Saturday, November 29, 2008

Do you know your Duct Leakage Rate?

It has been cold and rainy in the Bay Area lately and that means your furnace has probably been running overtime. So whatever inefficiencies in your heating system are amplified from the extended run time. Though the furnace efficiency or AFUE ratings gives you an indication of the unit performance, most homeowners don’t realize that the average duct system is an even bigger source of loss for heating and air conditioning system.

California Energy Commission (CEC) – a California State Government agency commissioned a study a few years ago and found that the average duct leakage rate on existing homes in California is at a staggering 30% (copy of the letter can be found on our website This leakage takes the warm air generated by the furnace and dumps it directly into your crawl space or attic. As a result of the study and a need to conserve energy, the State of California makes it a requirement for all inland regions of California that ducts be sealed as part of any furnace or AC replacement work. It is not a requirement in the San Francisco Bay Area yet and that’s why most contractors don’t do it or mention it to the customer. But if you are concerned about your utility costs and the environment, it is definitely an area to look.

To find out the duct leakage rate, a contractor equipped with duct testing equipment can perform a pressure test at your house. The set up and test take about 1-2 hours. Sandium is currently running a web coupon special for the test at $149. Based on the result of the test we can then determine whether or what action should be taken on the ducts. For residential customers PG&E has rebate of $350 to $600 for duct sealing if the leakage rate is brought below 15% but they require ducts to be tested by a certified contractor before and after.
We have done many tests in the south bay area and what we have found is that houses in Los Altos, Los Gatos and Saratoga area sometimes have a higher leakage rates than others. That is mainly because those houses were generally built 50+ years ago and have underfloor metal ducts that in many situations are rusted out. In those types of cases we recommend replacing the ducts. And for new ducts installation we can usually keep the leakage rate below 6%.


Sandium: Heating & Air Conditioning Experts said...

Summer said...
Hi Sandium!

Thanks for your cool *no pun intended* blog! My husband and I have been checking back. Quick question for you--While there are some health benefits to having your ducts cleaned, are there other benefits such as mechanical maintenance of the A/C or furnace or energy efficiency?

How often should this be done and what's a normal price range?

Sandium: Heating & Air Conditioning Experts said...

Mac said...
I've got to tell you, you saved our Cristmas! Me and my family are very greatful to you and Sandium. I called your company on the morning of 12/24, as my furnace wasn't working. I thought that we would have to go to find warmth at a friend's house for Christmas, how can you expect to get a new furnace installed on the day before Cristmas? I was afraid that I would have to spend $2K for a new furnace, and probably any other company would have made me buy a new furnace. Not Sandium, though, you guys are honest and straightforward. Your technician, Jacob came out and was able to fix the furnace, though it took him almost two hours, it really wasn't easy. Jacob is a very experienced and professional technician. Again, I was ready to pay for a new furnace, but you saved me the expense this time.
I'll definitely have you guys replace my furnace in a few months, and thank you again!
Also, feel free to use me as a reference, if you need it.
Mac Ischanov

Sandium: Heating & Air Conditioning Experts said...

Sandium Inc said...
This is actually a somewhat controversial subject. I will direct you the following page on the EPA website for some government guidance on the subject

Email me and I can give you my personal opinion.

As you noticed I have taken a few weeks off from the blog so I apologize for the late reply.