Best system for my application

[Scoot Man]

Hi guys,

First post here so be gentle on me. I am getting ready to install a new a/c unit in my under construction town home.

As this is new construction I cave carte blanche on what I can do.

I am located in HOT HUMID Houston. The temperatures have been around 100 here with high humidity.

I am looking for a system that will in the long run save me $$$ or a very efficient system.

What is out there? Can you cost effectively actively zone different rooms to different temperatures i.e. rooms that are not used much. Maybe with an electronic damper that can be controlled with an in room thermostat?

I am really looking for the best way to keep my bills down and help the environment, and don't mind spending a little $$$ up front to save long term.

The specs on the town home are 3&1/2 stories approx 2600 sq/ft.


Thanks in advance for the help,
Steve

[inf_sys]

I would look for a contractor with zoning experience. You will probably want to look at a whole house dehumidifier with some dedicated duct runs to assist with the dehumidification. Here in FL new installs require returns or transfer returns in each room so that affects the benefits of keeping stats up too high compared to the rest of the house as you are still pulling the warmer air back into the system any time it is running even if the supply damper is closed. Make sure you get that ironed out before the walls are up as zoning needs to be designed and installed back to main trunks based on what you are looking to accomplish as far as zoning certain room together etc. Zoning is great if installed properly but if it is not designed right it is very hard to change once it is in for a certain application. Keep in mind you have to have access to each damper/bypass/zone control board for service or replacement down the road. Poor power can also be an issue with zoning so you might want to consider a whole house surge protector if the power company offers it. In FL we have seen issues after storms or power outages where boards need to be reset so make sure they are in an easy place to get to. Remember you will not be dehumidifying if the system is not cooling the room with enough air exchanges due to the zoning that is why I would look at the whole house ducted dehumidifier.

[dan sw fl]

Hi guys,

I am located in HOT HUMID Houston. The temperatures have been around 100 here with high humidity.
1. Can you cost effectively actively zone different rooms to different temperatures?

I am really looking for the best way to keep my bills down and help the environment, and don't mind spending a little $$$ up front to save long term.

The specs on the town home are 3&1/2 stories approx 2600 sq/ft.

Thanks in advance for the help,
Steve

Go easy on you, WHY, are you one of the priveleged?
Just kiddin'.

1. Yes

You need a Real Pro in design to develop an integrated HVAC solution for a 3 & 1/2 story.
Email me (address in my profile) for a recommendation that you may wish to pursue.

[pstu]

Hi guys,

First post here so be gentle on me. I am getting ready to install a new a/c unit in my under construction town home.

As this is new construction I cave carte blanche on what I can do.

I am located in HOT HUMID Houston. The temperatures have been around 100 here with high humidity.

I am looking for a system that will in the long run save me $$$ or a very efficient system.

What is out there? Can you cost effectively actively zone different rooms to different temperatures i.e. rooms that are not used much. Maybe with an electronic damper that can be controlled with an in room thermostat?

I am really looking for the best way to keep my bills down and help the environment, and don't mind spending a little $$$ up front to save long term.

The specs on the town home are 3&1/2 stories approx 2600 sq/ft.


Thanks in advance for the help,
Steve
I am a homeowner a couple dozen miles west. If it were me building new, I would try like heck to design with ductwork inside conditioned space. And work hard to eliminate all infiltration possible. If you do it well, a small amount of fresh air intake will result in 2 pascals or more positive pressure inside, which will tend to keep out all the undesirable stuff from outside air: humidity, pollen, dirt, exhaust smells etc. This will also let you run a smaller AC leading to further energy savings.

Pay attention to Carnak and Shophound et al when they declare the quality of the building structure, is more important than any mechanical AC system. Nothing wrong with a sophisticated AC system, just emphasize the building structure as 1) the more important thing, and 2) the thing you only have one chance to get right.

Best of luck -- Pstu

[Scoot Man]

I am a homeowner a couple dozen miles west. If it were me building new, I would try like heck to design with ductwork inside conditioned space. And work hard to eliminate all infiltration possible. If you do it well, a small amount of fresh air intake will result in 2 pascals or more positive pressure inside, which will tend to keep out all the undesirable stuff from outside air: humidity, pollen, dirt, exhaust smells etc. This will also let you run a smaller AC leading to further energy savings.

Pay attention to Carnak and Shophound et al when they declare the quality of the building structure, is more important than any mechanical AC system. Nothing wrong with a sophisticated AC system, just emphasize the building structure as 1) the more important thing, and 2) the thing you only have one chance to get right.

Best of luck -- Pstu

I am thinking to insulate all exterior walls with closed cell spray in insulation for maximum efficiency and the least amount of air/humidity transfer.

[Carnak]

seal the attic, do not vent it.

Best roof scheme, insulate on top of roof deck and put a white roofing on top. If it is not a hip roof, insulate the gable walls of the attic as well.

Second best roof scheme, insulate with foam on the underside of the roof deck, white roofing, insulate any gable walls.

