Which air filter should I be using in my home's furnace/Air Con system?
I want to get the smoke out of the air where my children live. I want lower energy bills.

This is the question for health and measured performance. What difference does it make? Apparently, having a lower pressure drop across the air filter yields more airflow and less wattage used by the motor, (hopefully a permanent magnet, electronically cummutated motor of the right size.)



At BECT, designing duct systems, the most challenging data to find is the pressure drop across filters, "Y"s, evaporator coils, register boots, start collars, ducts, plenums and grills. Once we have all that data we input it to Wrightsoft software and we can prove/know/model the performance of the airflow. Without all those we are making educated guesses, hopefully correct.

Many of the components of a duct system are difficult to find pressure drop numbers for. Knowing that, we can eliminate variables and work with what we know to be true by specifying low pressure drop components. Oversized evaporator coils, up-sized return ducts and proven air filters matched to filter boxes with lo-resistance grills fit that bill.

Below is a note from 3M to a user about their filters and how much other manufacturers' filters rate RE: MERV and pressure drop in inches of water column. This is critical data when designing a high performance duct system.

"SUMMARY: The Ultra Allergen 1500MPR (for 1 inch depth HVAC) is the LOWEST pressure at 0.15 (vs .20 for the MPR 600). So it didn't make sense for me to go for MPR 300, MPR 600 or MPR 1000.

The complete response from 3M below:

Generally speaking, for most residential HVAC systems, the filter will become restrictive when it reaches a .5 pressure drop.
All of our filter media fibers are polypropylene and polyolefin plastic which will remove particles that measure 3 to 10 microns.
Microparticle Performance Rating (MPR), MERV Ratings, and pressure drops are as follows:

Elite Extra 2400
3-10 microns - 96%
MERV 13
pressure drop .21

Elite Allergen 2200
3-10 microns - 94%
MERV 12
pressure drop .18

Maximum/Ultimate Allergen 1900
3-10 microns - 93%
MERV 12
pressure drop .16

Allergen Deep Pleat 1550 (4").
3-10 microns 97%
MERV 12
pressure drop .12

Ultra Allergen 1500
310 microns - 90%
MERV 12
pressure drop .15

Odor Reduction 1200
3-10 microns - 85%
MERV 11
pressure drop .24

Micro Allergen 1000
3-10 microns - 80%
MERV 11
pressure drop .21

Dust & Pollen 600
3-10 microns - 65%
MERV 7
pressure drop .20

Dust Reduction 300
3-10 microns -35%
MERV 6
pressure drop .20

Flat Panel
3-10 microns -5%
MERV 1
Pressure Drop .08

Pressure drop is a measure of air flow resistance. It is measured by inches of Water Column (W.C.) at 300 feet per minute (FPM).
Clean/new filters are not restrictive to air flow. Filters will become restrictive if they are not changed when needed. A filter's life is actually determined by the user's living conditions and will vary for every user. Generally speaking, we recommend changing filters approximately every 3 mo nths.
To determine when the filter needs to be change, we suggest holding it up to the light. When you cannot see light through the filter, it is ready to be changed, even if it is before 3 months.
If you are concerned about airflow, you might want to use the filter with a lower pressure drop.
If you have a high velocity furnace with high fan speed, you may need to change the filters more frequently, every 1.5 to 2 months."

Compare the above when choosing filters. Doing so could be the difference between staying below .58 watts/CFM when doing Fan Watt Draw HERS tests. First you need the airflow to pass Total Airflow HERS test, then you need low watts from the motor to pass Fan/Watt Draw.

Register Sealing before having BECT do a duct leakage test

Subject : Register Sealing before having BECT do a duct leakage test

Hello,

Please make sure that the registers are sealed as in the photo below, before BECT comes to test the system for duct leakage.

Seal the register boxes to drywall or hardwood floor with UL 181 aluminum tape as shown below.

Aluminum Tape (must be UL 181)        

                              Register sealed to drywall with Al tape.

The photos below are examples of what the registers/returns should not look like.

Unsealed boot in drywall, on ceiling. This won't hold air.

Unsealed 1950s boot in hardwood floor, unsealed.

1920s register boot, unsealed to plaster yet painted black.

Also, please make sure that your forced air unit set on the highest speed so that you can achieve 350 cfm/ton​ for the 1. Total Airflow Test and 2. The Fan/Watt Draw Test.


Also, don't forget to drill a 1/4 inch hole in each side of the plenum (both supply plenum and return plenum) and mark the hole, HSSP, for Hole for Static Pressure Probe. Put aluminum tape over the hole but make sure marking is visible for HERS test. If those access holes are not there - you'll need to do it at the test. They are so that someone can insert a probe on each side and see the difference in temperature and humidity changes before and after the air moves through the evaporator coil.

