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5 Reasons HVAC Systems Don’t Maintain Comfortable Conditions

It’s the time of year when temperatures across the country push HVAC systems to their limit. You may have already received calls from customers who simply aren’t comfortable and want a solution. There are many situations where the issue is easy to find, such as a refrigerant leak or lack of maintenance. However, there are situations when the equipment appears to operate flawlessly, but it can’t keep up when outdoor temperatures rise. The equipment is in good operating condition, your refrigerant pressures are close, the temperature drop on the indoor coil is right, and the equipment is sized correctly. What else is there?
 
If this scenario sounds familiar, you know it’s frustrating and you feel helpless when you don’t know where to go next for answers. Let’s look at five hidden reasons HVAC systems might not keep up when the temperatures get hot, how to test for them, and potential repairs.
 
INCORRECT FAN AIRFLOW
When everything with the equipment appears to check out but the system can’t keep up, fan airflow is the first place to look. A system that is low on fan airflow cannot remove enough heat.
In cooling mode, a fan should typically move between 350 and 400 cfm (cubic feet per minute) per ton. If you’re testing a three-ton system, this means the fan should move approximately 1050 cfm (350 x 3 = 1050) to 1200 cfm (400 x 3 = 1200) across the indoor coil.
The easiest and quickest way to determine fan airflow is with a total external static pressure (TESP) test and fan table. Use them to plot fan airflow. You can add fan airflow to static pressure readings in four simple steps as I discussed in the November 26, 2018 edition of The NEWS. This provides you a starting point in your diagnostics. If airflow at the air-handling equipment is off, everything else will be.
Your testing may reveal the only issue is the fan speed is set too high for the outdoor unit airflow requirements. This is common when dealing with gas furnaces that have larger tonnage fans paired with smaller outdoor units. If this is your problem, you’re in luck. Adjust the fan speed to the proper setting to solve this problem and then recheck the system to assure it isn’t overcharged.
You may also discover that fan airflow is too low — this is when the fun begins. High TESP often accompanies low fan airflow. If you find it in the system, take some additional static pressure measurements to discover any airflow restrictions hidden from a visual inspection. Common restrictions include:
  • Restrictive air filter, even though it’s clean
  • Restrictive indoor coil, even though it’s clean
  • Undersized ductwork
  • Restrictive duct fittings and transitions, and
  • Poor design and installation (too many elbows, too long duct runs, too many restrictive turns).
Tip : Measure static pressure drop across these components to find the highest resistance. When you find the highest pressure drop, you also find the largest airflow restriction(s). Once uncovered, you’ll need to recommend repairs to lower pressure(s) and improve fan airflow.
 
DUCT LEAKAGE
Once fan airflow is correct, it’s important to assure that all air the fan circulates moves through the conditioned space. Mechanical connections in a duct system have the potential to lose air. Any air lost through these leaks negatively impacts system operation and prevents it from maintaining comfort in hotter outdoor temperatures. Supply ducts transport cool, conditioned air to the living area. If it is lost through leakage before making it into the building, the equipment will operate like it is undersized. It will run continuously and fail to provide comfort. This problem usually doesn’t show up in milder temperatures, when it takes less than full system capacity to keep the building comfortable. Return ducts bring back living space air to the air handling equipment for conditioning. If additional return air is brought in through duct leakage, it can add nasty air from unintended locations that you don’t want in the home.
If return duct leaks are in a hot attic, additional heat is added to return air that the equipment must remove. The same principle holds true for return duct leaks in a crawlspace. Instead of additional heat, they may add moisture to the return air that the equipment must remove. To test for duct leakage, you can use a balancing hood to measure total supply air and return air to the living space. Compare fan airflow to total supply register airflow to estimate supply duct leakage, and then compare fan airflow to total return grille airflow to estimate return duct leakage.
 
When leakage exists (and it always does), a quick TESP test will let you know if the duct system can handle tightening. If you really want to make things worse, seal leakage on an undersized duct system. As leaks are sealed, TESP will increase as pressure relief from the leaks are removed. TESP is a quick “go/no-go” test for duct sealing that can save you a lot of headaches..
 
