Over the past 5 years we have tried a variety of different cooling solutions for our short term rental (that doesn’t have central air conditioning or heating). It’s a beach house in San Diego and, because of the mild temperatures in the area, central AC and heating are not common features unless it’s newer construction.
But with every new option we tried, we found more headaches – some were expensive to operate, others were big and bulky and still left guests uncomfortably warm on the hottest days of the year. That all changed when we stopped being intimidated by a mini-split installation.
In this week’s video, we went into extensive detail about AC and heating options for your short term rental, or maybe even your own house. We covered all of the alternative choices to typical forced air systems and gave ratings and recommendations based on our experience. We’ll be recapping those ratings in this blog post as well as linking all of the tools we used in our own installations (including other helpful videos from other YouTube creators).
Even if you do decide to hire out the job, it’s so important to understand how these things work so (1) you don’t get taken advantage of and upsold on something you don’t need and (2) you’re choosing the right method that will make the most financial sense from a long term perspective, not just what the cheapest one to install is.
Installation cost and complexity are going to be important factors, but the most important one for us, especially in the southwest, is efficiency since electricity rates are high. Choosing an inefficient solution could cost hundreds or even thousands of dollars over the life of the unit so it’s a good idea to put a little thought into your solution up front.
Ok, ready to take some notes? Let’s get started.
Option 1 – Portable AC Unit
A portable AC is basically a unit on wheels. They’re about the size of a big rolling suitcase, but with a big tube in the back that you run to a window for hot air to be vented.
Here are a few options, click each photo below to view product:
Ease of Install – we’re rating these a 5 out of 5. because portable units are the easiest to install. You place the unit in the room you want to cool and run the hose to a window. They come with kits that adapt to different window types and hold the hose securely. No specialized skills are required to figure this out.
Power Consumption – we’re rating these a 1 out of 5. Portable AC units are the least efficient of the 3 options we’re covering in this post. Portable units typically have an EER range between 7.5-14.
You’ll have to pay a lot more money to get to the top of this range and most units are around 8. A typical portable AC unit will be 8000 btu/hr. This example makes our cost calculation very easy. Take the btu/hr rating – in this case 8,000 and divide it by the EER – in this case 8.
8,000 divided by 8 is 1,000 meaning that this unit consumes 1,000 watts or 1 kilowatt of energy per hour while running. Utilities bill in a price per kilowatt hour which means you pay X amount if you consume 1kw for an hour. In California, the average cost per kw/hr is 31 cents.
Let’s say with a guest in the house, they run your unit for 15 hours a day during the hottest times. 15kw/hrs would be consumed from the utility and that will cost you $4.65 per day to run the unit or $140 a month
WHAT IS EER? AC units are all rated with an energy efficiency ration or EER. You’ll also see SEER and CEER which we’re not going to get into today, but all of these ratings are derived from dividing the cooling capacity of the unit (expressed in BTU/hr) by the power consumption in watts. A lower EER means lower efficiency and higher power consumption.
Cost to buy: On average, for an 8000 btu portable unit, you’re going to spend about $300. You can spend over $500 for one with a very high EER. And remember high EER equates to more energy efficiency which equates to a lower cost to run.
Pros:
- Easy to setup and also take down.
- Simple to use
Cons:
- Energy efficiency (the least efficient of the three we’ll be discussing today)
- Expensive to operate (because of the energy efficiency, or lack thereof)
- No heating capability
- No WiFi connectivity or remote monitoring
- Loud
- Big and bulky, take up floor space
Option #2 – Window AC unit
I think everyone knows what these are, but this is a self contained unit that you hang in your window sill and plug it into a nearby outlet.
Here are a few options, click each photo below to view product:
Ease of Install – we’re rating these a 4 out of 5 because they’re a bit more complex to install than portables but still a very basic job. Most units come with some brackets to hold them in place on your window sill and some adjustable covers to seal the area around the unit. You may need an extra set of hands while you secure these in place.
Power Consumption: We’re rating these a 2 out of 5
Remember the EER rating system we talked about? Where the higher the EER the better the energy efficiency? We talked about how the EERs for portable AC units ranged from 7.5-14 with most being 8, well the EERs of window units are going to fall into the 9-15 range, with most run of the mill units coming in at 10.
And you’re going to usually find the same 8000 btu/hr with these window units as well. So let’s run the same scenario as our portable unit but with the window unit. We can plug our numbers into the formula – an 8000 btu/hr unit divided by the EER of 10 would consume 800 watts or .8kw.
If it was run for 15 hours per day in California, you’d consume 12kw/hr and the cost would be $3.72 per day or $111.6 per month, or about $30 per month less than the portable AC
Cost to buy: 8000 btu units can be purchased for less than $250. You can spend upwards of $500 for more efficient units or models that have heating capability.
Pros:
- They can be installed with basic tools and are pretty easy to remove if they aren’t needed year ‘round
- WiFi connectivity is common so you can remotely monitor and control the unit
Cons:
- They’re still pretty inefficient and expensive to run
- Very loud
- Heating capability is uncommon so you might still need to bring in space heaters
- If you’re near a beach, longevity won’t be good due to corrosive salt air. The average lifespan at one of our beach units has been less than 3 years.
