Heating/Cooling-Air Filters

August 13, 2011

 Indoor Air quality is between 2 to 5 times more polluted than the outdoor air (US Environmental Protection Agency, September 1999)

I am invoking the 90/10 rule on this subject. Good basic air filtration will reduce dust and keep your HVAC equipment in good working order. For the other 10%, specialized filtering may be required to obtain hospital grade filtration, reduce allergies or conditions that have caused your house to be considered sick. If you have concerns of that level you may try some expensive HEPA type filters or consult an air quality specialist.

aifilter

MERV 1-4

To help us understand filter performance,  the standards body ASHRA created the 52.2 standard for rating replacement air filters. MERV or Minimum Efficiency Rating Value defines filtration performance with a 1-16 scale with 16 being the most efficient. However, “efficient” in this context is about  the amount of  particulate collected through the filter at the cost of reduced air flow. Using  a filter with the highest rating will require more service as it may 1) clog more quickly, 2) require more regular replacements, 3) be more expensive, and 4) add undue wear to HVAC components, 5) cause your system to over work, in-turn use more electricity.  So, if you do not have specialized filtering needs, finding a happy medium between efficiency and air flow is the prime objective.

 MERV Rating 1-4: Typically a very thin membrane made of fiberglass strands. This filter will picks up the big stuff and will reduce particulate to your system but will not provide any real air quality value.  The efficiency rating is <20%.  A MERV 1-4 filter can be purchased for a around $1 each.

Pleated MERV8

MERV 5-8

MERV Rating 5-8:  Typically a pleated cloth type membrane is more efficient and should meet most normal needs. With an efficiency rating of >20 but <50% these pleated panel type filter will provide adequate filtration as well as keep your equipment in good shape. They are about $3 each.

MERV Rating 9-14: Used in commercial or industrial applications based on their ability to remove certain smells and oders are becoming more popular for the home market. Assuming you can find the size you are looking for it will cost you $8 or more. When you get past a MERV11 they can be more difficult to find and expensive.  See the ASHRA MERV table for specific filtering requirements.

TIP: When you jump from a MERV7 to a 11, the price triples. The biggest difference is the amount of efficiency.  Based on the NAHB (National Association of Home Builders) Green Building Program they recommend a MERV 9 or better.  ASHRA 62.2P  also recognizes proper air filter efficiency at 60% or 3 microns ( MERV 9).

When you visit your home center they will probably limit your selection to 3 or 4.

  1. The cheap fiberglass stran filter, MERV 1-4
  2. A large selection of MERV 5-7. They may even be packaged in quantity priced at about $3 each or a little less in quantity.
  3. A MERV 9-11. Fewer sizes but still a reasonable selection. About $7.95 each. If you are struggling with allergies, something greater than a 10 may help.
  4. Maybe a HEPA (MERV14-15) or another high-end disposable filter at $15 to $100. These may be recommended to you for specific algeric conditions.
electrostatic-air-filter

Lifetime Electrostatic

Reusable or Life-time filters: Unfortunately there is not a standardized rating method for these type filters and I have failed to find enough independent data to support their use. Depending on who you listen to, an electrostatic filter could be similar to a MERV 4 on the low end and a MERV12 on the high. An electrostatic filter can cost between $60 to $300. If you are using a MERV 9 or better you may consider a reusable electrostatic type filter. You will have to be the judge as to it meeting your needs. HomeownerBOB has no recommendation here but I have read more positive comments about the BOAIR brand. If it works for you, it will  pay for itself in less than 2 years and you won’t be throwing filters in the trash.  The biggest advantages of  electrostatic filter are 1) they can be washed out and reused, 2) their efficiency rating is in the 90% range and 3) the airflow is excellent and does not deteriorate at the same rate as a pleated filter. Once you wash it, it is completely restored. Many times electrostatic filters come with a lifetime warranty.

Hybrid pleated/electrostatic charged filters:  MERV does not rate this type filter either. The manufacturers market this filter by having the attributes of both pleated and electrostatic filters, but at $17, its still a disposable filter.

