Choosing the right brand for a mini-split

[Ashful]

That clears it up. They say right there, 31.9 amps rating, max fuse size 40 amps. You’re already on the right track, excuse my tangent.

 

[sportbikerider78]

That clears it up. They say right there, 31.9 amps rating, max fuse size 40 amps. You’re already on the right track, excuse my tangent.

No sweat. I appreciate the interest.

This manual has been my reading material for the past couple of weeks. It kinda sucks. I wish they would have an American technician/electrician add some comments to better represent standards here.

In this market, the US is likely very under-represented for sales. I can see why it is not worth the time.

 

[sportbikerider78]

Installed 3 of these kits from Amazon last night.
https://www.amazon.com/gp/product/B00CWNQL4C/?tag=hearthamazon-20

It all went pretty smooth. Will use the flexible section to cover through the deck, since there a 3/4" step out away from the house where the metal flashing is directly below the siding. I could not go straight down. It was VERY easy to cut with a vibratory tool. Perfect tool for the job. I used coated deck screws to secure it to the siding and pre-drilled all the holes to prevent the siding from pulling outwards. Worked great.
No worries about water, since this is all below a nice 2-3' eve in the roof.

It looks crooked in the pic,,but it isn't. Must have been the angle I took the picture.

 

[Soundchasm]

On a comedic note, primarily to tattle on myself, I've been waiting to spray off the condensers for both the mini-split and main heat pump. I've been keeping an eye on them all spring. Yesterday was finally the day opportunity met ambition.

The main 3 ton heat pump wasn't bad - pretty much just what I expected. HOWEVER, the mini-split condenser looked like a dryer filter!! Crap!! Of course it comes right off, but that had to happen in about a month, I think.

The units are 50' apart. Main heat pump at ground level; mini-split at second floor. For something I've trained myself to glance at all the time, I either forgot to glance or that happened overnight. ;-) Maybe it was a little of both.

I'd post a photo but it's too embarrassing!

 

[sportbikerider78]

When I bought my townhome in CT years ago, I cleaned the condenser outside. About an inch of s*** came off it like a rug. I don't know if it had ever been cleaned.

 

[peakbagger]

Looking good but expect you are going to regret not having it on line during the upcoming heat wave

 

[Ashful]

When I bought my townhome in CT years ago, I cleaned the condenser outside. About an inch of s*** came off it like a rug. I don't know if it had ever been cleaned.

I have four, ranging from 3 to 24 years old. None have ever been cleaned, nor to they look like there'd be anything to clean from them, so this is a surprise to me. Other than a little dirt in the bottom few inches of a 48 inch tall heat exchanger, mine don't seem to pick up any visible dirt.

But, you have me curious to give it a try. I assume you're removing the top grill, and spraying from inside toward outside, with a garden hose?

 

[sportbikerider78]

Looking good but expect you are going to regret not having it on line during the upcoming heat wave

Yeah. No doubt. I was at the mercy of many others when planning this project. Frankly, I don't think an installer could have gotten it done any quicker, being how my units arrived at the start of peak AC season. I was waiting for about 1 month to iron out the discounting that i would get with Mitsubishi. All said an done...I have a big smile on my face.

 

[sportbikerider78]

I have four, ranging from 3 to 24 years old. None have ever been cleaned, nor to they look like there'd be anything to clean from them, so this is a surprise to me. Other than a little dirt in the bottom few inches of a 48 inch tall heat exchanger, mine don't seem to pick up any visible dirt.

But, you have me curious to give it a try. I assume you're removing the top grill, and spraying from inside toward outside, with a garden hose?

However you have to access the front of the unit where the air first hits the heat exchanger. That is where you have to clean.

 

[Ashful]

However you have to access the front of the unit where the air first hits the heat exchanger. That is where you have to clean.

Yeah, but you want to blow in reverse of the airflow direction, right? On a mini split this might be easier, I have two of those. But on the traditional cylindrical units, it means going down in from the top. One of mine is large enough to require a ladder to do that, but it is do-able.

