Very nice install on that system. I'm an HVAC installer with 15 years experience in NC and you got a good contractor there, Matt. I can tell just by looking at the flex duct on the return, it's hung beautifully with straps every 2 feet and the turns are supported very well. The metal duct on the supply is wrapped nicely as well. Overall, it's a great install, and your contractor obviously takes pride in their work.
Vinny Mac Hello, I’d like to do this similar install, but I don’t have attic space. How can I do this? Is it better to do a mini split ductless and connect it to vents? Because I don’t want the inside wall unit. (It’s very tacky to me) and how can I connect it to a thermostat if there’s no wall unit? Thanks
@@Tiagbenasen ask an HVAC pro. Or waste money before you realize how important sizing duct correct is and how much you need to know. Someone needs to look at your house and do a load calculation. That will tell you what you need
Hello Matt: I haven't read all the comments yet and I realize this is Work in Progress but I didn't see an emergency drain pan with safety overflow switch. I'm sure will put that into system!
Thanks for sharing... I would prefer to see a square-to-round fitting on the return, especially on a low static air handler. Love the application though.
Adding a similar system to an investment property we picked up. House is 1910 construction with a packaged HVAC system outside. Upstairs you feel a major difference because of how leaky the HVAC system is. Buddy is installing this type of system just for upstairs- run on a separate thermostat- to give super efficient cooling or heating when needed. We’re going to seal off the ducting from package unit to the upstairs. Mainly because it’s wasting so many BTUs to get conditioned air delivered upstairs.
Always appreciate HVAC videos Matt. I'm also wondering if you have an opinion on cellular shades/honeycomb shades? From an energy efficiency standpoint.
This would be perfect for my parents. They are always dealing with a hot master suite. The existing dual-zone Trane 5-ton system can't keep up with a 3000+ SF house in Dallas!
Lucky, the contractor who did my house flex duct work did it with the "any which way you can" attitude. It was my hvac tech years later who pointed how wrong for routing the lines that way. We would have some areas that were cold and others hot, thought it was the sun bearing down on the walls.
Good video. What does a system like that go for? My second floor is always 5-6 degrees higher than my first floor. I have always been curious about spray insulation on the inside of the roof structure. I have seen people spray soft foam and a denser foam on the attic side of the roof. Isn't there a concern if the roof leaks and/or if the shingles and a section of decking need to be replaced? I've always been concerned about leaking issues. And are there any outgassing concerns for spray insulation?
How about an update on using split units for HVAC in new construction, especially now that new construction in parts of CA must be all electric, no gas allowed?
I run into the same thing here. Most HVAC contractors in my area don't like mini splits for various reasons so I'm just installing my own and having someone just finish the vacuum pull/etc for warranty sake.
Same here. Mine is tucked in between roof and home sealing so no access from the attic. My unit stop blowing cold assuming there is a filter shown in thos video but that door is like jam. Removed 2 screws but not opening. Any suggestions would be appreciated
So guys just a question from overseas, where this type of application isn't diffuse. Talking about allergies and allergens, how do you perform disinfection of ducting and tubing of both go and return lines, since I guess that ducting becomes black in dust and any kind of contaminants in a couple of months no matter how nice filter you put in between. There is scheduled maintenance that provides sanitation of the ducting system?
I always see these low or mid static systems supplying to multiple rooms , but never see returns coming from multiple rooms. Is it possible to use these systems to supply multiple rooms that are completely isolated from each other making central return not possible and hence the need to get returns from each of these rooms merging and connecting to return plenum of the unit ?
Concealed ducted units are labeled as high static or low static units meaning??? I understand the concept of static pressure in supply and return duct volume but not so sure about which units to purchase. My runs will only be 5-10' off the units.
This is a low static unit. Some are as low as .16 wc. They aren't really designed to be used with ducts though. Think soffit and direct return and supply vents.
