New construction design input requested; all elec HVAC

7 years ago

last modified: 7 years ago

New construction modern home with lots of glass and west-facing windows; 2300SF main floor; 900SF upstairs. Predominantly 9' ceilings (some 10.5'). Open floor plan from entry; living room; K; DR. Flat roof; well insulated ubt with so much glass really isn't that insulated. Will have honeycomb shades on Living Room windows to mitigate some of the summer late afternoon to sunset heat gain. Not sure I can get heat calcs.

Appreciate all of your thoughts on equipment, design considerations, and ?s I should be asking.

High desert climate in Oregon heating degree days 6926 cooling 151 both base 65. Very large 35 degree dinaural temp change during summer so will have opportunity to really cool things down overnight. Very little humidity.

All electric, no other option. Lennox contractor has very good reputation and bid was 35% less than Trane (who I somewhat favored due to forum comments) as later proposed two heat pumps.

Other info:
95% of the time only two people in house; both work at home mostly upstairs.
At home a great deal of the time rather than a family with alot of in and out activity.
Originally air handler was to be in garage, but contractor has suggested the 6' tall crawl space under DR as preferred to avoid impact of poor garage air quality being drawn into house.
I have and will use high quality air filtation units in addition to what is part of the AH.
Cost estimate for entire proj is already far over budget/expectation, however HVAC is not something to short change.

Some of my key ?s are:
1) Is splitting downstairs into 2 zones worth the $650 upgrade?
2) Is there an alternative to HRV that I should explore?

Common to all proposals:
Line set and condensate drain for heat pump.
Venting: 4- Bath fans, dryer, utility and up to 8" range.
5" MERV16 filter and cabinet.
Ducting: Flexible, R8 insulation.
Zoning: 2 zones (main living and upstairs) Honeywell VP8000
thermostats.
PTCS Duct Test & Seal per CEC requirements
PTCS Heat Pump commissioning as per CEC
electric co-op offers rebate and tests system before issuing rebate - this is nice for me to have 3rd party checking some aspects of install/functioning.

Equipment options:
1) $25,230 Lennox CBX40UHV air handler, variable speed, with aux heat.
Lennox XP25-048 heat pump, variable speed compressor, 10.2
HSPF, 20.5 SEER.

2) $23,090 same air handler Lennox XP20-048 heat pump, variable speed compressor, 9.6
HSPF, 19 SEER.

3) $21,885 same air handler Lennox XP16-048 heat pump, 2 stage compressor, 9.5 HSPF,
16 SEER

$2,000 upgrade will be done to use hard ducting in crawlspace

$2,755 Add a Lennox HRV5-200 heat recovery ventilator, stale air
and fresh air tied into furnace system, 5 speed, controlled
from thermostat. This is the only "fresh air" option offered

$700 Upgrade zoning system to Lennox iHarmony, communicating,
iComfort S30 WIFI main thermostat. I'd be inclined to use the less expensive Lennox wifi stat.

$650 Add a 3rd zone splitting the main floor into 2 zones. I'm open to this, but would be happy to save the money as well; but this is very little $ compared to the $3,856 Trane wanted to split downstairs in to two zones.

$750 Add a Lennox bypass humidifier, controlled from thermostat I'm inclined to say no to this.

Comments (4)

malba2366
7 years ago
If the HP will be your only source of heating I would look at the Carrier Greenspeed over the Lennox. Avoid contractors that only sell one brand of equipment, maybe ask your builder for the contractor he/she uses. HVAC contractors that do builder work are typically much cheaper than the big hvac dealers who sell directly to customers. The prices for the highest efficiency lennox/trane/carrier equipment is likely within a few hundred dollars of each other...if you want a particular brand and the quote is so vastly different find another contractor.

I would definitely spend the 650 for the additional zone. The ability to zone off that first floor bedroom will save you the $650 in a relatively short period of time and will help with comfort in the bedroom. HRV is probably a good idea in a new construction house that is very tightly insulated. An alternate would be to use bathroom fans that automatically turn on for a set period of time each day but you would lose efficiency as you would be exhausting conditioned air from the home...I have no idea what the payback time would be on the HRV.
tigerdunes
7 years ago
2 separate systems for both comfort and control first choice. Zoning off one system would be my second choice and if selected I would only use var speed condenser. I agree about getting Carrier/Bryant involved. Have never liked Lennox brand, always thought little of their heat pumps. Have you even considered GSHP for your home? I see no reason splitting main floor into separate zones unless that fits into your lifestyle and how this living area will be utilized. I still believe that Carrier/Bryant have the best total integrated zoning system in the residential market. Even without nat gas, lots of choices to consider. You might look into a mini split HP system for the upstairs.

