New whole house mini split project

[dneiding]

This is not directly garage related but since there is frequently talk about using a mini split in the garage, I thought I post my recent mini split install in my house.

I have two propane furnaces in my house and two rooms that use electric baseboard. I have no central A/C. I decided to install mini splits in the four bedrooms, living room and dining room. These six indoor units are hooked up to three outdoor compressors; a single-zone 18K BTU, a three-zone 27K BTU (only using two zones on that one) and a four-zone 36K BTU (only using three zones on that one).

I bought everything from www.alpinehomeair.com. They have a nice sizing program on-line. Once I had everything sized per their on-line tool I called and spoke to a CSR and he helped adjust a few things once he heard my specific plans - also offered me a small discount to buy everything at once vs piecmeal.

Everything was shipped via freight and I received it in two days.

I watched all the YouTube videos on installation I could find and felt pretty comfortable doing the installation. As expected, the first one took the most time and by the time I had two of them done I was able to zip through the rest.

A HVAC friend of mine came over last Saturday and pumped down all of the lines and we got them up and running. I finished the line-set covers today (bought those from Amazon).

So far, they are super nice. Very comfortable, consistent heat and quiet. The temperature has only been in the low-30's so far so I don't have any experience with the performance in very low temps. Literature says they are 80% efficient at -13 degrees so we will see how they work.

 

[theoldwizard1]

I have two propane furnaces in my house and two rooms that use electric baseboard. I have no central A/C. I decided to install mini splits in the four bedrooms, living room and dining room. These six indoor units are hooked up to three outdoor compressors; a single-zone 18K BTU, a three-zone 27K BTU (only using two zones on that one) and a four-zone 36K BTU (only using three zones on that one).

I am no expert, but from what I have read, the multi-zone units are not as efficient as the single zone ones. I am sure they will all work fine and you will enjoy the cool air next summer !

Having some kind of backup heat when you are using a heat pump as your primary heat source is a good idea !

A HVAC friend of mine came over last Saturday and pumped down all of the lines and we got them up and running.

Didn't the lines come pre-charged ? If he has the equipment and the time, that was probably a better option, but it is not longer a DIY job.

 

[dneiding]

I am no expert, but from what I have read, the multi-zone units are not as efficient as the single zone ones. I am sure they will all work fine and you will enjoy the cool air next summer !

No doubt a multi-zone will be less efficient.

Didn't the lines come pre-charged ? If he has the equipment and the time, that was probably a better option, but it is not longer a DIY job.

The lines do not come pre-charged. This brand is considered 90% DIY. Of course, if you have the pump and the gauges it could easily be 100% DIY

 

[fitter30]

Have two systems for my house three wall units per ,two condensers. Like the minis except in defrost no heat, have two with condensate pumps they get slimed up clean them couple time a summer and use a shop vac to **** lines out. Cleaning evaps is a pain pulling blower wheels and washing coils. Might want to check with your electric company for any rebates.

 

[SALIV8]

Looks great!!

 

[jjrbus]

Have 3 separate Daikin units in house, I like redundancy. Bought several hundred dollars worth of tools for self install.

Have mold problem in one, what a pain it is to keep the evaporator clean. Not the coils, they stay very clean, the blower fan. Seems 2% have mold problems. Most in humid areas, I'm in Florida.

 

[dneiding]

Might want to check with your electric company for any rebates.

Already submitted the paperwork for $300 rebate per outdoor unit!

 

[dneiding]

Like the minis except in defrost no heat, have two with condensate pumps they get slimed up clean them couple time a summer and use a shop vac to **** lines out.

How often do they defrost? The 27K unit I have hooked up in my master bedroom seems to defrost more than I would have expected. It hasn't even dropped below 30 degrees here and sometimes, it seems to defrost every 45-60 minutes. The others could defrost just as often and I probably wouldn't notice. If I am in the house I am usually in the bedroom.

 

[Kaizen]

Price tag?


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[dneiding]

Price tag?


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About $7,000

 

[yeldogt]

The key with any system is getting the proper sizing done -- buying the correct model for your application. Fear of not having enough capacity often results in oversized systems.

When you read the specifications -- the efficiency is achieved at a set point in the system band. The unit is not getting the highest EER SEER reported number all the time. Many are in the 75% - 80% power range for max efficiency ... Ideally you want to peg the needed output of the unit to match the load. It's not unusual for the multi head systems to stay in that band more often. So, while they may not be able to match a single at one output .. they can often still be more efficient.

