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 how as our homes vent or exhaust air the air needs to be replaced, this is 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.

      

I get a kick out of most things related to home ownership and repair. I subscribe to quite a few blogs that are home related and some are pretty good, one I've been reading for about 5 months, Life and Lawns, has been impressive. Plenty of posts, so topics stay current to the season, that are well written withadvice that is easy to understand and follow. If you care about your lawns appearance it's worth reading.

      

Recently I've had several people ask how to determine which home repairs are best for saving money. The question is easy to answer on paper but is a little tricky in real life. We are going to assume the decision
is based soley on dollars not architecture or environment or other factors that are legitimate. The first way to asess a repair is payback period. The calculation is simply, if a repair or retrofit is a $1000 and saves a $100 a year then the payback is 10 years and the annual return is 10%. Lifecycle costing is a little more sophisticated method of measuring cost effectiveness. The theory is that when contemplating any action, one should compare the lifecycle cost of taking the action against not taking the action. For example a standard hvac system will use $1200 a year for the next 25 years costing $30,000 if no action is taken. A new system will cost $5000 and use only $600 a year or $15,000 over 25 years. The new system's initial cost of $5000 plus its fuel usage of $15,000 equals $20,000 so it would be prudent to replace the system. The ext step is the BCR or benefit/cost ratio. In the above example take the savings ($10,000) divided by the cost ($5,000) to arrive at a savings-to-investment ratio of 2. An sir of 2 means the retrofit will pay for itself twice during the life cycle. Just for clarification the numbers above are made up just to show the ideas, I know a fair amount of factors were left out of the example. I will get more specific about individual retrofits later.

      

I know this isn't home related so please forgive. These are some of the sites that I have in my reader. I thought some peope would enjoy the information and the feeds.

     

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Rumors always flow heavy at supply houses the latest that has been gaining credibilty involves an hvac contractor advertising an $89 air conditioning tuneup. The issue comes after the work is ordered and performed and the tech hands the homeowner an invoice with a $20 "gas surcharge" added. I can't imagine a worse message to send to a customer, and if I was the homeowner I would refuse to pay the "gas surcharge".
Thankfully most people inside the trades are condemning this practice. I would go so far as to suggest not using a contractor that pulled this stunt.

      

On Home Comfort recieved a verynice review from NWI Reviews.  They are a sight reviewing a fair amount of subjects, most related to Northwest Indiana. If your from the region area go ahead and check them out.

      

I've made it clear I'm not a huge fan of fiberglass insulation for a new home. My objection stems from how often I've seen poorly installed fiberglass insulation. Now I've come across a study performed by the University of Colorado School of Architecture. The idea was to test real world performance of cellulose against firberglass batts.
Two similar structures were built one with r-19 fiberglass insulation in the walls and r-30 fiberglass insulation in the attic, the other had r-19 cellulose insulation in the walls and r-30 cellulose insulation in the attic. The cellulose insulated building was seven degrees warmer after a nine hour heat loss test. More importantly, after three weeks of monitoring building performance the cellulose insulated building used 26.4% less energy than the fiberglass structure. The conclusion drawn was that the cellulose building performed 38% better than the fiberglass insulated building. Keep in mind both buildings had the same stated r-value. Keep a look out for effective r-value instead.

      

This question was e-mailed by a reader.

I think a maintenance agreement or energy savings agreement is a great idea. Obviously it would only be worthwhile if it include 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?
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?

      

 

 

As a home owner you should be aware of what is involved in an air conditioning tuneup. If you read any home maintenance articles this spring, most will encourage an A/C tuneup; some will even claim 25% savings. Predicting savings without knowing what type of tuneup received is a little silly. Encouraging a tune up without explaining the difference between an average tuneup and a high quality tuneup is a shame and expensive.

Most tuneups claim to adjust, check, reset, or modify back to factory settings. What does that mean? It implies that when the service tech is done your system will be good as new. What it really means is that the ad is not  very specific; tough to figure if you got your moneys worth.