DUCT TEMPERATURE GAIN
Your system can have leak-free ducts that deliver the right amount of air and still fail to maintain comfort if duct temperature gain is an issue. Temperature follows a simple rule: hot goes to cold. If the space surrounding the duct system is hotter than air inside the duct system, heat will flow from the surrounding air into the air in the duct system. In an attic installation, it is common in many parts of the country for attic temperatures to reach 130° to 140°F in extreme conditions. Combine that with ducts in the same attic space carrying 55°F conditioned air and you have a recipe for an uncomfortable building. That’s a 75° to 85°F delta t (temperature difference)! Ceilings are often insulated with R-38, while duct insulation tops out at R-8. Something about that just doesn’t seem right. You can measure duct temperature gains with four temperature readings. Make sure the equipment has been running for at least 10 minutes before testing. Start at the air handling equipment and measure supply and return air temperature to determine equipment delta t. Next, measure the farthest supply register and return grille air temperatures to determine worst-case system delta t. To find equipment temperature drop, subtract the equipment entering air temperature from the equipment exiting temperature. To find supply duct temperature gain, subtract the equipment exiting air temperature from the farthest supply register air temperature. To find return duct temperature gain, subtract the farthest return grille air temperature from the equipment entering air temperature. If your duct system is well insulated with minimal leakage, the temperature change of the equipment and supply and return duct system should be close. There will be some differences, but the temperature change across the duct systems shouldn’t be more than 10 percent of the temperature change across the equipment.
 
Let’s say you measured a 20° delta t across the cooling equipment and a 10° delta t across the duct system. That would be a 50 percent duct gain (10° ÷ 20° = 50%)! If your equipment was rated at four tons, it would be the equivalent of a two-ton unit due to duct temperature gain. The most applicable repairs for duct temperature gain are adding duct insulation and sealing duct leakage. Be careful as you choose from various insulation options available. Some insulation types offer high promises but fail to perform in the field.
 
AIRFLOW IMBALANCES
An HVAC system that is perfectly tight should have balanced airflow through the building. Ideally, each room and the entire building should have the correct volume of airflow. When airflow imbalances exist, there is an unequal amount of airflow through the living space. This creates various issues that prevent a system from maintaining comfortable conditions. When return airflow from the living space is greater than supply air, negative pressure occurs. This leads to increased humidity and additional heat brought into the building that must be removed. In many cases, it can add load to system capacity that is already maxed out. When supply airflow into the living space is greater than return air, positive pressure occurs. More supply air is delivered into the space than returned. Conditioned air is pushed outside through any leakage in the building. When this situation happens, it can lead to condensation in building cavities if the dewpoint temperature is high enough.
 
Some of the most common airflow imbalance causes are:
  • Central return grille systems with closed interior doors
  • Air balancing issues
  • Duct leakage
  • Poor duct design and layout.
To discover these imbalances, you need to do a quick pressure test to the outdoors. This requires using a micromanometer and tubing long enough to reach outside, under a door. Turn the HVAC blower to its highest operating speed and watch what happens to building pressure. If it goes negative, there is more air pulled from the space than supplied. If it goes positive, there is more air delivered into the space than returned. The best repair for airflow imbalances is properly sized and sealed ducts equipped with balancing dampers. This repair assures you can contain and balance airflow. Another option with central return grille systems is to use jumper ducts and transfer grilles.
 
BUILDING DEFECTS
Up to this point, every issue discussed is related to the HVAC system. However, don’t forget to look at what contains the HVAC system — the building itself. Air leakage and temperature must be controlled in a building to maintain comfort. If a building leaks air or cannot minimize its temperature gain, you won’t be able to maintain comfortable conditions regardless of how well your HVAC system performs. These defects are hidden from HVAC diagnostics but will directly affect comfort and IAQ.
 
WIDEN YOUR DIAGNOSTICS AND SOLUTIONS
As you can see, dealing with systems that don’t maintain comfortable conditions requires you to look beyond the equipment. Many of these issues extend into the duct system, so airflow knowledge is an important skill to have. Other repairs fall outside the scope of HVAC work and require additional specialized training or trades being involved.
Whatever the cause, you will never discover the source of these hidden problems unless you test. Develop a systematic approach for how to handle comfort complaints when an HVAC system can’t keep up. Start at the equipment, move to the duct system, and then look at the building. I hope this overview points you in the right direction when you’re called on to address a comfort complaint.
 
