View Full Version : One Large Unit or Two smaller? Which is better

05-26-2009, 08:45 AM
In order to meet my budget the installer has suggested I go with a Single 6-ton unit for my house instead of using a smaller split system (5-ton 3 1/2-ton) which he initally quoted.

When I inquired the pro's and cons of a larger single unit he listed the following benefits:

- less equipment to maintain
- less electic draw with single system
- less excavation costs (horizontal closed-loop)
- costs less

The only con he listed is that the larger system would be more difficult to expand zones. So, why wasn't that priced out to begin with?

I was wondering if anyone else had any thoughts as to whether or not I should be concerned about going with a single 6-ton unit.

1st floor - 1700 sq ft.
HL: 80K btu
CL: 36K btu

2nd floor - 1400 sq ft.
HL: 65K btu
CL: 30K btu

basement - 1700 sq ft. (unfinished)
HL: 0
CL: 0

05-29-2009, 08:58 AM
One unit @ 6 tons or two units @ 8.5 tons.......doesn't make a lot of sense to me.

06-01-2009, 03:12 PM
I re-read the quote (it actually stated a 4-Ton NDV049111CTL/R and a 3 Ton NDZ038. So the split system added up to 7-Ton.

Mark T
06-10-2009, 08:27 AM
You have two (2) individual areas – the 1st floor @ 1700 Sf and the 2nd floor @ 1400 Sf – consider the issue of “comfort”. Two (2) systems is the way to go.

You may want to consider “zoning” of the individual systems to provide more comfort.

Are you considering Heat Pumps or Gas / Electric – perhaps Hybrid?

Your Utility may offer rebates - don't forget about the "tax credit".

06-10-2009, 03:03 PM
TWO SYSTEMS! Operating costs should be less as you only use what you need, and is better for comfort.If one system suffers a breakdown, the other will still run. Repair parts will be less expensive and more companies are likely to carry them.
Best Wishes

06-11-2009, 04:25 PM
where are you located? im a fan of 2 systems and big zoned systems. if the zones are done RITE then its a good option. but for total comfort 2 system is the way to go IMHO. also unless you're totally set in stone on going with geo, you should check out dual fuel setups. you could do a 2 system hybrid top of the line for the price of a single geo system (prolly cheaper)and still have low bills, again this is in my opinion.

06-12-2009, 12:20 AM
I vote for two

06-13-2009, 06:21 AM
The one unit system is configured with 4 separate zones. I can choose to put them anywhere something like upstairs, mstr. bdrm, first floor, basement.

I live in Virginia.

06-20-2009, 10:41 PM
With the Load provided, i wouldnt even offer a six ton system. Its to small for the job, and wont perform like expected. An 8 ton system would be MINIMUM. Most eight ton systems are 2 compressors, which will allow for two stages. I would also make sure it is zoned, and done correctly. In addition to all this, I would make sure my EWT would not go below 40, if possible. This will require extra excavation, but is WELL worth the money spent. This should still be less that a two system house, but is the very minimum i would install. Geothermal is GREAT only if it works well, other wise its just another Expensive heating and cooling system.

03-06-2010, 11:56 PM
Thanks to everyone who gave me advice. I discussed it with my HVAC installer. He insisted I'd be happy with the 6 ton unit. I've been in the house since October. I live in Virginia and we keep the house at 68 F degrees and have a honeywell steam humitifier on the system set at 40%. Our average monthy electric bill has been $170 / mo. I don't have a energy meter like a TED so don' know how much of that is the GSHP. So far, I'm not unhappy wih the amount.

The only complaints about the system I have is a noisy fan (I posted this issue in another thread) and the electronic dampers seem to be tempermental. They get stuck and buzz. I've had to have the HVAC tech come out to fix one and it's happening on another one again. I don't like that there isn't any fault monitors built into the dampers so I know when one is opening or shutting incorrectly.

Neither of those issues has anything to do with the unit size. I'll update this post periodically with my continued experience.