AC_Hacker installs a new Mini-Split

[AC_Hacker]

Originally Posted by Fionn

Any updates on the installation or performance?

Thanks Fionn,

I have been meaning to follow up on the Fujitsu install.

First, to answer your question, the Mini-Split works very well. It's not easy to verify the claim of efficiency with an Air-Source & Air-Delivery unit. But I'm watching my electricity bills, which won't be easy to isolate any performance specs, since I drive an electric car, charging only at home, and I have a house mate who uses varying amounts of electricity.

OK, now with the disclaimers over...

My last Mini-Split was a Sanyo, and the specs were not stellar, but it was very reliable and cut my heating bills for about 10 years. The operation sound of the outside unit was pretty modest, considering that this was the machine that heated my house, and the inside unit was virtually silent. I had to look for an indicator light to know if it was running.

The Fujitsu has much higher efficiency specs, but the same output specs as the Sanyo, so I think that comparisons are interesting. First of all, the outside unit was somewhat larger in size, taller, wider, and deeper. I also noticed that the fins were more densely spaced than the Sanyo. The inside unit was also larger in the same manner, including fin density. In operation, the Fujitsu is again very quiet, but the fan is passing more air through the fins, so I can hear it, but just barely when it is running.

The remote control/room temp sensor is much less cluttered on the Fujitsu than the Sanyo, but it offers the same options, including timer controlled on and off. But it has an additional feature that is amazing, I has an occupancy sensor. This means that the heating tapers down when the room is empty, and likewise it tapers up to desired room temperature, when someone is in the room. I'd estimate that the range of degree change is about 8 degrees max from bedtime to dawn, but during day use, the swing is less. But the changes are very gradual and comfortable. One curiosity is that If I'm sitting on the couch with my gal, watching TV, the Fujitsu thinks we left the room... in a way, I think the Fujitsu is correct. This feature is available with a button on the remote, and can be turned on or off. I turned it off for a day or so, and then turned it back on. However, it didn't seem to be working at first when switched back on. But over time it returned to it's previous mode. This make me think that there is some kind of 'learning' algorithm that controls aspects of performance. It works so well, that I haven't bothered to program on/off cycles, since it does it so well automatically.

In short, once I got over the "new", the Fujitsu has disappeared, and left me with a comfortable home.

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Regarding installation, there are so many well documented installs on this site, that I didn't think mine would add any value.

However, I did reuse the old line set, and saved some money there ($120). Looking back, I took a risk that seems to be OK, and that risk was that I used the old flares at the ends of the old line set. During the install (but after the fact), I did learn that soft copper, which is what line sets are made of, have a definite limit to bending (5 times) that they are exposed to, before they become brittle. Since I installed the Fujitsu exactly where the Sanyo was, I expect no problem. BUT the flares themselves are exposed to significant flexing when they are formed, which could make them approach brittleness, and my reusing the same flares was not the wisest thing to do. Looking back, I wish I had cut off the old flares and made new ones. I have the equipment, I just didn't have the knowledge.
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Best Regards,

-AC_Hacker

[Mikesolar]

Originally Posted by AC_Hacker

Thanks Fionn,


Regarding installation, there are so many well documented installs on this site, that I didn't think mine would add any value.

However, I did reuse the old line set, and saved some money there ($120). Looking back, I took a risk that seems to be OK, and that risk was that I used the old flares at the ends of the old line set. During the install (but after the fact), I did learn that soft copper, which is what line sets are made of, have a definite limit to bending (5 times) that they are exposed to, before they become brittle. Since I installed the Fujitsu exactly where the Sanyo was, I expect no problem. BUT the flares themselves are exposed to significant flexing when they are formed, which could make them approach brittleness, and my reusing the same flares was not the wisest thing to do. Looking back, I wish I had cut off the old flares and made new ones. I have the equipment, I just didn't have the knowledge.
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Best Regards,

-AC_Hacker

Hi AC. I haven't been on for a while but since you bought a Fujitsu, I take some notice partly because that is mostly the brand I install. You got a good price on that one.

As for installation, I now pressurize the linesets to 500psi and hold for few hours. It really prevents callbacks. I wouldn't worry about cutting off the flares and starting new. They are all made to the same standard anyway.

I have one of these units (12000btu) on test now and I have adapted it to heat a tank of water. I've just started so I won't have any real impressions of it for a while yet.

I hope it last at least a decade.

[Mountaintop]

Mikesolar - I would be interested in seeing your setup on how you connected the Fujitsu to a storage tank. Are you using the lineset to steal heat from the system when in heat mode or did you put a heat exchanger on the discharge of the compressor? What water temperatures have you attained? What have you been using the water for?

Thanks,
Matt

[Mikesolar]

Originally Posted by Mountaintop

Mikesolar - I would be interested in seeing your setup on how you connected the Fujitsu to a storage tank. Are you using the lineset to steal heat from the system when in heat mode or did you put a heat exchanger on the discharge of the compressor? What water temperatures have you attained? What have you been using the water for?

Thanks,
Matt

For my test rig, I sized a flat plate heat exchanger to the output of the HP and I have a pump with a flow meter so I can get proper readings. I am using the indoor coils electronics but changing the thermisters to fool the control into thinking it is heating 21C air when in fact it is heating 40C water. I am then pumping the water to 2 old cast iron rads in my shop. It has been working perfectly for the last 2-3 months. Next step is to make a control that allows me to get rid of the indoor unit electronics. So far, BTW, the COP of the system has been around 3.5.