Source : achrnews. com
 
 

Update to Enbridge Home Energy Program

Enbridge Home Conservation program is offering a limited time promotion. They will offer two packages:
 
Package 1: Receive $1750 + $550 Audit cost (Total $2300):
  1. Furnace/Boiler upgrade
  2. Attic Insulation
  3. Air Sealing
  4. Customer recieve bonus extra $150
Package 2: Receive $750 +$550 Audit cost (Total $1300):
  1. Attic Insulation
  2. Air Sealing
  3. Customer ecieves Bonus Extra $150
Please note:
1-The primary energy audit must be completed on or after September 1st 2019
2-The secondary energy audit must be completed on or before October 31st 2019
3-All paper work must be submitted by November 15th 2019

Tariff relief, or not?

After almost an entire year having to deal with steel and aluminum tariffs, it has come to an end. On May 21, 2018, the Donald Trump administration announced that tariffs would be applied to aluminum at 25 per cent on imports, and 10 per cent for steel imports. This was allowed based on an archaic American law that allowed tariffs to be applied in the case of national security.

In response, the Trudeau government retaliated in tit-for-tat style with their own tariffs on American imports. Manufacturers that buy Canadian steel but manufacture in the U.S. would be hit twice when shipping back products to Canada. Some companies lost a substantial amount of money resulting from the tariffs and were forced to absorb the cost. Some water heaters fall into this category.

At first glance, now that these tariffs have been repealed, I had originally thought that everything would go back to the way it was before Trump introduced them. But from the conversations that I’ve had with industry people, this isn’t exactly the case. Yes, there was relief felt in the industry since the tariffs have been removed. But during the era of American/Canadian steel and aluminum tariffs, steel costs increased, and this hasn’t changed either since the tariffs were repealed. “Things are not back to the way things were before because when the tariffs were imposed it caused the steel prices in the U.S. to increase… One of the impressions was that when the tariff came off the full 10 per cent that was imposed would come off. It can’t because in the middle of that period we had a price increase which is still there,” reported Paul MacDonald, president of Bradford White Canada, Halton Hills, Ont.

The tariffs allowed an opening in the market for tankless water heaters, resulting in a sales boost. The industry has balanced itself out again. But during the time of the tariffs, manufacturers were unfairly impacted if they were in Canada or the United States and rather favoured manufacturing in Mexico.

Whether or not the industry will ever go back to how it was remains to be seen. But at least for the short-term, prices will likely remain higher as a result of the tariffs.

 

Source :plumbingandhvac .ca/

Federal government support for small and medium sized business

Federal Minister of Environment and Climate Change Catherine McKenna yesterday announced two new proposed programs that will help owners of small and medium-sized businesses be more energy-efficient, save money, and take action to reduce pollution.
Under the Climate Action Incentive Fund (CAIF), small and medium-sized businesses (e.g. restaurant owners, farmers, truck drivers, convenience and small grocery store owners) in Saskatchewan, Manitoba, Ontario and New Brunswick -- the four provinces where the federal price on pollution, (a.k.a. Carbon Tax) applies -- will be able to apply for:
•    Refunds between 25% and 50% on the cost of new energy-saving equipment such as appliances, which could include fridges, dishwashers, heating and cooling equipment, anti-idling devices and high efficiency boilers;
•    Funding of up to 25% of eligible costs for energy-efficient retrofits and other projects to improve energy efficiency, reduce their energy use and save money.

The Minister plans to release details about the CAIF Rebate program in the next few weeks but it is expected that the rebate will be limited to a maximum amount of $20,000 per applicant, with no minimum amount per application. In addition, the Government will soon open up a new call for proposals for smaller projects from small and medium-sized businesses across the country under the Low Carbon Economy Fund Partnerships stream. Approximately $10 million will be available to help those businesses make investments to improve energy efficiency, reduce pollution and save money. This program will offer more options to smaller business by allowing applicants to propose smaller projects and to bundle similar projects together. Funding levels will range between $20,000 and $250,000. Small- and medium-sized businesses in all sectors and in all provinces and territories will be eligible to apply to the fund, which will be open for applications in the coming weeks.  

