Mini splits

BobC

I'm going to get rid of my 14,000 BTU window mount AC because it's just to big for me to handle any more, it does a great job cooling the first floor of my house (about 625 sq ft). I'm looking to get a 12,000 BTU mini split installed instead.

In my area the Mitsubishi's seem popular but I've read some complaints about the boards in these units being a reliability problem. I'd appreciate and feedback on this issue.

Bob

Paul S_3

Ive had some board issues with them over the years....mitsubishi still makes a fantastic product though. ...i recently started installing only Carrier mini splits the last 3 years with only one problem (bad reversing valve in a 4 ton) out of about 50 total installs....maybe hasnt been long enough i dont want to jinx myself....Maybe Carrier is another option for you....

ChrisJ

Stole from a FB page.

This is my kind of window unit.







In all seriousness, I have the same problem only it's a combination of I can't remove it alone, and have no where to put it. Mine is a 12,000 btu Sharp unit from the late 90s. I put it in back in 2013 and never removed it. I need to do something but can't find the time or money.

njtommy

I just installed a Fujitsu 12,000 btu heat pump in my sun room. It's very quiet and reasonably priced. The model I got is 30 seer.

I've installed and serviced pretty much all brands over the years. I really don't have complaints about any of them. I recommend installing a surge protector to Hopefully protect those expensive control boards.

http://www.supplyhouse.com/ICM-Controls-ICM517-ICM517-Single-Phase-Surge-Protective-Device-w-Metal-NEMA-Type-3R-Enclosure

BobC

Thanks for the replies. I have a whole house surge protector but would also install one on the condenser unit. The 14,000 window unit I have now is 18 years old and never missed a beat, I just want something reliable, I'd be willing to trade some efficiency for solid reliability.

I had 320 hours of schooling on AC's in the 70's but it really isn't worth it to buy the gear I'd need to do the job right so I have a couple of contractors coming over next week. I'll see what brands they offer.

Bob

ChrisJ

@njtommy I hope those "expensive control boards" have their own surge protectors. It's only a few cents in MOVs.

BobC

There are MOV's and then there are MOV's, good ones cost a little more and manufacturers don't like anything that costs more.

We use to build our own solid state relays into our equipment, it's very simple just a triac and a opto / driver IC. What most people don't realize is you have to overdrive the IC if your driving and inductive load - 3 or 4 times the rated IC current. If you drive them at the rated current weird things can happen and that can let the smoke out of the triac.

Bob

njtommy

Ok I'm lost what does MOV stand for?

BobC

Metal Oxide Varistor - essentially an electronic clamp that is open until the voltage across it exceeds it's rating. It then clamps the voltage and tries to prevent it from rising above the rating, they can absorb a lot but there are limits to what they can take.

Bob

ChrisJ

BobC said:

Metal Oxide Varistor - essentially an electronic clamp that is open until the voltage across it exceeds it's rating. It then clamps the voltage and tries to prevent it from rising above the rating, they can absorb a lot but there are limits to what they can take.

Bob

And this is why you often use multiples in parallel.

Here's, in my opinion, a good example.

http://www.digikey.com/product-detail/en/epcos-tdk/S20K130E2/495-1443-ND/593854

$0.99 if you buy one and it's rated to handle 100 joules.
Or, 10,000 amps for a split second.


You'll very often see these, or something very similar in PC power supplies, TVs etc.

They work very well.


@njtommy you basically take that blue disc, and connect it's leads across the AC line. If you exceed it's voltage spec, it becomes a short and absorbs the blow.

Dave0176

Mitsubishi is the original, I've installed quite a few over the last 16 years and I've never had a problem with any. I've also installed some Fujitsu mini splits, no problems either.

BobC

I don't know where the problematic ones I read about were but everything else I've about them has been good. I have one scheduled to be installed as soon as they finish siding the house.

Bob