Option #3 – our favorite option – The Mini Split
A mini split is a two part system with no ductwork. It has an indoor and an outdoor component like a typical furnace and condenser system, but the no ductwork part is a game changer for adding cooling and heating capability to an existing house.
Here are a few options, click each photo below to view product:
Ease of Install: We’re rating the mini split a 2 out of 5. It is definitely more involved than portable ac or window units. It does require some handy skills and some patience to follow a procedure. Steven has installed 3 units now and with the last one, he was done start to finish in less than 4 hours.
Power Consumption: we’e rating the mini split a 5 out of 5
This is where mini splits shine. Remember the EER of the previous two options? Typically 8 for a portable ac and 10 for a window unit. The mini split units we’ve bought all have an EER of 20-22. The last one we installed was 21.
Following our examples and calculations from before, for 15 hours of usage, an 8000 btu/hr unit would consume 5.45kw/hr and the cost would be $1.68 per day or $50.69 per month. This is almost a third of the operating cost of a portable unit!
Not only are these more efficient than a portable ac and a window ac, they’re often even more efficient and therefore less expensive to run than central air with ductwork. The cost of a mini split unit has a pretty wide range – typically between $550 and $1450 – and we’ll talk more about this variance.
Why is everything 8,000 btu/hr? We’ve been comparing 8,000 btu/hr window and portable units and this 8,000 btu is common because this cooling capacity is near that maximum electrical load that a typical household 15amp wall outlet can handle. Since mini splits are so much more efficient, you can get more cooling capacity on the same electrical circuit Because of this, the most common size you see for mini splits is 12,000 btu/hr for 120 volt electrical supply.
Pros: so many!
- Almost all of them include heating capability, meaning no more space heaters
- Most also include wifi connectivity for remote monitoring and control
- Mini splits are super quiet. The air handler in the room is barely audible with the fan on a low setting.
- Efficiency is great – operating costs in our area are almost a third of the price for alternative options
- Longevity – these units are more robust and should have a much longer lifespan than a window unit. The one we bought for the beach house has a corrosion resistant coating on the outdoor coils.
Cons:
- The install requires time and some handy skills.
- They’re also more expensive up front than the other two options.
Cost to Buy (DIY install): $550 to $1,450
What’s with the big price variance? It really comes down to two different ways to buy a mini split to install yourself. Basically you can buy a kit that includes everything you need to install, or you can buy the unit and piece together the other items you need for the install.
We’re going to compare the brand Mr. Cool – which is the DIY Mini Split Kit that you can buy – to every other brand when it comes to the installation procedure. They advertise and sell a DIY mini split kit that doesn’t require any special tools. Specifically what this means is you don’t have to pull a vacuum on the refrigerant lines during the install.
And the advertising is true – the first unit we bought was a Mr. Cool because Steven was still a little bit intimidated by the installation process. The kit that they sell really is complete and everything went very smoothly during the install. But one drawback here is the price.
Today, a 12,000btu/hr Mr. Cool DIY system is $1,450 from Costco. Now, this is still a huge savings compared to the cost if you were to have an HVAC contractor come out and install a system. For that, you’d be looking at $3-5k.
Every other company selling mini splits – besides Mr. Cool – has a bit more complicated installation procedure where you have to vacuum air from the refrigerant lines with a vacuum pump.
How refrigeration works can be a big rabbit hole of YouTube videos and engineering concepts but the gist here is that it’s a closed loop, hermetically sealed system of refrigerant flow and nothing else should be in that loop except the refrigerant. Air from our atmosphere, dirt, or other contaminants inside of the refrigerant lines can mess up the whole process. So will leaks because that will let air into the system and let the refrigerant out.
The most critical part of the “everyone else than Mr. Cool” systems is removing air from the refrigerant lines and ensuring you have sealed connection points.
This is not a How to Install a Mini Split post. We’re not trying to reinvent the wheel here. But here are some videos that we found to be super helpful when preparing to do the install ourselves. Big thanks to these guys for the extremely helpful content!
DIY Mini Split Installation Costs: For this, let’s assume you already have a fairly complete set of hand tools, a drill and a hole saw that can cut holes in the side of your house.
Steven also had a torque wrench but had to buy crow’s feet for the line fittings. We’ll link everything in the photos below.
The Mr. Cool unit we bought was $1,450 plus tax then we bought a mount to wall mount the outdoor unit for $55. There were a few electrical needs that added up to around $50 and this was it.
Total cost was about $1,555
The latest unit Steven installed was not Mr. Cool and required vacuuming the lines.
So we had the unit cost at $550, the $55 mount, $50 in electrical needs, a vacuum pump and gauge set for about $120 and connection sealant at $13.
Total cost was about $788
A significant savings compared to the Mr Cool and we can reuse the pump and gauges for other installs in the future.
Here are all of the tools we used for the installation, click each photo below to view product:
Takeaways:
Watch the video for our full breakdown, but if you feel confident you could replace a sink faucet and also replace an outlet or a light fixture, you can do a mini split. If not, now you know enough to confidently hire someone to complete the job for you.
Here’s to hosting calm, cool & collected guests!
K&S
