Contactor
27-11-2010, 06:22 PM
Hello :D
Attended a city multi this morning, rooms cold,:
It's a PURYP250YHMA with 5 groups, one group of four cassettes and one cassette in each of the other groups, all the cassettes are the 600x600 4kw model.
The discharge pipe warm but not hot, about half as warm as the other unit on site (PURYP350YHMA)
The outdoor unit was partially frozen up with no signs of regular defrosting.
Each group is controlled by a single PARF27 controller, all groups on one 7 day timeclock, (i think the PACYT34). Units blowing between 20-25c with the rooms at about 17-18c set point 25c.
No fault codes.
On arrival I SW2 - 7 was switched to on for the forced defrost. I was unable to check resistances of the defrost thermistors but they were removed and re-plugged. SW3-1 was found to be in the on position, I think this may have been to stop a noisy check valve, it was switched back to off to disable test run mode, (SW3-2 also off).
SW3-3 and 4 were switched on to lower / raise the defrost start and termination.
SW4-4 was switched to on to move the system off low noise mode, CND3 was closed but left open. SW5-5 was not checked.
The system was re-energised units blowing about 30c with a slightly warmer discharge pipe. Rooms up to about 20-21c after half an hour or so, set point 28c. The PARF27 were showing a room temp (measured at controller) of 17c which was incorrect.
However, system was fine for the whole of the last winter with the above settings, have previously measured supply air from the units at 35c+.
I'm really not sure why the head pressure is low or why the PARF27 are showing the wrong temperature.
This is an old stone building with very thick walls and I am presuming once the structure is heated the HP will rise, maybe the walls are so cold this is responsible for the PARF27 thermistor error.
But does anyone with Mitsu experience know why this has only shown up now and not last winter?
I had to leave site so could not stay to see if the defrost came on or whether the space temp continued to rise.
All thoughts welcome
Thanks. :D
Attended a city multi this morning, rooms cold,:
It's a PURYP250YHMA with 5 groups, one group of four cassettes and one cassette in each of the other groups, all the cassettes are the 600x600 4kw model.
The discharge pipe warm but not hot, about half as warm as the other unit on site (PURYP350YHMA)
The outdoor unit was partially frozen up with no signs of regular defrosting.
Each group is controlled by a single PARF27 controller, all groups on one 7 day timeclock, (i think the PACYT34). Units blowing between 20-25c with the rooms at about 17-18c set point 25c.
No fault codes.
On arrival I SW2 - 7 was switched to on for the forced defrost. I was unable to check resistances of the defrost thermistors but they were removed and re-plugged. SW3-1 was found to be in the on position, I think this may have been to stop a noisy check valve, it was switched back to off to disable test run mode, (SW3-2 also off).
SW3-3 and 4 were switched on to lower / raise the defrost start and termination.
SW4-4 was switched to on to move the system off low noise mode, CND3 was closed but left open. SW5-5 was not checked.
The system was re-energised units blowing about 30c with a slightly warmer discharge pipe. Rooms up to about 20-21c after half an hour or so, set point 28c. The PARF27 were showing a room temp (measured at controller) of 17c which was incorrect.
However, system was fine for the whole of the last winter with the above settings, have previously measured supply air from the units at 35c+.
I'm really not sure why the head pressure is low or why the PARF27 are showing the wrong temperature.
This is an old stone building with very thick walls and I am presuming once the structure is heated the HP will rise, maybe the walls are so cold this is responsible for the PARF27 thermistor error.
But does anyone with Mitsu experience know why this has only shown up now and not last winter?
I had to leave site so could not stay to see if the defrost came on or whether the space temp continued to rise.
All thoughts welcome
Thanks. :D