New Home HVAC System

[IXLR8]

I am looking to purchase a home that just had an all new HVAC heat pump system installed. It was installed by 'one of the most reputable and respected' companies in the area. The attic is full of soft duct work that is sagging and pinched off by at least 70% in several spots. If I buy the house, I am going to have to find a way to fix it. Hard duct work seems to be a thing of the past. Although what jk96 posted is a thing of beauty and I wish an install like that was done on the home I am looking at.

 

[Sigarms]

You don't see hard ductwork much anymore. I speced it for my house. The HVAC guy said, some atticks look like a birds nest with soft ductwork everywhere, no good. In his opinion.

Most guys in NC in my area will run hard rectangular duct as their primary supply and return run, with collars to run flex to the outlets from the primary (more guys are going round hard duct on primary for new installs which actually does make more sense). What most guys don't do is run hard round pipe from the primary to the outlets. In an unconditioned space, prefer wrapped ductwork instead of lined (different opinions on conditioned spaces, but will only help if insulated).

At the end of the day, it's the little things that adds cost to the job, particularly with hard ductwork.

 

[jk96]

Most guys in NC in my area will run hard rectangular duct as their primary supply and return run, with collars to run flex to the outlets from the primary (more guys are going round hard duct on primary for new installs which actually does make more sense). What most guys don't do is run hard round pipe from the primary to the outlets. In an unconditioned space, prefer wrapped ductwork instead of lined (different opinions on conditioned spaces, but will only help if insulated).

At the end of the day, it's the little things that adds cost to the job, particularly with hard ductwork.

Main trunks are lined inside. All hard round off the main trunks. Unlined or wrapped but it is all in conditioned space.

 

[jk96]

Also can't stress enough about good air sealing and insulation. Our home blower door tested at 1.92 ACH50 on the last test I ran when I determined additional improvements would be hard to come by and quit there. A couple days ago when our area was part of the rolling blackouts I was seeing posts on fb from friends who's homes were loosing 10 to 15 degrees in an hour of no heat. Turned ours off to test and took 1 hour 45 minutes to drop 3 degrees. Was negative 18 outside.

 

[ponytug]

Also can't stress enough about good air sealing and insulation. Our home blower door tested at 1.92 ACH50 on the last test I ran when I determined additional improvements would be hard to come by and quit there. A couple days ago when our area was part of the rolling blackouts I was seeing posts on fb from friends who's homes were loosing 10 to 15 degrees in an hour of no heat. Turned ours off to test and took 1 hour 45 minutes to drop 3 degrees. Was negative 18 outside.

That's fantastic! Congratulations!

All the best, Peter

 

[Sigarms]

Also can't stress enough about good air sealing and insulation. Our home blower door tested at 1.92 ACH50 on the last test I ran when I determined additional improvements would be hard to come by and quit there. A couple days ago when our area was part of the rolling blackouts I was seeing posts on fb from friends who's homes were loosing 10 to 15 degrees in an hour of no heat. Turned ours off to test and took 1 hour 45 minutes to drop 3 degrees. Was negative 18 outside.

You're the rarity, not the norm, in that your house is sealed tight, but you have also have a HRV for fresh air. I also did notice some of that round hard pipe. You were right in he might of got the load wrong, but the ductwork is nice.

That's the thing about mini splits, other than the ceiling recessed model, there is no way to bring in fresh air. You can buy dedicated fresh air ducted units from certain mini split manufacturers, but for residential use they are rare and ultra expensive. The added reality is you're still using ductwork on a new system which is kind of defeating the purpose of using a ductless mini split to begin with.

I see mini splits as having some great advantages in certain applications, but where unitary split product is now, at the end of the day, if you have the space for ductwork on a new home build, I don't see the advantage to mini splits. If I put a small "parents cottage" by our house on our land, I'd have no qualms using a 2 or 3 zone multi zone mini split system to save on indoor space (and it would be the high heat option in the multi zone selection).

 

[Wakey]

The electronic filter has been replaced with MERV 16 media filter and UV light.

That sounds like something to read up on.

 

[Sigarms]

That sounds like something to read up on.

And check your pressure drop after you install that MERV 16 on an existing system, and that's assuming the duct is sized properly.

 

[truckdiagnostics]

Mini splits are great until they need to be fixed. They are ok for small rooms homes garages. Once you zone, they are a bear to fix and finding someone that really knows how they work! and doesn't end up throwing parts at it, good luck. Fortunately they are reliable.

 

[Sigarms]

Mini splits are great until they need to be fixed. They are ok for small rooms homes garages. Once you zone, they are a bear to fix and finding someone that really knows how they work! and doesn't end up throwing parts at it, good luck. Fortunately they are reliable.

Thing is, if you use a mini split for a whole house with a multi zone, you should use refrigeration ball valves on both liquid and suction line to each head, so if a head needs to be serviced, you can keep running the system while the system is being serviced. Reality is, 98% of those getting multi zone systems never get those ball valves because they are very expensive (2 per each indoor head).

At the end of the day, a condensate pump for a mini split is 6 times more expensive than a conventional condensate pump. When you go multi zone with 4-8 heads, if you want to do it right, there is a crap load of money just for prevention of issues.

Honestly, as far as fixing, go to any manufacturers website for dealers to service the equipment, and you should be good to go. 20 years ago I knew a guy who wouldn't touch them. Now he's actually pretty good at it. Anything new, people are afraid of, but mini split inverter systems we're being sold when I got into the industry close to 30 years ago, and they are here to stay.

The reality is with mini splits being tied business wise to American unitary split products, you'll see more of these in the future (think gas furnace with coil, being abled to be tied into a mini split outdoor unit along with other indoor heads). That's where the market is going in the next 20 years.

FYI - R22 is no longer to be produced or imported in the US as of the beginning of this year. Starting in 2023, R410 equipment manufacturers can no longer make equipment which uses R410A (including mini splits). Another 20 years after that, perhaps R410A will be illegal. Point being, put yourself in the manufacturers shoes and it's a no win situation.