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  • Writer's pictureThe Belcore Team

Relining Gas Chimneys for a Furnace or Water Heater. Do I Need to Reline My Chimney

In short - potentially.

So you've upgraded your furnace or water heater and your mechanical contractor says that 'you will need to re-size your gas chimney to adhere to the gas code'.

And you're thinking.....I've never heard of this. You're not the only one, as the Natural Gas and Propane codes are updated, licensed professionals are regulated to ensure that the appliance adheres to the codes and standards that are enforced to date. This may mean what was working yesterday may not pass an inspection tomorrow if the appliance and parts involved in the system are not up to code.

To be technical:

"AS OF DEC 1, 2018 - The Office of the Fire Commissioner (OFC) has recently changed their enforcement of the code eliminating the allowance of a one-size variance in chimney size for your gas appliances to your home chimney.

The proper sizing of the gas appliance can be referenced through (1) the appliance's manual which often refers to (2) the CSA B149.1 15 - Natural Gas and Propane Installation Code."

How does that affect you?

If your home has a gas hot water tank and a gas furnace, your chimney was designed and sized to accommodate both of those gas appliances to operate in one chimney.

When converting a hot water tank from gas to electric or upgrading your furnace to high efficiency you will change the capacity of your home’s chimney, making it too large for only one gas appliance.

When you take one of these gas appliances away from the chimney, the new code enforcement could require you to install a chimney liner to downsize the chimney to the correct size.

Carbon Monoxide and Gas Chimneys

Gas chimneys need to be reliable, yet alone function properly as dangerous fumes can easily spill back into your living spaces.

Carbon monoxide is one of the toxic incomplete combustion byproducts. When exposed to it, the consequences can be deadly.

If you’re replacing or upgrading your furnace or water heater, you might be asking yourself if you should go even further. Should I be replacing the chimney’s liner to your new appliance?

When to Replace a Chimney Liner

When a new furnace or water heater is installed may be a mandatory time to replace your chimney with the correctly sized chimney liner.

This may not be the only time you should replace your chimney. If you see deterioration, cracking, back-drafting, or ice build-up on your chimney cap this would be a great time to talk to a chimney professional about the options to correctly address your chimney problems, which may be installing a chimney liner.

New Appliance - New Liner Possibility

Over the lifespan of your furnace or water heater, you may have to upgrade your chimney and the ventilation of the appliance.

For your appliance to vent properly, the ventilation and chimney must be small enough to keep the draft warm and large enough to expel the exhaust properly. A chimney or gas technician will be able to correctly size the ventilation and chimney following the CSA Gas and Propane Code.

If you have hired a mechanical contractor (HVAC or Plumber) to install your new appliance, they may have only quoted the cost of the new appliance and not included the cost of the liner that needs to be outfitted for it to draft and protect your home against these toxic fumes.

Be sure to ask if your new gas appliance needs its ventilation or chimney resized because it isn’t always done, despite the fact that you may need one.

If a chimney is not properly sized for the appliance, an inspection must follow all gas permits that have been pulled, and the inspector will let you and the mechanical contractor know that the chimney must be re-sized within 30 days.

Trust the Professionals

At Belcore, we're dedicated to ensuring that your chimney and ventilation are up to code and safe after any project.

Book an inspection or chimney liner installation by contacting us today.

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