Although the Heat Pump/HVAC system that I have in my 2,000 sqft house (actually 2000 upstairs, 2,000 basement) dates from 2004 and works okay, it was purchased by the contractor that built the house for us, and is probably the cheapest and least efficient system available at the time.
Also, the duct work is all flexible type, and wasn’t installed very well.
After getting slammed with a $300+ power bill this month (HOT in Georgia), I started thinking about at least replacing the flexible duct with rigid and routing the duct a lot better than it is now.
But I’m still stuck with a power gobbling HVAC system.
Does it make sense to upgrade the entire house with a mini-spit ductless heat pump and dump or seal off all of the duct work?
Or should I replace the system that I have now with a similar forced air system and redo the duct?
If I purchased the condenser and (probably 4 evaporators) myself and installed most of it, would I have a problem finding a tech to hook up the refrigerant line sets?
Well, start with the math. An AC system is going to cost you to run in a hot climate. If you replace the unit with a significantly more efficent unit, how much will it reduce your power usage? I’d guess not more than one-third, which, yeah, is a lot… but ROI might be a decade.
Many electricity providers offer free energy efficiency assessments where they come out to your house, run a bunch of tests and give you a list with suggested improvements and estimated savings for each of them.
Even if your provider doesn’t offer the service for free, it would be a good investment to have one done.
It’s very possible that you will see a much better ROI by adding attic insulation or a radiant barrier rather than re-designing your HVAC.
I agree with this. Something as simple as improving the seals on the ductwork could save a lot of money. An energy audit is a great first step (and cheap).
I just checked, and my energy provider offers nothing but a very basic online “Energy Efficiency” calculator. It’s pretty much worthless.
Current attic insulation is pretty good - at least 12" loose fiberglass.
Rigid duct work is hard to work with in a home. NOt much room. And then having to insulate adds to the problems. When I did my house I used flexable. If the connections are not made right then they can leak. I would put the work into checking the connections.
It isn’t the connections so much as the routing of the duct - lots of 90 degree turns and such. Some pretty long runs and some spots where the hangers seem to be choking the duct.
If I didn’t purchase a new mini-split ductless system I would certainly replace the ducts with rigid. Space is not a problem as all ducts are in the basement and the basement is not finished yet. When it is (if ever), the ceiling will be suspended so I’ve got lots of room.
I have a mini-split and it works well for me, but the downstairs is fairly open plan. You realize it just blows air from a single location? Placement is critical if you need air to go in two directions. And they don’t necessarily blow air like you might envision, mine blows 95% of the air from the right side of the exit grill, almost nothing from the left.
My upstairs is a large master bedroom with bath and I have a single window unit that I selected that blows air into both rooms. This way I am zoned nicely, I can run the downstairs and upstairs at different times and settings.
My third unit is just a small window unit in the downstairs guest room, since the mini-split does not reach there. But it is only used as needed.
This site has a good explanation of why rigid metal duct is better than flexible duct.
The split system has an advantage in that each indoor unit is it’s own zone, so you get the benefit of zoning automatically. Downsize is having to have a way to deal with condensate at each unit. Another downside is that the mini-split systems won’t bring in fresh air. Not that a central system necessarily will, but it can be equipped to do so easily.
If you frequently don’t use every room in the house…
Get a Mitsubishi mini-split which has the capacity to have 4 or 6 separate inside units (one outside unit).
Then place those units in the rooms you use the most. And only turn on the units in the rooms you are using. keep the old whole house unit and use that when you need the whole house cooled.
Then you save double. Highly efficient A/C / Heat pump. Plus cooling less space. At the same time replace all your light bulbs with LED bulbs.
Check with your neighbors, especially those with the same floor plan as your house. You may find that $300 isn’t a bad electric bill. If my electric bill for a hot month was only $300, I’d be deliriously happy.
What is your Kwh rate? You may not gain much, if anything depending, and you’ll have to drop several thousand $$ on top of it. $300 sounds excessive but it all depends on what juice costs in your area.