Diversity Factor

[Contactor]

Hi Everyone

Heat Pump VRF 2 pipe, large shop, lots of self contained fridge cabinets (condensing indoors)

Am using diversity factor of total x 0.85.

Does anyone think this is about right?

Thanks folks

[Contactor]

Thanks everyone for the informed and helpful responses to this exciting thread.

[Brian_UK]

Yes, it does seem to have fallen on sad times doesn't it?

Hopefully it will get picked up soon.

[Iceman1956]

When you say total, I take it you have either calculated the total heat rejection from your equipment or you are working on manufacturers data ??

[Abby Normal]

ypou need to calcualate the peak loa of the building as a whole and size it accordingly.

Wetting your thumb in the air and picking 85% is simply a guess. Good luck.

[Contactor]

Peak load x 0.85

[Thermatech]

Be carefull with Relative Humidity in the area of the shop with the cabinets & integral condensers.
I have had to troubleshoot a number of shops with this setup over the years with multi split systems & VRF systems installed.
The problem is the integral condensers only produce sensible heat.
The a/c is constantly dehumidifying & the RH gets very low , like 30 % RH & then the indoor units are stopping cooling 1/2 the time on coil frost prevention. Then the room temperature get too hot because the indoor units only cooling 1/2 the time & RH still stays around 30%.
The inverter split systems or VRF systems monitor the suction pressure / evaporating temp & because its very low due to the low RH room air on coil the outdoor unit slows down the compressor to raise the suction pressure to match target evaporating temp.
This results in poor cooling performance at all the indoor units.

The lowest indoor operating on coil WB temp for most split systems & VRF systems is 15 deg C WB & for sure the WB temp in the area of the shop with integral condensers will be lower than 15 deg C unless you address this issue.

Really for this application diversity is not the most important issue as greater efficency savings can be achieved by using remote condensers for the cabinets & then the SH ratio is within the operating range of the split or VRF systems.

Did you consider using heat recovery vetilation on your project ?
With 12 months of the year cooling requirement & free cooling available for more than 6 months of the year with fresh air large energy savings to be made.

[Contactor]

Very helpful post Thermatech, thanks.

Had not considered heat recovery but makes a lot of sense.

Remote condensers are not really an option as the shop is using stand alone cabinets, I wonder if these can be modified.

They also have a large kitchen and it's all open plan. The kitchen is not very well vented, either.

They're spending a FORTUNE on electricity.