HVAC - mini split or full conventional system - not that it matters because no one wants to do the work...

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GrumpyDad

Minister of Fire
Feb 23, 2022
553
Champion, PA
SO half rant, half curious what people think here.
I have a frankenstein cabin that Im trying to figure out how to get heating/cooling in there. Right now, it has a very old trailer oil furnace that blows into two sides of a 20x30 cabin. Attached to this cabin also is another 20x30 expansion, half of which is a 'sunporch' the other half is our bedroom. This was built on telephone piers scooped out half moon with telephone poles laying down on those as support. Not joking, then oak flooring (not T/G and you can see daylight). This area is heated with ONE 8' baseboard that actually does the job rather well until the temps dip below 15 deg f or so, and there is a strong wind underneath (not insulated, I plan to address this). There is also another 10x8 expansion that is literally just built inches from the dirt that I dont have access to underneath or above. This is a bunkbed room/office. And wait, there's more, I just put on a 24x26 expansion.

The bunk area has no heat, it just gets heat from the main area naturally but it gets cold in there without a space heater.
The new expansion (24x26) has a new VC stove in there so Im not worried about that area for heat. In fact, it was only 6-8 degrees cooler than the main area at most during the winter last year because I used the absolute most insulation I could when I built this area. Im hoping the VC stove puts heat into the other areas as well.
So I'm not too concerned about heat, but where my oil heater is at , it takes up alot of real estate for an area that I would like to take over for a washer/dryer , water heater, and to the one side a mini bar. Not to mention it is very old.

I do have a small attic in the main cabin area that is 5' tall at the tallest then it goes out from there 4/12 roof pitch, I could hit the two other main areas easily from there within 10' or so.

I called 8 different hvac companies in the area over the last 5 years or so, including one that comes out and cleans / maintains my current 1970s oil furnace. Only ONE group, 5 years ago, provided me a quote for 3 mini splits (I really need four) and they wanted 18k. I really didnt like the idea of mini splits to be honest. I dont like how they look, and I dont want to heat the place other than to a bare minimum while we arent there. My neighbor has a mini split and it takes forever to heat his place. He kicks it on thursday for friday arrival and it's generally about 60 degrees at the time when he arrives, then he kicks on his stove. He loves the AC though and feels it's better for that.

I really wanted a conventional system and even considering trying to DIY it, using flexible ducts with foam insulation wrapped around them to make it easy to run duct work to the various locations. They use this stuff in office buildings ALL the time, I see it when I used to pull wires through drop ceilings etc. But no one wants to quote me for that. They all say, oh no you cant get that - you need a mini split that's pretty much your only option, ....then they never provide me a quote.

For a mini split, the main unit would sit outside the new expansion, about 3' off the ground mounted on a wall. Im not saying it would be easy, it would take two guys two days of work for sure. 3 runs would run up through the soffit of the new expansion into an area where the old/new roofs meet..sort of an attic with a sloped from / shingled from the old roof, then it would run into the old attic and would hit the OG cabin, new expansion and the bedroom. The 4th run would literally just go feet away sideways and up to hit the tiny bunk room.

I considered just getting one of those crawlspace dehumidifiers to try and keep the moisture down. That's our biggest issue during the summer. It's like a swamp there, and very uncomfortable. Indoor humidity exceeds 80% and it's causing some of my new wood work to buckle. I've had to cut expansion spaces into the smaller pieces, and the larger ones are pulling away from the wall my to my shock/surprise. Not alot but enough that a rubber mallet forces them back 1/8 an inch flush to the wall. All t/g paneling. So I have to do something about dehumidification (or start adding more expansion joints between the boards when Im putting wood up/around during the summer). It would be nice to be cool during the day/night as well, not cold but cooled off a bit. We have a window AC in the livingroom, and one of those floor model / window pipe exhausts in the bedroom. The one in the bedroom just cools things down to the point that you can sleep a bit but the humidity is still so high it feels like you are sleeping on wet sheets.

