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. 

"Like Italy in the 1960s", HVAC contractors have no idea how to build to California's Energy Code.

A lovely guest house in the country. Brand new, white, gleaming and beautiful. The owner is British. I tested the performance of her new HVAC system. It failed three HERS tests.

I explained to her each of the tests and why the system failed. The ducts leaked too much air. The system did not move enough air for the size of the air conditioner. Why? The return ducts are either too few or too small. The MERV 8 filter installed is restricting air flow so it should be bigger or perhaps there should be two of them. The 2017, airtight, well insulated 1500 square foot house with low e, argon dual pane windows doesn't take much to heat or cool. How did it end up with a 3 ton AC and restricted, leaky ducts?

The homeowner told me that it was "like Italy in the 1960s." A top-heavy bureaucracy well insulated from those doing the actual work or needing to get things done. The individual people are often brilliant, but people are not working together. Some were also incompetent.

We have a real problem in the SF Bay area with HVAC contractors installing air conditioning systems without following the CA energy code's "Mandatory Measures", nor CalGreen. Every day I test new systems that have not been sized and designed as per code requirements. This yields systems that use more energy and provide less comfort. This has a real effect on energy use in the SF Bay Area. These improperly designed system can last 30 years or more and will waste energy daily 'til near 2050 when they will fail.

California Title 24 Energy experts say that 1% of residential HVAC systems are properly calculated for sizing and have their ducts designed per the specs in Title 24. Only 10% get permitted and tested.

Of course, the Energy Commission did not make up these design specs. They use the Air Conditioner Contractor's of America Manual J, Manual D and Manual S sizing, duct and register grill design specifications.

Sadly, there is no continuing education from the Contractors State License Board for HVAC contractors. Hence, they have no idea of what is in the California Energy Code or how to build comfort system that conform to it.

We are now in the 2016 energy code. Builders and HVAC contractors are nowhere near understanding what is in the current code or how to meet it. At the same time we are nearly 2 years away from the 2020 energy code when new buildings will be "Zero Net Energy", meaning that houses will generate as much energy in a year as they use in a year. We have a lot of work to do to educate the building industry workforce in order to get up to speed with upcoming code changes.

Let's fix this problem.  Just like engineers design our building so they stand up to earthquakes via code required structural design, let's have our HVAC systems engineered per our energy code. We need to require building department design review first, before permitting these long lasting, energy using systems to get built.

CSLB and California local Building Departments, please get up to speed educating the building industry workforce and enforcing the energy code.

George Matthews, owner
Building Energy Compliance Testing
Serving the San Francisco Bay Area

Why get a professional load calculation and duct design for your new air conditioning system?

At Building Energy Compliance Testing I’ve been testing HVAC systems in the Bay Area since July 2014. In that time, I’ve tested hundreds of heating and air conditioning systems that don’t comply with code. The problem? They were guessed together using outdated rules of thumb. I commonly see furnaces and air conditioners that are 200 or 300% of the size they need to be. The ducts usually have return ducts and filter grills that are puny compared to what engineered systems call out and wildly undersized according to what the California Energy Commission states in title 24, part 6. None of these systems are designed to get the exact amount of air to each room according to what the room needs to stay comfortable. They don’t provide comfort, economy and clean interior air.

The problem. When you have a big furnace or air conditioner with a small return duct system you get low airflow with a lot of heat or cooling. This causes short cycling, the systems comes on and then turns off shortly thereafter because all that conditioned air satisfied the thermostat. Meanwhile, there is no air circulation or air filtration. Often the farthest rooms stay uncomfortable. This tends to make people in the house uncomfortable and unhappy about the expensive system they just installed. It also does not make for the lowest energy bills or long system lifespan. The home owner who just spent $7,000 or more on what they assume is a state of the art system has a bunch of equipment that is not optimized for they home and they are stuck with it.

What the code requires
California’s energy code and Calgreen, the green part of the code, require manual J, Manual D and Manual T system design. LEED and Build It Green’s Green Point Rating also require that Calgreen be adhered to. These above code, green building documentation systems also give points for such HVAC design. Cities such as Palo Alto and Santa Monica also call out, again, on the plans, that approved HVAC system design shall happen. On a typical set of plans for an addition or remodel, system design might be called out three times. These plans are signed by the architect, builder and homeowner. Still, California energy experts state that 99% of HVAC systems in homes in California do not get designed according to accepted engineering protocols.

Problems with guessed-together systems
Inadequate  air flow from small return duct.
Short cycling
small, quickly clogged air filters that strangle air flow
furnace/air handlers with old style, low efficiency motors
Lack of dampers on ducts to control airflow room by room.
Register grills that don’t direct air where it belongs
Outdated register placement the contractor’s Grand Dad brought from the east coast in 1947.
Wrong filters, hampering airflow or allowing contaminants in the home’s air.
Lack of air duct mastic on joints, leaking conditioned air, wasting energy and allowing in contaminants.
Long duct runs causing excessive static pressure in the system.
Rooms that don’t heat/cool because the door gets closed for privacy.
Register/duct placement where it does not need to go or lacking where it should.

I seem some combination of the above problems every day. We know how to avoid them all. When you eliminate these problems and incorporate proven energy design, you end up with systems that keep homes comfortable, quiet, energy efficient and provide superior air quality.

Further, when a system is designed using state-of-the-art design and built with advanced equipment and assembled professionally with ducts sealed tight with mastic at every connection and then commissioned so that every performance test is passed, you get systems that really perform.

What Design protocol is acceptable? There are a variety of ways to achieve Manual J Load calculations, Manual D duct design and Manual T air grill design. Energy experts tend to agree that Wrightsoft Universal software is the gold standard design software. This company in Cambridge, Massachusetts is the leader in HVAC design software. We at BECT use Wrightsoft and love it. The software is a joy to use, the company has outstanding support help and it is committed to educating its users how to use the product. They have scores of videos on how to use every facet of the software from homes to multistory commercial buildings.

At BECT we can take your home plans and design a custom home comfort system that incorporates our knowledge of ducted air systems and home energy efficiency to bring comfort and value.

Hiring BECT to do load calcs and duct design can save you money. Often times, a contractor will “rule of thumb” a system at 4 tons of air conditioning. When we calculate the plan of the house, room by room, including how much insulation is in the walls, ceiling and floor, window type and how the house is oriented, we have, a number of times, come up with around 2 ton as the proper size. Two tons of AC cost less than four. Money saved.

We’ve seen some houses where a contractor wants to install two systems. While this is usually best for 2 story houses, we’ve seen cases where, upon calculation of sizing, a single system can suffice,  saving capital costs.

Need a closet? Sometimes a family needs more space for coats, hats and the vacuum cleaner. We sometimes get clients a new closet by moving the furnace into the attic or garage as part of the new design. The added space makes it easier to get access to the new system so the contractor can assure that the plenums and duct start collars are accessible so they can be sealed properly. This adds value to your home.

Allergies or respiratory health issues?
Sometimes a respiratory ailment is not from disease but from the environment. The environment we live in today is inside houses and office buildings. All the air in buildings moves through HVAC systems. Is your interior environment designed to keep contaminants out and make the air clean?

Planned, well-thought-out, engineered systems always work better than those hastily thrown-together. If you want comfort and economy with long term performance, load calcs and duct design are something a homeowner wants to incorporate into their strategy.

At BECT, we have decades of experience in energy efficiency in buildings.

www.bect.us