Do your homework on manufactures. While their are many brands, warranty service is another issue all together. I will not name companies or brands, but there are only two systems I will sell my clients because of difficulty in getting repair parts for the others. Remember you get exactly what you pay for.

There are systems made now that have picture frames covering the indoor part of the system. Unique idea, but steer clear of them. I have removed a few of these systems in the past because of part issues not available in my area. They also have poor air flow. They do not push the air out across the room and only blow it out sideways. If the room is larger you want the air to move around to get the best effect from them.

On cost, these systems cost more then a new system for central AC does. equipment alone. Your not really saving much with mini-split other then to not having to install ducts in the rooms which is often difficult with head room in a basement.

Good luck.

Your saying its inside the product? How you do know that? Environment regardless of location or facing of sun will allow molds, moss etc to develop. It is just harder for this to occur in some climates then others. Quite frankly I doubt there is any mold growing inside of the material. And I think the advice they provided to you although you disagree is correct.

Any good quality house cleaning chemical that you spray on siding will work. Simply spray on with the device they sell to apply it. Or use a garden sprayer and wet the deck completely. The best time to do this is early AM before the sun comes up and heats up the deck, or on a overcast day to prevent early evaporation of the cleaner. Then using a scrub brush on a pole scrub the deck down to work the loose dirt and moldy surfaces up. Once done a good strong spray from your garden hose should do the trick, or a power washer around 1800 psi max can be used to wash the stuff away. Do not use bleach. It can damage the surface of the deck and can kill grasses and plants during the rinse cycle of the project.

In addition Marilyn, mold can develop everywhere. There is nothing that will prevent it from occurring if conditions are correct for it to grow. Decking, siding, stone and even glass will develop mold if allowed to get dirty enough to support the development of it. Its not growing on the deck, its growing on the dirt that is on the deck. Even if you think its clean, its not. There is no such thing as a maintenance free deck. Even if they say that in their sales presentation. What they are saying you do not have to stain and paint. But they all need cleaning.

Depending upon your states energy star program your monthly savings should be more then it would cost you to finance the project combined with the new energy bills. In other words done correctly with the rebate programs, your combined finance loan with the new utility bills should be less then what your currently paying now for your energy use without doing any of the work. Paybacks can be as little as 7 years. This is what folks in my area have been experiencing with the work I do.