Anyway, just random ramblings about my situation. Hard for people to envision for me what I have to deal with , without extensive pictures. Just curious if anyone else has had a similar experience and what they did about it.
 

stoveliker

Minister of Fire
Nov 17, 2019
6,197
Long Island NY
If your neighbor can't heat with a minisplit, it's undersized, or not suitable for a colder climate.
The technology is the same as a ducted system, just the minisplit has better efficiency. If a properly sized minisplit system can't do it, the ducted heat pump will also be unable to do it.

I think the DIY minisplit installs are even easier than messing with ducts.

There are systems where the inside unit is mounted in a ceiling. So if the attic layout works, you can hide the lines there, mount the inside unit there, and not be bothered by the aesthetics of that. This is only for the more expensive brands, though, I think (rather than e.g. a MrCool DIY).

My $0.02 for a happy current minisplit user (and having used ducted heat/AC in TN).
 

EbS-P

Minister of Fire
Jan 19, 2019
3,518
SE North Carolina
I’m going down the HVAC rabbit hole. My quick take aways it’s really hard to find someone to do a perfect hvac install and would probably be cost prohibitive if you could find them.

Sizing a traditional single speed compressor heatpump for heating and cooling in your climate is hard. Heating demand is probably 3x (just guessing l) greater than your cooling demand. The solutions are the expensive variable speed units(whole house is what I’m referring to here).

Dehumidification is important and an appropriately size hvac system still is not adequate during the 2-3 most humid months.

Heatpump water heaters are good for humid spaces in the fall summer and spring. Keep all venting inside the building envelope.

Air sealing is the key. Then insulation.

Ducts in vented crawl spaces or attics are not efficient but easy. Understand the issues and trade offs .

More people should look at package units as possible DIY heating and cooling solutions.

I really think any heatpump needs to be installed with supplemental heat. Resistive strips is easy. Refer to my package unit option.


If I was you wanting a decent install. Would air seal air seal air seal. Insulate, insulate, insulate the living space. moisture barrier insulate and dehumidify the crawl space. Then pick my heat source. You could install a package unit DIY. And the mr cool mini splits too.

Cheapest option per ton is probably the MR cool mini splits. A single stage package unit might be close I just don’t have any idea how much materials for ducts would cost. And American standard single stage 3.5 ton unit 14 seer costs my dad 6500$ two years ago. No clue what it’s up to now. I have decided to hold off on everything but a possible mr cool mini splits


Just some thoughts.
 

GrumpyDad

Minister of Fire
Feb 23, 2022
553
Champion, PA
If your neighbor can't heat with a minisplit, it's undersized, or not suitable for a colder climate.
The technology is the same as a ducted system, just the minisplit has better efficiency. If a properly sized minisplit system can't do it, the ducted heat pump will also be unable to do it.

I think the DIY minisplit installs are even easier than messing with ducts.

There are systems where the inside unit is mounted in a ceiling. So if the attic layout works, you can hide the lines there, mount the inside unit there, and not be bothered by the aesthetics of that. This is only for the more expensive brands, though, I think (rather than e.g. a MrCool DIY).

My $0.02 for a happy current minisplit user (and having used ducted heat/AC in TN).
hey thanks for the reply. Well I would be going with an oil furnace so, those handle heat pretty well. As for the neighbor, he has only ONE for his entire cabin which I will say is pretty small. Maybe 20x25 with a ceiling (attic for storage). He said he loves it because he got rid of a big furnace and freed up space for a seating area, and he doesnt have to worry about or pay for propane heat (which is super expensive compared to oil).

I like the idea of the ceiling system for the one room and thought about that, but for the main living room area it's cathedral with big beams, and the expansion is the same so it would need to be mounted on a wall. I looked at LG and even had a dealer come out and look at my place for an estimate but they never got back to me.

Im worried about a DIY system for a few reasons: First they are ALL made from the same factory, and while it's unlikely they will go under any time soon, if Mr Cool goes out and doesnt provide coorelating parts to say, blue ridge, then Im screwed. Second, I dont like the idea of having a coiled up set of excess lines, not to mention they dont really offer a ton of options for length so I wouldnt be able to reach as far as a pro job would. Third, im terrified I will spend 6-7k on a big DIY effort, screw it up or have it be screwed up from the manufacturer, then fight fight fight to get a pro to come out and look at it. Everyone I've talked to about DIY systems has said, they will NOT come out and look at nor touch those units.
I’m going down the HVAC rabbit hole. My quick take aways it’s really hard to find someone to do a perfect hvac install and would probably be cost prohibitive if you could find them.

