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Ruby - go ahead and get someone out to look at your house/system and give you an idea IF a zoned system will work, and what it would cost. Tell them up front that this is not an immediate need. After all, you have to start somewhere. A lot of people that call for estimates are not ready to buy right that moment.
Cerequas - Go with the zoning guy.
I have inspected lots of houses with zoned systems, and they all seem to work really well. Of course, a lot still depends on the configuration of the house, but for the most part, zoning works great.
There is nothing quite like a "properly designed" zoned HVAC system. You can increase your comfort, increase system efficiency and increase system longevity.
The con is:
Finding a HVAC contractor who knows how to do it right. 99% of zone systems are not designed very well. Most install them for others and don't take the time to do the same to the own house they live in. Anyone can do it, doesn't mean they should.
A complex system contains complex problems:
equipment lockouts, duct work blown apart, system failure to name a few. However, these things don't occur with proper design and installation.
I live in a single story house a little over 1700 square feet. I have a 4 zone set up. The most I pay "typically" for air conditioning is about $30 a month. 76 all day long and 74 at night in the zone I am in. If I go into another zone of the home it's not uncommon for those areas to be around 85-88 or so depending on out door ambient temp. The efficiency comes from cutting waste. If no one is in the zone being conditioned, what are you cooling / heating it for?
The $30 I pay for air conditioning does not include lighting and appliances. (Take summer bill and subtract from lowest winter bill to see what you pay for air conditioning... be careful of a pool pump that runs in the summer and off in the winter.)
A zone system is dependent on the structure... I wouldn't put one in just any home. There are certain requirements I have for that and this can only be done by visual investigation.
It is best to pair a zone system with a new HVAC system. Some equipment works better with a zone set up and if your current HVAC system is older greater efficiency gains are achieved with newer equipment. Trying to piece meal an HVAC zone system is not something I would ever recommend, but every situation is different just as much as different models of equipment and so on.
Very easy for me to ramble on and on... check out the info for yourself if you are interested in better comfort that pays for itself via lower utility bills and increased system longevity. I have a plethora of information on my website as well as proof to what I say here. You can find this info through my profile listing.
Funny thing about this old thread. Earlier this year I changed out my 20 year old HVAC system. My house originally had one system for two floors. It didn't work out very well, so I had a second system installed on the 2nd floor about 8 years ago.
When I was going to replace the original system, my hVAC contractor suggested we remove the 2nd floor system and go with a zoned system. It's been in since January and I can tell you that it is great. Not only have our utility bills dropped like crazy (20 year old technology compared to 2014 technology), but both floors are very comfortable.
Funny thing about this old thread. Earlier this year I changed out my 20 year old HVAC system. My house originally had one system for two floors. It didn't work out very well, so I had a second system installed on the 2nd floor about 8 years ago.
When I was going to replace the original system, my hVAC contractor suggested we remove the 2nd floor system and go with a zoned system. It's been in since January and I can tell you that it is great. Not only have our utility bills dropped like crazy (20 year old technology compared to 2014 technology), but both floors are very comfortable.
I know you must see lots of good HVAC work as a home inspector, but you also probably see some horrendous work. That gives you a huge advantage in choosing a contrator with the skills to "do things right".
In selling / buying and remodeling homes I have seen LOTS of poorly installed HVAC systems and too often the complex zoned systems are among the worst -- basic principles like balance between supply & return ducts cannot be ignored. Planning for moisture removal cannot be ignored. Access to service parts cannot be ignored. Air sealing cannot be ignored.
For most folks the best way to equalize temps between floors is to address the largest cause of upper floor temperature differnces: solar heat gain. Better insulation and things like radiant barriers have a VERY quick payback in nearly all climates. Do that before you consider zoned A/C.
You are correct Chet!
I know several HVAC contractors, and a fair amount have very little knowledge with regards to designing systems Most are in the business to do repairs, and change out equipment. I contacted a couple high end builders in my area and asked them who they used, and I got a good referral.
I went from a 1993 gas furnace to a multi stage, multi speed heat pump. All of my preconceived ideas and experiences with heat pumps went out the window with this unit. I wanted to go with a dual fuel heat pump, but my HVAC contractor did the energy load calculations, and showed me where the unit I put in would actually perform better, and give me more savings per year. He estimated close to $900 per year savings, and if the past 4 months are any indication, we will meet that, or maybe beat it. We also just had a record breaking (for low temps) winter.
You are correct Chet!
I know several HVAC contractors, and a fair amount have very little knowledge with regards to designing systems Most are in the business to do repairs, and change out equipment. I contacted a couple high end builders in my area and asked them who they used, and I got a good referral.
I went from a 1993 gas furnace to a multi stage, multi speed heat pump. All of my preconceived ideas and experiences with heat pumps went out the window with this unit. I wanted to go with a dual fuel heat pump, but my HVAC contractor did the energy load calculations, and showed me where the unit I put in would actually perform better, and give me more savings per year. He estimated close to $900 per year savings, and if the past 4 months are any indication, we will meet that, or maybe beat it. We also just had a record breaking (for low temps) winter.
