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Thread: VRF systems

  1. #1
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    VRF systems

    Earlier today I was part of a Webinar by Mitsubishi where they were giving a some what brief explanation on their VRF systems and honestly to me it seems like some great technology.

    Especially the systems with a branch controller, they are energy efficient and can provide cooling and heating simultaneously.

    After reading some articles I came upon one that claimed the US Navy and US Army Corps of Engineers seem to be against it.

    They listed various reasons, but what do you guys think?

    Some of those reasons were safety, impossible finds of leaks due to long line sets and controls do to them being proprietary.

  2. #2
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    Itís a love hate relationship.
    I love them, and theyíve made me quite a bit of money.
    The cons are they are very proprietary, require specialized techs to work on them, and also the whole thing with refrigerant lines running all over the place.
    However, leaks are not impossible to find. Iíve located and fixed every single one thus far, even one in a lineset up under an outdoor unit I had today.
    But they can be the ultimate zoned system. And be a one stop shop as far as service. And not have to have a mechanical tech, a chiller tech and a controls technician to service your building.
    Iím big into Samsung, but we work on Mitsubishi, LG, and Daikin as well.
    ďI havenít failed. Iíve just found 10,000 ways that wonít work.Ē - Thomas Edison

    ďItís not whether you get knocked down, itís whether you get up.Ē - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

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    As a service tech who works on them infrequently but frequently enough to know about them, and has taken multiple manufactures training courses, I have a dislike for them. You often need specialized software to get in-depth with the programming and troubleshooting of them, their cramped design makes repairs a pain to preform, they are often installed in awkward locations so can be difficult to service. When their controller or head unit becomes obsolete you are SOL. Parts are often not off the shelf available or universal like a typical air handler. If the controls are not user friendly enough for the user then you end up having to re explain how to preform basic operations every time you visit a customers house. I typically find this issue with older people who are less tech savvy. They just want a mercury bulb thermostat or something just as easy.

    When they work then they work great, if they meet your design requirements. They are quiet. But if you get a bad install then you may pay for it for the life of the system. Their are strainers throughout the system and they are not always well documented so they can be costly to locate if there are issues with the system or pipes werenít purged properly.

    Leaks are possible to find but can be more work to locate. If there is a leak or a compressor failure, or some other system issue then the whole system goes down instead of one zone. We have one building where hacks installed the system. Leaks everywhere, ongoing issue, etc... they have one VRF that controls each 1/4 of the building, all residences. Well one unit went down and now those residences in that quarter of the building have no heat or cooling until itís repaired. A water loop system isnít typically crippled quite so easily to a failure. Leaks are easy to find, there are redundant pumps, have one unit fail 30 years down the road and there are 10 different brands that make a new unit to fit that location, configuration, and capacity that will drop right in. Have one unit fail and only one resident is effected. Tower goes down and you can fix it with off the shelf parts and after hour repairs are relatively painless.


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    Thanks for the replies guys, I guess the presenter of the Webinar was a pretty damn good salesmen and he got me.

    Although he said the opposite of the point "thatguy" mentioned of crippling the system. He stated that each line set has shut off valves so that only the "zone" with the leak would be impacted and not the whole system, but if a compressor did go down or control board of course the whole system would be impacted, and as you mentioned if they do use proprietary technology/parts repairs within a reasonable time is just out the window.

    Maybe this is ideal for residential buildings/homes but not for commercial use.

  6. #5
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    Actually, I’d say they are great for commercial spaces.
    My biggest VRF account is a 10 story building that’s entirely Samsung VRF heat recovery. Each floor has a main and sub outdoor unit. I can still run with a failed compressor.
    ďI havenít failed. Iíve just found 10,000 ways that wonít work.Ē - Thomas Edison

    ďItís not whether you get knocked down, itís whether you get up.Ē - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

    Local 486 Instructor & Service Technician

  7. #6
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    As, ThatGuy, stated the proprietary nature of a VRF system is the main reason why the government frowns upon them. I sort of work but don't work for government projects and on government equipment. The government does have a manual, BOOK, out there that goes over everything they want when it comes to equipment. Main reason is really whittles down to the proprietary software and firmware needed to operate systems like these.

    With the ever growing cyber threat, it is getting very difficult to introduce proprietary software or equipment that may operate on their own proprietary firmware, for example Lennox Prodigy/IMC, Trane Tracer/Tracker/Reliatel, York Simplicity/Legacy, Aaon PrismII, Daikin MicroTech, ...now think global with the Chinese and Japanese markets, the threat of sleeper programs are worrisome not only to the government but for government contractor that do critical government work and must abide by the same anti-cyber rules, like Boeing, Northrop Grumman, Lockheed, L3, Honeywell, etc. Government is not only concerned about outside attacks but also VERY focused on inside attacks.

    Majority of our equipment for government stuff is basic solid state only, parts are easily found and not designed to be married to OEM. If OEM there are critical part lists that the government will use to order and maintain those specific parts to prevent lengthy shutdowns. The equipment is managed or controlled by government approved building automation systems. The boards get digital input and generate analog outputs.

