Why is the installation the most important part of choosing a furnace?

 I've been doing some research in preparation for next year when I will
be replacing my gas furnace and a lot of people seem to mention that
the make of the furnace doesn't matter as much as the quality of the
installation ... but what exactly does that mean?

The furnance comes preassembled from the factory more or less so it's
not like the contractor is building the thing.  How can a poor
installation ruin a good furnace?  What makes it a poor installation?
Are we talking about the preparation part of the installation, like
getting the correct size (BTUs), proper chimney size, correct vent
sizes, etc. ... or are those persons refering specifically to the
installation part ... what can go wrong during that part?

Thanks,
Harry

P.S.  The more technical the information you provide the better ...
thanks.

  Well I have seen plenty of systems the wrong size (too cold/hot).

And I have seen plenty of systems where one or more rooms are colder or more
hot than the others.

And then plenty of systems where it may be very cold around the outside
walls, and the problem with this is that the return ducts are located on
inside walls in each room (to save money on duct work I suppose).

*But* I have seen most modern commercial high-rise buildings which have very
good systems all around. Every room perfect temp.!


"Harry Muscle" wrote in message

 However, since this is a remove and replace situation, will any of the
points you mention really apply?  The house is prefectly comfortable as
is right now, it's just that the existing furnace is 35 years old.

The reason why I posted this question is that the comments I've read
about the installation being most important are usually part of answers
to persons just like me ... replacing a furnace, not a brand new
installation.  I can understand a brand new installation where all the
duct work needs to be run, etc.  That's a lot more planning and more
chance of things going wrong like you mention.  But what can go wrong
when you're basically swapping in a newer furnace.

Thanks,
Harry

 I have seen situations where the air flow was more than the old unit and the
duct work was not modified - caused problems. If same BTU, same air flow,
then this will reduce a lot of potential problems.

Then could be problems with a newer high efficiency unit. Old venting for
exhaust gases might not be right. Also venting for fresh air might need to
be modified.

Then new code regulations may apply and modifications may need to be made to
bring everything up to code.

Old thermostat may have problems with new unit.

And of course do they know what they are doing? Know codes, wiring, etc...


"Harry Muscle"  wrote in message

 

not as critical...however it never pays to have a hasher do
the work.