We just had a complete new Carrier system installed. Top of the line
high efficiency gas furnace (96%) and central air condenser (18 SEER).
The thermostat is an Infinity Control model which is supposed to
eliminate the hot/cold syndrome of forced hot air heat.
Well, it sure as hell hasn't done that. This unit doesn't recognize a
change in the room temperature until it's changed by at least three
degrees. That means it gets very cold before the furnace kicks on. It
stays on for a long time - sometimes twenty minutes or more, then goes
off for as long as an hour. It's four degrees outside right now and
the furnace came on once in the past hour. When it does go on and off
it "thinks" that the inside temp has changed by one degree when in fact
the swing is about five degrees.
The guy who installed it agrees there is a big problem but he is having
trouble convincing Carrier.
Does anyone else have a similar problem with this new model? It's very
frustrating considering the little sucker cost about $400.
So your installer doesnt know, what a pro he isnt. Is location same as
old stat, maybe its a poor location or cold wall or bad stat, or getting
drafts. Im no pro but am sure it has a settings for temp Swing or
Anticipator if it is anything other then your basic cheap stat, it is
listed under swing or anticipator settings in your stat manual. Narrow
its on off range. Is it a carrier stat. You say 96%, curious what size
unit because the only 96% Infinity unit is 38000 input btu from what I
saw all other infinitys are around 94.5%, more marketing deception. Is
your unit with the VS DC motor designed to be left on 24x7.
Thermostat is in exact same spot as the old one. I'm not sure what you
mean about size. I know next to nothing about furnaces. The quote
says "Carrier 58 MVP 96%". Also don't know what a "VS DC" is. It
does have a variable speed fan that can be left on all the time at low,
medium or high and an auto setting.
My installer is going to have someone from Carrier come. He's
convinced there's a bug in the thermostat. All I know is we are
i had one installed last year and the temp reading was 2 to 3 degrees
off. i called out favret co. here in cols ohio and the guy adjusted it
to be right on. i use a photography therm. and it is accurate. so if
they installed it they can adjust it. if not replace it period. the co.
here where i live is great. also the motor saves elec.
The installer spent about two hours here yesterday. When he first came
he thought we were just some crazy complainers and that it would be
fine. Within a short time he realized he was wrong. He had some fancy
infra-red thermometers to read the temps in different areas. He saw
that the temp would vary by as much as five or six degrees between heat
cycles. It may be that he doesn't know how to calibrate it properly.
He is having someone from Carrier come. Hopefully they will know more
than he does.
Yes it has a problem. If all is set up and operating correctly your room
temp (measured at the user interface or remote sensor, will remain
fairly constant.) Does this happen to be a zoned system?
In that case the first order of business is to recheck
connections--color coding (G,Y,W,R), tightness, etc. It's characteristic
of the terminal strip in this furnace to have screws that are difficult
to turn. This can lead to a tech or installer believing that the
connection is tight when it isn't. I have encountered this problem more
than once. It's a pin connector as well and may not be seated onto the
pins all the way. Have them check the screw connections by pulling on
the wires *individually*. Beyond that it could be a system fault, which
should be easy to diagnose since the t-stat data-logs all faults, even
runtime history, for easy retrieval. It could simply have the db set to
high in the setup menu.
sorry you are having problems, but once they fix it you will be happy.
i know the fan motor is expensive to replace, but does save on elec.
i leave the fan on low year around. very happy with the system.
What is the "db"?
The problem is the room temp on the thermostat is wrong by about three
degrees. The temp in the room has to go down or up two or three
degrees before the thermostat sees any change in the temp and reacts.
Would the "db" have an affect on the thermostats temp sensor?
By the way - the installer came and put in a new thermostat and it did
the same thing. He also said he had two other customers with the same
problem. He thinks it's a problem with the thermostat. I think it's a
problem with the setup.
What do you think?
db , I dont know, maybe he meant sb or set back as in anticipator or
swing, set it to the minimum Swing or Anticipator setting for now till
you figure it out. It is in your thermostat manual . Or your " pro"
should know the answer on the phone.
VS DC is variable speed direct current, you have it. Learn about it.
96% efficient no, I bet yours is only 94-94.5% efficient, just BS
marketing as I expalined
Deadband, the temp swing, if you will, between off and on.
It might appear to, but no. If db is set too high it will cause
variations from the set point by up to the amount of db set.
That should be a valuable clue.
Unfortunately I can't see it from here.
I can't diagnose it from here based upon the minimal info that you've
given, sorry. Contact Carrier yourself if you have to. The fact that he
has other customers with the same problem indicates that he's either
installing and/or setting up the systems incorrectly. The only settings
on the controller that would cause this would be the db, already covered.
If the temperature offset adjustment (a different setting mentioned
elsewhere in the thread) were off by a few degrees this wouldn't result
in the setpoint reading on the stat being off from the actual room temp
reading on the stat.
It really sounds as though your unit is simply malfunctioning, e.g.
misfiring, locking out, etc, and simply not getting the area around the
stat up to the setpoint temp. This could be caused by several different
installation errors involving combustion piping or indoor airflow
issues. The blower speed setting may also be set incorrectly. There
could be a restriction in the ductwork. The vent pipes may be too small
in diameter or not sloped properly. The list really does go on and on.
Best bet is to get another company out, or else get the current company
to go through the installation guide page by page checking the
instructions there against the actual install. If the manual is over
their head then that could also account for several install issues, and
unfortunately this isn't unusual in the real world.
According to the manual for the Carrier Infinity Control unit the
"deadband heat/cool" setting only controls the minimum change of temp
when the unit changes from heat to cooling. There is no other deadband
setting that I could find. I don't know if you have time to take a
look but here is the installation guide:
We have noticed some improvement by setting the fan speed to low, but
the actual room temp stills varies by two or three degrees without the
change being recognized by the thermostat. Very frustrating.
Thanks for trying to help. I really appreciate it.
Well the deadband and differential are sometimes reversed in their
definitions depending upon whoever wrote the manual. My last Carrier
stat install had deadband as the on/off swing and differential as the
difference between heat and cool settings. But this is all beside the
point. The on/off swing setting, regardless of what this is called on
your stat, is the only t-stat setting that could cause what you are
seeing,as settings go. A fault with the t-stat is a highly remote
possibility, but you may have gotten that one of those 1 out of umteen
faulty ones. But like I said, this is going to be impossible to diagnose
over the intenet because there are too many parameters on your
particular unit that require manual testing and/or checking. Good luck
resolving this, and remember that you are free to contact Carrier
yourself, they won't mind, and will even be happy to take your calls and
Well, looks like we solved the problem. I put a thermometer on top of
the thermostat. I kept track of when the temps changed and noticed it
happened AFTER the furnace came on and shut off. That made me realize
that the cold and warm air was getting to the thermostat from somplace
other that the area around it. I looked around and found two heat
registers that were closed in the dining room, which meant that area
was colder than the living room. We almost never use the dining room
but it's closer to the thermostat than the living room is. It was
screwing up the heat. When I opened them up fully things improved
We are thinking about getting a remote room sensor so that the
thermostat can react to the temp in the living room and not in the
dining room. Do you know if the remote sensor can be easily
deactivated so the furnace and/or air conditioner responds to the
thermostat sensor if we want it to?
Anyway, things are much better. Thanks all for your help.
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