I recently had a Lennox G61 two-stage gas forced air furnace
installed. The thermostat is a regular 1 stage programmable. The
furnace has a jumper on the control board to work with a one stage or
two stage thermostat.
My question is, am I better off to replace the thermostat with one for
two stages of heating, or leave it the way it is? My thinking is that
controlling the stages from the thermostat would be the way to go.
I'm not sure how the furnace decides when to turn on stage two, but I
believe it is simply based on time.
I'm thinking of putting in a Honeywell 8624D instead of the stat that
is there now. Is this a good choice?
Ok, I got 2 stage gas furnace but have just 1 stage thermostat. I decided
not to upgrade my 1 stage thermostat as I did not see much of the benefit.
From what I understand, this is how system works:
Furnace is setup to work with one stage thermostat. It starts at lower
output and works like that for 12 minutes. If thermostat still calls for
heat, furnace switches to higher output.
With 2 sttage thermostat - thermostat decides if to call for low output or
high output. That is if lets say current temparature is 2 degrees from
required temperature, thermostat right away will start furnace at higher
output. So you are losing that lets say after setback it takes a bit longer
to recover. But that is it. Is there any other advantages on having 2 stage
For this type of furnace, I don't honestly see why you want to change the
thermostat. The objective is to 'low fire' the furnace for the first 12
minutes. If that heats the residence sufficiently, then fine. Instead of
firing high and using more gas, or overshooting the temperature. If the
'low fire' rate isn't getting the job done, the computer on the furnace
switches to high after the 12 minute interval. So you only use the 'high'
when necessary. Your using a 2 stage thermostat when the furnace
manufacture provides you with a solution to use a 1 stage thermostat, and
saves you from firing on the higher rate (more gas usage.) (I fully
understand the 2 degree differential between 2nd stage and 1st stage.)
For my 2 cents, you have a newer 2-stage furnace is designed to work either
with a 1-stage state, or 2 stage stat. It is more efficient only to use
that amount of fuel that you need to keep your family comfortable. Using
high fire when it's not necessary is like going as fast as you can from
traffic light to traffic light, instead of just steadily getting there.
Are you seeing a need to switch to the 2 stage stat? Is the furnace getting
the job done now? Is your family uncomfortable (too hot or too cold?)
"J Kelly" < email@example.com> wrote in message
I wasn't sure how the furnace was supposed to work. The installer
said the time delay was "about 5 minutes" which seemed way to short.
Therefore, I wasn't sure if a different stat would work any better (or
worse for that matter). On a further note, am I weird to want an
installation manual for my furnace? I did not get one, but did have
one for the furnace in my last house. I know I don't need it, but I
like to know as much as possible about these types of things. Maybe
it would explain in better detail how the two stages sequence.
I do plan to change the stat no matter what because I do not like the
one that the furnace guy installed, it does not have separate programs
for each day of the week, which for me is an important feature due to
my non-standard work week. I also like to have the fan on all the
time when I'm home, but on auto when I'm not home. That was my main
reason for liking the 8624D.
Zypher you are not correct, the second stage on my unit does not
require a higher blower speed there by making 2nd stage more efficient.
Remember Blowers take apx 360 watts . Or 35$ at .125Kwh 24x7. An AC
blower will cons`ume the same Kwh at any Btu or CFM.
2 stage is for comfort...
I knew about needing an extra wire, and already have a roll. I
checked out the routing and it is a simple matter to fish the wire to
the basement. I figure I can do it in 10 minutes or so.
Will give me something to do on my next day off, by then I should have
the thermostat which I have already ordered.
One thing you forgot is your warranty, putting in a new stat is not
beginner stuff, I would not do it unless I knew and checked all wiring
and I don`t on 2 stage. You have 3 month old equipment, don`t risk
damage or your warranty doing it yourself, you may be denied a warranty
claim. Which leeds me to an earlier question, why even bother, you paid,
it isn`t right. Unless you are the installer or got it used.
This is Turtle.
Look A two stage thermostat is alway better on a two stage furnace. The next
best thing is a single stag thermostat on a 2 stage furnace.
I would think it would work better and keep the air a even temp. in your home
with the two stage thermostat than with the single stag thermostat.
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