Mini Split Heat Pumps

Old 08-04-11, 12:16 AM
Workin Man's Avatar
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Mini Split Heat Pumps

I don't know much about mini split systems. Other than what I have read via the internet. Does anyone here know how reliable they are ? My situation just about demands I get one of these. My homes roof is unlike any other I've seen in my area. The old duct work had to have been installed when the roof was still incomplete. My guess, there is less than 2' clearance at the highest point in my attic. It's not totally flat, but it don't like much being flat.

Just looking for some opinions here before I go out searching for a contractor. Which brings up another question. Many of these mini splits are pre charged with the new 410a refrigerant. Would it be a good idea to do a self install ? Most, as I understand come with a self install kit. I am not licensed HVAC, but I shouldn't need to be if this is true about being pre charged. I wouldn't think a license is required to pull a vacuum on an uncharged line. And the use of nitrogen wouldn't require it either, right ? And one more question. I'm sure it's a little different, depending on when you live. What is the average price of these little units ? I understand there are a lot of variables to that question. Just a ball park figure. One Condenser unit and three or four evaporator units. And that brings up another good question. Can the evaporator units be of different sizes ? Say, 20k btu for the living/dining area, 15k btu for master BR, two 9k btu in two smaller BRs.

Thanks, Workin' Man
Old 08-04-11, 03:49 AM
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Most systems you buy over the Internet will have NO warranty. Always go to the manufacturers website to be sure. Internet sales are typically forbidden. I use Mitsubishi units and have good luck with them. You can do it your self but although the units are recharged that ia only for a specified length of lineset. Go over that length and you must add charge, under remove charge. You would need to buy gauges, vacuum Pump, nitrogen regulator capable of 300 psi, micron gauge, and other things im sure im forgetting. Best to leave it to a pro. Last thing you want to do is spend a lot of money just to screw up the install. I can't comment on price as it varies by location and contractor. Call some contractors and get at least 3 quotes. I have had bad luck with LG AND anything bought from im working on a Fujitsu and like most of these units you have to call tech support if there is ever a problem. The manuals don't give you all the info you need to diagnose on your own. Now I have to wait for the control boards to come in as no suppliers stock them. When they work, they work great no matter the manufacturer, some just don't work all the time.
Old 08-04-11, 02:32 PM
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I totally agree with hvactechfw. The prices for the Chinese copies of the better brands (Mitsubishi is one) are considerably lower than the name brand units BUT their quality is questionable.

Doing ANY work on a sealed refrigerant system using anything but R134A (automobile A/C) is prohibited by US law unless the worker holds a valid certification issued by the US Environmental Protection Agency. The websites I have seen with the Chinese copies often sell them with a 25 foot lineset but the unit's themselves only are charged for 15 foot linesets. As far as I know, it is impossible to purchase R410A in anything less than a 25 pound container and THAT amount of refrigerant will cost more than a service visit from a certified tech. Plus, without the EPA certificate you would find it difficult, if not impossible, to purchase the refrigerant.

If you want to install one of these Chinese knock-offs (understand that the instruction manuals are EXTREMELY poorly written) then I would suggest that you first contact a certified tech in your area to see what he/she would charge to do the nitrogen test, vacuum and additional refrigerant after you have done the mechanical and electrical work of installation. Remember also that in most areas you will need electrical and mechanical (or refrigeration) permits and inspections from the local building department.
Old 08-07-11, 08:49 AM
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Whenever we install these, and the lineset is over 20 feet, they never last.

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