Sizing a traditional single speed compressor heatpump for heating and cooling in your climate is hard. Heating demand is probably 3x (just guessing l) greater than your cooling demand. The solutions are the expensive variable speed units(whole house is what I’m referring to here).

Dehumidification is important and an appropriately size hvac system still is not adequate during the 2-3 most humid months.

Heatpump water heaters are good for humid spaces in the fall summer and spring. Keep all venting inside the building envelope.

Air sealing is the key. Then insulation.

Ducts in vented crawl spaces or attics are not efficient but easy. Understand the issues and trade offs .

More people should look at package units as possible DIY heating and cooling solutions.

I really think any heatpump needs to be installed with supplemental heat. Resistive strips is easy. Refer to my package unit option.


If I was you wanting a decent install. Would air seal air seal air seal. Insulate, insulate, insulate the living space. moisture barrier insulate and dehumidify the crawl space. Then pick my heat source. You could install a package unit DIY. And the mr cool mini splits too.

Cheapest option per ton is probably the MR cool mini splits. A single stage package unit might be close I just don’t have any idea how much materials for ducts would cost. And American standard single stage 3.5 ton unit 14 seer costs my dad 6500$ two years ago. No clue what it’s up to now. I have decided to hold off on everything but a possible mr cool mini splits


Just some thoughts.
INTERESTING! I hadnt even known these exist. Im curious as to the applications. Honestly, running flexible ductwork may be just as easy, if not easier for me than running mini split lines. Then I still need to hang the mini splits.

Im very curious how a packaged unit connects to duct work though. If this unit sits outside, it would be wildly inefficient to have duct work exposed outside. Sure I could build some sort of cabinet/seal it possibly for the two ducts coming out, but...it just seems kinda crazy to me.
I wonder if something like this could be installed in an attic space. I bet it would be NOISY as heck up there though.
 

stoveliker

Minister of Fire
Nov 17, 2019
6,197
Long Island NY
if you run ducts, you won't have to hang minisplits.
That's the point of "split", the two heat exchangers are one outside and one inside. With ducts all that is in the same place and only conditioned/heated air moves.
 

EbS-P

Minister of Fire
Jan 19, 2019
3,518
SE North Carolina
hey thanks for the reply. Well I would be going with an oil furnace so, those handle heat pretty well. As for the neighbor, he has only ONE for his entire cabin which I will say is pretty small. Maybe 20x25 with a ceiling (attic for storage). He said he loves it because he got rid of a big furnace and freed up space for a seating area, and he doesnt have to worry about or pay for propane heat (which is super expensive compared to oil).

I like the idea of the ceiling system for the one room and thought about that, but for the main living room area it's cathedral with big beams, and the expansion is the same so it would need to be mounted on a wall. I looked at LG and even had a dealer come out and look at my place for an estimate but they never got back to me.

Im worried about a DIY system for a few reasons: First they are ALL made from the same factory, and while it's unlikely they will go under any time soon, if Mr Cool goes out and doesnt provide coorelating parts to say, blue ridge, then Im screwed. Second, I dont like the idea of having a coiled up set of excess lines, not to mention they dont really offer a ton of options for length so I wouldnt be able to reach as far as a pro job would. Third, im terrified I will spend 6-7k on a big DIY effort, screw it up or have it be screwed up from the manufacturer, then fight fight fight to get a pro to come out and look at it. Everyone I've talked to about DIY systems has said, they will NOT come out and look at nor touch those units.

INTERESTING! I hadnt even known these exist. Im curious as to the applications. Honestly, running flexible ductwork may be just as easy, if not easier for me than running mini split lines. Then I still need to hang the mini splits.

Im very curious how a packaged unit connects to duct work though. If this unit sits outside, it would be wildly inefficient to have duct work exposed outside. Sure I could build some sort of cabinet/seal it possibly for the two ducts coming out, but...it just seems kinda crazy to me.
I wonder if something like this could be installed in an attic space. I bet it would be NOISY as heck up there though.
Some package units have a gas stage of heat.

