Mitsubishi Electric city multi

[sumsor]

Hi there,
I`m currently installing a ciy multi system PQRY series with water heat exchanger in a big hotel complex.
Has anybody got any experience with this system and if so, any common faults/problems while installing or during testrun?

Cheers

Sven

[Thermatech]

The water cooled PQRY system is exactly the same as any other ME City Multi system except for the water heat exchanger.
So installation & commissioning procedures are all the same except for water flow rate.

If you cannot directly measure the water flow rate then try this.

Make sure you have plenty of heat load at indoor units
Put complete system in test cool.
When the compressor is ramped up to max speed
measure temp diff water in / water out
Aim for about 5 deg C diff with regulator valve & water flow will be near enough
If the water circuit flow temp falls below 5 deg C or rises over 50 deg C the system will stop on water temp faults.

Ideally you want flow temp arround 20 so at max cooling water out will be 25 & max heating water off at 15.
If the water flow temp is higher then the system runs with higher than nessessarry discharge pressure & comp amps in cooling mode
but if water flow temp is much lower than 20 then in heating mode then you start to get close to the low water heat exchanger fault conditions.
So 20 is about safe water flow temp for max heat & max cool operations.

Normal for main contractor to be late on finishing & commissioning water pipe installation.

[marc5180]

A thanks would have been nice

[K.R.Iyer]

I agree with you Marc5180. Sumsor must be probably busy in installing his unit!!!

People like me also got some good tips from Thermatech on water cooled VRF.

[sumsor]

Hi there guys, I`m indeed very busy installing the system. 12 hr days 6 days a week and a one year old baby keeping me awake.
First time since I`ve posted my question that i`m online again.
But you`re right.
Many thanks to Thermatech for the good advice. It`ll be another 10 month before the kommissioning starts, but I`ll try to give some feedback.

Cheers

Sven

[sumsor]

Hi guys,I`m halfway through the job now(approx 40 CU`s and 200+ Fcu`s), and a problem I`ve struck is that I can`t get flow through some unit coils/BC unit.
The Fcu`s are one PDFY P 32 VME and one PEFY P 250. The BC unit is a CMB p 104v GB slave box.
I`ve struck the problem trying to purge nitrogen through the unit onnections for brazing. On the two FCU`s i couldn`t get any flow, tried with pressure up to 300psi, on the BC box i could only get flow through the low pressure liquid pipe, nothing through the other two main ports.
Any suggestions?

Cheers

Sven