As far as conditioning the attic space, duct leaks will take care of it most likely, other wise a small amount of air up there like 25 CFM per 1000 sqaure feet is fine.

[jramunni]

I would look for a contractor with zoning experience. Here in FL new installs require returns or transfer returns in each room . . Zoning is great if installed properly Keep in mind you have to have access to each damper/bypass/zone control board for service or replacement down the road. . You will probably want to look at a whole house dehumidifier. Remember you will not be dehumidifying if the system is not cooling the room with enough air exchanges due to the zoning.

There is a learning curve with zoning, but most of us zoning product manufacturers offer great design support.

In any room that might have a door closed to the rest of the house must have either a return (undampered) or a transfer grill.

Zoning is great if installed properly!

Please do not conceal any dampers or controls above drywall...they are mechanical devices and will someday need to be accessed. Although we offer a ten year warranty on our dampers since they are air driven and very reliable, we still recommend that they be accessible.

Zoning, especially with two stage equipment, will typically do a very nice job of dehumidifying while it serves individual zones, as it serves the higher load areas of your home it provides more run time (and moisture removal) than a single thermostat system.

We do offer a dehumidification cycle on our HPP zone panel. With a call for dumidification from zone 1 stat it will lower the blower speed and open all zones to remove moisture. See the following thread for more info, http://hvac-talk.com/vbb/showthread.php?t=349402&highlight=arzel

jcr

[Cold Feet]

What is out there? Can you cost effectively actively zone different rooms to different temperatures i.e. rooms that are not used much.

True room-by-room independence is very difficult. Zoned forced air systems are intended to work with comparably large zones--e.g. three or four rooms on one thermostat. If you really need separate temperatures on a per room basis, then you're out of the realm of forced air zoning: you'll need a VRV system or some kind of chilled water setup.


I am really looking for the best way to keep my bills down and help the environment, and don't mind spending a little $$$ up front to save long term.

Insulate the heck out of your house, install the smallest windows you can put up with, and get a ground source heat pump.

[mchild]

If you really need separate temperatures on a per room basis, then you're out of the realm of forced air zoning: you'll need a VRV system or some kind of chilled water setup.


VRV/VRF systems allow for up to 6-9 indoor air handlers to be connected to a single outdoor unit (number of indoor units is determine by outdoor unit capacity). This approach allows for the most control over each of the zones as each indoor unit is operated as a separate system allowing for different temps and even having indoor units off while others are operating. Refrigerate lines and communication cables is all that need to go to each unit. With a conventional ducted zoning system you can not shut down a zone and the ducting will have to go to each floor so space will be needed from the bottom floor all the way to the top.

You also have the flexibility for the indoor units to be either ducted or ductless but it sounds like ducted units would be your desire. You could break the home into multiple small zones to be fed by each air handler. The air handlers are small in physical size - think of a large bread box. A small remote sensor located in each zone is all that would be visible. The system controls can be located anywhere - even in a closet.

These are state of the art variable capacity systems where the compressor is inverter driven operating from about 25% of nominal capacity to over 100%. The indoor units are also fully variable in output operating from 10% up to rated installed capacity. Check out Daikin, Mitsubishi and Sanyo for their VRV/VRF systems.

[Cold Feet]

VRV/VRF systems allow for up to 6-9 indoor air handlers to be connected to a single outdoor unit (number of indoor units is determine by outdoor unit capacity).

That would be 2 to 9 indoor units depending on the brand and type of outdoor unit. As far as I'm aware the only exterior unit that supports 9 indoor units is Sanyo's CHX05252, which is targeted at the light commercial market and is capital E-Expensive. The residential stuff (e.g. Daikin 4MXS32GVJU & Mitsubishi MXZ-4A36NA) maxes out at for indoor zones per outdoor unit.

What VRV system did you ultimately settle on for your project?

[Carnak]

VRV/VRF systems allow for up to 6-9 indoor air handlers to be connected to a single outdoor unit (number of indoor units is determine by outdoor unit capacity). This approach allows for the most control over each of the zones as each indoor unit is operated as a separate system allowing for different temps and even having indoor units off while others are operating. Refrigerate lines and communication cables is all that need to go to each unit. With a conventional ducted zoning system you can not shut down a zone and the ducting will have to go to each floor so space will be needed from the bottom floor all the way to the top.

You also have the flexibility for the indoor units to be either ducted or ductless but it sounds like ducted units would be your desire. You could break the home into multiple small zones to be fed by each air handler. The air handlers are small in physical size - think of a large bread box. A small remote sensor located in each zone is all that would be visible. The system controls can be located anywhere - even in a closet.

