New HVAC system for new house.
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  1. #1

    New HVAC system for new house.

    I'm in the construction phase of building my new 2 identical houses, and I want to hear about your expertise and experience on what kind of HVAC system I should install.

    Some info about each house:
    - 3 floors
    - Total built up area is approximately 4300ft squared. First 2 floors are equal in size. Last floor around 450ft squared.
    - The ambient temperature in the summer reaches 122F

    What I know so far and my options.

    1. Wall mounted split units - this would cost me around $$$ per house. What I don't like about that however is the presentation of the house inside. The finishing of the houses as a whole is above par, so i would like that to match with the inside. Also, having wall mounted units takes space (a total of 10) and having 10 condenser units sitting on my roof is not the most pleasing eye sight.

    2. My other option is ducted split units. This would be great as they would be concealed from the inside, but it's pretty much the same on the roof, 10 CU's sitting there. This would cost me around $$$ per house.

    3. A third option is a rooftop package unit. This is convenient, but its running cost is relatively higher. Also, I don't get the luxury of controlling the temperature of each room separately, even if I install VAV boxes, that will stop air flow, but not running cost. I do not have a quote for this as it least interests me.

    4. My last option is a VRF system. This seems to nail it for me. I would have 1 or 2 units on the roof, I get to control each room separately and its running cost is cheaper. This would also cost me around $$$$ per house.

    I'm not sure of the lifespan of the VRF and its ease of maintenance on the long run. And its cost tends to be around 3 times the wall mounted. Is it worth it? I'm waiting on a quote to have only the ground floor as a VRF system and the top 2 floors as wall mounted as that would get the price down.
    Any recommendations? What other issues should I be aware of?

    Sorry for the long post.



    Pricing isn't allowed
    Last edited by jpsmith1cm; 03-22-2013 at 05:15 AM.

  2. #2
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,225
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  3. #3
    Quote Originally Posted by Lmasterz View Post
    I'm in the construction phase of building my new 2 identical houses, and I want to hear about your expertise and experience on what kind of HVAC system I should install.

    Some info about each house:
    - 3 floors
    - Total built up area is approximately 4300ft squared. First 2 floors are equal in size. Last floor around 450ft squared.
    - The ambient temperature in the summer reaches 122F

    What I know so far and my options.

    1. Wall mounted split units - this would cost me around $$$ per house. What I don't like about that however is the presentation of the house inside. The finishing of the houses as a whole is above par, so i would like that to match with the inside. Also, having wall mounted units takes space (a total of 10) and having 10 condenser units sitting on my roof is not the most pleasing eye sight.

    2. My other option is ducted split units. This would be great as they would be concealed from the inside, but it's pretty much the same on the roof, 10 CU's sitting there. This would cost me around $$$ per house.

    3. A third option is a rooftop package unit. This is convenient, but its running cost is relatively higher. Also, I don't get the luxury of controlling the temperature of each room separately, even if I install VAV boxes, that will stop air flow, but not running cost. I do not have a quote for this as it least interests me.

    4. My last option is a VRF system. This seems to nail it for me. I would have 1 or 2 units on the roof, I get to control each room separately and its running cost is cheaper. This would also cost me around $$$$ per house.

    I'm not sure of the lifespan of the VRF and its ease of maintenance on the long run. And its cost tends to be around 3 times the wall mounted. Is it worth it? I'm waiting on a quote to have only the ground floor as a VRF system and the top 2 floors as wall mounted as that would get the price down.
    Any recommendations? What other issues should I be aware of?

    Sorry for the long post.



    Pricing isn't allowed
    edit: Option 2 and 4 cost around three times as much as option 1.

  4. #4
    Quote Originally Posted by dan sw fl View Post
    Choosing an outdoor unit isn't my concern, besides, for the specific model you mentioned:
    Operating Temperature Range
    Cooling (Outdoor): 23 ~ 109F (-5 ~ +43C) DB

    I want to know if the VRF system would be best. Any cons I should be aware of that can make me have second thoughts?

  5. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,231
    Where is the house located? Are you providing fresh air ventilation? What are your concerns about fresh air ventilation?
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  6. #6
    Houses will be located in the Middle East where temps r very high in summer time.

    FAV is not a concern for me. My only concern is choosing the HVAC system from the options I mentioned earlier.

    I'm leaning more towards the VRF system just unsure of its lifespan and its ease of maintenance. Is its maintenance hard and costly after the first 5 years? What issues should I be aware of?

  7. #7
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Overseas, the VRF systems are fairly common and probably one of the most cost effective solutions. One advantage is that if you have 2 units linked together, you have soem redundancy. Also, when these unts get dirty, they usually just reduce capacity (and effceincy), rather than shutdown altogether like a fixed speed unit. A properly maintained unit should last 20 years like any other system.

    With the VRF, the key will be having a contractor that is well trainied on their installation and service. They should have factory training. The major brands seem to be Mitsubishi, Daikin and Samsung. Mitsubishi also has versions that are normal air handlers so you could also install one of those on each floor then zone it, but still have a single outdoor unit. They also have a fresh air ventilation module. With the poor quality air in most of thsoe locations, you might want to pressurize the building slightly at all times with one of those units and install a MERV 13 filters and maybe even carbon filters. In that dry climate, you also might install a steam humidifer on the floor occupied the most, usually where the bedrooms are.

  8. #8
    Quote Originally Posted by motoguy128 View Post
    Overseas, the VRF systems are fairly common and probably one of the most cost effective solutions. One advantage is that if you have 2 units linked together, you have soem redundancy. Also, when these unts get dirty, they usually just reduce capacity (and effceincy), rather than shutdown altogether like a fixed speed unit. A properly maintained unit should last 20 years like any other system.

    With the VRF, the key will be having a contractor that is well trainied on their installation and service. They should have factory training. The major brands seem to be Mitsubishi, Daikin and Samsung. Mitsubishi also has versions that are normal air handlers so you could also install one of those on each floor then zone it, but still have a single outdoor unit. They also have a fresh air ventilation module. With the poor quality air in most of thsoe locations, you might want to pressurize the building slightly at all times with one of those units and install a MERV 13 filters and maybe even carbon filters. In that dry climate, you also might install a steam humidifer on the floor occupied the most, usually where the bedrooms are.
    Ya the major players here are Samsung and Daikin. I'll look into the MERV 13 and carbon filter and humidifier. They sound like something I'd be interested in.

    Thanks for the useful information. Really Appreciate it.

  9. #9
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,225
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  10. #10
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I forgot abotu Sanyo. There's also Fujitsu, but I don't know if they do larger VRF's. I think they stop at 5 tons.


    One other thought. With you hot dry climate, depending on water restrictions and city codes, you could put in a small cooling tower and use water cooled heat pumps. Off hand, I would guess you'll need around 7-8 tons total even with descent construction. Make sure you get an engineer to do the load calculations. Air cooled equipment has ot be derated for the high ambient temps.

    On you construciton desing, of course use plenty of radiant barrier and methods to slow solar heat gain. Personally, if money wasn't an object, I would build all in concrete and attach insulation with a radiant barrier to the exterior. The thermal mass offers huge benefits in hot climates as well as the strength, security and durability of concrete.

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