Many professional will encourage you to change filters on a monthly basis and depending on where you live, that may be the right thing to do. HomeownerBOB recommends that you replace your filter some where between 2 to 4 times a year. You will need to be  the judge on the conditions that may warrant more or less frequent changes.

Reasons to change/clean your filter more frequently may include:

  • Continued use of heating or air conditioning throughout the year
  • Living on or near a busy street, highway, airports or rail road track
  • Living in a dry/arid part of the country
  • Living in an area with a low percentage of annual rain and or high winds (Texas, New Mexico, California, etc)
  • Living on rural property with a lot of exposed dirt
  • Living on an unpaved road

As I said in the beginning of this article, these filter recommendations are based on the larger body of population that does not have health related conditions. There are many more filters, filtering systems,  filtering strategy (cascading) and air exchange studies that can be used to solve air quality issues.

Recomendation:

It should be pretty obvious, unless you have special needs, or live in a very dusty enviornment, the MERV 5-7 should work fine.

Key Inspection Points and Action Items:

  1. Change, or clean your HVAC filter at least 2 to 4 times per year.
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Attic Insulation – The Choices

September 20, 2009

batt insulationAccording to the US Department of Energy, as much as 45% of a home’s energy loss is through the attic. Furthermore, 80% of homes built before 1980 suffer from inadequate insulation

A friend of mine was looking to buy a house recently, he asked me to come by and check it out. It was apparent the owners of the house were fairly interested in reducing their electric bill. Most all of the light fixtures were using CFL’s, they were using a set back thermostat and they had recently replaced an exterior door with one that was Energy Star rated. But what really shocked me was my trip to the attic.  Three  things, 1) they had sprayed radiant barrier paint on the roof decking but 2)  there was less  than 3 inches of insulation in the attic and 3) the air conditioning ducts lacked adequate insulation requiring the HVAC unit to work extra hard to provide the conditioned air throughout the house. I’m not knocking the radiant barrier (I’m a believer), but even most of the radiant barrier folks will tell you to increase you attic insulation first. There are good reasons why HVAC  installers sometimes throw in insulation or RB as part of their package… it works and it also reduces the strain on the HVAC. Blown in insulation is cheap and it can be added in a mater of hours.

Attic Insulation is best applied as blown in loose fill when you need to add  more to an existing home. The product will reach into every nook and cranny, is easy to apply (with the proper equipment), and has instant results. The best way to determine the amount of insulation needed is to refer to this US. DOE  site as it will provide the recommended R-Value down to the zip code.

Making the choice

What is the difference between the attic insulation products and why is one better than the other? If you spend any time looking at the comparisons of the products you will find advantages and disadvantages in all the of them. Its very easy to get caught up in the data, in fact some make a point in overpowering the consumer with too much data. The following chart reflects the most popular products and comparable characteristics that most consumers can understand and recognize value in them. This comparison is for blown-in type insulation only, and these products are typically the most popular. 

 Insulation Table2

 Concerns associated with the compared products:

Rockwool: Rockwool insulation has been classified by the US Gov. as a class 2B carcinogen with   “possible” evidence but lacked conclusive results to be considered a “probable” contributor as a cancer causing agent in lab rats. Additionally, chards of the material will cause skin irritation much like fiberglass. It was very popular prior to 1970 and with some limited concern is still used as an insulation product.

Fiberglass: Fiberglass insulation has been shown to reduce its effectiveness during both high and low temperature ranges (due to convection heat loss), potentially reducing its effectiveness by up to 50%. Even though fiberglass chards can easily irritate the skin, once installed, little risk to the homeowner has been proven. However, the US Gov. has recognized fiberglass as a carcinogen, the levels have been shown to be too low to impact the homeowner.

Cellulose: Cellulose has become recently popular due to being composed of  recycled paper products. Cellulose is heavy compared to the other two and the added weight in the attic may cause standard 1/2″ sheet rock to sag or droop when applied to ceilings with joists spaced at 24″ centers. Additionally, since Cellulose will retain water, moistened by a roof leak may cause the  sheetrock to prematurely fail. Even though the product is treated with chemical flame retardant (generally with a lifetime guarantee), additional care should be exercised by providing adequate space around recessed light fixtures, chimney flues, water heater and HVAC vents.