 

[fbelec]

sorry i forgot you had a electrician there. prob will draw a lot less the the rating says. i had a amprobe on a reg central air unit today it was a 3 ton and only pulling 14.9 amps. so you'll do better.

 

[sportbikerider78]

Power to the condenser is complete with 50A disconnect. It was cheaper then a 40A disconnect.

Unit is anchored with concrete anchors.

Next step is linesets and control/head unit power with 14/3 cable + the condensate line..which is easy.

The head units are two 120V hot, 1 ground and 1 low voltage communication wire.

There is a lot of confusion on what type of cable to use to power the head units. Many use shielded, 14/4 stranded, and a few others. The manual only specifies 14 guage. I called Mitsubishi technical support and the tech emphatically said "You will have no problems using 14/3 standard home romex..that is what you should use." Music to my ears as it will be quite cheaper. I asked about burial outdoor cable and he said that you can use that but it would be an overkill. I couldn't find any, so standard Romex it is.

 

[Ashful]

Power to the condenser is complete with 50A disconnect. It was cheaper then a 40A disconnect.

Unit is anchored with concrete anchors.

Next step is linesets and control/head unit power with 14/3 cable + the condensate line..which is easy.

The head units are two 120V hot, 1 ground and 1 low voltage communication wire.

There is a lot of confusion on what type of cable to use to power the head units. Many use shielded, 14/4 stranded, and a few others. The manual only specifies 14 guage. I called Mitsubishi technical support and the tech emphatically said "You will have no problems using 14/3 standard home romex..that is what you should use." Music to my ears as it will be quite cheaper. I asked about burial outdoor cable and he said that you can use that but it would be an overkill. I couldn't find any, so standard Romex it is.

I have had four Mitsubishi mini split systems, three are at my current house, installed by three different installers at three different times. Two of them made special mention of the condensate line. Namely, it should be very highly sloped, as they have had a lot of problems with condensate lines backing up on these.

 

[sportbikerider78]

I have had four Mitsubishi mini split systems, three are at my current house, and all indoor units were wired with Romex. They were installed by three different installers at three different times, so seeing they all used the same makes me think that’s the standard way of doing them.

Two of them made special mention of the condensate line. Namely, it should be very highly sloped, as they have had a lot of problems with condensate lines backing up on these.

That's great to know..thank you for the input. Most of the posts I saw about romex involved an old electrician throwing a fit for using romex outside.

Yup..I have at least a 15° pitch from inside to outside with my condensate tube. Thanks for the heads up.

 

[Ashful]

That's great to know..thank you for the input. Most of the posts I saw about romex involved an old electrician throwing a fit for using romex outside.

Yup..I have at least a 15° pitch from inside to outside with my condensate tube. Thanks for the heads up.

You know, I hate to admit this, but I was wrong. I know they ran Romex to the indoor units at my old house, but there was a junction box between. I just got home and checked each of the outdoor units on my current house, and they are all multiconductor THHN/THWN with black UV-rated jacket. Sorry for posting bad info above, I will go edit that out.

 

[fbelec]

my last code update class had a guy come in and said that the only wire legal to use is a special uf cable that is stranded wire. as of late i have changed the cable that is run in the slim duct or liquid tight for different brands between the units that are 120 or 240 volt indoor unit's to uf. anything that goes outside has to be uf cable even in pipes. uf or thhn. it's funny the last unit don't remember if it was a mitsu or daikin it had to be run from compressor to the indoor unit a 6 wire that was shielded. they wanted the shield because the didn't want interference in the units talking to the compressor. low voltage motor

 

[Ashful]

my last code update class had a guy come in and said that the only wire legal to use is a special uf cable that is stranded wire.

Do you mean UV-resistant cable, fbelec? There is a UV-resistant Romex variant, usually colored gray or silver.

Each of mine have flex conduit for the 240V main, and the above mentioned THWN for the run to the head unit.