Matt, Love your videos. I own an HVAC company and install 100's of that exact system here in Hawaii. You should be aware that the AHU shown in the video is a major pain in the neck to service.....service the coil, access the fan...ect...also the internal pumps fail in about a year. I have stopped installing that AHU model and have exclusively moved to the PVFYP18NMAU-E series. In the long run the PVFY AHU is a way better option. It took me 2 years to realize this. That Mitsubishi CityMulti system is the best of the best.....just like everything else you do....good choice in equipment....just talk to your Mechanical guy about using different AHU's next time.
@OFFSHOREAIR Thanks for the AHU tip. I’m planning a retrofit for a 1920s 2 story and was debating what to put in the attic (not my first choice, but in LA it’s tolerable) for the 2nd floor zone.
This is exactly what I need. I would like to consult with a company. I live in Corpus Christi, which is 6 hours away from Austin. Do you know of a company in my area that could do this? Thanks!
The double bend on the supply discharge is concerning. But with low CFM, maybe it’ll be OK. And what’s with the air filter being in the attic? Strange design.
Why? Most systems with air handlers or furnaces in the attic, the ideal location for the filter is right on the return side of a/h or furnace; less static pressure loss!
Hey, has anybody heard of using flex duct in an older home with a conventional blower system? We have an older home from 1929, have flex duct SDHV outlets in ceiling and upstairs in attic, but we had an upright blower system... we just recently had our system replaced due to it being from 2002, and no longer functioning correctly. The new HVAC co installed similar blower unit, swore it was not a high velocity system, now coils are freezing up, thermostat is erratic, the outside condenser is a GOODMAN 1.5 ton... and oddly the HVAC co has no images of our older unit... but we are at a loss here... need some help. Thanks so much!
Installed a few of them. Work great when installed properly like that one. But 99% of installers put them where there is no Access. (Dumb ) And finding a good tech to repair them is tough. But very nice install there
Same here. Mine is tucked in between roof and home sealing so no access from the attic. My unit stop blowing cold assuming there is a filter shown in thos video but that door is like jam. Removed 2 screws but not opening
You could put a 1--1/2 Ton wall-mounted unit outside and run supply duct thru attic and cut wall for return in the proper space. This is an all electric system.
It appears that the threaded rods are hung from a channel strut (Unistrut or equivalent) attached to the rafters. Regarding the use of the strut and rods: a) given the strut is not mounted perpendicular to the rods how exactly did you attach the rods to the strut (what specific fasteners / fittings were used)?; b) how exactly did you attach the strut to the rafters (what fasteners were used and at what location and angle were they driven?; c) what other methods might you use to hang the rods from the rafters (I read a suggestion to use a deck tension tie bracket)?; d) I've read projects where channel strut was laid across joists (for loads in the room below) -- for small loads in the attic (say 100-200 lbs.), what about laying the strut across collar ties?; and e) are there any issues regarding metal near the ridge line (particularly re lightning)? General comments / suggestions re the use of threaded rod & / or channel strut in the attic?
Hello: I want a system just like this for a 500 square foot theater, but I want to be able to bring in fresh air with the room closed. I was told Mitsubishi systems do not have this ability. Is there a system that allows you to bring in fresh outside air? Thanks
Nice system but the reasons he gave for the bend didn't make sense as there is 'plenty of room'. He could have given more info supporting this choice such as efficiency overall, cost, reliability. mostly it seems related to wanting more control over space conditioning. I still wish they would comment on why the attic isn't more insulated, because otherwise it will still keep coming on and sweating, won't it?
terre tulsiak The main duct for master bedroom is short and goes immediately down and to the right as can be seen in video at two minute mark. The duct that is doubling back is only for master bath and closet. Not ideal, but was better to have short direct run for the main space being served by this unit. Also, there will be spray foam on underside of decking but has not been installed yet.
I understand the logic on the hard metal ducting, less restrictive air flow, However I wonder about the heat loss/gain due to the higher conductivity of the metal over non metal ducting?
That duct work is crap. Whoever installed that doesn’t know much.. they even insulated the return lol. All he had to do was turn the. Unit around and your supply would for. Those being “ low static” you don’t put 2 damn 90s right off the supply plenum.that increases your friction rate and static pressure…and there goes any efficiency. I would not post videos of that install.
