Mitsubishi Electric Par21 controllers

[marc5180]

We look after several site across the UK that use PURY-YGMA and YHMA, They normally use Par 27 controllers in each of the rooms that require a controller and a main G50.

However today i've been working on one of the sites and have found that most of the controllers on the city multi have Par 21 controllers.

When you try to check address settings in the individual controllers there is no option to do so, so i don't understand how the controllers are assigned to the indoor units.

Why use Par 21 controllers over Par 27? I thought Par 21's were for mr slim (12v) and par 27's were City Multi controllers (30vdc).

[Brian_UK]

It seems Par 21's are also for Multi's...
http://www.celsiusair.co.uk/equipmen...i/controls.htm

[moondawn]

hi marc

my understanding of par 21 and par 27 is they can both be used on vrf, the par 21 are wired to the remote terminal block and not the M Net terminal block in the fan coil unit.

So to install for example: Three units off a VRF for par 21 you would need three remotes with three lots of cabling to each fan coil.

where as with par 27 u could use 1 remote and address the three fan coils using only 1 cable and 1 remote.

hope this helps

cheers lee

[regcooldude]

ma21's are a lot cheaper thats why people use them. also 1 ma21 can be used across multiple fan coils, you just link the cables across the 12v terminals

[marc5180]

I have worked on many City Multi's and they always seem to have Par 27's.

This is the 1st one that i have come across ( or have noticed) that has par 21's
I've installed a few City Multi myself and we have always fitted Par 27 controllers on the mnet to the indoors and registered the addresses on the controller

So is the reason for using Par 21's cost more than anything? Surely there can't be that much difference in price?

[regcooldude]

they are a lot cheaper apparently, don't know exact cost and of course they come with a built in 7 day time clock

[back2space]

I had a few of these I sold on ebay, got about a £5 each, they come up all the time.

[Thermatech]

The story is

Many years ago Mitsubishi only supplied 30v dc Mnet remote controllers for City Multi VRF.
But
Mitsubishi sales reps used standard excuse that they lost sales to Daikin because Daikin remote controllers were cheaper than PAR27 30v dc Mnet remote controllers.

Well ofcourse simple technology 12v dc remote controllers are cheaper as you have to directly connect to the indoor unit or group of indoor units with daisy chain control wiring.

So Mitsubishi design department called sales department bluff by providing a cheap 12v dc remote controller eqivalent to the Daikin remote controller.

Now sales have to dream up new excuse for lost sales to Daikin.

The ongoing problem for install & service engineers is the on site confusion between 30v dc Mnet remote controllers with Mnet address & 12v dc direct link controllers with no address.

[R1976]

Every Mitsi VRF I have installed has had PAR 21 controllers. They may be cheaper to buy but It then costs in cable and time for all the additional wiring.

They do have 7 day timeclocks though which is a good benefit.

[marc5180]

Ok thanks for clearing that up guys