Archive for the ‘air infiltration’ category

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

Insulation Near a Fireplace?

December 17th, 2013

Question:

Can I insulate the underside of my first-floor fireplace chase? I would like to put batt-insulation, and a ceiling below the fireplace. I currently use the area as a storage closet. The area is very cold, and the air seems to migrate upstairs. I also get frost above the basement wall, on the framing. The fireplace is ~20 years old, and non-gas.

–Eric

Answer:

You’ll need to check on the installation requirements for your specific type of pre-fabricated fireplace. They must be installed per specific installation requirements. In general, they require clearance around the metal firebox, and around the metal flue that is routed up through the boxed-in chimney chase. I don’t think your real problem is in the basement. I think the real problem is the exterior wall behind the fireplace. Insulating below the floor will be of little value.

The areas around the fireplace can be a big heat-loss, because the outside wall behind the fireplace may not be properly insulated. The exterior wall should be framed so that it can be insulated and sealed like a typical exterior wall. This does not always happen when the wall is buried behind a manufactured fireplace, and brick facing.

F007 - Metal-Framed Prefabricated FireplaceThe area below the fireplace (above the foundation wall) should be independent from the fireplace installation. Ice in this area (and around the sill/band joist) occurs because air moves through the fiberglass batts, and moisture condenses on the cold surface.

The ideal fix at the top of the foundation wall is to have the area sealed and insulated with spray foam. This will seal the air-leaks, provide a vapor-barrier, and insulate the area.

If you want to work with fiberglass, you need to remove it and caulk any gaps in the area around the sill-plate to the sub-floor. Fill the space with tight-fitting fiberglass, then seal it with drywall and plastic caulked in place on the heated side. It sounds like the foam is a much better option.

–Mr. Fix-It

Leaks Coming From the Attic

November 18th, 2013

Question:

I have frost in the attic of my five-year old, two-story house. I noticed a small leak coming out of the can light in the bathroom. Do I have enough insulation in my attic? I have 2″ x 4″ ceiling rafters, with ~16 inches of blown-in white insulation. I also have a ridge-vent running along the peak. Could heat be exiting through the attic door, exhaust vents, or can light, then melting the frost?

–Kevin

Answer:

Most folks who study moisture and home systems would identify your issue as an air-leak problem into the attic. Warm, moist air from the heated space is escaping into the attic, and moisture from that air is condensing on the cold roof deck. This may show as ice in very cold weather, and water in warmer weather. The problem is not insulation.

 

I025 - Air Leaks - Top of Wall

You need to search for air leaks at can lights, plumbing, electrical penetrations, chimneys, trap doors, etc. Seal up the air leaks, and the problem will be solved. Sounds easy? It’s not. You need an experienced contractor, who knows how to locate and seal the leaks. However, stopping theair leaks will save lots of energy.

I suspect you saw the leak at the can light because the light heat was melting the frost. The plastic vapor barrier is also open at the can light. If you want more information on attic insulation and air sealing, read my article Insulate Your Attic – But Don’t Stop There!

–Mr. Fix-It

Energy Savings in Window Replacement

June 7th, 2013

QUESTION:

I have an old farm house with some updates. The first floor has double-pane windows (15+ years old), and the upstairs has old single-pane windows. We replaced 11 windows with Energy Star-rated windows. I reviewed my energy use, and found that it did not decrease at all. Could I have been sold bogus Energy-Star windows?

–STU

ANSWER:

Evaluating any energy improvement in a home is difficult. You need to compare energy use based on similar heating degree days. Degree days take into account the dramatic variations in temperatures. But you also need to consider wind, interior temperatures, heating plant performance, air leaks, ventilation, use of fireplaces, and other variables.

New, Energy-Star rated windows with thermally insulated glass will normally perform better than old wood windows. If they are rated and certified, the window should not be an issue. But on-site installation and air sealing is a key detail affecting the window and wall system performance.

If your old single glazed windows were tight fitting and you had tight fitting wood storms, the actual change in the heat transfer through the new windows will not have a large effect on your energy usage. The replacements just don’t save much money if the original windows were in pretty good shape.

If you were given some type of guarantee or promise from the window installation company, I suggest you contact them with your concerns and read all the claims and fine print.

In my mind, the biggest reason to replace old damaged wood windows is lower maintenance, ease of operation, appearance, comfort, and finally energy savings.

–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

Insulating Value: Old Cedar Siding vs. New Cement Board

February 18th, 2013

QUESTION:

Last summer, we had our 50-year old cedar siding replaced with fiber cement. They did a good job of caulking around all the windows, however, I am wondering about the insulating properties. I asked to have insulation added, but was talked out of it. They said adding insulation was inconsequential, and not worth the cost. Do you think there is a significant difference in insulating properties between cedar and fiber cement? Our gas bill for period ending Dec ’11 used 60% more therms than last year with 8-degree average lower outside temperature. We did set our thermostat one degree higher.

