Digital Scroll VRF Systems & Inverter Systems

[weeliang82]

Dear all,

I have some questions that I would like to know ..For Digital Scroll systems, I have an understanding that each of its condensing units contain only 1 Digital Scroll compressors aided with 1 or more fixed scroll compressors. The Digital Scroll compressor will modulate its loading and unloading of its scroll to achieve capacity modulation required.

What I want to know is that, is it similar for Inverter based VRF systems? Is it also 1 Inverter Scroll compressor aided by 1 or few fixed scroll compressor? Or all the compressor is of Inverter Scroll compressor?

Hope that you guys can help me with the questions above..

Thank you...

[DEVIL]

Hello

It depends on the brand, Daikin uses 1 inverter and 1 or 2 standard scroll , and mitubishi electric, 1 or 2 inverters, and depending on the combination, 1 inverter and one standard scroll

[VRVIII]

Hello

It depends on the brand, Daikin uses 1 inverter and 1 or 2 standard scroll , and mitubishi electric, 1 or 2 inverters, and depending on the combination, 1 inverter and one standard scroll

Hi Devil,

Daikin also use 2 inverter scrolls in VRV 14 & 16HP hest recovery.

[DEVIL]

Hi Devil,

Daikin also use 2 inverter scrolls in VRV 14 & 16HP hest recovery.

Hello VRVIII, yes thous are with 2 inverters probably because they didn't had the compressors to add up to maintaine the relationship bitwin the size of the inverter and the size of the standard so to not start producing a new spec compressor they added another inverter or they had some issues the other way around.

But this 2 units make up a little part of the Daikin VRV range, and this is only valid for the REYQ , if you cross to REMQ the 14 & 16 hp have 1 inverter and 2 standard and this makes it even a smaller part of the VRV range

[weeliang82]

Dear all,

Meaning to say that most of the VRF systems (Inverter based) is also a combination of 1 Inverter Scroll compressors + Fixed Scroll? I know that for Mitsubishi's system that is less than 10HP, they uses 2 DC Inverter compressor.

A lof of people in the market had stated that Inverter based VRF systems uses all Inverter Scroll compressor to modulate refrigerant modulation. For example, a 30HP VRF uses all 5 or 6 Inverter Scroll compressor.

[Sridhar1312]

For which type VRF with digital scroll is appropriate and for which application inverter based VRF is applicable.
Off late one of the manufacturer aggressively markets for with VRF /VRV with Digital scroll. Out come is in many projects there are lot of failures and even the manufacturers themselves are not able to reason it out the cause for failure and attribute to high ambient and High ambient is 35 to 39 degree C for 372 hours in a year of 8760 hours.

[VRVIII]

Hello VRVIII, yes thous are with 2 inverters probably because they didn't had the compressors to add up to maintaine the relationship bitwin the size of the inverter and the size of the standard so to not start producing a new spec compressor they added another inverter or they had some issues the other way around.

But this 2 units make up a little part of the Daikin VRV range, and this is only valid for the REYQ , if you cross to REMQ the 14 & 16 hp have 1 inverter and 2 standard and this makes it even a smaller part of the VRV range

Hello Devil,

Yes only the individual REYQ14/16P units have 2 inverter compressors, also the RXYQ8P only has 1 compressor. This is possible due to new compressor design (high press shell G2 compressors) these have an additional internal oil line continually injecting oil onto the scrolls.

This has 2 benefits;
1. Increased sealing of scroll improving pumping efficiency
2. The additional lubrication allows the compressor max frequency to be increased
Both of which allow an increase in pumping capacity with the same physical size of compressor.

[VRVIII]

Dear all,

Meaning to say that most of the VRF systems (Inverter based) is also a combination of 1 Inverter Scroll compressors + Fixed Scroll? I know that for Mitsubishi's system that is less than 10HP, they uses 2 DC Inverter compressor.

A lof of people in the market had stated that Inverter based VRF systems uses all Inverter Scroll compressor to modulate refrigerant modulation. For example, a 30HP VRF uses all 5 or 6 Inverter Scroll compressor.

