Project Description

Mitsubishi Multi-Room Ducted Mini Split Retrofit

We are a Mitsubishi Diamond Contractor which means we can get up to 12 years parts and compressor warranty on residential mini split air conditioner installs.  We have extensive experience with installing mini splits and ductless systems.

This project is of a house that had a 20 year old 4 Ton Heat pump that used a lot of energy because the backup heat would come on a lot during the winter. The mini split system was designed to have 3 air handlers with only 2 of them being installed and 1 being installed a later date when a 400 sq ft add on will be added. A new system won’t have to be installed, only the refrigerant line and air handler will be added to the existing system

The new system is more energy efficient and very quiet. See videos of the before and after noise levels. The inside system doesn’t sound like a train every time it comes on. The temperature spread throughout the house is absolutely amazing on an old 1946 brick home.

Before Install

After Install

Mitsubishi Multi-Room Ductless Mini Split Retrofit

This was another fun project. The house is a 2 story house with no attic space or any real way of installing ducts. This was the perfect project for a ductless mini-split system. There were a total of 3 air handlers, 1 ducted and 2 floor/wall mounted ductless air handlers. We used an M Series Mitsubishi system that had 1 – 3 port branch box.

The 3 port branch box was installed in the crawl space. The branch box allows for the installation of several different types of air handlers. Interestingly the Branch box is powered by the outdoor unit and the branch box then supplies power to all the indoor air handlers. With this setup you don’t have to run separate power to an electric panel. This is one of the reasons why these mini split systems are incredibly energy efficient.

The upstairs rooms were conditioned with 2 wall mounts. Fortunately the way the house is setup there were crawl spaces on the sides of the rooms we mounted the units, making easy to run new line sets and drain lines. These 2 units run ultra quiet and maintain temperature in the rooms fairly easy.

Lennox Mulit-Room Ductless Mini Split Retrofit

The customer located in the Dallas area for this ductless air conditioner project called us in 2018 to install a lennox multi room mini split air conditioner. They liked it so much they wanted to add on to the system in 2019. That’s the great thing about multi room mini splits, if you plan ahead you can account for additions or doing more when the budget increases.

For this project they originally only wanted to install 2 ductless wall mount units in the living area and dining area. The home was originally built in the 1940’s so it’s almost 80 years old. It never had central heating or air conditioning, only window units and floor furnaces which still work. They were only looking at the air conditioner only system but they do not come in multi zone configurations. We ended up installing a lennox multi room heat pump mini split that allows for heating and cooling. Thankfully we installed this because the floor heater did go out at 1 point before they could repair it, so the heat pump was there for backup.

Any type of home is great for whole house mini split systems but older homes are perfect for retrofits when they’ve never had any type of central HVAC system. A blank slate is perfect because it’s easier to run refrigerant lines than attempt to install ductwork from one central location.

This year they wanted to add a zone to their bedroom which was an easy add-on due to 1 extra port that wasn’t being used on the heat pump. The install didn’t take long, the hardest part was getting through the shiplap and brick exterior.

When it comes to multi room mini split installations it’s good to take a few things into consideration.

  • Your budget: Mini splits come in all different configurations and setups. There are multiple brands entering the mini split market and some brands are more expensive than others. Not all brands can achieve the same heating and cooling capacities as other brands. Also, when comparing mini splits to regular split systems, it is important to compare apples to apples. Mini splits are variable speed systems so it’s important when comparing to mini splits that you look at comparable SEER rated variable speed split systems
  • Goal of the project: The great thing about mini splits is they are modular. Whether you decide to use multiple 1-to-1 mini splits or 1 to many multi zone mini splits you don’t have to do everything at once if it’s a retrofit.
  • Proper Heat load Calculations: This is probably the most important part of mini splits that most AC companies or installers do not take into account. Although if using ductless systems you don’t have to take into account heat load losses in the duct systems you have to account for rated outputs when installing on multi zoned systems. The ratings for the different types of air handlers for multi zoned systems vary depending on the number of units connected plus the length of all the refrigerant lines connected.
  • Aesthetics: Mini split indoor units come in different shapes and sizes. There are wall mounts which most people think of when it comes to mini splits. There are floor mount units, ceiling cassette units, ducted units and concealed ducted units. With all these options multi room mini splits can appeal to everyone.
  • Installation: This is something to pay attention to whether it’s new construction, remodel or a retrofit. Retrofits are probably the hardest when it comes to installation because the boundaries of walls and floors are already set. But on new construction and complete remodels it’s actually is easier to install than regular systems because you don’t have to run ducting. Refrigerant lines are a lot easier to install and run through walls than ducts.
  • Long Term: Mini splits just last longer than regular split AC systems because of the variable speed compressors. Without the hard starts and stops the wear and tear on the equipment is a lot less. Long term investment is great for mini splits because of the longevity of these systems.

For this project, when we met with the customers we discussed all of these factors. Because they had been living in the house for a while and planned on staying there for a very long time, they had a certain budget each year to achieve a complete installation.

They actually liked the look of the ductless wall units so they wanted that look. Originally they wanted the floor mounts in one of the rooms but we couldn’t fit it in the area they wanted it.

The installation was fairly easy because they were ok with running refrigeration lines on the outside, then covering them – for 1 of the lines we were able to use the crawl space.

We are going to be adding another mini split for the upstairs attic conversion at a later time.

Mitsubishi Ductless Single-Unit Addition

This project was more than just the ductless mini split addition. The homeowner had purchased the house a year ago so they got to experience 1 summer and 1 winter in the house. There were many issues with this renovated home but we are only going to discuss the issues with addition to the home. The way the house is laid out didn’t allow for proper air flow from the central HVAC system on the far side of the house to get to that portion of the house.

The master suite is a 400 sqft addition and the way it was added, the majority of the walls are exterior walls. Normally this wouldn’t be an issue but most Real Estate investors that flip houses never pay attention to energy or comfort when remodeling a home. Typically all renovations are geared towards aesthetics without regard to actual comfort.

My advice to anyone considering purchasing a home that was renovated by a house flipper is to have a professional electrician, plumber and HVAC technician inspect the home. Inspectors are great but they are generalists and aren’t licensed in any of those trades. Have a specialists check out all major systems before making such a large purchase. From our experience we have seen this happen too many times where a home has some plumbing, electrical or hvac issues once the home is sold.

When we inspected the house last year after they already moved in, we found there was no insulation in the attic at all and the ducts weren’t sealed. We fixed several items on the HVAC system but there wasn’t much we could do at the time to help the master suite area. The addition is facing west with no trees to block the sun, uninsulated attic, a black low profile roof with an uncovered concrete patio in front of it. To sum it up this addition turns into an oven during the summer months.

During the summer months the lowest it would get was 85F and that was during the day. At night it wouldn’t get below 80, making the room somewhat unliveable. In the winter they could never get it above 65 when the temperature dropped below 40.

Finally the owner wanted to make the upgrades, so we installed as much insulation in this portion of the attic by taking off the siding to the addition to get to the attic. To ensure proper heating and cooling we installed a ductless ac. The mitsubishi ductless heat pump is a MUZ-HM15NA and the indoor ductless wall mount is a MSZ-HM15NA. The system is working great so far and the homeowner is very pleased at how fast the system heats and cools the space. Oh and it’s extremely quiet.

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