Manual J/Blower Door/Duct Testing

[scooterfj62]

Time to replace my aging (18 years) AC systems in our 2 story house. Down stairs unit has stopped cooling completely and upstairs unit cannot keep up with demand, both are 2 1/2 ton Carrier units. I have received a couple of quotes and a Manual J was performed by one of the contracters, the other just eye balled everything and made recommendations.

My question is after reading so many posts on here, is it necessary to do a Blower Door test and Duct blaster in order to properly size the new units? None of the contactors I called, including some of the larger businesses here in Orlando, offer this service or think its necessary for proper sizing.

[jtrammel]

Without a blower door test you have to guess on the infiltration rate of the house which is a major factor in sizing correctly, with a blower door test you know exactly what the infiltration rate is and know where you can improve to reduce the infiltration this allowing smaller size equipment. Duct leakage in a typical home is 25-40% of capacity lost, you don't necessarily need a duct blaster, the blower door can tell you if the duct system is leaky but a duct blaster test is good to do. A leaky duct system would be like going to the gas station and filling up your car at 3.50$+ a gallon and having a bunch of holes in your gas tank, not a very smart move.

[hcong]

You probably have to get a HERS (Home Energy Rater) aka third party to do the testing. Not bad though, they aren't usually contractors so no conflict of interest and trying to sell you stuff.

[cuchulain]

here a duct blaster test is required to pass inspection. it is done by a 3rd party to avoid conflict of interest.

[scooterfj62]

Thanks for the responses, jtrammel your analogy makes sense. Now its just a matter of finding someone who does these tests.

The only requirement, at least here, is that the contractor perform a Manual J. Interestingly enough, the contractor who actually did the J recommended downsizing the upstairs unit to a 2 ton and the guy who eye balled everything recommended upgrading to a 3 ton and adding another return.

[jtrammel]

www.bpi.org or www.comfortinstitute.org contractor locator on these sites

[jtrammel]

Florida power and electric will test, not sure how much testing they do but they do test

[energy_rater_La]

resnet.org is another source for an energy rater. we aren't called auditors.

blower door using subtraction method can measure duct leakage.
blower door measures house leakage also. different steps..same equipment.

resnet raters use duct blaster or pressure pans to test
ductwork you would have to request if you chose to test differently.

usually houses are depressurized to get leakage amount.
if you pressurize you can feel the air leaking out of ductwork
so you know exactly where to seal.


sealing house leakage means less of the great outdoors to heat and cool
sealing ducts means all of air you pay to condition comes into the space
where you live. return should also be tested.

sealing both leakage areas (house & duct) can change how many
tons of hvac is required.
manual J would have to reflect reduced infiltration numbers.


best of luck.

[scooterfj62]

www.bpi.org or www.comfortinstitute.org contractor locator on these sites

Thanks, only one contractor in the area listed on these sites, will call and see if they offer these services as part of a quote or installing new systems.

Florida power and electric will test, not sure how much testing they do but they do test

Not a FPL customer, we are OUC here.

resnet.org is another source for an energy rater.

Sure about this website? What comes up is some sort of Business referral network.

[energy_rater_La]

sorry www.resnet.us

http://www.resnet.us/directory/search

[jtrammel]

Thanks, only one contractor in the area listed on these sites, will call and see if they offer these services as part of a quote or installing new systems.



Not a FPL customer, we are OUC here.



Sure about this website? What comes up is some sort of Business referral network.

Most will charge a fee for the testing because it is rather involved, takes time and the testing equipment is very expensive some will discount the testing fee off the invoice if awarded the job. Even if it costs a couple hundred bucks its well worth it when making an hvac investment. You will be more comfortable, save more on utilities and improve your indoor air quality by implementing some or all of the solutions to the problems that are found by the testing, lots of what you will find can be done by the homeowner with minimal skill and little investment (a few tubes of caulk, weather stripping, receptacle gaskets etc.) others may need to be done by hvac pros, insulators, electricians etc.

[energy_rater_La]

how much are you willing/able to diy?

[udarrell]

Most will charge a fee for the testing because it is rather involved, takes time and the testing equipment is very expensive some will discount the testing fee off the invoice if awarded the job.

Even if it costs a couple hundred bucks its well worth it when making an hvac investment.

You will be more comfortable, save more on utilities and improve your indoor air quality by implementing some or all of the solutions to the problems that are found by the testing, lots of what you will find can be done by the homeowner with minimal skill and little investment (a few tubes of caulk, weather stripping, receptacle gaskets etc.) others may need to be done by hvac pros, insulators, electricians etc.

Right-On, JT

[scooterfj62]

Most will charge a fee for the testing because it is rather involved, takes time and the testing equipment is very expensive some will discount the testing fee off the invoice if awarded the job. Even if it costs a couple hundred bucks its well worth it when making an hvac investment.

Took a bit of doing but found a company that would do the testing for a few hundred. No company I called would do it as part of their quote for new AC systems. One said that they do it after a contract is signed and only do the Manual J that way as well, they eye ball for the estimate.

[scooterfj62]

how much are you willing/able to diy?

DIY a blower door and duct testing? Thought they both require a bit of specialized equipment?

[jtrammel]

DIY a blower door and duct testing? Thought they both require a bit of specialized equipment?

No he's talking about improvements to problems with your home if/when any are found at testing. Are you fairly handy? in other words

[energy_rater_La]

boy this just isn't my week is it?
diy the air sealing duct sealing per findings of the blower
door duct testing.

while allowing the duct sealing to be done by hvac company,
the blower door will show leakage areas in the house.
some you address from attic..others from inside the house.
are you willing to diy the caulking from inside the house?

personally I find the homeowner does a better job caulking
as they take the time time to do it well. some areas will
require caulking twice. as the caulk dries it shrinks so
a second application is necessary. just isn't cost
effective to send crew to caulk the second day.

its hard to price caulking jobs. cheap material but time
& finesse to properly seal.
is this something you are willing to do?
if so, buy by the case, caulk with long life that goes on
white and dries clear.

hopefully you'll share your testing results with us.

best of luck.

[jtrammel]

Took a bit of doing but found a company that would do the testing for a few hundred. No company I called would do it as part of their quote for new AC systems. One said that they do it after a contract is signed and only do the Manual J that way as well, they eye ball for the estimate.

I feel like you will see a lot of value in the testing, it's a pretty eye opening experience it was for me tge first time i saw it done. I'm glad you are doing your homework before you make such an investment. Lots of companies don't do man j until they get the job bc it takes time and effort and they don't want to do it then you tell all the other contractors the numbers and someone else gets the job after they have taken the time to evaluate and calculate the size

[hkempf]

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[hkempf]

This is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary or ask questions of the OP here. Please apply to the AOPC today, thank you.

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