    Quick story. There was a building erected for some reason last month. For whatever reason a large Aaon unit was installed for make-up air purposes. Factory start-up is not available since getting a strange unknown Aaon rep onto the property was not going to happen. The Aaon unit was shipped, apparently programmed ready to just power up and go....Yeah right!! So here I am on a cold winter morning opening up the control panel to see two black plastic boxes (Wattmaster Orions) looking at me. Okay, how do I troubleshoot this? Come to find out you need a laptop with PrismII software, not only the software but you need the drivers for the USB Link to communicate with these black boxes!! Try going to the government IT department and saying, hey I need to download these programs to this laptop...LOL It took two weeks to get approval! On top of that they set it up as a sweeper program, which means they allowed it on the laptop for the day but I must keep the laptop in the network overnight to have the software swept out...more or less 12 hour use privilege. Well I was able to work with Aaon that day and learned that the chip on the board had a version of software that was not compatible to what the unit was designed to do. This is why the government frowns on this type of stuff.

    To get this unit to operate, I temporarily isolated the black boxes, threw a remote temp sensor in the return air, ran a temp t-stat line outside from the RA to the control cabinet, have a t-stat in the cabinet set for remote sensor, hand set the VFDs to run the blower continuously, and allowing the direct fired system to run its own course based on the discharge air temp, it is doing great, high probability it will just stay like this until season changes and then I will have to rethink things for cooling.

  8. #7
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    Here is the government site that has all THEIR building codes: https://www.wbdg.org/ffc/dod/unified...s-criteria-ufc

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    Here is the manual just on HVAC controls.
    https://www.wbdg.org/FFC/DOD/UFC/ufc...02_2018_c1.pdf
    They talk a little bit about VRF proprietary stuff in Chapter 2, Section 4.2.

  10. #9
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    Hey slctech, that was a great and detailed response. Thanks for the reading material as well!, I'll definitely be reading those articles!

  11. #10
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    Quote Originally Posted by BuildingMech88 View Post
    Thanks for the replies guys, I guess the presenter of the Webinar was a pretty damn good salesmen and he got me.

    Although he said the opposite of the point "thatguy" mentioned of crippling the system. He stated that each line set has shut off valves so that only the "zone" with the leak would be impacted and not the whole system, but if a compressor did go down or control board of course the whole system would be impacted, and as you mentioned if they do use proprietary technology/parts repairs within a reasonable time is just out the window.

    Maybe this is ideal for residential buildings/homes but not for commercial use.
    You can isolate each zone after you find the leak. And if you manage to find it before itís an issue then people arenít affected except for that one that has the leak( unless itís on a main or branch line without a local ball valve to isolate it).

    Typically I find leaks are not found until people start reporting lack of system performance, or error codes on the displays. At that time everyone had already been effected and they will continue to be effected until the main system has been brought back up again.

    The building I mentioned has random compressors so there is a level of redundancy.... unless there is a bad burnout, then the second compressor just helps to pump the crap in the system further down the lines and can make clean up more difficult.

    Cooling tower/boiler setups with WSHP is my preferred method. One persons cooling can still heat another persons room just like a VRF. Although I believe it would be less efficient than a VRF, the lower ease of repair and universal nature of the system makes up for it in my opinion.


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  12. #11
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    We have a building that has 3 miles of
    Piping installed. When that piping was installed, joints were soldered together and
    Shoved up into chases between the floors.

    All systems passed the 24 hour 600 psi verified test. Within the last ten years. 4 leaks have developed and luckily been found.

    There have also been MANY electrical and sensor failures.

    Personally, I think they Are the newest fad for salesmen to show great environmentally friendly, energy efficient, LEED point greatness.

    Donít get me wrong, Iím all for energy efficiency. But, Iím not sure the potential for leaks, 100ís of heads, and the amount of refrigerant in the systems, is the way to get there....not to mention the software/proprietary side of it all.

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    Quote Originally Posted by 71CHOPS View Post
    Donít get me wrong, Iím all for energy efficiency. But, Iím not sure the potential for leaks, 100ís of heads, and the amount of refrigerant in the systems, is the way to get there....not to mention the software/proprietary side of it all.
    Agreed. When does the cost of expensive repairs take away from what is being saved so much so that in the long run, WSHP are just as or are better on the bottom line?
    "It's not that I'm smart, it's that I stay with the problem longerĒ
    Albert Einstein

  14. #13
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    Quote Originally Posted by BuildingMech88 View Post
    Earlier today I was part of a Webinar by Mitsubishi where they were giving a some what brief explanation on their VRF systems and honestly to me it seems like some great technology.

    Especially the systems with a branch controller, they are energy efficient and can provide cooling and heating simultaneously.

    After reading some articles I came upon one that claimed the US Navy and US Army Corps of Engineers seem to be against it.

    They listed various reasons, but what do you guys think?

    Some of those reasons were safety, impossible finds of leaks due to long line sets and controls do to them being proprietary.
    Can you Post those articles?

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