“They said my chimney was blocked and shut off the hot water!” At A1 Chimney we get many calls to this effect every day. The funny thing is, it is about 95% of the time an incorrect assessment.
This assessment is made when a gas technician services a hot water tank and then turns it on and immediately checks for carbon monoxide and notices that this is a bit high. He says, “The chimney must be blocked.”
Using the chimney to vent your gas appliances is becoming much more rare. With high-efficiency furnaces and power vents (fan on top) and on-demand water heaters being the more common installation. Hot water tank technology hasn’t changed much though.
Higher Levels of Carbon Monoxide
On the top of the hot water tank is kind of an upside-down funnel (called a draft hood). This catches the hot exhaust from the water heater and leads into the chimney. There are many reasons for this “spilling” carbon monoxide:
- There is low pressure in the basement causing the chimney to “want” to suck air downwards rather than vent upwards. TIP: You can check this by putting your hand or a match under the funnel to see if air is pushing out into the basement.
- There is now a high-efficiency furnace, and the liner for the old furnace is still in the chimney. This can create a double problem as the new high-efficiency furnace is drawing MORE air from the room where the hot water tank is (creating a lower pressure as in above); and secondly, the hot air from the hot water tank is venting to too large a space and doesn’t flow very well.
- The chimney is blocked or the liner is broken.If it is a problem as in 1 or 2 above, opening a window in (or near) the furnace room will relieve that low pressure and allow the hot air to flow upward. Test it, as in 1 above. In addition to this, if the liner is too big, you should consider getting a smaller one or replacing the hot water tank.
If the problem is actually a blockage, then we can help! Call A1 Chimney at (416) 231-6560 or reach out to us online. Our turnaround time is usually very fast!