 

[sportbikerider78]

my last code update class had a guy come in and said that the only wire legal to use is a special uf cable that is stranded wire. as of late i have changed the cable that is run in the slim duct or liquid tight for different brands between the units that are 120 or 240 volt indoor unit's to uf. anything that goes outside has to be uf cable even in pipes. uf or thhn. it's funny the last unit don't remember if it was a mitsu or daikin it had to be run from compressor to the indoor unit a 6 wire that was shielded. they wanted the shield because the didn't want interference in the units talking to the compressor. low voltage motor

That is awfully strange about the shielding needed for interference. In the automation world, low voltage (12-24) is run very close to high voltage. Most of the time, most is unshielded.

If there was a large interference issue between unit communication, they wouldn't put the terminal blocks right next to each other.

Quite frankly..no one will know what wire I used. It will be safe. It will be per manufacturer's recommendation. I can sleep well.

 

[begreen]

Depends on the application and the type of communications but EMI is real.
(broken link removed to http://www.smar.com/en/technical-article/tips-on-shielding-and-grounding-in-industrial-automation)
That said, if the manufacturer doesn't specify shielded wiring for communications, then it's likely the low voltage wiring is just for LV transformer feed, relay triggering, etc..

 

[Ashful]

That is awfully strange about the shielding needed for interference. In the automation world, low voltage (12-24) is run very close to high voltage. Most of the time, most is unshielded.

If there was a large interference issue between unit communication, they wouldn't put the terminal blocks right next to each other.

Quite frankly..no one will know what wire I used. It will be safe. It will be per manufacturer's recommendation. I can sleep well.

EMI is a huge problem in automotive, one of the number 1 technical problems that plagued auto manufacturers for 40-50 years. With the advent of coil packs and the death of AM radio, which operated in the band of your ignition system, you just don’t hear as much about it today. Likewise with resistive plugs and high-impedance ignition wires on small engines, the lack of which used to cause neighbors all sorts of grief, before you were born.

 

[fbelec]

as far as just uv the thermostat wire we run from a c compressors is sun light resistant. the wire i'm talking about looks just like regular 14/3 uf cable the only thing that is different with the wire is stranded and not solid and as of my last code update class it was the only legal cable to use and it was made for just this application for the units that require it. i'm not sure how many are still running 120 volts between the compressor and the indoor units. we had the man that owns the wire company come and speak at the class. he is the only company that makes it. personally i run the regular uf cable and have never been called on it by the inspector but i'll bet most don't know about it. if the unit has a spec for a wire with shielding i have to put it in incase the company rep comes to the site for the unit running weird that should be in place. the shield is for the different frequency's for the communication. and yes the company reps have been out for problems which ended up being new control boards. the last board that went was on a sanyo machine. the board blew because of a not a direct hit but a near by lightning strike. cooling company's cost for that board was $750.00

 

[sportbikerider78]

UV is not a concern to me. No wires will be exposed.

 

[fbelec]

hey now is the perfect weather to see how you did

 

[Soundchasm]

Here's a related/unrelated head's up. Went to clean the filters on my Panasonic mini-split with a fresh, curious eye, so to speak. I'm talking about the indoor part. This unit is from 2010.

Holy crap, there seems to be an entire ecosystem come to life on the scroll fan and drain tray. I'm calling a professional to get both of them out of there and clean it. Sheesh! Frightening.

It's clearly my responsibility to dig into this stuff and learn all about it, but it's a tough assignment to figure out what you don't know.

 

[begreen]

Here's a related/unrelated head's up. Went to clean the filters on my Panasonic mini-split with a fresh, curious eye, so to speak. I'm talking about the indoor part. This unit is from 2010.

Holy crap, there seems to be an entire ecosystem come to life on the scroll fan and drain tray. I'm calling a professional to get both of them out of there and clean it. Sheesh! Frightening.

It's clearly my responsibility to dig into this stuff and learn all about it, but it's a tough assignment to figure out what you don't know.

Ordered some cleaner yesterday. Looks like I will be tackling our system's cleaning soon.