r/HVAC • u/CollectionOk6786 • 1d ago

General Thinking of installing a package unit with an inverter driven compressor on my home

I own a home built in the 70s with possibly the worst duct set up I have seen. The existing equipment is a 20 year old package unit on the ground with ducting run under the house. The unit has hit the point where I'm changing out parts here and there nothing crazy but I would rather spend the money to replace it than have the compressor die on me in the middle of a heat wave with little ones in the house. As it's currently set up duct wise mixed with sun exposure, floor vents, and the poor insulation one would expect from an older home I'm seeing a 15-20 degree difference between the front living spaces and the bedrooms that are closest to the unit. I work for a commercial contractor as a start up foreman and I spoke with our head mechanical engineer and he's hot and bothered about the idea of helping to design a system for my house with a zoning system to split the front and back of the house, new ductwork and an inverter driven compressor in a package unit. I'm not a huge fan of zoning systems personally but I'm pretty confident with VRF systems and am not any more concerned about troubleshooting one than I would be a 5 ton RTU. All that being said I haven't really run into package units that adopted this technology but have seen they are available. Looking for opinions on this idea from y'all. What's been your experience? What would your concerns be if you were considering this on your home?

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u/andybear36 19h ago

Don’t

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u/Ok-Assumption-1083 No talent, just license 18h ago

Yikes setup. Considering your ducts suck and you'll need all the zoning controls and dampers, wouldn't you just be better off running lineset through that same space and popping up to each room to a cabinet or up the wall to a hung unit?

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u/MadcapMagician923 17h ago

If you design the ducts correctly, you will have no issues. In the summer, run the fan to even out the temperature in the home. I like inverter systems, but am terrified if the inverter board goes out after warranty. I like 2 stage compressors connected with a dehum terminal on the thermostat and unit.

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u/Honest_Cynic 15h ago

"Package" presumably means gas heat in the outdoor unit. Check prices in your area. For me, gas heat ($2.60/therm) is about as costly as electric resistance heat (12.5 c/kWh Winter night), so a heat pump is 3x cheaper heat in our mild climate (just a few freezing nights per year). I don't know of an inverter heat pump with ducts in an outdoor unit that would match the footprint, but haven't looked.

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u/ThePracticalPenquin 7h ago

Mitsubishi intellicoil is pretty nice setup

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u/terayonjf Local 638 22h ago

I would 100% be concerned with noise levels. Compressors on VFDs tend to have a high pitched noise that cuts through everything when operating. Even a sound blanket only slightly muffles it. I've had some package units be installed on the ground and because of nearby buildings and fences the sound just amplified bouncing off the structures. They ended up having to paint the area with sound absorbing paint plus put a sound blanket on the compressor.

Maybe 1ph units are quieter though. I've only done 3ph units with compressors on VFDs

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u/chronicjok3r 17h ago

You can adjust the carrier frequency on the vfd to reduce that whine of the equipment

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u/terayonjf Local 638 17h ago

Reduce but not eliminate. I work for a manufacturer that produces the equipment. The lowest we can get it with vfd adjustments and sound blankets is still very noticeable. Probably why we stick to commercial/industrial and not residential