Ductless split A/C – tubing in walls?
PeteBradley
| Posted in Energy, Heating & Insulation on
Looking at ductless split systems. I see some get installed so that the tubes go down the outside wall. I’m wondering how common it is to run the tubes down through the wall. This is 2X4 construction, sheetrock, about a 6′ run.
Pete
Replies
I've installed quite a few and they all run down the outside. Do you want them to run to run inside the walls?
Remember there are the two refrigeration lines plus the condensate line and the electrical wiring.
We used to cover all the lines with evestrough and it looked pretty good. Not great but pretty good. I guess you could box all that stuff anyway you want.
roger
Roger,
Thanks. I thought that might be the case. New construction goes inside the wall though, true? This house is partly covered by T-111, so I also considered removing a sheet, opening the stud bay from the outside, and then closing it up after installation. Seems like a lot of hassle, but this is a carefully architected house ("house of the future" ca. 1960) and the tubes for two heads are definitely going to be noticeable.
Any rules of thumb on pricing? I've read $1500-$2K per ton, but not sure how real that is.
Pete
P.S. Yeah, I know, T-111 and architected sound funny together but this one actually works.
Pete
Edited 3/6/2008 5:37 pm ET by PeteBradley
No. I've never seen them in walls. THrough walls but not in walls. Sometimes those refrigeration pipes sweat and you don't want that in a wall.
We used those units where it was "location specific" in that one room or area had a huge heat gain (big friggin widow) and it was silly to put a bigger central air for the whole house when only one small area needed it. Upstair areas were good spots for those because upstairs got so hot and the central air couldn't keep pace. All the same rules applied if it was really needed for heating. The heat pump model is only slightly more money that just a/c and well worth it.
Those things are highly overpriced. In central America and south east asia they are less than half the price but they do a fantastic job and are very pleasing to the eye and quiet inside the house.
roger
Edited 3/7/2008 7:39 pm ET by roger g
Sometimes those refrigeration pipes sweat and you don't want that in a wall.
Armorflex ?
I have seldom seen it fail on interior applications, but after years of exterior exposure it will start to break down onless it has a protective wrap over it.
Armaflex always on the low side. Depending on the manufacturer(heatpump) they might want both lines in one armaflex or sometimes separate armafles lines. Sometimes only onthe one line.
I've installed probably over 50 and never saw in any instructions of an inside wall install nor have I seen anybody else install that way. Not saying it isn't done but I haven't seen it. Remember the condensate line, which was always the biggest problem in unusual applications.
In my minds eye I'm trying to think what I would say if I was asked to install that way. It's been almost 5 years since I installed one so maybe the instructions say something but I would probably call the manufacturer or distributor and ask.
I,m one of those guys who always reads the manuals.
I remember years ago I phoned a manufacturer about installing something a different way than what they recommended. They said"Roger, your way MIght just work but we can prove OUR way does work. In a law suit can you prove your way?"
What a great answer! Something I've never forgotten.
roger
What about split systems with the condenser unit setting on the ground and the ahu in the attic?
Effectively the same situation.
There are literraly thousands of units in operation just like that, and you seldom see refrigerant lines running down the side of new construction.
Up here in Canada(Ontario) it was rare that the furnace was upstairs and even more rare in the attic. I think I saw an attic one once. In western Canada they do have a tendency to use another furnace in a 2 story house but don't know how they do central air. Then again central air in western Canada isn't needed as much due to the dryness and the cool evening temps.
I've also installed hundreds of central a/c units in new and existing homes and can't remember ever puting a lineset within an insulated wall. Run lots of linesets through chases and the like but not in an insulated wall.
I'm remembering one (new home) where we went through and outside wall, along a joist space and then up through an interior chase into a furnace room on an upper floor
On a a/c unit only the high side line (not insulated) is hot and the reason it's not insulated is that it has to get rid of the heat(or as much as possible) and if it is surrounded by insulation it isn't getting rid of the heat to the degree it should. If the manufacturers had wanted the high side insulated they would say so.
Good points though. I can only comment on what I've done and seen.
roger
Edited 3/7/2008 7:43 pm ET by roger g
I know of one attic unit here. But then again, we are blessed with basements, and yes, we do need CA if only for 3 weeks a year.
My problem with lines in an insulated wall is what happens if the lines freeze up? Nothing like a block of ice buried. I know, moisture shouldn't be in the wall, but........
And what happens if you need to replace the lines due to a burnout or the system becoming obsolete?
