1. Variable Refrigerant Volume
Munters Applied with
Variable Refrigerant Volume
A Great Combination
VRV is a Daikin Registered trademark, which stands for Variable Refrigerant Volume
The VRV technologies were developed and introduced by Daikin engineers to bring to market a revolutionary, high efficiency HVAC system that would have unique attributes not found in traditional HVAC systems
Variable - Adjusting the system capacity up and down to match the load as it changes
Refrigerant – Use multiple DX Fan Coils connected to one Condenser unit on a single refrigerant circuit, to provide individual zone temperature control.
Each fan coil has the ability to adjust it’s subcooling and superheat to maintain accurate and comfortable space temperature control under all load conditions.
Volume - Regulating Refrigerant Flow through the system using EEVs and Variable Speed compressors
Over 1 million Daikin VRV systems have been installed throughout the world, in the past 28 years. To date there are over 5,000 VRV installations in N Amer.
The Daikin VRVIII was introduced In mid 2008, as the 7th generation of the VRV system.
Scott McGinnis– DXS North Texas

2. Other Great Combinations

3. Variable Refrigerant Flow Systems require a DOAS
OAU
Vent Air to Space

4. OA Direct to Space
ASHRAE 1565-RP: ASHRAE has commissioned the Univ of Nebraska to write the official: “Design Guide for Dedicated Outdoor Air Systems” Will state that the best design practice is to duct the OA direct to the space. Estimated publication in 2014

5. Sensible Heat Ratio Sensible Energy / (Sensible + Latent)
Auditoriums, Theaters - SHR :
Banks, Court Houses, Municipal Buildings - SHR :
Churches - SHR :
Cocktail Lounges, Bars, Taverns, Nightclubs - SHR :
Hospital Rooms, Nursing Home, Patient Rooms - SHR :
Malls, Shopping Centers - SHR :
Medical/Dental Centers, Clinics and Offices - SHR :
Retail, Department Stores - SHR :
School Classrooms - SHR :

6. How to Divide the Sensible Heat Ratio (SHR)
latent
Sensible
75F

7. 3 Issues Munters can add value to VRV
VRV Fan Coil Units have high SHR coils; space can’t keep up with all latent
Munters low dew point air takes care of entire Latent Load, then VRV is downsized
Munters HCU technology offers energy savings over other 100% OAUs trying to reach low dew points with brute force

8. Why Low Dewpoint? Loads in a typical K-12 classroom = .71 SHR
VRV FCU’s Engineered around ~ .85 SHR
At full load when the sensible load is met, roughly half the latent load is unaccounted for…

9. “Normal” Neutral Air Supply
Delivering the ventilation air at 70 deg & 55 DP:
Provide 1925 btu sensible but ZERO latent…
This makes the SHR .68

10. Munters 48 Dewpoint Air Supply
Delivering the ventilation air at 72 deg & 48 DP:
Provides 1156 btu sensible AND 4345 btu latent
This improves the SHR to .93
VRV systems can keep up!

11. How to Divide the Sensible Heat Ratio (SHR)
latent
DOAS Dew
75F

12. VRV Design Improvements
Size VRV for sensible loads (lower tons)
Eliminates nearly all zone condensate
Maximum efficiency and comfort control
ASHRAE recommended, Application Ch 7

13. Free Standing Emergency Departments
VRV plus Munters DryCool = Lower $$

14. VRV selection with Neutral Air Unit (72F/55dp)
VRV selection with Neutral Air Unit (72F/55dp). Select for Total Space Load
= 28 tons

15. With DOAS to cover Space Latent Select VRV to Cover Sensible Only
= 20 tons

16. How dry does the OA need to be?
OA = 5295 Space Set Point : 75Fdb/50%rh Latent Load = 74,100 BTU 74,100 = (5295cfm) x .68 x (64.92gr/# - ?) ? = ~45 dew point

17. 55 F

18. Variable Refrigerant Flow / DOAS Divide and Conquer
Vent Air to Space 46F Dew

19. Brute Force DX down to 46F dew point
Cooling
Airflow (SCFM)
5295
Entering DB (°F)
Entering WB (°F) 84 76
Leaving DB (°F)
Leaving WB (°F) 46
MBH required
510.5
Tons
42.5
MBH sensible
218.3
MBH latent
292.2

20. VRV and Munters Munters HCU uses 30 tons DX Coil down to 55F
Delivered Dew is 46F (hoping for 45F, close enough)
Option 1: 28 tons of VRV plus 30 tons of DX down to 55F
No latent control of space, higher tonnage, higher %rh
Option 2: 20 tons of VRV plus 42 tons of Brute DX to 46Fdp
Latent control via DOAS, better comfort, Higher energy
Option 3: 20 tons of VRV plus 30 tons of Munters HCU to 46Fdp
Latent control via DOAS, better comfort, lower energy

21. Energy Analysis Daikin has a VRV analysis:
2. Munters has a couple of analysis:

22. Munters vs Brute Force
40 tons

23. VRV Analysis with Latent: $9,548.00

24. VRV with all Sensible: $6,747.00

25. VRV and DOAS First Cost and Energy Cost
VRV with 28 tons and Latent Box: $58,055.00
Brute Force OAU at 55F dew point: $36,000.00
Equipment $94,055.00
Total Energy Costs: $22,445.00
TOTAL FIRST YEAR COSTS $116,500.00
VRV with 20 tons and Sensible Only Boxes: $43,850.00
Munters HCU with 46F dewpoint $51,000.00
Equipment $94,850.00
Total Energy Costs: $19,981.00
TOTAL FIRST YEAR COSTS $114,831,00

26. VRV and DOAS First Cost and Energy Cost
VRV with 20 tons and Latent Box: $58,055.00
Brute Force OAU at 46F dew point: $
Equipment $106,055.00
Total Energy Costs: $28,826.00
TOTAL FIRST YEAR COSTS $134,881.00
VRV with 20 tons and Sensible Only Boxes: $43,850.00
Munters HCU with 46F dewpoint $51,000.00
Equipment $94,850.00
Total Energy Costs: $19,981.00
TOTAL FIRST YEAR COSTS $114,831,00

27. Conclusion
Munters DOAS can control space Latent, allowing VRV to be sensible only. Better use of coil capabilities (SHR) Better control of space temp and moisture (%hr): ASHRAE best design practice Downsize VRV outdoor tonnage and collected indoor tonnage More efficent, less first cost Use of Munters HCU saves energy over similar Brute Force DX Systems