Woke up. Blower running, but no heat. Cr@p
Turn thermostat off, wait, turn back on.
combustion blower runs, but no ignition.
Try several times.
Gas seems OK, water heater has pilot light.
Light up the fireplace to get some heat going. 53F
Later, tried power cycling the furnace main.
Furnace ignites. Heat back on around 8am.
Air King will still come out to inspect what can cause this fault.
============
OK root cause analysis: air intake clogged with ice crystals.
Technician said under very rare conditions, only when it is extremely cold for 3+ days, when the wind is right, the exhaust moisture freezes into crystals and gets sucked back in at the inlet.
Has to be kind of calm, tiniest crystals floating over in the right direction, getting sucked into the air inlet side. Regular snow is too large and heavy to get sucked in.
There is some kind of pressure sensor that knows when flow is blocked, cutting out the burners.
Like now, they might get 5 of these per week out of 100 service calls. fairly rare, but not unknown. Only happens when extremely cold.
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Yesterday morning my 1 year old hi efficiency gas furnace would not fire.
ReplyDeleteThe problem was easy to find and fix. The air intake was plugged with frost
(ice crystals). It would appear that some freak condition caused it to suck
in its own exhaust which condensed and plugged the intake. A call to the
service technician informed me that this problem is rare but can occur
under the right conditions of temperature, wind, humidity, etc, etc. He said
it may never happen again but that I should always be wary of it. I don't
think that there is a problem with the installation as there is about
eighteen inches of separation between intake and outlet.
The technician's explanation makes sense to me but I still think that there
may be something else I can do to prevent this from happening again? I am
going away for a weekend in February and don't want my house to freeze.
Do you have any ideas ?
Note: The furnace keeps cozy a house in Northern Ontario where it has been
bitter cold with temps approaching minus 40. It was also quite frosty the
morning this problem occured. Also, this installation ran trouble free all
of last winter.
http://www.homegardenguides.com/garden-forum/home-repairs-forum/66640-gas-furnace-intake-freezup-problem.html
Venting & Draining Condensing Gas
ReplyDeleteany door, window or gravity air inlet into a building. ... This also keeps large ice build ups from forming on the ... The installation instructions will give you crystal clear instruction on where you must make your ...
http://www.totalairsupply.com/files/9%20November%2007%20Venting%20&%20Draining%20Condensing%20Furnaces.pdf
http://www.google.com/search?q=furnace+intake+clogged+with+ice
ReplyDeleteSome heating units have air intake and exhaust pipes near each other on the outside. The warm, humid air passing the intake pipe condenses and freezes during extreme cold. Hot water can be poured on intake pipe or blow dryer used to heat and thaw the pipe. And electric heat tape may be helpful.
ReplyDelete