The firms that do the full calculations can really help you choose what makes sense for your budget and long term energy savings.
Nothing wrong a skilled repair guy, but folks that don't have the skills / take the time to understand all the options for more efficent system AND the ability to explain the correct options to get "pay back" on more efficient systems give a bad name to the industry. It take more training / knowledge to understand which combination of technology is worth the extra expense for long term savings...
The firms that do the full calculations can really help you choose what makes sense for your budget and long term energy savings.
Full calculations only mean something if they do them right. I have witnessed many just over the past few years where calculations were skewed to the upside in putting in a half-ton system or larger than what was really necessary.
A half-ton larger system than necessary can make a 16 SEER unit perform as efficient as a properly sized 14 SEER. What complicates this further is manufacturer's don't make half ton increments in many of these upper SEER units. Which in laymen's terms: You've got your work cut out for you to get a properly sized unit. Let alone matched with a properly sized duct system. People don't want to pay for duct work unless the stuff is breaking apart and blowing air everywhere other than where it should be.
When doing the calculations we are told to guess? Say what? I thought you said it was calculated?
It is calculated... based on a guess. We have to determine what insulation R-values are in the home to do the calculations. Typically not too hard if you are in a 10 year old house... not so much in an older home.
What is the "proper" R value in insulation behind the walls? The blown-in insulation in the attic with peaks and valleys as far as the eye can see? What is the R-value of the windows? Doors?
Guess, Guess, Guess, Guess.
Experience is much more crucial... if you base an HVAC equipment sizing decision on the parameters of the dwelling "today" and fix by sizing rather than fix by correcting... well you know... and if you don't you may find out the hard way.
I am not saying a calculation shouldn't be done, but just because it is done doesn't mean it shouldn't be scrutinized based on size of current system and overall utility history of the dwelling in question. It's best to be undersized than over sized... undersized you can always increase insulation levels.
Oversized... the unit must be replaced with proper sized unit.
How can I get rid of the heat smell coming from vents when the high heat kicked in. The colder outside the stronger heat smell inside.
This often happens in areas that usually use a heat pump and only have the electrical resitance heat kick in on the coldest days. What happens is a layer or "dust" literally burns off the resistance heat.
The way to deal with is by regularly replacing the filters with quality panels so that minimal amount of dust are circulated / accumulate. Always a good idea to have a skilled professional clean the duct work on a regular schedule too.
This is will minimize but not totally eliminate problems, short of having a "clean room" level of air filtration you won't be able to prevent some dust from settling on hot surfaces...
Full calculations only mean something if they do them right. I have witnessed many just over the past few years where calculations were skewed to the upside in putting in a half-ton system or larger than what was really necessary.
A half-ton larger system than necessary can make a 16 SEER unit perform as efficient as a properly sized 14 SEER. What complicates this further is manufacturer's don't make half ton increments in many of these upper SEER units. Which in laymen's terms: You've got your work cut out for you to get a properly sized unit. Let alone matched with a properly sized duct system. People don't want to pay for duct work unless the stuff is breaking apart and blowing air everywhere other than where it should be.
When doing the calculations we are told to guess? Say what? I thought you said it was calculated?
It is calculated... based on a guess. We have to determine what insulation R-values are in the home to do the calculations. Typically not too hard if you are in a 10 year old house... not so much in an older home.
What is the "proper" R value in insulation behind the walls? The blown-in insulation in the attic with peaks and valleys as far as the eye can see? What is the R-value of the windows? Doors?
Guess, Guess, Guess, Guess.
Experience is much more crucial... if you base an HVAC equipment sizing decision on the parameters of the dwelling "today" and fix by sizing rather than fix by correcting... well you know... and if you don't you may find out the hard way.
I am not saying a calculation shouldn't be done, but just because it is done doesn't mean it shouldn't be scrutinized based on size of current system and overall utility history of the dwelling in question. It's best to be undersized than over sized... undersized you can always increase insulation levels.
Oversized... the unit must be replaced with proper sized unit.
The same skills needed to perform a full energy audit, including a blower door test of air infiltration and IR thermography, are applicable to properly understanding the heat load on a home.
Ideally a energy audit should be a "before and after" type endeavor with all the data from the first pass used to plan out suggested improvements, upgrades made to the weather sealing / insulation and confirmatory tests showing the improvements. The final energy audit data would then be used to properly size replacement HVAC equipment.
Of course these things take time & money to implement and few homeowners budget enough of either for even the largeest renovations...
Even well meaning HVAC firms staffed with "folks that know better" often end up falling into the "upsize" trap becuase while few people will call back about a bedroom that they need a blanket in the heat of summer to feel cozy, they gets LOTS of calls from folks that are angry that their "brand new system" can't keep up with a house full of guests celebrating some special occaison in a house overfilled with four generations of family when the outside temperature is setting records...
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Best Comfort, Best Efficiency
