Toshiba VRF systems

[puddleboy3]

Ive been asked to inspect some tosh VRf systems and i must admit im not to up to date on tosh equipment, im more of a Daikin man. But hey i'll go where ever they want to pay me! LOL. Ive a good idea that it has not been installed corrrectlly, my question is what should i be looking for? Is it pretty much the same as Daikin as for pipe lengths refnet joints etc?

[frank]

Pretty much so. Some time ago I went on the Tosh VRF trainingcourse and I've got the paperwork in the office.
It's not something I work on everyday but if you find a problem, give me a shout and I'll try to look t up for you.

[Jase]

Also look out for the 'multibox' if system is 3 pipe. It's basically like a bs box, only difference is that the piping from outdoor connects to it and a number of indoors are fed from it. Hopefully it will be accessible;if not, then boy you will have probs especially if you have any valves to change!

regards
Jase

[puddleboy3]

Thanks for the replys, went and had a look over the system, was pretty straight forward. I managed to get my hands on a technical cd with install manuals, service manuals and application manuals. The biggest problem on site was its a R407c multi system pretty much the same as the daikin R407c plus system, the manuals state that the inverter unit must be installed closest to the first refnet branch then in order depending on capacity of unit for example 28HP the outdoors would be lined up as so 10HP inverter, 10 HP fixed speed unit and then the 8HP fixed speed. This was not the case and the inverter was lets say last in line. The systems were working a treat so my question is what difference does it make in this situation?

[frank]

for example 28HP the outdoors would be lined up as so 10HP inverter, 10 HP fixed speed unit and then the 8HP fixed speed.

This sounds like the Daikin R407C VRV Plus

[puddleboy3]

LOL my thoughts exactlly frank, makes you wonder who copies who? Also noticed it was the same pressure sensors on the system, and the control wiring was pretty much the same, the only difference was it was screend cable. Heres a question my understanding of screening a cable was that you terminated the earth at one end. Is this right?

[frank]

Heres a question my understanding of screening a cable was that you terminated the earth at one end. Is this right?

Thats correct. If you ground at both ends you may get dual earth paths which can lead to interferance. I've got some info on this, I'll dig it out.

[BritCit_Juve]

I think that they want the units in order of largest capacity as they have the highest compressor flow rate and if the smallest unit is first it has to work harder to discharge into the pipeline.
If a screened data cable is installed with the earth connected at both ends it acts as an arial with interference introduced into the data cables. The eath should only be connected at one end and preferably at the outdoor unit. The screen should be continuous along the lensgth of the data cable
BritCit

[John Wood]

I look after after a site, with one of these Toshiba multi condensing unit vrf systems. We have had a lot of trouble with the PMVs sticking closed. Have just sent one to Toshiba for analysis, has anyone else had this problem? System is 2 pipe with PMVs on the cassettes.

[rbartlett]

I know Macwhirters has a load of trouble with a Toshiba VRF on 407c regarding the fractionation problems. Got very political and ended up nearly going to court before the cheque book was opened...

I too remember going on the VRF course- in Plymouth.
However we went the night before andwere with an ex Navy guy who knew the area very well-I spent the whole of the course clutching the coffee dispenser...:-/

On the note of who copies who I remember a conversation with someone from high up of one of the big Jap manufacturers and he basically said that they not only copy, in fact the factories pretty much collude and share information

Cheers

Richard

[bebad]

Tosh PMV's
Had several troublesome sites, evil to change in splitter box too

[puddleboy3]

I have since been to site and re arranged the outdoor units as per the install manual, but i have got one system. Its a two pipe system with 8 four way blow units on it and one remote controller when on auto the system seems to go to heating even though all fan coils should be demanding cooling due to the high heat load in the room. Any ideas?

[frank]

"One remote controller, when connected to the correct site wiring, can control up to 16 units.

Units in a group will always obey command signals from the Master unit, albeit they will cycle in the heating/cooling or cooling mode in response to the local requirements.

Twin units will always follow instructions from the Master.

A Group of units may comprise of single units, twin units, or a combination of both.

In a large installation, group control will minimise conflicting commands and be simple with economical running."

I copied this from the Tosh manual. Not sure if it relates to VRF though - I couldn't find anything in the VRF book.

[Andy]

I have since been to site and re arranged the outdoor units as per the install manual, but i have got one system. Its a two pipe system with 8 four way blow units on it and one remote controller when on auto the system seems to go to heating even though all fan coils should be demanding cooling due to the high heat load in the room. Any ideas?

I seen something like that on a system once. Units would not heat, going to cooling. It was a high ambient at the condensing units, the condenser though it was summer and it would be crazy to heat in the summer.

Kind Regards Andy

[puddleboy3]

I am attending site tomorrow, to investigate the problem, I know that when the outdoors come from the factory they are set to heating priority. Meaning that if any one fan coil on the system demands heating then the full system would change over to heating mode. My system has been set to cooling priority. I know what you are saying frank about the master unit determining what mode the system is in! I know this is the way with Daikin, but speaking to the Tosh helpline which wasnt very helpful, it was explained to me that when connected as group control any of the units will change the system over, you cant just set one unit to do your heat/cool change over like Daikin systems

[Loops]

Puddleboy3

How did you get on with that Toshiba 'Modular Multi' system?

These systems did not have a 'master dicates the mode' function. Each fan coil has it's own return air sensor and refers to the set conditions on the controller to determine the operating requirements.

This system could be set up for either cooling or heating priority via dip switches on the outdoor pcb. So if any one indoor unit wanted the priority mode (irrespective of the number of other units in opposite mode) .

I'd double check that the system really is set up for cooling priority - from the factory heating is priority.

I'd then check the return air sensors. If using the auto-mode then a dodgy air sensor could be the reason why the system goes into heating mode all the time.

BTW the reversing valves are energised for heating mode.

Cheers

Loops

[puddleboy3]

Thanks for all the replies guys, my only problem is i'll never find out how the job ended up as ive moved company and left the problems behind me, but i suspected a return air thermistor to be at fault and causing my system to go to heating. But hey sh*t happens so upward and onward. Thanks again for all the replies