24 Reasons to STOP Specifying VRF
24 Reasons to STOP Specifying VRF
2. Claims of heat recovery substantially exaggerated. The system as typically piped serve zones with similar loads, especially for schools where all spaces have day light, making the cassettes ALL either in cooling or in heating mode. There is no heat recovery.
3. Oversizing of Equipment, especially Condensing units for a heating dominant climate. By as much as 30% of cooling load. We’ve seen shop drawings showing VRF (connected to a cooling tower mind you) sized at 1.5 KW/ton.
4. Heat pumps do not perform at low temperatures, according to their AHRI testing. They perform because their compressors are oversized (sized for heating, not for cooling). Lack of supplemental heat requires cassettes and condensing units to be oversized to match the building heating load. The elimination of electric supplemental heaters is hidden into the cooling oversizing of compressors.
5. Use of DX rooftop units for large spaces such as Multi-purpose rooms, Gym, cafeterias. A chilled water system will not have DX RTU’s. A chilled water system will have a 50% cooling block load compared to VRF system.
6. Claims of energy savings available are always comparing VRF with DX RTU with electric reheat, the comparison is to the least efficient HVAC system. DX RTU with electric reheat does not even meet ASHRAE 90.1 for large commercial spaces.
7. Studies comparing Geothermal heat pumps to VRF indicate that GSHP beat the VRF in energy savings for a lot less first cost and LCC.
8. First cost is the highest of any system. As much as twice of a 2-pipe CHW/HW system using air-cooled chiller with condensing boilers.
9. No LCC available for VRF anywhere.
10. Many cassettes and Branch selectors in ceiling space to maintain.
11. High pressure refrigerant piping in space. Resulting in installing multiple units to comply to ASHRAE 15.
12. Proprietary systems for government projects.
13. Proprietary control system – Not BacNet compatible.
14. No data available to engineers on cost or on drawback of proprietary system on client.
15. System is not ducted type distribution. Low static pressure capabilities for ducting. Additional ducts make the system even more expensive.
16. Cannot add any additional units to the piping system.
17. VRF piping requires higher skilled labor for installation, resulting into higher prices and elimination of competition.
18. No high efficiency filtration capability.
19. No local humidification capability.
20. Requires DOAS system.
21. They tell you their compressors have inverted VFD, etc, they can go down 50%. What they don’t tell you is that in heating mode, their compressors (already oversized by 50% remember) will go to 150%, i.e go from 60 to 90 Hz to address the heating load. The same affinity law applies. You go down in cubic root in when slow the compressor, you also go up by cubic power when you speed the compressor in heating mode. If you oversize a system by 50% and then speed it up by another 50%, where are the savings exactly?
22. This is just another craze, just like the UFAD and the chilled beam fads (aka induction units that came from Europe with a chic name). No disrespect to Europeans. The same way raised floors for electrical wiring in office space craze.
23. The system hurts the local Economy. The VRF system puts ALL the money only in two pockets
a. The VRF manufacturer - exclusively Japanese and Korean
b. The local Vendor
24. Many trades are put out of business – Many jobs are lost in local economies:
1) Piping manufacturers and installers
2) Boiler manufacturers and installers
3) Pumps manufacturers and installers
4) Insulation manufacturers and installers
5) Chiller manufacturers and installers
6) Valve manufacturers and installers
7) Sheet metal workers
8) Air device and accessories manufacturers and installers
10) Pipe fitters
11) Controls manufacturers and installers
12) Balancing contractors
13) So many jobs are lost in various parts of the country due to the VRF system
14) Design MEP firms when renovating projects in the future