What a shitty install.... depending on the location that unit is screwed. Is that going to be in conditioned space??? The duct is ran right up against the roof deck???
I really appreciate your insight and dedication to building science & knowledge.
Very nice install on that system. I'm an HVAC installer with 15 years experience in NC and you got a good contractor there, Matt. I can tell just by looking at the flex duct on the return, it's hung beautifully with straps every 2 feet and the turns are supported very well. The metal duct on the supply is wrapped nicely as well. Overall, it's a great install, and your contractor obviously takes pride in their work.
Vinny Mac Hello, I’d like to do this similar install, but I don’t have attic space. How can I do this? Is it better to do a mini split ductless and connect it to vents? Because I don’t want the inside wall unit. (It’s very tacky to me) and how can I connect it to a thermostat if there’s no wall unit? Thanks
@@Tiagbenasen ask an HVAC pro. Or waste money before you realize how important sizing duct correct is and how much you need to know. Someone needs to look at your house and do a load calculation. That will tell you what you need
Bet you have seen some interesting installs in those NC housing tracts lol
Hello Matt: I haven't read all the comments yet and I realize this is Work in Progress but I didn't see an emergency drain pan with safety overflow switch. I'm sure will put that into system!
Thanks for sharing... I would prefer to see a square-to-round fitting on the return, especially on a low static air handler. Love the application though.
Adding a similar system to an investment property we picked up. House is 1910 construction with a packaged HVAC system outside. Upstairs you feel a major difference because of how leaky the HVAC system is. Buddy is installing this type of system just for upstairs- run on a separate thermostat- to give super efficient cooling or heating when needed. We’re going to seal off the ducting from package unit to the upstairs. Mainly because it’s wasting so many BTUs to get conditioned air delivered upstairs.
Good idea!
Neat. Never a bad video.
Always appreciate HVAC videos Matt. I'm also wondering if you have an opinion on cellular shades/honeycomb shades? From an energy efficiency standpoint.
This would be perfect for my parents. They are always dealing with a hot master suite. The existing dual-zone Trane 5-ton system can't keep up with a 3000+ SF house in Dallas!
If their home is over 3000 SF in Dallas, it will need another 5-ton system additionally!
Awesome build Matt, I love the mechanical designs you're installing. There are about a million shiners coming through that roof deck though.
Nice! I want to do that to my master bedroom
Lucky, the contractor who did my house flex duct work did it with the "any which way you can" attitude. It was my hvac tech years later who pointed how wrong for routing the lines that way. We would have some areas that were cold and others hot, thought it was the sun bearing down on the walls.
That’s what happens when someone doesn’t know what they’re doing…just like this shit work in the video
Good video. What does a system like that go for? My second floor is always 5-6 degrees higher than my first floor.
I have always been curious about spray insulation on the inside of the roof structure. I have seen people spray soft foam and a denser foam on the attic side of the roof. Isn't there a concern if the roof leaks and/or if the shingles and a section of decking need to be replaced? I've always been concerned about leaking issues. And are there any outgassing concerns for spray insulation?
Sprayed foam insulation in attics and walls can be a big liability and costly repairs!
hi, is the return a flex duct or or solid insulated pipe?
How about an update on using split units for HVAC in new construction, especially now that new construction in parts of CA must be all electric, no gas allowed?
I totally wanted to do this in my build in 2013 but was talked out of it. Next time, I will do it.
I run into the same thing here. Most HVAC contractors in my area don't like mini splits for various reasons so I'm just installing my own and having someone just finish the vacuum pull/etc for warranty sake.
I was wondering if I could hook up a mini split to existing duck work
Same here. Mine is tucked in between roof and home sealing so no access from the attic. My unit stop blowing cold assuming there is a filter shown in thos video but that door is like jam. Removed 2 screws but not opening. Any suggestions would be appreciated
What was the square footage of the master suite?
Will the attic be insulated?