I'm a glass is half empty kind of guy. LOL
And BTW, Vancouver and the island isn't western Canada, it is the west coast. :)
Edited 3/7/2008 11:21 pm ET by rich1
Edited 3/7/2008 11:22 pm ET by rich1
You are right about the lines freezing up. In central air if your filter starts to clog up or the blower wheel gets dirty or some idiot closes most of the air vents in to house to force the cool air to another area, you get poor air flow over the evaporator coil. When that happens the low side (big pipe with insulation) starts to freeze up and that freeze up can go all the way from the evaporator to the compressor. I've seen them 6 inches in diameter!!. Imagine all that ice within an insulated wall and then it melts.
Most refrigeration lines sweat and freeze up at one time or other but in most cases we never see it or if we do, we don't care because it goes away. Inside a wall what's left doesn't go away.
As far as having to replace lines, lots of times we can't put refrigeration lines where they originally were for lots of different reasons and we have to try to pick another route for new lines.
We consider everyone on the mainland and east, "easterners".
We even call redneck Albertans easterners. Great fun.
roger
Edited 3/7/2008 11:48 pm ET by roger g
> You are right about the lines freezing up...the low side (big
>pipe with insulation) starts to freeze up and that freeze up can
>go all the way from the evaporator to the compressor. I've seen
>them 6 inches in diameter!!. Imagine all that ice within an
>insulated wall and then it melts.Is that possible? In order to build 6 inches of ice on a cold pipe, you'd need a steady supply of warm moist air, something you definitely should not have in an insulated wall cavity.Pete
What I've said is that I've never seen the lineset within an insulated wall. Through it but not in it so I can't say what would happen in an insulated wall. What I have seen many times is the low pressure line which is insulated covered in very thick ice. I've seen many times well insulated compressors which are hot but insulated more for noise also completely covered in ice.
So, the scenerios that I just talked about all were insulated and there was ice. If by chance there wasn't any moist air in an insulated wall cavity the cold would eventually transfer to an inside or outside wall where there is moisture. You could end up with either a line of ice or a wet line which collects dirt and moisture.
All in all it might work but I sure wouldn't put it in my house. A/C units are fairly forgiving in that most people don't know if it is operating properly. Linesets that have free air around them dry out if they do get damp whereas in an insulated wall the insulation stays damp.
When a/c's work properly there isn't any condensation to worry about freezing but operating conditions change. When there is a problem, the evaporator(inside coil) start to freeze up and then that freezing starts to back up the line all the way to the compressor.
If anyone is curious, punch in "frozen evaporator" on line or something like that and you will see all the causes of that. Those causes, I believe, could cause problems within an insulated wall. But that's just my opinion:)
roger
I'd have a fit if our HVAC guys wanted to run the lines outside a wall if there was access to get it inside, but that's something they would never do.
Beer was created so carpenters wouldn't rule the world.
We had 2 of them installed on our house last year (central air was not an option for us), and pipes are on the outside, and yes I hate the look of them (covered in evestrough downspout material), but I certainly would not have wanted those refrigerant lines etc sweating away inside my walls. The units do work very well though.
My house (not the one in question) has central air, and the refrigerant lines go up through the wall to the attic. This is recent new construction. There is foam insulation on the supply line, maybe they insulated all the way down.
Pete
Pete,
Have you looked at seperate room A/C I'm talking about window units put into the wall..
Major advantage is high efficency at low cost
Several other advantages..
First if new technology comes along you can easily affordably replace the unit. Same if the unit should become more expensive to repair than to replace. In addition you can take a unit from the wall replace it with another that's not working..
I have 5 units in my house and seldom are all 5 on. (in fact they've never been all on ) I don't have more than $1200 in all of them.. since I bought them all at the end of the cooling season at blow out prices.
I put window trim around the unit and mount it up high in the wall.. I can take the unit out for winter and put a plug in place to regain the insulation. Looks good!
What is the difference with lines running in the house for a mini-split versus a central system. As long as they are insulated line the sweating should not pose a problem. Routing these lines is a bear, and I had a few tears to fix when I did ours. I just put in a mini-split with one outdoor unit and 3 separate indoor units. Our cooling load is very small and this seemed to be the most efficient solution. The unit is 16 seer (draws 6 amps 220 for all four units) when going full out. The DC inverter driven motor throttles down when the demand is low for even less electrical consumption. Total investment is just under 3K for units, wiring, lineset and condensate hose. Personally, I can't imagine looking at lines coming down the outside of new construction. Hope it goes well for you.