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I was debating using a mini-split for an addition I’m currently remodeling, and I ran into the same issues. I ended up going with a heat pump PTAC unit. You have to cut an opening in the wall for the sleeve, but I don’t think it looks any worse than a mini-split would.
"because cool air falls" true, but if aesthetics are a major concern, perhaps a ceiling fan could overcome that....just a thought.
If ceiling fans are an interesting option, or for anyone shopping for ceiling fans, I have purchased several fans from these folks...link....not the cheapest, but they offer a great value in choosing the right fan. I use fans with dc motors, said to use 75% less energy than ac motor fans.
Regards
Gemstone1
We have ceiling fans in the first floor rooms, they definitely help to move the cool air around, or on a borderline hot day they provide enough to feel cool on their own.
Right now we just use a single window unit in one of the first floor rooms, and with the ceiling fans it actually cools off the whole floor (about 1000 sq f). I think the unit is only 8k btu, fairly small. The proposed unit for the first floor is 12k btu so I expect this to be enough.
You know looking at the window unit right now, and thinking about a floor unit, I think the floor unit output would only be about a foot lower then the current window unit.
Upstairs the ceilings are lower, not sure if we could safely put up a ceiling fan, we use other small fans. The rooms are more closed off and the air can’t really move around the whole floor. I only expect the one room to get cool up there.
Ever seen houses in the Caribbean? Very high vaulted ceiling that allow the heat to rise; and those that have a/c are split systems mounted up high on the walls- because cool air falls.
99% of the time, I agree with you. However, in this case I have to disagree. While people will do this, thermodynamics and decades of studies will prove them wrong. If you are utilizing a displacement strategy with high ceilings vs a traditional mixed approach, you should deliver the cool air low, around the floor level, while allowing the warm air to rise. This is much, much more effective.
This will be backed up my any technical HVAC association and the manufacturers themselves (ASHRAE, Titus, Price all have good guides for displacement ventilation).
After 6 months, you won't notice the mini-split air handler mounted in the correct spot on the wall up near the ceiling. You don't want to mount one on the floor. It will have lousy air flow.
Your probably right here, there were so many things that bothered me when we first moved in, but after a little time passed you don’t notice it anymore.
Quote:
If you don't like the aesthetics of visible vinyl covers to the A/C lines outside your house, just box it in and shingle it so it's not visible. Where I am in New England, sheet copper to cover it would have a nice patina after a couple of years and look like it was meant to be there.
I have a Fujitsu mini-split A/C. I really screwed up when I bought it. I should have bought a heat pump so I have a backup heat source if the gas boiler somehow fails. When this system eventually dies, I'll replace it with a Mitsubishi heat pump system. My A/C lines have a 7 or 8 foot run from the compressor on the pad up to the air handler with the usual white vinyl covering. It's the side of the house where I only have 10 feet of setback. I really don't care what it looks like. If it were on one of the visible sides of the house, I probably would have removed some sheet rock and run the lines inside the wall. An HVAC installer wouldn't want to do that job so I'd have to bring in a carpenter to open up the wall cavity and drill holes for the A/C lines.
Boxing it in is an idea to consider. I even still have some boxes of shingles left over from the re-shingle we did in 2016. The main issue here is not having a straight vertical run up to the room. One side has a bay window roof in the way, the other side has the porch roof in the way.
This is the most visible side of the house unfortunately.
We have plaster and lathe walls in good shape and I am reluctant to disturb them. As mentioned all of the plumbing and heat pipes are visible and outside of the walls now so I think I could make this look like just one more of these pipes.
I have been looking at Mitsubishi units, and it seems that once you go to an outside unit that can handle more than one inside handler, they only come in a/c and heat pump combinations. I was not interested in the heat component, thinking I would never use it (we have gas heat) but you are right it could serve as a backup heat source. I am usually more worried about complete power loss in the middle of winter, which makes me want to get a backup power source.
Mini-splits (ductless) are not a displacement system- they are a recirculating system.
