Chimney Relining & Liner Repair in Snowflake, AZ

The Farmhouse Chimney That Serves Two Things at Once

Snowflake's older housing was built around a single central masonry stack, and a century ago that stack routinely took more than one appliance - a wood cooking range on one floor and a heater on another, both breaking into the same flue. Nobody thought it was a problem, because with a range and a stove burning at similar times and a house that leaked air everywhere, mostly it was not.

The arrangement is still in service in that part of the county, except now the appliances are different. We regularly open chimneys with a modern airtight wood stove and a gas water heater or furnace connected into one flue, sometimes with the second connection buried behind drywall and unknown to the current owner.

Why It Has to Be Separated

Two appliances on one flue compete. Whichever draws harder wins, and the other one spills its exhaust into the house instead. With a wood stove and a gas appliance sharing, the wood stove wins almost every time once it is up to temperature - which means the gas appliance is discharging combustion products into a basement or utility room while the stove runs beautifully upstairs. It is invisible, it has no smell worth noticing, and carbon monoxide is the product.

There is a second, slower problem. Gas exhaust is wet and comparatively cool. Run it up an old masonry flue sized for wood and it condenses on the brick, and the condensate carries sulphur compounds that break down lime mortar from the inside. A century-old flue treated this way deteriorates far faster than one taking wood alone.

What the Fix Looks Like

Either two separate liners in the one stack where the cross-section allows it, or one liner for the appliance that stays and a proper alternative vent for the other - a direct-vent or power-vent arrangement for a gas appliance is usually cheaper than fighting for space in a chimney that does not have it.

What we will not do is sweep it, say nothing, and come back next year. If we find two appliances on one flue in a Snowflake house we will show you the connections and explain the options, and if you decide to leave it we would ask you to at least put a carbon monoxide alarm on that level first. That advice costs us the job and we give it anyway.

Where the stack itself is sound and it is only a sizing question, this is a straightforward job. Where the brick has had a hundred and forty years of weather, it turns into a conversation about the masonry too - see crown and masonry work in Snowflake for that side of it.

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