All the ducts are insulated. Hence the sealed insulated and dehumidifier crawl space. Some package units are installed on flat roofs. The volume of air going through the condenser is so large I doubt it would work in an attic. Mine works fine down to 25. A gas pack unit would be my choice for cold but would require propane.

I have similar feelings abou
 

GrumpyDad

Minister of Fire
Feb 23, 2022
553
Champion, PA
if you run ducts, you won't have to hang minisplits.
That's the point of "split", the two heat exchangers are one outside and one inside. With ducts all that is in the same place and only conditioned/heated air moves.
you lost me.
So minisplits, you have to run the refrigerant lines, drain hose and orient / plan in a way that the drain hoses have a constant drain path in a downward slope. You also have the big ugly white box hanging on the wall of a rustic cabin.

The traditional systems, you have duct work. In my case, we have none that extends out of the unit. The current oil furnace sits on ductwork that blows heat directly under the unit and into the next room through the wall that the furnace is located. That's it. However, I do not think it would be a big deal to run flexible insulated ductwork (with plastic hangers to keep it off the ground) throughout the two main areas. I would however have a challenge getting into the bedroom as there is no crawlspace access, so I would almost need to create a chase from the floor up and into the next building where our room resides, and I would be pretty much SOL for the 'bunk room'.

This system you mentioned, 'both' the interior units and exterior you traditionally see in a traditional center air/heat system sits outside.
What I questioned was, the duct work running outside. During the winter it would get very cold and transfer that cold throughout the duct work when not running, and during the summer same there. Im curious how people are handling that. That has to be a massive loss in efficiency.
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,254
South Puget Sound, WA
Flex duct in any area that has rodents and other vermin will likely be very leaky and worthless in a few years. They love the insulation for nesting and even for homes. Once they have penetrated the inner jacket they have a highway to the cabin's interior. Don't ask how I know.

Note that the larger mini-split companies make different indoor exchangers besides the big white wall wart. In this case, a floor mount console might be more appealing.
 

GrumpyDad

Minister of Fire
Feb 23, 2022
553
Champion, PA
Flex duct in any area that has rodents and other vermin will likely be very leaky and worthless in a few years. They love the insulation for nesting and even for homes. Once they have penetrated the inner jacket they have a highway to the cabin's interior.
Flex inside, not outside. I would run flex only inside.
Mice are a big problem for us. We had birdseed delivered, and then couldnt visit our place for 2 months due to a ton of commitments and illnesses last year. We returned to find nests in drawers, cabinets, ...everywhere. The little bastards took the birdfood inside and made our cabin a hotel. It took me an entire weekend, 14 hours a day cleaning and disinfecting everything.
Now I have traps....lots and lots of traps. I also have perimeter deterrence as well.
After cleaning and heavily trapping, I caught 5 mice the next day. 4 the day after that, then the next weekend came back to 3, the weekend after that 2. Now I get about 1 every 2-3 weeks.
Ive become quite adept at what the best mouse trap is. The good old fashioned ones are absolutely the best. They make ones now that are easier to set but resemble the old fashioned ones and those work best.
The worst are the ones that look like paper clips. The mice know they can step on that big yellow cheese looking thing, and they can gently eat all the peanut butter off of the clip. I still catch mice in them occasionally, but only when I put the peanut butter all the way toward the very back of the clip - they get greedy and WHAMO dead...(well after awhile Im sure).
I also like the traditional ones as well because I think they probably are a bit more humane, as in death comes quickly vs them struggling and trying to chew their way to freedom.
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,254
South Puget Sound, WA

GrumpyDad

Minister of Fire
Feb 23, 2022
553
Champion, PA
So not in the crawl space or an attic where vermin may roam?
yes crawl space and possibly attic. The vermin problem will need to be addressed, regardless of duct work (metal, foam, etc). Ive already heard that split mini lines become an avenue for intrusion as well. So I dont think there is a perfect solution for me. I have a good bit of sealing to do as well, likely a next spring effort as we are now in get ready for winter mode.
 

stoveliker

Minister of Fire
Nov 17, 2019
6,197
Long Island NY
you lost me.
So minisplits, you have to run the refrigerant lines, drain hose and orient / plan in a way that the drain hoses have a constant drain path in a downward slope. You also have the big ugly white box hanging on the wall of a rustic cabin.

