For furnace problems related to safety, reliability and potentially
expensive repairs (without any assurance that the problem will definitely be
solved - called guesswork), it's best to get diagnostic information directly
frm the manufacturer. Try contacting a Trane National Service Manager.. it's
his/her responsibility to take care of problems like yours.
Dealers don't always have the latest technical information.

On the topic of surges and spikes on the line.. if there are any other
motorized or high current appliances (such as a freezer) on the same circuit
as the furnace, this can cause line voltage lags and spikes as it cycles
on/off.

A furnace with a microprocessor controller should have some (maybe minimal)
protection from line voltage problems.
If it was certain that voltage spikes were the cause, individual suppressors
could be installed across the line-ground (and neutral-ground) connections
where the AC voltage enters the furnace.
These are small inexpensive devices with 2 leads that can be wired into the
furnace's power terminals. These are the same supressors found in most surge
supressor power strips.

WB
................

"Laurie Forbes" wrote in message
...
This group is knowledgeable about so many topics I though I'd ask
about a problem I'm having with a Trane high efficiency (condensing,
model TUX080) furnace installed in my house. Every once in a while,
the furnace gets stuck in the cool-down part of the heat cycle wherein
the flame is out and the blower keeps running until the microprocessor
is manually reset by turning the power off/on. This is particularly
annoying when it happens in the middle of a cold night as it's usually
discovered because the house gets cold and one has to get up to reset
it. The processor is flashing an error message but, with the help of
the dealer, I've checked out the suggested fault possibilities to no
avail (ignitor, voltage level or grounding problem).

Anyhow, the dealer also mentioned that line voltage noise and spikes
can also glitch the processor so I am thinking of installing a surge
suppressor in the line input. One way would be to use a suppressor
typically used for electronic equipment such as computers but they are
plug in rather than permanent wired. Any comments on using such a
device (by installling a plug in the furnace line and plugging it into
the suppressor) would be appreciated, or, any other suggestions.

Another possibility I don't want to think about is an intermittant
processor board problem (a replacement board is nearly $500 CAN with
no assurance that it will correct the problem).

TIA for any help............


Laurie Forbes