Archive for the ‘air conditioning’ category

Quick Tip #35 – A Ton of Cooling

October 16th, 2014

Ever hear of a two- or three-ton central air conditioner? Does that mean a two-ton air conditioner weighs 4,000 pounds? Is the term related to cooling capacity, or is it a random term that tech folks use to impress us?

When engineer Joe Cool (at least I think “cool” was part of his name ) developed the standards for measuring mechanical cooling, ice was commonly used for cooling. You know, in the old days, food was stored in the ice cooler, and there was no air conditioning. So Joe decided that the cooling capacity measurement should relate to ice.

A standard was set equating one “ton” of cooling to the amount of energy needed to melt one ton (2,000 lbs.) of ice over a 24-hour period. For tech folks: the exact figure is 12,000 btu per hour.

So what is a btu? It stands for British thermal unit, and we will cover that detail in another tip. Just remember: one ton of cooling equals melting one ton of ice in 24 hours – 12,000 btu per hour.

To put it another way, the change of phase from ice to water requires 144 btu per pound or 288,000 btu per 2,000 pounds.

A047C - A Ton Of Cooling_300dpi

Quick Tip #5 – Save Money with a Filter Change

March 10th, 2014

H009Maintaining the filter on your air conditioning and heating equipment isn’t fun or glamorous. So why bother? Because a clean filter allows for proper air flow, and that makes the equipment run efficiently, saving you money. Also, a clean filter helps your system perform better, so your home environment will feel more comfortable.

And because a dirty filter restricts air flow and can make a heating unit overheat or an A/C unit freeze up, maintaining the filter helps you avoid a service call.

Filters come in various types, so take a look at your equipment. If you have a cleanable filter, note on your calendar when cleaning is due. Otherwise, buy an appropriate replacement filter to have on hand when you need it. Filters are inexpensive and should be changed or cleaned when they are visibly dirty. When you do change the filter, note the directional arrows on the side. Place the filter so that the arrows point in the direction of air flow.

By Tom Feiza, Mr. Fix-It

Quick Tip #4 – One Cold Room

February 21st, 2014

H020Does your home have one room that’s always cold? Is there very little air flow from the heating grill, even when it is fully open? The culprit may be a heating supply duct that’s been closed.

In the basement, find the main warm-air supply duct, which originates directly above the furnace. Often this is a rectangular duct running down the center of the basement. It may branch off into smaller circular ducts serving individual room registers.

Where the round duct attaches to the rectangular main, look for evidence of a duct damper: a wing nut around the end of a quarter-inch threaded rod. At the end of the rod, you’ll see a screwdriver slot.

If this slot is perpendicular to the small round duct, the damper is closed. If the slot is parallel to the duct, the damper is open. You can loosen the wing nut and change the position of the damper. Then secure it by retightening the wing nut.

If opening the damper solves the problem, great. If the room is still cold, you may need to partially close other dampers to direct more air to the cold room. Often, dampers fit loosely, and even when fully closed, they can leak lots of air.

By Tom Feiza, Mr. Fix-It

Insulating Hot Air Ducts – Energy Saver???

April 30th, 2013

QUESTION:

Does it save energy to insulate hot air ducts in the basement? I have long runs of ductwork,  and work in the basement often.

-DAVE

ANSWER:

Insulating the heating ducts saves very little energy in a home with a full basement, and the heat ducts in the basement space. Essentially, the basement is within the heated space of your home. The answer would be different if the ductwork was outside the heated space (e.g. the attic).

I would be concerned with any major air leaks in the ductwork – those should be sealed or caulked so the heated air moves to the correct area of your home. With most full basements, a heated space above, and some ductwork leaks or supply vents keeps the basement a few degrees below the heated space. Allowing some heated air to leak helps heat the basement, and tempers the air below the fully heated space – not a bad thing.

 

I026 - Foam Insulation_Seal Box Sill

 

For energy-saving and comfort, look at insulating/sealing the area above the basement wall, up to the sub-floor. That area is a potential for a huge heat/air loss to the outside. The best insulation and sealing here would be a spray foam, from the top of the basement wall to the sub-floor (if it is allowed by local code officials). Also, check the basement windows – are they efficient?

–MR. FIX-IT

More Insulation … More Savings?

March 1st, 2013

QUESTION

I am building a commercial building with a rubberized flat roof. I want to go to R45 insulation on the roof, but my friends say that after R23 you don’t see a return on your investment. Is that true?

Also, what is the best way to insulate the walls of a commercial building? What is more efficient – an exterior HVAC system, or an interior in a basement? I am looking to save cost for natural gas, so any advice would be greatly appreciated.

PAUL

ANSWER

I009 - Insulation – Diminishing ReturnIn most cases, an insulation value of R38 is recommended for roof or attic insulation in residential and commercial construction for northern climates. But, the insulation will also depend on the usage of the building, and how warm it will be kept. The wall insulation is dependent on the type of construction and finishes.

A heating, ventilation and air conditioning system is always more efficient if you can keep the complete system (and the ductwork) inside the building’s conditioned air space. Units are much easier to service if they are in the space, and if duct leaks occur, they will leak into the space. Roof-mounted units are often used to save interior space, but are never as efficient.

Contact the folks at Focus on Energy. Check their programs for energy efficient construction. They are residential and commercial experts who have lots of experience with saving energy. They also have rebate programs for energy efficient construction. With our economy, and the increasing cost of energy, it will be a good payback to build an efficient building.

MR. FIX-IT

Distributing Humid Air via A/C Blower

January 18th, 2010

Question:

I live in a 1200-square-foot condo that has radiant heat and an A/C blower located in the foyer. The A/C fan ducts are v-shape, no longer than 15ft, and go to the master bedroom, a second bedroom, the kitchen, and the great room.

Now that the air is more dry, if I place a humidifier in the foyer will it go up the air intake of my fan blower, thus sending the humid air to other areas in the condo?

The air intake is 36″ x 48″ and requires a filter. Can the humid air pass through the filter? Will it gum up the filters and/or cause other problems?

Jeff

Answer:

Humidity or moisture in the air moves at about 5 mph due to vapor pressure. You can place a humidifier anywhere in your unit – as long as the doors are open, it will move throughout the unit without the fan. If you choose to run the fan (without the A/C I assume) it will move the air quicker.

Tom