These programs are subject to Royal Assent of the Budget Implementation Act and subsequent decisions from the Minister of Finance. When the Government of Canada announced details of its carbon pollution pricing system in October, the plan included a provision that for the provinces where the carbon tax would apply, proceeds would be returned to the jurisdictions in which they are collected. In provinces that have either requested the federal system or have not proposed a system that meets the federal standard (currently Manitoba, New Brunswick, Ontario and Saskatchewan), 90 percent of proceeds from the carbon tax will be returned directly to individuals and households through Climate Action Incentive payments when they file their tax returns. The remainder of the revenues (10%) is earmarked to be deployed to support small and medium-sized businesses, municipalities, universities, colleges, schools, hospitals, not-for-profit organizations and Indigenous peoples through the Climate Action Incentive Fund (CAIF).

Funds available through the CAIF for small- and medium-sized businesses in 2019-20 will come to about $150 million, based on the percentage of revenue collected within each province:  
•    $13 million in Manitoba
•    $5 million in New Brunswick
•    $102 million in Ontario
•    $30 million in Saskatchewan

Under the program plan, it is expected that between 2019 and 2024 nearly $1.5 billion will be available to support energy efficiency efforts by small- and-medium-sized businesses. These funds would be in addition to tax benefits from the Accelerated Capital Cost Allowance changes [see previous story on this] announced in 2018.
Environment and Climate Change Canada plans to establish an External Advisory Committee for the Climate Action Incentive Fund, made up of experts and representatives of business associations, to provide advice on outreach to small- and medium-sized businesses and continuous improvements to the delivery of funds. HRAI is in discussions with the Minister’s office on how the HVACR sector can be properly represented.

Summer Heat and Health in Canada

An estimated 70 deaths have been connected to the scorching temperatures and humidity that rolled over Canada's Quebec province last week, and officials say the number may rise as hospital and nursing home records are reviewed. Most of the people who died as the region reached temperatures up to 95 degrees are elderly men and women living alone in apartments with no air conditioning, and many had chronic health conditions.
David Kaiser, a physician manager at the Montreal Regional Department of Public Health, confirmed to NPR that 34 of the deaths occurred in the city from June 29 through July 7. With few exceptions, he said, the people were over the age of 50, many between 65 to 85. About 60 percent were men and most had an underlying medical or mental health condition, Kaiser added. He explained the death toll has continued to rise despite a return to more normal seasonal temperatures, as the public health department continues to collect data from a variety of sources. Officials plan to issue an updated report next week. And now that the immediate crisis is over, the department will soon embark on an even deeper dive into the records of every person who died during the eight-day window, including coroner reports and medical charts, a Montreal public health spokesman told NPR.
"We do this because it's always possible that we may have missed someone who maybe didn't die of heatstroke but died due to heat-related complications ... those can be hard to tell sometimes," Kaiser said.
It is a practice that was implemented after Montreal's 2010 heat wave that left 106 people dead. In that case, authorities discovered a handful heat-related hospital deaths that had previously gone unreported, Kaiser recalled. Paul Brunet, president of the Council for the Protection of the Sick, a patient advocacy group, called for an independent investigation into the abrupt deaths of all people who recently died in a hospital, public nursing home or a public long-term care residential facility known as a CHSLD.
"Some figures that we have had in recent years do not always correspond to reality," Paul Brunet explained in an interview with LCN on Saturday.
In a statement issued on Monday, Brunet said he plans to file a class-action lawsuit against the publicly run CHSLD network over "the marked deterioration in the care and services that are offered in these facilities" — specifically the absence of air conditioning units in individual rooms. A spokesman for Montreal's public health department told NPR none of the victims had died in public health care institutions. Annick Lavoie, Executive Director of the Association of Private Convention Institutions, called Brunet's suggestion that patients are receiving inadequate care "horrific."
"The heat wave we knew hit the entire population hard. Why does Mr. Brunet really want to create the scandal where there is none?" she wrote in a statement, calling the allegations "dangerous." "He sows suspicion with the public rather than emphasizing the hard work done by staff and volunteers," the statement said.
CTV News channel reported patients in some Montreal hospitals were in rooms without air conditioning, upsetting their families. Kaiser told NPR that public policy changed after the 2010 heat wave. During periods of extreme heat, government-run health care facilities are required to provide an air-conditioned common area that is kept cool 24 hours a day.
Brunet argued that is not enough. Especially not while nursing home administrators work in air-conditioned offices, The Montreal Gazette reported. "Don't tell me you don't have the money to put air conditioners in patients' rooms. These are facilities where people live, and these should be decent living conditions," Brunet said.

Source : npr .org

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