problem and introduced a new problem by programming the controller in some way so now when it is in Heat or Auto it flashes between Heat and StandBy and so when it's really cold e.g. 8C it takes a long time to warm up because it not in full heat.

It would be really helpful if a clever bod here could help me to program the controller correctly and provide kudos to me and them for sorting it out.


Many thanks in advance for any help you can provide.

Spencer.

[stufus]

There is a 3deg off set for high ceiling applications (stratification)
So when heating is selected you will notice a drop of 3deg on the return air value and the opposite in cooling.
You need to disable this function.
Due to a three year old knocking my laptop of the table onto a tiled floor and wrecking the hard drive I lost all my manuals
But If your installer has the manual for the units he should be able to figure it out.
Cheers
Stu

[install monkey]

get the model numbers . also you can programme system to operate of the sensor on the remote controller. if its a par 27 then switch dip switch sw1 1 to on on both units, also in auto mode there is a 2 deg diff between heat and cool so that 4 deg swing can give a poor control, try in just heat(if women are in the room) or cool ( as all blokes are immune to coldness) and see how that works, also how high is the ceiling

[funklet]

Hi Gents,

Many thanks for your time so far.

The installer is no help. Not local and clearly supplied units beyond their comprehension.
The ceiling is about 2500mm.
I will get the model numbers of all of the units in the set.

I'm sure with your help we can get us to where we need to be.

The office is cold in a morning and hot in the afternoons due to office equipment / people / sun so the setting needs to work properly in Auto. We have to manually change it to heat/morning and cool/afternoon most of the time because it doesn't work properly. This means waiting until we are way too hot and then changing it to cool and changing the temperature. And the day programming isn't set either.

What we ideally want is to cancel the "stand-by" "feature" and program it so it comes on Monday to Friday 8 to 5 and have it maintain 22C with a deadband of 2C. My understanding of deadband for this situation is it will heat if the temp goes below 21C and cool if the temp goes above 23C.

I hope my understanding of how the system should work is correct and will just need a little bit more help to get there.

Many thanks, I will update with model numbers shortly.

[funklet]

I forgot to answer one of the questions.

If it is left in heat then it carries on heating and the office becomes uncomfortably hot.
The temperature reading on the control stays at the set point but the actual temperature goes as much as 6 degrees over that.

Leaving it in cool is not an option as it needs to heat for at least a few hours in the morning.

[install monkey]

is there fresh air input to the cassette? giving a false return air temperature?- contactor sticking on outdoor?- is it 2 indoors , 2 outdoors, 1 controller or 2 indoors, 1 outdoor, 1 controller

[AbsoluteWDJ]

Hi,


I am a refrigeration engineer for drinks systems / milkshake machines etc. but now work in the office on IT and technical.

About 2 years ago we had 2 split ceiling grid mounted air source heat pumps fitted with a PAR-F27 or similar controller. I don't have the exact model of controller handy but I can get it if required.

Despite calling the installer back they seem unable to solve a problem. It had been a bit tricky to understand but I have the hang of it now.

The temperature in Heat or Auto doesn't read the correct value. When you come in in the morning it will read ok, e.g. 15C. You put it in Auto / Heat and it will heat. Then later on in the day e.g. 11am the office will be too warm. At that point the controller is reading the set point and still heating, e.g. 22C. If you then put it into Cool then then after about 5 seconds the controller then reads the actual room temperature, e.g. 26C and starts to cool spectacularly!
Strangely if you put it back into Heat or Auto it will then read 22C again and start to heat again. The installer was challenged about this but they couldn't really understand the problem and introduced a new problem by programming the controller in some way so now when it is in Heat or Auto it flashes between Heat and StandBy and so when it's really cold e.g. 8C it takes a long time to warm up because it not in full heat.

It would be really helpful if a clever bod here could help me to program the controller correctly and provide kudos to me and them for sorting it out.


Many thanks in advance for any help you can provide.

Spencer.

Spencer

If the controller is in an ideal position then I would disable both return air sensors and 4c offset in heating mode for both indoor units. If it's a PAR27 then you'd probably have a City Multi indoor units and would set these via indoor dip switches. If you have split systems then the chances are you'd have PAR21 and you'd set these via function settings. You'd need to give us more model information indoor and controller.

[funklet]

I have popped to the office to get the information requested.

Ok so we have:

1 x Remote Control
PAR-21MAA-J

2 x Duplicate Independant Splits with no composite air so:

2 x Indoor Unit.
PLA-RP100BA3

2 x Outdoor Unit.
PUHZ-RP100VKA

Approximate Manufacture Date Jan 2010

The dip switches on one of the indoor units is set as follows:

SW1
ON ON ON OFF ON

SW2
ON ON ON ON OFF

These look correct based on the information under the cover of the box.