These are state of the art variable capacity systems where the compressor is inverter driven operating from about 25% of nominal capacity to over 100%. The indoor units are also fully variable in output operating from 10% up to rated installed capacity. Check out Daikin, Mitsubishi and Sanyo for their VRV/VRF systems.
I am doing a job using the mcquay mds so is some sort of daikan. I have about 20 fan coils, 4 condesners so averaging 5 per condenser.

i think the asians need to work on their ducted air handler systems a little yet. The high static horizontals are tough to get into a ceiling space, too damn wide. Their vertical air handlers are too noisy.

using mainly cassettes and lower static horizontal conceal fan coils.

as discussed across the atlantic, these fans will be stopping when they have modualted down and their is no refrigerant flowing.

You need to size them like an office vav system-- find the peak load on the condenser then size the fan coils/cassettes for peak load in the zones.

I am still a little leery on repairing them in place, cassettes should be easy, but a little tricky with fancy access panels for the horizontal fan coils.

This is for a rather substantial home.

I do not have much faith in air zoning residential equipment until it becomes like true vav.

Rheem mod was almost there 10 years ago-- a system that maintains an air temperature rise and alters the air flow to meet demand.

[thrashme]

Regarding the question about 8 indoor units with Daikin, here is a quote from their page. "The Daikin VRV-S system enables up to eight separate fan coils to run off of one condensing unit containing an inverter "variable speed" compressor. All zones can be individually controlled by the use of individual and central (Multi-Zone) controllers and is ideal for the residential, condominium and light commercial sectors. A feature of particular importance for residential applications is the 'night set' mode, which can be set on site to function over a 9 hour period during which operating sound is reduced progressively in three increments of 3dBA." The rest of the page is at
http://www.daikinac.com/residential/productsUnits3.asp?sec=products&page=55
fyi

[Cold Feet]

VRV-S is primarily marketed to the commercial segment and is priced accordingly. VRV-S will work in a house (it doesn't require 3 phase power or anything like that) but you're gonna pay for the privilege. Daikin's multi zone low-end (residential) offering is the G series, which is limited to a 4:1 connection ratio.

[mchild]

That would be 2 to 9 indoor units depending on the brand and type of outdoor unit. As far as I'm aware the only exterior unit that supports 9 indoor units is Sanyo's CHX05252, which is targeted at the light commercial market and is capital E-Expensive. The residential stuff (e.g. Daikin 4MXS32GVJU & Mitsubishi MXZ-4A36NA) maxes out at for indoor zones per outdoor unit.

What VRV system did you ultimately settle on for your project?

The range I mention of 6 to 9 were strictly VRV/VRF systems with 6 indoor units on each of the Daikin, Mitsu and Sanyo 3 ton systems. The Daikin and Mitsu 4 ton systems can have 8 indoor units and the Sanyo system can handle 9. They have decided that system is no longer a 5 ton but closer 4.3 tons.

I was not mentioning the multi head systems as I understood the OP needed more zoning than they would provide.

I agree these systems can look pricey but when compared to the typical two high end system zoning solution (one up and one down) of any of the major manufacturers (Carrier and such) then they don't look so bad. Plus, when you consider the total cost to include operation, with the high heat output of these system and the reduced requirement for expensive supplemental heat (typical strip heat set up) then they look better yet.

There is not an American made system (maybe Nordyne) that has the self diagnosis capability. Keeping a system from self destructing has to be worth something.

Specifically, I went with Daikin. Used a 4 ton with four indoor ducted fan coils, three 18K and one 9.5k (plugged down 12K). Zoned the house up/down and east/west. Used existing supply ducting with minimal changes and added returns for the two additional air handlers. Heating capability is fantastic with the system able to carry the load to the mid teens. Our design temp is 10* and we only have a few hours between 15* and 10*, so my cost for supplemental heat is about $20 per winter.

My overall savings in heating and cooling per year is about $2,500 from the old systems.

[teddy bear]

I suggest as simple a system as possible. A better chance of getting it installed right and being able to service as it ages. A mid range SEER, VS fan with enough capacity to handle recovering a set-up t-stat when the home is unoccupied for 10-12 hours or several days, when the heat is above design, or you have visitors. A whole house dehumidifier that is capable of keeping the home dry when the a/c is "off" or during wet cool weather. You will save a lot of electricity setting up the stat when unoccupied. The long cooling pull down removes a tremendous amount of moisture. Even leaky homes do not breathe during calm warm weather. I have a small amount of fresh air during the hours of occupancy, dramaticly improves the air quality in the home during the calm summer weather. The ventilating option of the whole house dehumidifier makes your home healthy and comfortable. I promote the Ultra-Aire which the father of the whole house dehus. With these type of dehus, you set the temp you want and the %RH desire, with minimal energy both are maintained. Regards TB

[thrashme]

mchild I went to Daikin's school in Carrollton, TX in 2007. At that time they did not quite the product line that they have now. Can I ask which ducted fan coils you are using? Maybe we could carry on a discussion either on a new thread or email. I have recently moved and am really wanting to change this system. I have previously owned two homes which I installed single Condensing unit, single Furnace w/ Carrier's Comfort Zone II. After this summer is over, I may go back to Daikin's school to check out their new products as the home I moved in already has a ducted system.