The blown-in insulation business is fairly competitive and you may find (as I did) that hiring a professional is about as cheap as doing it your self. HomeownerBOB recommends the professional route. The difference in the choices are fairly close, cost may be the most important factor, on the other hand it might be the environmental impact. Either way, make the decision, you will be happy with the results.


Lawn Sprinkler Efficiency Upgrades Part II

April 26, 2009

sprinkler-head3Nearly 60% of residential water consumption can be attributed to landscape watering.

Hopefully you have read my previous posts on “Lawn Sprinkler Efficiency and Chasing Lawn Sprinkler Leaks “. If so, you recognize that a fine tuned system can provide greater efficiency and reduced water usage. However, you may want to go further. Stage III and IV represent some significant decisions regarding  the way you treat your landscape.

Stage III:  Plan to get wet and dirty. This stage will impact the designed water delivery. These changes are a  bit lengthy and involved and may take several weekends to complete the items.

  1. Make a sketch:If you don’t have a drawing of your system, use sprinkler flags to identify each sprinkler head in the zone. You want to identify all heads associated to a zone, one zone at a time. Each existing nozzle/head should include a brand and  a number on the top edge, 10, 12, 15. As well as a pattern identifier 1/4, 1/2 or F.  Sketch out your lawn and zone. Typically, residential irrigation systems are designed based on 30 PSI of water pressure at the head. Go to the manufacturers webpage and look up the GPM usage for each head.   On your sketch identify each head by pattern, radii and GPM. Total the GPM per zone. TIP: Whatever changes are made in the following steps, do not exceed the calculated GPM by more than 10%.  
  2. Correcting design issues: After completing item 1 and 2 you may have noticed some sprinkler heads are not exactly in the right place. This may be based on poor placement, changes or growth in the landscape material.  If relocation is required ensure that you retain adequate head to head coverage with the neighboring sprinkler heads. TIP: Read the nozzle; if the nozzle is stamped with a 10′ on the top, you should have other heads within 100 to110% of the distance of that number  from the head location. So if you decide to move the head, locate the neighboring heads to ensure the relation lawn20edge20pop20up2011stays comparable.
  3. sprinkler-bodies1Replace Sprinkler Body: Similar to #2, but the solution may be to obtain a sprinkler body that allows the nozzle to extend above an obstruction.  If you find pop-ups in flower beds but the spray is obstructed by plant material, changing the head to a riser can provide the necessary reach allowing sufficient coverage. TRICK: Risers (ridged plastic pipe with nozzles) can use the same nozzles as pop-ups but require a transition fitting to convert the threaded pipe to a sprinkler head nozzle. These fittings are brand specific as well.  
  4. Convert from Spray to Stream Nozzles: This is a dramatic change, not to be taken lightly and I would only convert one section at a time to see if you are okay with the results and performance. Even though everything you have done to this point will be beneficial, changing the nozzles will drastically reduce your water usage, but may require longer watering durations. Look for a future write up on Nozzles for a comparison in the water usage. As an alternative to this you may try finding nozzles that are low arc, as lowering the trajectory arc  you are spraying less water high up in the air. Since the  low arc nozzles typically have shorter radius patterns, this may not work, but is worth keeping in mind as you can use nozzles with different arc’s in the same system. Read my article on changing sprinkler nozzles; the payback is not as much as you might want but its worth a look.
  5. Parkway’s: In my neighborhood, I see a tremendous amount of water traveling down the street (everyday) due to this type of runoff. If the area is watered with standard half and quarter circle nozzles, you may consider changing the nozzles to strip spray nozzles. Strip spray nozzles project a rectangular pattern and may help you manage the water usage and overspray. Technically this is still a spray nozzle and it is okay to mix this head with other spray nozzles.  As I mentioned earlier, Irrigators will collect sprinkler heads together to complete a zone water budget, so this zone may include heads in the main body of the lawn and this could complicate your efficiency measures.

Stage IV: More dirt more wet. This stage is very severe, so only consider these steps if you believe you are still not where you want to be with regard to water usage.  Some of these steps are major redesign initiatives and its a lot of work. Hiring someone to do the irrigation work can be expensive as installing new sprinkler systems. You will need to be the judge on Stage IV. I don’t consider these items in order, so weigh your options. 

