How To Keep that Chimney Safe
in a High Performance World
Annual maintenance of your gas or oil furnace is a must for a
safe and efficient combustion
Venting systems are designed to properly, reliably and safely
vent products of combustion to the outdoors. Yet homeowners give
little thought to the chimney or venting system, it's condition,
performance, and safety to themselves and their families. This
is a mistake, say experts.
"These types of appliances should never be installed and forgotten
about," says Brian Baker, President of Custom
Vac Limited a Heating, Ventilation, and Air Conditioning (HVAC)
Contractor serving Manitoba residents.
The majority of problems found by Technicians are directly related
and a result of poor maintenance. Chimneys, venting systems and
appliances should be cleaned and inspected every year. It is the
Homeowners responsibility to make sure that this happens. Good
Contractors such as Custom Vac offer customers an annual appliance
maintenance mailing card program. A friendly reminder that says,
"it's time again to have the inspection and cleaning preformed
on your appliance". "Today with parents both working, everyone
is time poor we realized educating and reminding homeowners was
the first step, " said Baker.
Attention to Detail is Vital
Proper installation is the key to ensure safe, reliable operation
of the chimney, venting system and appliance. "The devil is in
the details," says Baker. "Even the most minor thing, not done
right, can result in disaster."
Some Homeowners take it upon themselves to replace a chimney,
chimney liner or venting to a furnace, fireplace, water heater,
etc., thinking that this is an easy way to save some money. The
problem is, homeowners are not properly trained. Understanding
the basic principals of combustion venting, appliance application,
National and Provincial codes and material standards take years
for most competent tradespersons to understand. Code changes regarding
the venting of combustion products have been the single largest
section to be revised in the last 10 years. This is an area that
I would recommend a Homeowner leave to the professional Contractor.
Problems that Technicians find on the do-it-yourself jobs:
- Incorrect sizing (Oversized & Undersized)
- Improper selection of materials
- Improper installation of liner and venting
- Too long venting length
- Failure to seal the chimney chase or close in chimney
- No access for inspection of the chimney
- Failure to properly attach and support the venting system
Energy Efficiency and Depressurization
Today's new appliances are so efficient that it is a battle to
get enough heat into the chimney and venting system. A good rule
of thumb is, the more efficient the appliance, the less temperature
that will be generated. This is where the task of knowing what
to do and how to do it comes in. This whole principle of heat
rising has been changed somewhat. The temperature of the combustion
gases in many cases can fall below (dew point) the point of condensing.
"Not only do you get condensation and acid formation that deteriorates
the venting materials, but, the serious potential for back drafting
of combustion products into the home" says Baker.
Homes built in Manitoba are among the tightest homes built, not
just in recent years, but even back 50 years ago. Adequate air
for combustion and house depressurization
is the single greatest concern when dealing with combustion vented
appliances. Homes must strike out a balance of being tight (energy
efficient), yet still having sufficient combustion air to ensure
proper combustion. This means possibly having to introducing combustion
air directly to the appliances to meet code. Symptoms of insufficient
combustion include a poorly tuned and operating appliance, condensation
on windows, household plants that don't grow well, etc. The most
serious and the one that gets the attention of the media when
it happens is Carbon Monoxide (CO).
New products are being developed to assist Contractors the Selkirk
Inc. model DWC flexible double wall insulated flexible vent connector
that minimizes temperature loss. Another item may be relocating
the appliance to reduce venting length. When converting an appliance
from one energy source to another as with oil to gas, one item
that gets overlooked is the cleaning of the existing chimney prior
to a new approved liner being installed. It is very important
that the chimney be cleaned first because fuel oil is very high
in sulphur (S) so, when mixed with a small amount of moisture
(water H20) sulphuric acid is formed destroying an aluminum liner
in a very short time. This is the reason why fuel oil chimneys
are made of stainless steel and not aluminum.
Choosing the Right Appliances for Peak Efficiency
"One of the biggest problems that we face is Contractors over-sizing
of appliances," said Baker. The result is poor venting performance,
loss of comfort and loss of appliance efficiency. If I were to
ask a homeowner to look at three of the same cars and tell me
to match up which car gave 25 miles per gallon (MPG), 21 MPG and
33MPG. Could they guess them right? Maybe. Now, if they were able
to have someone tell them the condition and efficiency of each
car, would they still pick the car with 21MPG knowing the price
of fuel to keep it running? I don't think so!
Unfortunately Homeowners every day buy appliances from Contractors
who have little regard for their comfort, equipment and energy
costs. Why? Most Homeowners don't know that proper equipment sizing
can have such negative effects on them. "The Federal Government,
"Office of Energy Efficiency" has a program called EnerGuide for
Houses that Custom Vac is participating in," said Baker. This
is not the only method of determining equipment size or air leakage
rates within houses. "It is however, according to Baker the most
sophisticated and scientific method approved in use today that
takes into consideration the entire building envelope and what
is going on within that envelope." A full report detailing what
energy efficiency upgrades can be done to reduce air leakage,
and energy costs, etc. is generated for the Homeowner after the
approximate 3-hour in-home evaluation by a trained Energy Evaluator.
In addition, booklets and materials that offer educational information
are also left.
Early results show that homes in Manitoba are very tight and that
most home are experiencing some level of depressurization of the
building envelope. These results prove that no one can guess any
more about the need for combustion air, ventilation air, chimney
size, appliance size, etc. The program is also noting that some
home built in the 1950's are as tight today as new homes. This
is why just looking at the car to determine MPG we cannot just
look at a home and say "yes" we a need 6" combustion air duct
and/or 5" ventilation duct connected to the return air duct from
outside. Baker admits, "We used the rules of thumb and tips that
we learned on-the-job and through educational and trades training,
but, like everything times change and we have had to change. Things
that we did as little as 3 years ago are lo longer being done
due to better research and testing."
The tools are here today that enable us to help homeowners make
better-educated decisions regarding their home and appliances.
Homeowners need to ask their Contractor why he is guessing and
not using the technology that is available?