If you have any questions on how to seal it, we also have a video on our website detailing how to properly seal your ducts. Click this link here to watch the video, http://bect.us/videos/. You can also watch our other videos on energy efficiency in the home on BECT's YouTube channel. Check it out here, https://www.youtube.com/channel/UCAd8LCb6fzHAkzqOu9loGrQ/videos?view_as=subscriber.

Stay cool and comfortable, 

BECT

Dear CEC, Please approve Wrightsoft software for alterations and additions compliance, (Title 24 performance)

Dear Commissioner McAllister,

I am writing to request that you to approve Wrightsoft software to perform title 24 energy compliance (performance) for residential alterations and additions in California.

I am told that the software is now able to perform compliance for new homes but not for alterations and additions, the far more common jobs found here in the San Francisco Bay Area.

I have been using Wrightsoft for the last year and am extremely impressed with it as a tool to perform load calculations, duct design and equipment selection. As a HERS rater I see failure to perform to code every day in the HVAC systems I test, with about 75% of them fail to move enough air in AC mode. Having HVAC systems be designed properly yields systems that perform to those design standards.

I understand that the CEC is now evaluating Wrightsoft. If that is so, I ask you to accelerate the evaluation and allow Wrightsoft to be used in title 24 compliance in alterations and additions.

It is my understanding that 1% of California residential HVAC changeouts get load calculations done. This must be why I see such wildly oversized air conditioning systems in my testing.

Here is what I’d like you to do to improve energy efficiency and efficacy in new/alterations in California,

1.       

Allow Wrightsoft to be used for T24 compliance in Alterations and additions.

2.       Compel the Contractors State License Board to teach HVAC contractors to use load calculation software and that calculations, design and equipment selection is code required.

3.       Sponsor classes to teach HVAC contractors how to use load calculation/duct design software.

4.       Encourage title 24 consultants to use load calculation software and do both compliance and design.

Doing only compliance misses the greater point of creating heating/cooling/ventilation systems tailored to a particular house and actually achieving efficiency and performance. I see “T24 compliant” houses fail HERS tests every day.

If you need any help, please do not hesitate to call me.

Thanks for your help in creating an energy efficient economy in California.

Very truly yours,

George Matthews

Building Energy Compliance Testing www.bect.us Phone 510 520 4443

Walnut Creek, CA 94597

In an affluent Bay Area suburb a custom builder turns over the newly remodeled 1950 ranch house, 3000 square feet of beauty for the young successful professional's family.

The builder is proud of the beautiful house, new again, gleaming, high ceilinged great room and chef's modern show kitchen. The contractor awaits his final payment and joy of a job well done and onto a new project. The new project photos look fantastic on the builder's website.

The HERS rater shows up and performance tests the new addition's forced air heating and cooling system. Failure on 3 of the first 4 tests. The contractor failed to read the energy report and the required Quality Insulation Installation (Translation: insulation installed to manufacturer specs) was never installed.

Here is the letter.

Dear owner and General Contractor,                                                                                                      3/1/2018

As per our conversation, this letter is detailing the results of my visit to 987 Oak Drive, Santa Suburba, CA.  

The house is failing to pass the energy code. I tested the duct leakage and airflow for the two HVAC systems on the property. Three of the four tests for duct leakage and total airflow did not pass and therefore the house did not comply with the HERS  Energy Code Standards.   The new addition HVAC system had 719 CFM total airflow (pass) and 165 CFM duct leakage (40 CFM max is passing). The new ducts in the south HVAC system had 1055 CFM airflow (1400 min. to pass) and 401 CFM of duct leakage, (70 CFM leakage is maximun leakage to pass). 

Below is a list of energy efficiency measures as they now exist in the house. These items are the most likely to be modified in order to comply with the California Energy Code.  

• Quality Insulation Installation, a required measure in the Title 24 energy report, was not done. 
• No radiant barrier in the roof sheathing plywood was installed 
• 80% efficient furnace installed instead of a 90%+ efficient furnace. 
• The water heater is 62% effiecient rather than 90%+.  
• Insulation is missing in areas in the new addition's attic. 
• The mandatory measure (in both energy code and CalGreen): Manual J, D and S, HVAC load calculations, equipment selection and duct design, were not done. 

In order to pass and receive your final, I suggest that you get in contact with your energy consultant to determine how to get the house to meet the 2016 California energy code given the above conditions. 

Please do not hesitate to call me with any questions.  

Very Truly yours,

Geo

It was most unfortunate to have to write a letter like this. The energy consultant obviously did not get the point to the GC that QII had to be done and documented by a HERS rater in order to pass. Once the insulation was covered over with  drywall the opportunity to inspects was gone.

Please read the energy report and CalGreen. Spend a few minutes reading the mandatory requirements in each. The reference above equipment can last 30 years. Energy consumers are poorly served when equipment from the 70s or 80s is thoughtlessly put into a house designed for the next generation.