Where could I go from here..

[install monkey]

http://www.mediafire.com/view/?5ht8v87cm7phewl
par 21 manual with fuction settings for sensor
also on a par 21 with power inverters-you can check comp freq , pipe temps,valve positions

[funklet]

Many thanks install monkey.

From the manual it seems I should set the following:

'00' '00' for settings 1-6
Mode 2 Indoor temperature detecting Setting No. 3 (Main Remote controller)

'00' 'AL'
Mode 24 Set temperature in heating mode 4deg up Setting No. 2 (OFF)

Possibly the 4deg up will not make any difference after changing the indoor temperature detecting to the main remote control?

Do you guys have any idea what setting I need to change to stop it flashing from StandBy when heating?

It is possible this was only happening when it was very cold outside. Could it be that when it's too cold the standby is to allow the evaporator temperature to recover?

Many thanks for all the help so far,

Am I missing anything else?

[install monkey]

standby will show up for upto 4 mins to allow for defrost when its cold outside, and also when heating demand starts- until the coil temp reaches 33 deg then the indoor fan will start to speed up- cold draught prevention.
try it with just ur 02 3 setting for ur remote control sensor first

[install monkey]

http://www.mediafire.com/view/?r3gro61tdnmc9wr
check the performance of each unit via the par 21- inverter current,frequency

[funklet]

Ok so all set nicely now. This time it heats up to 22 and maintains temperature and I think it went into cool nicely. Many thanks Install Monkey.

Hit a bit of an issue however. I turned off the units to program the timer at about 1pm and while I was doing this the temperature in the office warmed up to 23. When I turned it back on again it went into cooling dramatically and cooled the office down to about 21, the units are above the main desks though so it felt a lot cooler there because of the ferocity.

I guess if it had been left for an hour longer the temperature would have stabilised back to 22C but my question is this.

How can I have some control over the deadband so it doesn't get so carried away..

[install monkey]

the controller should be mounted at 1 mtr high- disabillity awareness act-or similar, preferably on an internal wall, not influenced by sunlight or draughts

as a last resort theres also the bodge of jamming a bit of cardboard between the grille and the cassette unit- small phillips to take the corner panels off then loosen the corner screws to allow u to slide it in between, doesnt affect the louvre motor there and looks quite neatt
ry - airflow fan speed to quiet- 08 1
energy saving heating mode - 12 2
also try the vane setting1,2 can prevent draughts
just a matter of playing about with it- in the par 21 manual you can fix the angle of each louvre individually ,so you could have 3 in swing and 1 fixed

[back2space]

Ok so all set nicely now. This time it heats up to 22 and maintains temperature and I think it went into cool nicely. Many thanks Install Monkey.

Hit a bit of an issue however. I turned off the units to program the timer at about 1pm and while I was doing this the temperature in the office warmed up to 23. When I turned it back on again it went into cooling dramatically and cooled the office down to about 21, the units are above the main desks though so it felt a lot cooler there because of the ferocity.

I guess if it had been left for an hour longer the temperature would have stabilised back to 22C but my question is this.

How can I have some control over the deadband so it doesn't get so carried away..

Unfortunatly there is no way to adjust the deadband its + 1C or -1C below the set point - if your set point is 22C and your room temp is 23C the system will call for cooling and will continue cooling until 21C at which point the system will then stop calling for cooling. During this time the inverter outdoor unit will reduce its output and the compressor should ramp down. It then has to rise to 23C before calling for cooling again. Set your fan speeds to low & ensure the louvres are not set to swing.

Re your earlier point about auto changeover mode. There is a dead band of 2C + - above set point. So if set point is 22C and unit is in cooling mode it will not go into heating mode until room temp is at 20C or below for a specific period of time - I think its half an hour??? For it to change back into cooling mode it has to go to 24C or above for a specific period of time - again half an hour and parameters not adjustable.

As install monkey has said set "airflow fan speed to quiet- 08 1" your systems may be oversized for the application and cassette units have high airflow rates. Setting them to quiet should reduce the turbulence and means the system will reach temperatures at a more steady pace rather than just rapidly cooling down. This should also give the outdoor unit inverter time to adjust its output.

At our gym they use Mitsi Cassette units similar to yours they were all on high fan speed for the airflow however at non peak times they continued to be used at high fan speed, problem was they never dehumidified the air properly and reached the setpoints within a matter of about 2minutes compressor on then 7 minutes off, reducing the fan speeds to low or setting them on auto means that the cooling rate is reduced but is more suited to the enivornment. Even at peak times them being on low they still maintain the set points of 19C easily as the units are oversized for the room and running them on low reduces the capacity & means they are probably at the correct cooling output.

Hope that makes sense.