Get more estimates. Go to a place that sells furnaces and ask
them for a local recommendation.

Compare the esimtates: it'll give you a start on who's who. BTW,
an estimate is just that: an ESTIMATE! Be sure to read the fine
print. Doesn't sound like you should be doing this yourself to
be honest.

Pop


"Marina" wrote in message
...
My sister says she needs a special air filter for her Trane
furnace/air
conditioner.
(that's all the info I got from her).

The technician came out to measure for a filter today and said
it would
cost $700. She needs extra filtering due to asthma and lots of
dust in her
house.

I'm hoping there is a good site where the cost is a little
lower and you
know they are a good honest site?
Thanks.
Marina