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Home Guy

wrote:

Can someone explain why you need a contractor to install a
furnace?

I do a lot of my own projects, but installing a furnace/AC is not
one I'd tackle.

I was speaking more about the furnace, not the AC. The furnace is just
a glorified barbeque unit. If you were replacing the AC as well, then I
guess it depends on what parts of the old system you were keeping -
naturally the outdoor unit would be replaced, but the evaporator coils
near the furnace could stay.

As I haven't had the need to shop for a furnace, I don't know how many
of them come with integrated evaporator coils (or perhaps none of them).

Because I have lots of space around my furnace, I'd probably get
creative and build a separate air-handling system for the furnace and
evap coils - there's no reason why both air systems need to go through
the furnace. I could have a separate motor and filter for summer use,
and with some sheet-metal ducting and gating I can easily change the
system over to winter heating and completely bypass the evap coils.

Another thing I'd do for the summer system is to have the ability to
draw return air directly from the outside through a dedicated duct and
gate off (close off) the return air from the house-hold interior return
air duct. This allows me to pull cool air directly from outside and
force-flood the house with cool air - on those warm or hot days where
the house has warmed up by evening and your only normal option is to run
the AC to cool the house. So I pull cool return air from outside, open
some windows and the fan will force the warm air out the windows.

None of this is normally done, because home-owners can't imagine or
don't know about this, and HVAC contractors would charge a fortune to do
it for someone else, but I bet some of them do it for their own homes.
Just like some of them put their AC condensor coils in their swimming
pool to heat their pool while efficiently removing heat from the coils.

IMO, there are just two many issues. Examples would be
correctly sizing the new furnace.

New furnaces with variable gas valves gives them the ability to dial up
or down the heat output.

I do this right now with my 34 year-old furnace. I dial down the gas
going to the burners so that maybe they're getting 1/3 of the full gas
supply. If I turn it down too far, the fan cycles on and off while the
burners are on. By turning down the gas, I'm modulating the heat output
of the furnace much like a super-expensive modern furnace does. So my
furnace runs more constantly (like a modern furnace does) and my
heat-extraction efficiency goes up (because the temperature of my
combustion exhaust is lower).

Most people don't know that they can dial-down the gas supply of their
old furnace - just like you can with your barbeque or your gas stove.
There's no reason why you need to operate an old furnace heat-output
either full-on or full-off.

If I find that in the coldest part of winter that my furnace is running
all the time but the house temperature is lower than I want, then I'll
just go down to the furnace and turn the gas valve at the regulator a
little more clock-wise and increase the size of the flames and that will
do the job.

Then as you pointed out, you have the issue of removing the freon,
charging the new system, etc. I guess if you know someone that
will do it, that could be dealt with.

I agree that you need a contractor to deal with freon extraction,
balancing, charging, etc, but the more you can do yourself (like run the
lines, connect as much of the system as you can) the more you'll save.

Then, what about the warranty?

That's why I'd preferr to retro-fit the furnace with standard technology
and do away with all the sensors.

It's crazy that they removed the standing pilot light (which uses maybe
$10 worth of gas all year) and they went with electronic ignition, and
by doing so they had to add all sorts of temperature sensors to know if
the main gas supply should be shut off in case the ignitor doesn't
work. Talk about over-kill to save $10 worth of gas (even less if you
normally turn off your pilot light in the summer).

If you install it yourself, isn't the warranty likely voided?

I reject all attempts to sell me warranties for the things I buy. We
all laugh at the warranties that are sold at electronic stores - don't
we?

Do you think I'd replace an ECM furnace motor with another ECM furnace
motor? Hell no. If I didn't already retrofit a new furnce with a
regular AC motor, I would certainly do that if the ECM motor died on
me. To hell with the warranty. It's less agrivating to fix most things
yourself than to deal with the warranty (the exception - vehicles).

Most electronics have a manufacturer warranty anyways, and their small/
portable enough the shlep them back to the retailer or manufacturer when
they break.

I'd also look at the specific reqts for the tax credit, ie
what documentation, etc is required.
That might preclude self-install.

I bet that most HVAC companies have hiked their prices because they know
that home-owners are getting these gov't rebates.

I'd rather spend $2000 on a new furnace and install it myself, rather
than spend $6000 to have a contractor install it and then later I get
$2000 back in gov't credits. Do the math.

You're also aware that the tax credit requires it to be
installed by the end of this year, right?

In what country?

Home Guy is the poster I was referring to in my original post
when I said I know what one guy will tell me. Which is to
just keep running the 26 year old system, because it's the
smart thing to do. He thinks the new systems have too much
complexity, so they are more failure prone, cost more to
repair, etc. He has a point. But given the current tax
credit, utility rebates, energy costs, etc, it's hard to
imagine how we won't come out ahead.

Once the credits are gone, contractor prices will also come down.

You'd think that if he were rational, he's at least use a
new system as it was made and wait for it to fail, then
find out how much the part costs before ripping it apart
and rebuilding it.

Once it fails, it's too late to tinker and retro-fit it with standard
technology. You don't have that luxury when your house needs the heat.

Since he's so concerned about maintenance cost, I wonder what
ripping it apart does to the warranty?

Well, if it no longer has an electronic ignitor, control motherboard and
ECM motor, then why exactly should I care about the warranty for those
items?