Case for VRF Part 4 of 4

Here's the last installment on our 4 part series about VRF HVAC Systems. Special thanks to my guest presenter Kristof Irwin.
Best,
Matt Risinger

[god]

excellent presentation ! I am looking to model my new 3000 sqft apartment and vrf is now very much in contention. thanks Matt and Kristof. You rock.

[bob_frazier]

Wow, just crazy great stuff Matt! And that you found a guy like Kristof - what a duo. Thanks to both of you! Now, what will my gc do when I as a homeowner start asking about multi-split VRF systems in my new build.... ha!

[CrystalMCruz]

Hello Matt, Kristof mentioned (20:47) an auxiliary duct can be used along with the 4-way large cassette. We're building a home and will be putting in our HVAC system soon and curious to see what these auxiliary ducts look like. I've seen many of your videos and love them!

[chriswelles]

This series has been great.  Best material I've seen regarding VRF's by far and it's really focused my attention on them.

One big question I've stumbled into regards the ramping up or down of capacity on an individual head unit in a multi-split system.  When I look at mini-split units, I see a supported capacity range.  When I look at units in a multi-split system, instead they list a particular capacity.  This implies to me that the multi-split heads only modulate on and off rather than ramp up and down, thus losing a lot in terms of improved latent control, precise temperature control, and more comfort.

The Mitsubishi MSZ-FH18NA is a case in point.  It has one submittal for use in a mini-split, and a different submittal for use in a multi-split with specs that imply the multi-split configuration doesn't ramp.  Trying to read between the lines on the material from other vendors, it seems to imply the same situation.

My question for Kristof is, do the multi-split head units actually ramp up and down in the same way mini-splits do, or is that something they generally don't do at this time?  The current duct zoned variable speed systems seem to advertise a lot about how precise their temperature and latent control is, but I don't see the same thing for the VRF based multi-zone systems.

Thanks again.  This material has been really fantastic.  I'm a fan.

[hillmancentral]

As you guys allude to in the four videos, aesthetic considerations are important for homeowners considering VRF verses other HVAC systems.  In my area of the US, almost all residential systems are heat pumps with standard ducting.

As you guys continue to install these units, it would be helpful to see how these products look in-situ (after the home is completed).  Wall hung mini-splits will not gain any traction in most high-end homes.  I'm curious to see how the cassettes and concealed ducted units look in homes.

It'd also be interesting to hear from a few homeowners their thoughts on the systems.

[NotOurRemedy]

I’m blown away by the idea of a 4 way cassette that can have a small bathroom duct.

Do you know the brands that have this capability?

[DA-PICKLES-VR]

Hey Matt. Based on healthyheating.com cost grading tables. Where do your customers hvac budget typically fall. The only experience I have with your projects is what I’ve seen in the videos.

[tbtlh]

Thanks for 4 part video series. I have been researching mini-splits for about 2 years now. I know Kristof mentioned that the mini-split was a misnomer but I need a little clarification before I call them anything else. First, are mini-split and VRF synonymous? Is VRF and DC Inverter system synonymous? From everything I have learned over the past 2 years, it seems like they are, if so then I will start calling them VRFs. The other thing that I found interesting is that Gree was mentioned. I have been researching that company for the last few months. The biggest difference they have from virtually all others major brands is the suction/low pressure line size (3/8 vs 1/2) .  The price is also consumer friendly. They seem to be the largest producer of the systems in the world. They are Chinese and they company is relatively young compared to the Japanese and Korean players (LG, Mitsubishi, Sanyo, etc). However, they offer the the same 7yr/5yr compressor/parts warranty as the other names. It is always said that is is always about the installer and install. I can understand that, but things do happen in real life and I am curious what experience has been with the product in the U.S. I can only get a little information from different customer reviews at the site.

If I can't go with Gree, LG and Mitsubishi are at the top of my list for different reasons. According to a few distributors I have talked to, LG has the best warranty service for parts and their parts facilities seem to be located here in the southeast (I am in north Florida). And as you mentioned, they are really chasing the aesthetic appeal. Meanwhile, it seems Mitsubishi has the easiest installation due to some of their systems not requiring refrigerant removal for shorter line sets. I think that explains why most vendors here in town who normally install traditional split systems prefer Mitsubishi (it does more thinking for them and they incur less risk). While you may say that one should make sure they have an A+ top of the line installer, I don't believe that helps the product grow because I feel like only about 20% in the business are true Master's of the trade and most of those are going to try to ram one product down your throat and will refuse to install anything else. That effectively negates my trust in their knowledge or their trustworthiness. I believe a good company should collect hundreds of data points on each install they make and keep up with the customer for a minimum of two years, preferably longer. Those data points should be aggregated and shared with the next customer. Giving anecdotal info on why you don't like Brand X is not good enough for me. The true Masters also have the rate to go with it, which is out of reach for most consumers. 

[czmiccommando]

I am considering a multi split system for my home (retrofit). What size ducts are required on the ducted indoor units? Is it one size or a range of sizes based on area? I had originally spec-ed a bunch of the wall mount units for most of the house but the ducted units would work just as well in some locations and reduce the total # of units needed.

[ethanheerwagen]

Hi Kristof, you touched on controls and lack of standards.  Which of the manufacturers is compatible with Nest?  And if the answer is 'none, yet' which would you recommend as having the control architecture that is most likely to be opened up?  Or the best 'proprietary' web-based control system?  Love your work, wish you were in Bay Area.
J