This should not be confused with output over a temp range .... you will see the units that are designed for heating in cold temps will often give a lowest temp where they still give full output ... this is not efficiency. You want to match this number to the load of the house -- sometimes with non hyper heat units this number drops off and the solution is to get a larger unit for heating .... this will often make the unit oversized for cooling. Also - not all units have the pan heater ..make sure if you are using for cold heating that it has a pan heater and intelligent defrost

Another factor is the heads -- some companies are coming out with small heads (6k) ... people get confused with sizing. It's not uncommon to have more head output vs what the outside condenser will supply .. again it's matching the load. This gets hard in small rooms.

Mini splits are great .. although ... they have issues. The heads require some placement thought .. they work best when centered in a room ... not the most attractive things. I have used the ceiling in a few applications to try and hide ... the high end Mitsubishi head has twin output vents and an occupancy sensor -- so it's a bit better with odd room placement and still circulate the air.

I did a wall mount on my first multi head -- I can feel some vibrations/ noise. It not really objectionable .... but .. I will never do another.

Running the lines is always an issue as they are unattractive. My new build will have two systems -- I was going to do a single with three heads ... but the needed outputs make having one a single .... it's going to rarely be used for heat.

Remember -- because the expansion occurs in the condenser. It's really important to insulate the lines -- the heads are basically just coils. Both lines need to be fully done .... the multi will always be transferring some refrigerant to all the heads .. even when off. That's why the multi heads need to be thought out

 

[Kaizen]

About $7,000

In your research did you happen to look at those large outdoor units like Mitsubishi has? Same concept but it runs lines to several handlers instead of head units.
Also why would a larger four zone be less efficient then several smaller units?


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[dneiding]

In your research did you happen to look at those large outdoor units like Mitsubishi has? Same concept but it runs lines to several handlers instead of head units.
Also why would a larger four zone be less efficient then several smaller units?


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I did look at those units and price was at least 3X and require professional installation.

As far as mulit-zone vs single-zone efficiency, the outdoor compressor has to find a speed that fulfills the needs of each head attached to it. Since each head is in a different room (and therefore potentially a different temperature) the compressor will run at something compromised. My understanding is the advertised SEER and HSPF ratings are when running at max efficiency so when running in a compromised state you are not getting max efficiency.

That being said, for me, the cost and look of having 8 outdoor units makes my choice of multi-zone a no brainier.

 

[justinjoyal]

They have a nice sizing program on-line.

Which recommended over 6.5 Tons of cooling ?

 

[yeldogt]

I did look at those units and price was at least 3X and require professional installation.

As far as mulit-zone vs single-zone efficiency, the outdoor compressor has to find a speed that fulfills the needs of each head attached to it. Since each head is in a different room (and therefore potentially a different temperature) the compressor will run at something compromised. My understanding is the advertised SEER and HSPF ratings are when running at max efficiency so when running in a compromised state you are not getting max efficiency.

That being said, for me, the cost and look of having 8 outdoor units makes my choice of multi-zone a no brainier.

It's cumulative -- it's matching based on delta coming back. That's why you look at overall use when picking ... some units can ramp to 110% -- this further eliminates oversizing multi head Also -- the outdoor is not sized based on adding up internal heads. I have two systems w/ 3x12kBTU heads on a 30KBTU condenser -- within factory specifications for the loads.

 

[dsimatt]

How often do they defrost? The 27K unit I have hooked up in my master bedroom seems to defrost more than I would have expected. It hasn't even dropped below 30 degrees here and sometimes, it seems to defrost every 45-60 minutes. The others could defrost just as often and I probably wouldn't notice. If I am in the house I am usually in the bedroom.

That's not excessive at all, there's really no set time but I've found the damper it is outside makes it defrost more than temp.

 

[dcg9381]

I like it. I'm glad you posted this up.


I've looked at doing this, but for me, here's why I haven't done it:
1) Multi-zone gets expensive quickly compared to single head, for me it's approaching the cost of ducted AC (installed for me)
2) Not pre-charged - there's a little more skill (and tools involved)
3) Compared to ducted AC, there are a LOT more parts to fail in the above install - a bunch of compressors and all the head units.

I do love that this will give individual controls to rooms... I