Most VRF/VRV manufactures use multiple modules when higher system capacities are required.
Example: A 20hp unit would consist of 2 x 10hp or 1 x 12hp + 1 x 8hp modules, each with 1 inverter and 1 standard compressor giving a total of 2 inverter & 2 standard compressors.
The unit would then have a far greater number of capacity steps available allowing the system to meet the required indoor capacity demand.

[DEVIL]

Most VRF/VRV manufactures use multiple modules when higher system capacities are required.
Example: A 20hp unit would consist of 2 x 10hp or 1 x 12hp + 1 x 8hp modules, each with 1 inverter and 1 standard compressor giving a total of 2 inverter & 2 standard compressors.
The unit would then have a far greater number of capacity steps available allowing the system to meet the required indoor capacity demand.

hello VRVIII
you are a little bit wrong on this one, you don't actually need so many inverters for the unit to have the grater number of capacity steps, you would need only one inverter and as many as you want standard comp, and you would fine adjust the capacity with the INV and large adjust with the Standard.
Way you have in any unit (not Mitsubishi) one inv and 1, or 2 standard comp. is because, in case of a large failure on one of the outdoor units, you can take the unit entirely out of the system and go on with the rest, you wouldn't be all out. (been there done that)

and the second reason is that you would have large amount of working hours on the INV compared to the standards.

So, it's for long life reasons.
And that's the theory, and the answer to the original question, yes almost all VRF/VRV brands use one inv and 1 or 2 Standard compressor , but in some cases all the standard compressors are replaced with inverters

[VRVIII]

hello VRVIII
you are a little bit wrong on this one, you don't actually need so many inverters for the unit to have the grater number of capacity steps, you would need only one inverter and as many as you want standard comp, and you would fine adjust the capacity with the INV and large adjust with the Standard.
Way you have in any unit (not Mitsubishi) one inv and 1, or 2 standard comp. is because, in case of a large failure on one of the outdoor units, you can take the unit entirely out of the system and go on with the rest, you wouldn't be all out. (been there done that)

and the second reason is that you would have large amount of working hours on the INV compared to the standards.

So, it's for long life reasons.
And that's the theory, and the answer to the original question, yes almost all VRF/VRV brands use one inv and 1 or 2 Standard compressor , but in some cases all the standard compressors are replaced with inverters

Hello Devil,
I totally agree with you .
Maybe my previous post was a little unclear resulting in a misunderstanding, I wasn’t saying you need additional inverter compressors.

What I meant was; when you have 2 or 3 units joined together as multi system you would then have between 4 & 9 compressors in total, depending on the system capacity. Obviously a greater number of compressors = an increase in capacity steps available.

When used in multi application VRV2 will only modulate the speed of 1 inverter compressor the others will be used at fixed frequency (acting like a standard).
The unit will also auto rotate the modulating compressor every time the unit starts up to ensure even run hours.

Hopefully we can now agree on this one

[desA]

For which type VRF with digital scroll is appropriate and for which application inverter based VRF is applicable.
Off late one of the manufacturer aggressively markets for with VRF /VRV with Digital scroll. Out come is in many projects there are lot of failures and even the manufacturers themselves are not able to reason it out the cause for failure and attribute to high ambient and High ambient is 35 to 39 degree C for 372 hours in a year of 8760 hours.

At these high ambient temperatures, the Te,sat for the compressor may very well exceed manufacturer's recommended operating envelope. This may affect both compressor motor cooling & compressor discharge temperature.

Be careful of operating the compresor continuously with discharge temps greater than 107'C for long periods of time - this will be outside the continuous operating envelope.

[DEVIL]

Hello Devil,
I totally agree with you .

Hello VRVIII

It's a mister how we could finally agree on a post
It's a new begging

[mekaniko5]

At these high ambient temperatures, the Te,sat for the compressor may very well exceed manufacturer's recommended operating envelope. This may affect both compressor motor cooling & compressor discharge temperature.

Be careful of operating the compresor continuously with discharge temps greater than 107'C for long periods of time - this will be outside the continuous operating envelope.

Does any one of you have a copy of the operating envelopes of Inverter and Digital Scroll compressors?

[weeliang82]

Thanks for all the prompt reply and discussion, where now I did had a better understanding on both the systems..

From my understanding, Digital Scroll based systems only have 1 Digital compressors to modulate refrigerant capacity regardless of its size, and the same cannot be said on the Inverter based VRF systems..