The traditional systems, you have duct work. In my case, we have none that extends out of the unit. The current oil furnace sits on ductwork that blows heat directly under the unit and into the next room through the wall that the furnace is located. That's it. However, I do not think it would be a big deal to run flexible insulated ductwork (with plastic hangers to keep it off the ground) throughout the two main areas. I would however have a challenge getting into the bedroom as there is no crawlspace access, so I would almost need to create a chase from the floor up and into the next building where our room resides, and I would be pretty much SOL for the 'bunk room'.

This system you mentioned, 'both' the interior units and exterior you traditionally see in a traditional center air/heat system sits outside.
What I questioned was, the duct work running outside. During the winter it would get very cold and transfer that cold throughout the duct work when not running, and during the summer same there. Im curious how people are handling that. That has to be a massive loss in efficiency.
Yes, with minisplits, you run refrigerant lines, no air ducts.
With a traditional system you run air ducts. That is a big part of the inefficiency of ducted systems: the losses due to the air ducts. (The other being the compressor.)

You mentioned "Honestly, running flexible ductwork may be just as easy, if not easier for me than running mini split lines. Then I still need to hang the mini splits."
That was the reason for my "if ducts, then no hanging of minisplits" remark.
 

EbS-P

Minister of Fire
Jan 19, 2019
3,518
SE North Carolina
It’s all about compromise. I’m pretty sure if I wanted a new system with all new duct work(which I need) I’m looking at 20k$ for a 20+ seer system. More if I want while home dehumidifier. Current system is 13 years old. 16 seer and under sized for heating.

Once could envision using a package unit like an old floor furnace. Need to place return(s) thoughtfully.

Retro fits are hard to figure out the best path. I don’t envy your situation. Quote I heard this week was if you can’t afford to do it right the first time you can’t afford to fix it your mistakes either.


Now is the absolute worst time in the last decade to be having to get hvac work done. Look one 18 or 24 k btu mini split might be enough to get you by for another winter. Down here insulation has not gone up that much.
 

GrumpyDad

Minister of Fire
Feb 23, 2022
553
Champion, PA
It’s all about compromise. I’m pretty sure if I wanted a new system with all new duct work(which I need) I’m looking at 20k$ for a 20+ seer system. More if I want while home dehumidifier. Current system is 13 years old. 16 seer and under sized for heating.

Once could envision using a package unit like an old floor furnace. Need to place return(s) thoughtfully.

Retro fits are hard to figure out the best path. I don’t envy your situation. Quote I heard this week was if you can’t afford to do it right the first time you can’t afford to fix it your mistakes either.


Now is the absolute worst time in the last decade to be having to get hvac work done. Look one 18 or 24 k btu mini split might be enough to get you by for another winter. Down here insulation has not gone up that much.
I have three goals when I break it down. We only go there during the weekend fall, winter, spring - and spend most of the summer there.
1. reduce the humidity. For my new expansion I will be putting down around 4.5-6k of hardwood and 17k of cabinetry for a new kitchen, this is my #1 goal is to protect that wood. I have a vapor barrier down, but it's not as it should be (all the way to the plate and over 2" of foam), I will be doing that this fall. I also considered a large crawlspace dehumidifier but worry about that adding heat during the summer months.
2. prepare for the inevitable which is the complete failure of my late 70s oil furnace. We rely on the oil heat to heat the place up to a minimum when we arent there during the week, when we first get there on Friday, in the evening when the wood in the fireplace burns down. A wood stove may help a bit since being installed, not sure. But I still wont be having fires when Im not there.
3. cool the place down a bit. It doesnt need much if humidity is taken care of. We have window AC that does nothing for humidity but makes it tolerable during the summer. We usually only run the one in the bedroom for when we go to sleep. Two other areas dont have any AC. One is my office area in the new expansion and it's quite hard to concentrate.

Only #2 requires some sort of immediate planning and only for freezing concerns. Even then, I could winterize the place in about 15 minutes honestly. SO it's not THAT big of a concern if my furnace were to crap out, although it would be uncomfortable waiting for that sweet sweet wood heat to permeate the walls enough to take the chill off.