    First a little insight, the tuneup is the basic advertising model for most HVAC companies. The idea being they sell you a $59 tuneup hoping you're so impressed with the work that it will lead to a new furnace install when the time comes. Any HVAC company will happily service a customer for years just for a chance at landing the new equipment job. If that logic is stretched out the more tuneups the more future jobs so why not drop the tuneup price?  Just one problem as price drops, pressure to do more tuneups per tech increases and the quality of the tuneup suffers.

        What should a quality tuneup include?

 

 

1. Measure airflow of system, absolutely critical for capacity and efficiency. Most air conditioners require 400 cfm of air to operate at capacity. There are three ways to measure airflow

        A. Static pressure measurement. This is the most accurate  method providing the blower wheel is cleaned.

        B. A duct traverse. This involves drilling a series of holes in your return drop to measure air flow with a wand style meter.

        C. Tru-flow air meter. A measuring device installed in the filter slot. Some techs believe its accuracy drops with poor duct design.

 

        D. Temperature drop across the system is not an accurate measurement of air flow, while temp drop is important in diagnosing

             it will not accurately  determine air flow

 

2. Clean the condenser. The out door unit should be sprayed with a heavy foaming cleanser that soaks for ten to fifteen minutes before rinsing.

 

 

3. Measure indoor and outdoor conditions. Indoor wet bulb, indoor dry bulb and out door dry bulb should all be measured. A qualified tech will have the tools for this. After all measurements are taken the tech should plot them on a sliding chart that will determine required super heat. Super Heat is an HVAC mesurement that sets proper refrigerant charge.

 

 

4. Adjust refrigerant charge, as important as airflow.  After airflow is set, the condenser is cleaned and super heat is determined, the tech can hook up his gauges and set the refrigerant charge.

 

 

5. Other useful measurments. 

 

         A. Temperature drop across coil should be 18-22 degrees, this is universal. 

         B. Temperature drop across outdoor unit. The tech will know this depending on unit.

         C. Amp draw of compressor:b this will depend on size of unit.

 

 

 

For any company to do this work correctly it will cost more than $59. Tell the dispatcher what work you want done and understand that it will cost more. If it costs twice as much as a junk tuneup it's worth it for your comfort and wallet. Some companies will only pull and clean blower wheels on a Time and Materials basis and thats okay. Now you can talk to your tech with out worrying about being bluffed into a bad job.

      

See how a simple mistake can cost you 10-12% on utility bills


I went to a home in Munster IN to look at the hvac system. The homeowner was concerned his utility bills were higher than than needed. When I looked at the furnace in the attic I noticed the filter access cover was missing. The homeowner said he didn't recall ever seeing a cover.  He audibly scoffed when I told him replacing the cover would save him more than any of the other measures he was considering. A missing cover in an attic allows the furnace blower to draw cold attic air into the duct work. After mixing with the house air brought through the returns the overall temp entering the heat exchanger is considerably lower making the furnace run longer than it should. I guessed he kind of believed me but didn't really want me to do any testing. Without testing I can only give some estimates but it will still make the point. 




The upstairs furnace blower should have been set at 1000 cfm. The open filter cabinet could allow 350 cfm through depending on the static pressure of the duct work, to be safe I'll use only 200 cfm.
The house is 70 degrees and the attic is 35 degrees.


So what happens? The thermostat calls for heating, starting the furnace. An 80% furnace should have a 55 degree temp rise. That just means for 70 degree return air the supply should be 125 degrees. But we have only 800 cfm of 70 degree air and 200 cfm of 35 degree air, yielding 1000 cfm of 63 degree air and supply air of 118 degrees.


What does that mean? First that seven degree loss equates to 12% of capacity and about 11% loss in efficiency, and thats at 35 degrees the colder it gets the worse the effect. Losing that much capacity and efficiency will be clearly felt in comfort and seen on high utility bills. I didnt even touch on the effects during air conditioning season 
I made some assumptions in the calculations:

1. The furnace was tuned correctly.
2. The insulation around the attic duct was correctly installed.
3. The furnace was truly 80% efficient.

Overlooking seemingly small items can add up quickly in cost and comfort.