What model is this unit? It’s look nice and compact
Do you install a drain pan or in this type of units is not necessary ?
So guys just a question from overseas, where this type of application isn't diffuse. Talking about allergies and allergens, how do you perform disinfection of ducting and tubing of both go and return lines, since I guess that ducting becomes black in dust and any kind of contaminants in a couple of months no matter how nice filter you put in between. There is scheduled maintenance that provides sanitation of the ducting system?
Is the air handler in unconditioned space? Also, it would be interesting to see the whole system as designed by Positive Energy.
www.mitsubishicomfort.com
I always see these low or mid static systems supplying to multiple rooms , but never see returns coming from multiple rooms.
Is it possible to use these systems to supply multiple rooms that are completely isolated from each other making central return not possible and hence the need to get returns from each of these rooms merging and connecting to return plenum of the unit ?
A nice big continuous radius coming off that far end would have been better than two 90 degree elbows, yes?
Concealed ducted units are labeled as high static or low static units meaning??? I understand the concept of static pressure in supply and return duct volume but not so sure about which units to purchase. My runs will only be 5-10' off the units.
This is a low static unit. Some are as low as .16 wc. They aren't really designed to be used with ducts though. Think soffit and direct return and supply vents.
Would hv liked to see 2x 45's on that 90 bend.
Hey Matt: What product are you using to insulate the ducts, thanks?
Mark Britton looks like FSK foil scrim kraft. Strong stuff and the tapes made of the same stuff so it matches well and is durable also.
Where is the auxiliary drain pan? Do these units have a built in safety switch? Better have one or it could flood the room below if a clog happens.
Do the units transmit vibrations through the house?
cool, pun intended
Matt, Love your videos. I own an HVAC company and install 100's of that exact system here in Hawaii. You should be aware that the AHU shown in the video is a major pain in the neck to service.....service the coil, access the fan...ect...also the internal pumps fail in about a year. I have stopped installing that AHU model and have exclusively moved to the PVFYP18NMAU-E series. In the long run the PVFY AHU is a way better option. It took me 2 years to realize this. That Mitsubishi CityMulti system is the best of the best.....just like everything else you do....good choice in equipment....just talk to your Mechanical guy about using different AHU's next time.
@OFFSHOREAIR Thanks for the AHU tip. I’m planning a retrofit for a 1920s 2 story and was debating what to put in the attic (not my first choice, but in LA it’s tolerable) for the 2nd floor zone.
Question in this kind of units they need a drain pan ?
@@josedaza544 Yes all ducted AHU's in an attic need a drain pan for Just in case, its cheap insurance over drywall damage.
What kind of insulation is being used in this install? I do not see that used in my area. Is it an aluminum foil?
This is exactly what I need. I would like to consult with a company. I live in Corpus Christi, which is 6 hours away from Austin. Do you know of a company in my area that could do this? Thanks!
What about the drain pan ?
This would be nice for skoolie build
The double bend on the supply discharge is concerning. But with low CFM, maybe it’ll be OK. And what’s with the air filter being in the attic? Strange design.
Why? Most systems with air handlers or furnaces in the attic, the ideal location for the filter is right on the return side of a/h or furnace; less static pressure loss!
Darned few homeowners will go the attic to change a filter. Make it easy on the consumer, and they may do their job.
@@drakbar5957 They can have a maintenance agreement! Also check units twice a year! That's what civilized people do!
How do you clean/service these?
Ooh ok👍👍
Hey, has anybody heard of using flex duct in an older home with a conventional blower system? We have an older home from 1929, have flex duct SDHV outlets in ceiling and upstairs in attic, but we had an upright blower system... we just recently had our system replaced due to it being from 2002, and no longer functioning correctly. The new HVAC co installed similar blower unit, swore it was not a high velocity system, now coils are freezing up, thermostat is erratic, the outside condenser is a GOODMAN 1.5 ton... and oddly the HVAC co has no images of our older unit... but we are at a loss here... need some help. Thanks so much!