  1. Change Landscape Material: By changing your plant material to drought tolerant regionally specific plants, you can successfully reduce your watering requirements for your flower beds. Granted if you still have a large amount of turf your water demand is still high. You may consider reducing the percentage of turf. You can replace it with plant material or porous aggregate (gravel, crushed granite, river rock, etc.)
  2. Stop Using The In-ground Lawn Sprinkler: Simple to accomplish and it will dramatically reduce your water usage. Granted, you are back to dragging hoses around the house but point-of-use sprinklers will not use near the water an in-ground system uses.
  3. sprinkler-controllerReplace the Lawn Sprinkler Controller:  Understanding that better water management can further reduce our water usage, typical Sprinkler Controllers (or Timers) provide water on a timed bases. If  the timer is equipped with rain, wind or freeze sensors they will provide a higher degree of water management. Hopefully you already have those add-on devices to your existing controller at this point. However, in Stage IV stepping to a digital grade of water management is required to reduce your water consumption further.  At this point, I have found limited products available directly to the public as most of the “Smart Controller” are defined to be professionally installed.  Many of them require a monthly fee as they are tied to a weather database for regular downloads (I dont like monthly fees). However, I recently found a product called Cyber-Rain. They appear to be headed down the right track, by using your PC and the Internet to upload the most current weather conditions to adjust the water settings accordingly. They use a wireless connection to get to your PC and provide you proprietary software to further manage the water delivery. At $400 it’s a bit steep if you compare it directly to a entry level $60 water timer, however here in Stage IV, we are very serious about water conservation. I have not tested this product but so far I like what I see.
  4. Water Only The Flower Beds.  In my part of the country watering flower beds serves two purposes, 1) to keep the plant material alive and, 2) it reduces opportunities for foundation problems associated with the expansion and contraction of the soil. Assuming your system design has the flower beds in their own zones, it will be simple to just turn off the other zones at the controller.  If you have Bermuda grasses, you can stop watering them  and the grass will go dormant, but don’t try this with St. Augustine or Fescue as this grass will die without water. If the flower beds are combined with the turf sprinklers you may consider #5.
  5. Rezoning  sections: By now you should know where each section is, what it waters and how much water (GPM) per section. Segregate flower beds into their own zones. This may include digging and re-piping some heads from the flower bed zone to another zone.
  6. Convert Flower Beds To  Drip Irrigation: This is all based on the flowerbeds being zoned separately. Since drip system run at lower pressure, you will need to change the zone valve that can support the lower pressure.  Then its a matter of capping the existing sprinkler heads (or turning them off). I have used the (brown tubing) drip-line style, its not quite as efficient as the point-of-use designed to water individual plants as it just has an emitter every 12″ but its a lot less drip-linework and maintenance. If you use this style, the home supply stores can provide you the material required to transition from a sprinkler riser to the new drip lines.
  7. Convert Parkways And Grass Strips to Drip Irrigation: Assuming you can isolate the parkways into their own zones you can use the same drip line mentioned in #4 by burying it about 3-4 inches below the ground spaced at 12″. I did this at my house and have been very pleased with the results. TIP: If you do this, be very careful if do any digging  in the future as this type line is very pliable and can easily be damaged with a shovel.
  8. Add Rainwater Collection: This can be  a major undertaking, I have wanted to do this myself and have researched it for several years but due to certain limitations  on my property its not feasible…yet.  By creating a full house rainwater collection system you could technically rework your system to rain-water-collectionuse nothing but rainwater to irrigate your property.  But here are some things you would need to consider if you are interested. 1)Storing the water, probably in the neighborhood of 1000 to 3000 gallons. 2) Pumps may be required to transfer the water and drive the water through your sprinkler system. 3) Zone valves may need to be changed to accept the water as it will have a bit of dirt in it, 4) Additional filtration may be required to keep the system from prematurely stopping up the standard sprinkler heads. On the other hand, as a simplier approach, using water barrels at the gutters you can easily use this water for hand watering applications.