RALPH

ANSWER:

I023 - Heating Cost vs. R Value - Cold ClimateAs far as insulating value, old cedar siding or new cement board siding would be about equal. It is likely the newer siding provides a little better seal against air infiltration.

The best way to install the cement board siding is to remove the old siding down to the studs and then add a rigid foam board insulation. The joints can be taped, and a house wrap can be added to further limit air infiltration. This allows the siding to be securely fastened to a flat surface and allows more options when working around the windows and doors.

The rigid board insulation does add significantly to the insulation of the exterior wall. I suggest using a 1-inch thick panel of rigid foam. This adds an R-Value of about 5 or 7 and insulates over the edges of all the wall framing studs. The edges of the studs are about 25% of the surface of the exterior wall. Without the foam, they have no insulation.

It sounds like you gas bill is about normal given the very cold and windy weather we have had this winter. Just switching from cedar to cement board should have no impact.

MR. FIX-IT

Frost on One Side of Garage

February 17th, 2013

QUESTION:

We have a new home. With the cold, windy weather, we have noticed frost on the screw heads in the drywall garage ceiling edge. This issue is on the north side; none of the other walls have this problem. The garage is unheated, and the walls/ceiling are insulated. There is also a vapor barrier over the insulation. My husband says cold air is coming through the outside soffit, and there is no way to insulate this. There is also an electrical switch with frost on the screw heads on that wall. What can we do? Should we be concerned?

SHARON

ANSWER:

I014 - Air Bypass at Insulation - OverhangThe problem is caused because the screw heads are colder than the dew point temperature in the garage. In fact, the screw heads are below freezing so the moisture condenses and freezes. You have two solutions – raise the temperature of the screws or reduce the relative humidity in the garage.

Assuming you don’t want to raise the temperature in the garage, you can try to raise the temperature of the screws. I think your husband is correct – cold air is leaking into this wall area, either at penetrations, gaps, or through the roof venting. The cold air blows in and cools the wall.

For the attic venting, you should check above the soffit vents and make sure there are air chutes that direct the ventilation air over the insulation. If it blows into the side of the insulation, it will chill the wall. At times the best solution is to seal the air chute from the top of the wall to the roof deck with spray foam insulation. You want the air flowing over the insulation.

You should also look for any exterior gaps that may need sealing – perhaps around light fixtures, at the lower edge of the siding and around windows and doors. Any penetration in the wall and house wrap is suspect.

You could heat the garage; that would solve the problem, but I don’t suggest that. Lowering the relative humidity in the garage is virtually impossible, however you could sweep out snow and ice that may drop off your car.

MR. FIX-IT

Infrared Quartz Heaters

February 12th, 2013

QUESTION:

What are your feelings about infrared quartz heaters? Which brands have you tested? I have one and it seems to provide all the energy representations made. Is it true that this technology was developed for the space station and utilized in the space shuttles?

BILL

ANSWER:

I have never tested any of the electrical heaters or quartz heaters and can’t comment on any specific brand. But wow, there seems to be a lot of marketing for electrical space heaters these days. I am an engineer who studied some of that thermodynamics and heat transfer stuff in college. If the claims are too good to be true, they are not true.

The fact is, you can’t create or destroy energy; you can just change it from one form to another. Electricity has just so many BTUs per kilowatt hour. You can convert electricity to heat with a cheap electrical resistance heater, a light bulb, or an electrical burner on the stove with the same result and always the same amount of energy.

Because we are all trying to save energy and money, all the marketing for the new space age or high tech electrical heaters sounds great; and we want it to work. But it can’t defy the laws of physics. Any type electrical heater will provide the same amount of energy for the amount of electricity used.

MR. FIX-IT

Furnace fan, to distribute heat throughout the house?

January 31st, 2013

Question:

I have a two-story house with a basement, built in 1952. Is it a good idea to turn the furnace fan on, to distribute the heat throughout the house?

– Marian

Answer:

H014 - Warm Air Furnace Fan and MotorYes and no. If you have a problem with a cool area when heating or a warm area when running the air conditioning, operating the fan continuously will even out the temperatures in your home. The downside is this will cost electrical energy to run the fan and cause some wear and tear on the fan. However, you can run a fan on a newer, high efficiency forced air furnace with an ECM or variable speed motor for little cost – about 1/10 the cost of a typical fan motor. Finally, I think your first step is to have a contractor inspect and adjust your system. At times, duct dampers can be adjusted to correct cold spots and air flow problems. Often you need to make a spring and fall damper adjustment for a two story home.

– Mr. Fix-It