HVAC - retrofit / upgrade - single unit zoned system heat pump (Welcome: house, construction)

[jnct]

We have a 2700sf home (basement, 1st and 2nd levels) with one 3 ton heat pump/matching air handler, time to replace both. We're getting quotes from folks recommended by friends.

The suggestions for replacement are varied both in cost and opinion for replacement. I would really like 2-3 quotes to compare "apples to apples."

We have determined it will not be worth the cost and complication of retrofitting our house for 2 units and want to get an appropriately sized zoned system in our home. I have received 2 quotes recommending zoning (price difference of approx 25%), one quote to simply replace unit/duct work (he said zones are too complicated), one quote for 2 units (which everyone else says is too costly/complicated) and then one guy told me "this is too complicated" for his small company, but recommended finding a larger operation do zoning. So 3 of 5 say zoning.

So if you have changed a system similar to what I'm describing, please recommend a reputable, local company that can:
- Properly assess and install appropriately sized heat pump/air handler and duct work.
- Properly install a zoning system (2 thermostats).

Thank you!!

[Starglow]

Welcome to the land of HVAC contractor he** in the Triangle!!! Every HVAC contractor does things a bit differently so you won't ever see a true apples to apples comparison approach. I've talked to almost a dozen HVAC contractors since 2009 and no two bid proposals were ever the same. Many contractors operate on the fast in-fast out principal meaning they don't want to deal with any complicated installations so they can quickly move onto their next job and maximize profits.

Zoning systems have to be properly tuned after installation for optimum performance and many contractors simply don't have that level of expertise on staff or don't want to spend the extra time required to do so which means the customer is left with a poorly performing system.

You didn't say how old your house is, but one thing you must be cautious of when installing a new higher efficiency system into an older home is mold growth inside the duct work if the system isn't installed and configured properly...my neighbor is going through that right now dealing with mold issues on a newly installed system where no mold issues existed before with the old system.

Proper installation of both the system and duct work is the key to success more than equipment selection.
I'm currently shopping for two new systems and duct work myself so I feel your pain. I'm very close to selecting a contractor, but haven't found "the one" I'm comfortable with yet although I did meet with one tonight that looks promising. But when you hear the words "too complicated" that means keep looking.

Good Luck....!

[cheapdad00]

Do you have a single zone for all 3 floors now? Which floor is the thermostat on for your current system?

[jnct]

House was built 1981. Currently 1 thermostat in downstairs hall for entire house. The upstairs is cold (under heated) in winter, hot in summer. 1st level and basement fine.

[ncdust]

Ask if they are willing to / going to perform the three Manual calcs (J, S, D) or if they're thinking about sizing everything by the seat of their pants.

[frankpc]

I'd say you're pretty lucky it works as well as it does. A lot depends on the air sealing, insulation, ductwork, etc. but one thermostat for three levels is challenging. I suspect some insulation upgrades from 1981 construction if a Manual J rates 3 tons over 2700 sq ft.
Zoning works well in principle, but as others noted it needs to be done correctly - have your contractors provided references of similar installs? The compressor capacity (re: your comment about "appropriately sized") is also a problem as you really need a variable capacity system (i.e. an inverter based system) or a least a two stage compressor system or you may suffer insufficient run time problems. That 3 ton system running against just your upstairs space would likely cool quickly but fail to dehumidify.
Since the existing scenario has good balance for the first two floors - you have no options to add a separate unit for the top floor? (obviously the systems would to be resized to the new spaces).
Since you asked for a contractor - in "complex" cases like this, I'd ask Matson Mechanical for a quote. In my experience they typically are among the most knowledgeable in the Triangle.

Frank

[jnct]

Yes we knew when we bought the house (5y ago) we needed to probably install larger unit/system. Thanks for the rec - a friend also recommended them so will def call!

I should clarify: All recommendations are for 4 ton system. The zoning folks are quoting automatic dampers.

[frankpc]

Originally Posted by jnct

Yes we knew when we bought the house (5y ago) we needed to probably install larger unit/system. Thanks for the rec - a friend also recommended them so will def call!

I should clarify: All recommendations are for 4 ton system. The zoning folks are quoting automatic dampers.

Not surprised that a Manual J would drive 4 tons for 2700 sq ft. Of course that makes the run time situation worse. I'm making assumptions here, but assuming you've been quoted a single stage compressor and the zoning splits basement/first floor as one zone and the second floor as the second zone then you have a situation where short run times in the summer due to the large compressor capacity will likely leave the upstairs cool but humid. The solution there is a multi stage or ideally a variable capacity compressor. But that means more $$$.
As an aside, while two zone systems with two compressors are very popular in this area, the industry is really moving towards single variable capacity compressors and zoning for better efficiency. Unfortunately you're a bit ahead of that curve.
Interesting to see what Matson thinks ... I don't know much about your situation, but if it was me I'd be very serious about considering a second system for the second floor. In this climate the "cooling" season is really about getting the humidity controlled. The Manual J will look at "Sensible" (temperature) and "Latent" (humidity) loads so you should get some idea from that. As a bit of a cheat, some thermostats will allow a humidity setpoint call. So you can set the stat to keep the humidity below a certain value even if that drives the temp below the temp setpoint. Not ideal, but you might need a bandaid or two ..

Frank

[BoSox 15]

Originally Posted by jnct

House was built 1981. Currently 1 thermostat in downstairs hall for entire house. The upstairs is cold (under heated) in winter, hot in summer. 1st level and basement fine.

You should have someone out to your house every spring and fall to adjust the dampers (or whatever they're called). I'm the the same boat as you, two floors, one thermostat.

Basically in the summer configuration, you're blowing more air upstairs than downstairs (since cold air sinks) and vice versa in the winter. I did not adjust my air flow last winter and it was freezing downstairs!

[Starglow]

Originally Posted by BoSox 15

You should have someone out to your house every spring and fall to adjust the dampers (or whatever they're called). I'm the the same boat as you, two floors, one thermostat.

Basically in the summer configuration, you're blowing more air upstairs than downstairs (since cold air sinks) and vice versa in the winter. I did not adjust my air flow last winter and it was freezing downstairs!

That would really suck to have someone come out twice a year to re-balance the system let alone expensive. I'd be learning how to do the adjustments myself in that case.