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SkyWalker
09-12-2009, 09:49 PM
sorry guys but this may be long and confusing but i will do my best.......

basically we have recently taken on a site which has 10 or so r22 heat pump (2 pipe) condensers, (don't know there models sorry) we have one MJ103MTRA central control, and a few indoors have a local remote but most dont, now each condenser has a Y-ACO connected to it, and each yaco has a low level indoor sensor.

now i "believe" this y-aco is essentially a heat/cool auto change over, fine. but for some reason on site they are being used to control the set point and the central control is being used for essentially nothing.

but something doesn't add up to me, i understand these yaco select mode (set point of yaco +/- 2C will change mode accordingly) but surely the central control can still set the set point, as long as its within the yako temperature band? (yako set point +/-2c)

on site at the mo, they believe the yaco is "god" and has complete control?? is this true?

to make things a bit more complex the groups on the central control don't match the yako, let me try and explain....

group 1 has units 1+2,
groups 2 has units 3+4+5+6
group 3 has units 7+8

units 1+2+3 are on condenser #1 (yako #1)
units 4+5 are on condenser #2 (yako #2)
units 6+7+8 are on condensor #3 (yako #3)

(it goes on like this for about 25 indoors)

will this set up ever work correctly?, the reason they are grouped like this is because it matches the room layouts but completely ignores the refrigerant cycles.

(the numbers are not the real addresses purely hypothetical to try and explain)

as you may have worked out they are having temperature control issues, everything works well refrigerant wise, but there are control issues. im new to Misti kit let alone all this extra control, spoke to them direct but trying to explain over the phone is a complete nightmare, any help much appreciated guys, sorry its sooooooo long :rolleyes:

Thermatech
09-12-2009, 10:52 PM
If yako heat cool selectors are installed then the City Multi outdoor units are Y series heat pumps.

The yaco control is connected to an outdoor unit to dictate heat mode or cool mode.

If any central control is connected to all systems then carefull consideration of indoor unit groups & outdoor unit configuration need to be taken into consideration to ensure no conflict between mode & temerature settings at the central control & the yaco auto mode selector control.

Clearly if any group of indoor units has more then one outdoor unit which has different yaco mode control then there will be conflict between settings made at the central controller & the yaco mode control.

Temperature control problems will result & as the systems are R22 & with MJ103 central control we would have to assume the enduser has endured this poor temperature control for the best part of 10 years.

SkyWalker
10-12-2009, 07:43 PM
yes thermatech you would be correct, the systems where installed in 1998, i am going to change the groups on the central control so all the indoors with the same condensor are in the same group with no others, hence i will finish up with 10 groups, dont suppose you know where i can find setup manual for the old central control? i got a mitsi disk but this is 2008 onwards,

thank you for your informative and promt response, + rep power