IMO
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@tigerdunes thanks Above you suggest Trane XV18 TAM8 air; I like alot about XV18; however ... In other threads, you've cautioned against XV18 as newer mdl little hist; & also: "I prefer Trane heat pumps over Carrier primarily due to electronic demand defrost, a feature Carrier/Bryant does not have." "If you plan on zoning areas of your home off one system, I still believe Carrier/Bryant offers the best integrated zoning system and components under one umbrella." I'm a bit confused. 3 zones 830SF upstairs; main floor 1430/900 air handler will certainly be variable speed, but what about HP? It seems like a VS HP is what you suggest, and definitely like the quiet db ratings, but should I look at comparable Carrier/Bryant vs HP which I believe have better efficiency specs? High desert Oregon heating degree days 6926 cooling 151 base 65. Very large 35 degree dinaural temp change during summer so will have opportunity to really cool things down overnight. Very little humidity.
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Duh. It is not the job of a thermostat to sense the temperature 80 ft away. A thermostat should accurately sense the temperature in the area in which it is located. It is the job of the HVAC designer to specify the location of each thermostat so the measured temperature is representative of the environment it controls. So in other words when the area that is 80 ft away and too hot, you can then say duh to the customer / prospective homeowner? You'd be surprised how many times people have requested me to physically move a thermostat not realizing that simply moving it will create "NEW" problems. (colder in other areas relative to the new area it was place in.) IE: a solution is one that doesn't create new problems. Otherwise not a solution. Oh let's add sensors to various rooms... same difference. It's going to keep pumping air and try to magically create comfort. There's every kind of garbage contraption you can imagine. I've had to stop people more than once, maybe more than a thousand times from making a dumb mistake. Some listen, some think they know everything even when what I do isn't what they do. I often tell prospective customers that if they think they know more than me... they don't need me. I am not a third wheel that is going to get dictated to. Been doing this for over 26 years. Had more than my fair share of disagreements with engineers, while some actually listen to what I say. Your climate in Virginia entirely different... different climate different concerns. Your cooling season is short. Mine is nearly always 10 months long, sometimes longer. I've heard every excuse in the book when it comes to builders. I can't say they've ever used DUH as an excuse. The design sheet doesn't know what that room or rooms 80 ft away is going to be used for. Does the thermostat know? (I'm in the home when people are actually living in it.) PS: humidity control... real humidity control is another separate system that is best tied to a humidistat. That system is in addition to your air conditioner, requires maintenance and up keep, repairs and eventual replacement. More money. More electrical cost on the light bill. It's a separate system tied to the HVAC system. An air conditioner does not "control" humidity. Remember I said HVAC market was built on problems. In my market it's not just what humidity is created in the house, it's also humidity that makes it into the house in a humid climate. A very humid climate (Katy, Texas) Technology has made better inroads into helping with humidity via Inverter AC's and the ability to modulate up and down. But these systems run off temperature, not humidity. I'm sure you're well aware that you can have high humidity at lower temps. But these comments that I make aren't for you wise guy... They are for the people who read these threads months, sometimes years later that are searching for someone like me. I know my lane, now you know yours. Stay in it.
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lite1
Original Author
7 years ago
Thank you both for your input. From what I have read the downstairs as an additional zone would make for more even temp control but energy savings would never recoup the extra cost, and based on @Tigerdunes will most likely skip. Carrier GSHP was considered early on, but prelim bid was very high; person I met with kept pushing their equipment and panning others rather than touting how good their installation was. When I learned of the electric coop efficient heat pump rebate program they had dropped this subcontractor and had no Carrier/Bryant sub on their list of qualified contractors. Unfortunately upon further research the Carrier sub had a so-so reputation with my GC, and other professionals I checked with. As indicated in OP while I favored Trane (perhaps due to Tigerdunes and others) the cost at least 40% more is just not in the budget. Will post in about a year after HAC is complete and I have some experience to report. Again, much thanks.
mike_home
7 years ago
Factory authorized dealers tend to sell only their
manufacturer's brand. They tend to be expert on how to install the equipment. I
feel that is a good thing versus a contractor which will sell any brand and may
not be as familiar on how to install some of the high end equipment. There are
always exceptions to this. The last thing I would want to see is a contractor
reading the manual during the installation.

You can ask the builder for a recommendation, but they tend to
use the cheapest guys who can get the job done quickly. That usually leads to a
poor installation.

It is hard to compare prices across brands due to the variations
of the equipment. I find it easier to pick one brand and get 3-4 proposals from
contractors. In some areas that is hard to do, so try to get the proposals from
dealers from the sister brand (ex: Trane and American Standard).

New construction design input requested; all elec HVAC

Comments (4)

malba2366

tigerdunes

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New construction design input requested; all elec HVAC

Comments (4)

malba2366

tigerdunes

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