» Energy Savings and Comfort

Duct Cleaning- Buyer Beware

Administrator — Mon, 21 Jun 2010 13:32:20 +0000

Thinking about getting your air ducts cleaned? Make sure to do your homework before hiring someone to do the work. Consider a few things:

- Are they certified by NADCA or the IICRC?

- What type of machinery or equipment is used to perform the work? Typically a “Whip and Blast” system with a high powered vacuum or the “Roto-Brush” would be adequate.

- Does the company provide before and after pictures of the ductwork? Pictures empower the homeowner with a piece of mind that the work is being done properly.

- How long will they be at my house? In order to do a good job, the average residential air duct cleaning takes two technicians anywhere from 4 – 8 hours.

- Are they using chemicals? There is no magical fogging or sanitizing agent that will rid your ductwork of contaminants. It must be agitated under negative pressure, then lightly sanitized vent by vent.

According to the National Air Duct Cleaning Association, if you have your ducts professionally cleaned and sanitized, you should not have to have it done again for 6 to 8 years. Think twice about hiring a company to clean your ductwork for $100 – $200. For good workmanship, expect to pay anywhere from $400-$600.

Mechanical ventilation = better air, money saving, safety and a more comfortable home

Administrator — Tue, 01 Jun 2010 18:15:31 +0000

Anyone who has spent money on tightening up an existing home or spent extra for energy upgrades for a new home will be irritated by the concept of mechanical ventilation. Understandably it doesn’t make sense to make a home more airtight then add a way for more outdoor air to come in, but having your home ventilate properly is critical. Why?

Indoor Air Quality- Indoor Air Quality or IAQ has become a buzzword in the HVAC industry. Sometimes buzzwords come about from marketing or misinformation but here there is a legitimate need, as homes are tightening up pollutants are trapped in the home. Older homes are ventilated naturally, but at the cost of comfort and efficiency. Indoor air starts as outdoor air and becomes “dirtier” from pollutants in the home, ventilation removes dirty air and dilutes the existing air.

Common sources.
Excess moisture. High humidity can lead to condensation which can lead to mold.
Chemicals. Paint thinners, cleaning products, insecticides such.
Building Products. Most newer products contain chemicals from their production like glues or formaldehydes.
Pets. Dirt dust and dander
Smoke. Candles smoking or even deep frying let off contaminates that hinder breathing.

Energy Savings- The issue is air is coming in whether you want it to or not, any home exhausts a certain amount of air through bath fans, kitchen exhaust hoods, water heaters, older furnaces or one pipe furnaces, stack effect from leaky can lights, hvac boots, attic hatches or clothes dryers. All the air that leaves will be replaced through cracks, outlet boxes, open doors, or far worse a back drafting water heater flue. Since that air is coming in our goal should be to control it. Mechanical ventilation allows us to bring it into the duct system where it will be conditioned and filtered before coming into the living area. Some types of equipment have heat exchangers that pull the heat out of air before it is exhausted.

Comfort. By controlling where the air come in we reduce drafts and cold spots.

Safety. We know as our homes vent or exhaust air the air needs to be replaced, this is a condition called negative pressure. The safety concern comes when a home has a fire place or b-vent water heater that begins back drafting from the negative pressure. If air is being introduced through the b-vent when the water heater fires the exhaust gases will spill from the draft diverter allowing co2 into the house. mechanical ventilation reduces this condition. Regardless of your situation you must have co2 detectors in your home.

Higher end filters worth the cost?

Administrator — Thu, 29 Apr 2010 18:17:25 +0000

When I’m in Home Depot or Menards, I walk down the heating aisle to look at how different products are marketed. Almost always someone has an “allergen”(these are the more expensive filters promoting clean air) air filter in their cart. Almost always I ask them about why they picked that filter, and always, my embarrassed wife vanishes. Most responses involve wanting better Indoor Air Quality (IAQ) or not minding the cost if it’s a better filter.

I wonder how the responses would change if they new that allergen filter was costing 7-8% of the furnace or ac’s efficiency and maybe capacity. First, the furnace filter is not designed or installed for IAQ. It is installed to protect the equipment. Dirt and dust travel through the ducts, and any dirt that settles on the fan blades, heat exchanger, in the blower motor, or the wet ac coil will reduce efficiency and equipment lifespan. Furnace manufacturers design their equipment, mainly the blower motor, to provide a certain cfm against a certain resistance measured in static pressure.

To explain that I need to touch on duct design a little bit. When a duct system is designed and sized several factors are taken into account.

1. CFM. Cubic feet per minute. This is a measure of volume, similar to gallons, of air. A very specific amount of air must travel through the furnace based on its btu input. Too much variation of this cfm will change the equipment performance.

2. The resistance of the duct. A duct’s resistance to airflow is measured in static pressure.

3. A fan chart. A manufacturer’s fan chart is available for any furnace a designer might spec. That chart lists the amount of air that can be delivered against a duct systems resistance or static pressure. The fan chart allows for a filter pressure of .1 inches of water column. If that makes no sense don’t worry you will never need to know or remember it. The .1 rating is about 20% of the total resistance.

What does any of that mean? It means your homes ducts should have been designed to move 1200 cfm (for a 3 ton ac) with a static pressure in the duct of .5 inches of water column. If tested, it will almost certainly be underperforming. Most houses are running with the SP (static pressure) higher than design standards. Meaning, the airflow is delivered at the edge of the systems limits and any change in resistance can reduce the desired airflow. An hvac system can never perform at full efficiency or capacity without correct airflow.

“Allergen” filters would be any that advertise high”merv”, better IAQ, or just cleaner air. They will also cost $5-6 as opposed to less than a dollar for fiberglass. I will agree that the more expensive filters will stop more dust. The filter accomplishes this by being much more restrictive than your fan can overcome. Their static pressures may be as much as 3 times as figured in the design stage. A system that is already
underdesigned can easily lose 7-8% of capacity with the addition of a restrictive filter. I’m not in the field anymore so I dont test as much as I used to but every summer during a hot streak it was not uncommon to find one house that would be at half capacity, causing an expensive and uncomfortable house.

If you are concerned about indoor air quality you will have a much more effective and efficient system with a bypass HEPA, EAC or PHI CELL air purifier that can be installed by your HVAC contractor. You will be money ahead.

Should I have an air conditioner maintenance agreement?

Administrator — Thu, 29 Apr 2010 18:14:48 +0000

I think a maintenance agreement or energy savings agreement is a great idea. Obviously it would only be worthwhile if it includes a quality air conditioning tune up. A few considerations in choosing your HVAC contractor.
1. Are they providing a proper tune up?
2. Are they a full service company?
3. Do they have a seperate service department? You don’t want to wait all summer for an understaffed company.
4. Do they offer a 15% discount if you should need service outside of the maintenance agreement.
5. Are their techs uniformed in lettered trucks? You want to know who is pulling into your driveway.
6. Are they considerate in explaining what they found?
7. Is your home left clean free of footprints?
8. Are you offered priority service for breakdowns?

9. Do they waive the diagnostic fee for repairs found during the tune up?

If you feel comfortable with those questions, then yes I think a maintenance agreement is a good idea.