Installed a few of them. Work great when installed properly like that one. But 99% of installers put them where there is no Access. (Dumb ) And finding a good tech to repair them is tough. But very nice install there
Same here. Mine is tucked in between roof and home sealing so no access from the attic. My unit stop blowing cold assuming there is a filter shown in thos video but that door is like jam. Removed 2 screws but not opening
My attic highest is 21” so it’s a low pitch roof, is it possible for me to install something like this for a 800sqf house
Yep, ductless would be much easier though.
You could put a 1--1/2 Ton wall-mounted unit outside and run supply duct thru attic and cut wall for return in the proper space. This is an all electric system.
It appears that the threaded rods are hung from a channel strut (Unistrut or equivalent) attached to the rafters. Regarding the use of the strut and rods: a) given the strut is not mounted perpendicular to the rods how exactly did you attach the rods to the strut (what specific fasteners / fittings were used)?; b) how exactly did you attach the strut to the rafters (what fasteners were used and at what location and angle were they driven?; c) what other methods might you use to hang the rods from the rafters (I read a suggestion to use a deck tension tie bracket)?; d) I've read projects where channel strut was laid across joists (for loads in the room below) -- for small loads in the attic (say 100-200 lbs.), what about laying the strut across collar ties?; and e) are there any issues regarding metal near the ridge line (particularly re lightning)? General comments / suggestions re the use of threaded rod & / or channel strut in the attic?
LVL??
Filter in the attic? 🤔
Probably accessible via staircase... our old house had one in the crawlspace O.o
Yes is very common in areas without cellars or closet space. In Houston we have many thousands installed in the attic
Is that a pead-a36aa7?
Can it verticaly mounted behind wall?
I'm pretty sure Panasonic makes a unit that can be mounted vertically.
Hello: I want a system just like this for a 500 square foot theater, but I want to be able to bring in fresh air with the room closed. I was told Mitsubishi systems do not have this ability. Is there a system that allows you to bring in fresh outside air?
Thanks
I know I'm late to the comments by a few years but what size of return duct is that? and how many BTU's is the unit
Nice system but the reasons he gave for the bend didn't make sense as there is 'plenty of room'. He could have given more info supporting this choice such as efficiency overall, cost, reliability. mostly it seems related to wanting more control over space conditioning. I still wish they would comment on why the attic isn't more insulated, because otherwise it will still keep coming on and sweating, won't it?
terre tulsiak The main duct for master bedroom is short and goes immediately down and to the right as can be seen in video at two minute mark. The duct that is doubling back is only for master bath and closet. Not ideal, but was better to have short direct run for the main space being served by this unit. Also, there will be spray foam on underside of decking but has not been installed yet.
+terre tulsiak this is still under construction. The Attic will be insulated at the roof line.
@@buildshow Many neophytes round here!
What's the model of that unit?
Low static indoor air handlers are SEZ models up to 18kbtu and Medium/High static models in PEAD models up to 42kbtu
I understand the logic on the hard metal ducting, less restrictive air flow, However I wonder about the heat loss/gain due to the higher conductivity of the metal over non metal ducting?
thedge7 moot point. Attic will be semi-conditioned space once spray foam insulation is applied to decking.
+Chest Rockwell yes correct
Why not go with mini splits ?
+MasterBuilt Designs this uses the same technology but gives "standard " grills and registers on the ceiling. Plus better filtration
Lg low static duct
video: "This is a minisplit." No other details shared. cool.
Use a minispilt
nice but pricey
That duct work is crap. Whoever installed that doesn’t know much.. they even insulated the return lol. All he had to do was turn the. Unit around and your supply would for. Those being “ low static” you don’t put 2 damn 90s right off the supply plenum.that increases your friction rate and static pressure…and there goes any efficiency. I would not post videos of that install.
Yes, isulate the return. Why heat the return air up, only to have to cool it back down? I agree that the two 90's are bad.
What a shitty install.... depending on the location that unit is screwed. Is that going to be in conditioned space??? The duct is ran right up against the roof deck???