And this isn't about "thermodynamics"- it's fluid dynamics.
I know it's not the exact same as a true displacement system, but you can look to a lot of the same mechanics even though it is recirculating. If one is actually trying to utilize the tall ceiling during summer cooling, you still are better off delivering low and only condition/recirculate in the occupied zone. Especially with a single zone terminal type AHU - you are much closer to a displacement idea here than a central AC.
And don't get me wrong, most houses youre just going for the standard mixed approach. I'm just pointing out that if you're actually truly trying to take advantage of a noticeably tall ceiling to allow the hot air to rise and stratify, you don't want to be delivering high and causing mixing. It's quite inefficient.
Last edited by Sunbather; 08-21-2019 at 12:55 PM..
"Seems like the usual installers only want to run the connections along the outside of the house."....just like cable/telco installers....take the easy way. If you were to offer to help them do it your way, they may be more receptive. Perhaps you could do the drilling in the floor and ceiling, per their specifications, so they are not responsible if something happens during that process. You could possibly run an over-sized conduit from point A to point B, then all they have to do is fish a pull rope and pull in their plumbing/electrical....(you could even place the pull rope)....then you frame in the conduit to hide it in a chase.
Regards
Gemstone1
Second that: read the install manual for your chosen mini on line, paying attention to a charged length of pipe it is supplied with and the type of the refrigerant. You could be charged extra for charging the extra length of refrigerant line with the additional refrigerant
If you are even a bit handy- you could prep all the install yourself- slowly but surely- cleaner as well. All you need is a 3” hole saw from HD, read manual regarding what line supports needed, etc.
Then all you need- a visit from the electrician- - could do electric simultaneously.
You can even hang the indoor unit yourself.
To have the warranty- bring a licensed HVAC specialistto connect the refrigerant line even if he is not a dealer- the manufacture will not refuse the warranty if your supply the license number, etc of the HVAC installer.
HVAC guy has a specialized tools and can connect, check and charge a refrigerant line with extra if needed( some splits have 15 ft pre- charged line, some 25- check the manual.
As far as I understand even HVAC guys do not have skills of weighting tge refrigerant properly- a lot of just doing an old school beer can cold touch evaluation
Apologies to professionals, but most of you guys- are not very good. I became cynical over the years.
So no guarantee that the company you talked to are very experienced- they could be just “trained- do just a standard install, without intricate measurements needed for success.Go to vanguard energy website and educate yourself about the pitfalls of improper sizing/ installation of HVAC equipment in the US - mini splits especially.
You can get creative- but probably have to do a lot of “ grind” work yourself.
They want to just come, drill 3” hole, hang it and be on their way with the cash/ check in 3 hours+ travel time to from the customer- the day is gone, beer time.
Even with money, I guess I will have to do some myself or coordinate different people to get it done.
For the placement, are you saying don’t bother with floor mounted units?
Choices on the walls up high are limited due to window frames and clearances, and the units seem to me to be pretty clunky looking.
I know down low is not good for a cold air outlet, just hate the thought of seeing them up on the wall.
I think as I remember the floor mounted units are slightly less efficient. Read the manuals
If you don’t care to “squeeze” all possible efficiency- floor units are fine- make sure no furniture obstruction- they make them- they will work
The best mini manufactures are all about good design of the way the air is mixing and spreading- don’t worry about high low on the wall- the proper sizing and a proper amount of refrigerant ( not too much and not too low) is the most important.
Again, read extensively the manuals before you buy and select your placement. It is simple to understand the way the internal unit sends the air out for good mixing and their limitations regarding the best placement
Don’t forget to read about a drain line- it has to lean slightly and discharged so no damage to the house and no mold- maybe that is why your installers are reluctant to do a creative install- not worth it to them.
To summarize:3” hole in tge outside wall and 3 lines: electric, drain tube, refrigerant copper line
They may give you a crazy install price to get you off their back or if you don’t care- they will get a lot more money then they deserve.
Last edited by Nik4me; 08-22-2019 at 11:37 AM..
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