1 more questions, did any one here ever do a projected calculation on the payback period when you compared between a Digital Scroll/Inverter based VRF systems and Single Split air conditioner?

For example, a 10HP VRF vs 2HP (Single Split) x 5 ...

[DEVIL]

Thanks for all the prompt reply and discussion, where now I did had a better understanding on both the systems..

Your welcome
We are here for that reason

From my understanding, Digital Scroll based systems only have 1 Digital compressors to modulate refrigerant capacity regardless of its size, and the same cannot be said on the Inverter based VRF systems..

Not realy

The difference bi twin the Digital and Inverter is that it is a different approach from the compressor producer Copeland did the digital and all the others did the Inverter.

The typical VRV/VRF is on variable flow compressor (digital or inverter) and 1-2 standard and for larger models you have the same X n(module) in case one module is having a large electronic failure go on with the other modules

and for your question, it's difficult to answer there are ***** cases with ***** situations
Just for example if u have a VRV/VRF with heat recovery, you could use up to 45% less electricity consumption then single split , but the money recovery depends on the unit usage and the heat recovery possibility .
another factor in heating mode, in multi outdoor unit, one unit defrosts the other unit.
another factor the pipe length is bigger for VRV/VRF
another factor for VRV/VRF you have one outdoor unit witch handles all the need, for single split you have a Christmas tree on the face of the building.
another factor you can match cheaper add it to the building management system(or ad an A/C management system ), so for the time no one is in the building you can shut it all off (big electrical bill difference)

[weeliang82]

Dear all,

I noticed that most VRF manufacturers such as Daikin and Mitsubishi only publishes they are using Inverter Scroll VRF systems, but they didn't specify that their system is using 1 Inverter combined with standard scroll. This had given the wrong idea to consultants and end users that their system is fully made of Inverter scroll compressors. For example, a 20HP outdoor consist of 4 Inverter Scroll compressors.

Is there any website that can explained thoroughly how many inverter scroll and standard scroll they are using in their outdoor units? Or from their catalogues, is there any way to understand how many inverter and standard scroll in 1 system...

As i'm gonna do a presentation to consultant and consumers, I really need to understand this. Hope that you all can help.

Thanks..

[DEVIL]

To manage to match the building needs you don't need more then one inverter, and mitsubishi is having mainly inverters in the units.

But you don't need all of the compressors to be inverters, because you go large capacity steps with the standards, and fine tune with the inverter.

[weeliang82]

I understand that the Inverter Scroll compressor are mainly used to achieve the target capacity, and one Inverter is actually enough ..

However, the problem I am facing is that a lot of people believed that the more Inverter compressors in a VRF system equals better energy savings. Hence, when they find out that the Digital Scroll only operates with 1 Digital compressor, it cannot achieved energy savings as much as an Inverter VRF system...

[DEVIL]

nor daikin or mitsubishi uses digital scroll, they use inverters, you should contact the sales department of the brand you want to explain to the customer and get more details on how they use their technology and how they behave

[richard19800]

Mitsubishi Heavy Industries uses all Inverter scroll compressors (no fixed speed comps) in there VRF, I believe Samsung use a Digital Vapour Injection Compressor in there DVM (VRF) systems and there compressor is made by Copeland,

This may Help?

[manender]

daikin has only 1 inverter and 2 standard compressors in 14 ~ 18 HP

[manender]

samsung has digital compressors,

[manender]

Dear All,
there is no site where it is mentioned, you can figure out from catalogues.

Dear all,

I noticed that most VRF manufacturers such as Daikin and Mitsubishi only publishes they are using Inverter Scroll VRF systems, but they didn't specify that their system is using 1 Inverter combined with standard scroll. This had given the wrong idea to consultants and end users that their system is fully made of Inverter scroll compressors. For example, a 20HP outdoor consist of 4 Inverter Scroll compressors.

Is there any website that can explained thoroughly how many inverter scroll and standard scroll they are using in their outdoor units? Or from their catalogues, is there any way to understand how many inverter and standard scroll in 1 system...

As i'm gonna do a presentation to consultant and consumers, I really need to understand this. Hope that you all can help.

Thanks..