Carrier Infinity Control being wonky

[Sergroum]

Greetings.

Does anyone have any experience with infinity controls? Currently, I am experimenting with systxccitn01 Carrier Infinity Control and 59 MN7 furnace. I am having problems with it.

Basically, the furnace never shuts off if the temperature is set to 23+ and the difference between the desired temperature and room temperature is less then 2 degrees. 

So, a very well insulated house, 0 Celsius outside, 22 Celsius room temperature and 23.5 Celsius desired temperature at the thermostat. The furnace would start at 40% and slooowly ramp up as it heats the house. By the time it hits 23.5, I would be running at somewhere around 70-75%. Once it hits the desired temperature, the furnace drops down to 40% and 'never' shuts off.

I am flabbergasted personally, because at that point, the furnace would work for hours and hours  without ever stopping. Just upkeeping that 23.5 temperature continuously. I do have an HRV working at the same time that's probably bringing in fresh cold air, but I have the same problem happening to me even when I turn HRV completely off.

No matter how much I explore the Infinity Contorl, I fail to see any options on how I can make it to cease upkeeping the temperature and allow it to fall down 1-2 degrees, or disallow low stage somehow.

[Admin]

Is the furnace sized correctly?  Also the control board has a model plug connector on the PL4 terminal.  It's a chip that stores info for the model of furnace you're using.  Sometimes the wrong one was installed by the manufacturer.  The schematic wiring diagram should list the correct model plug connector.

[Sergroum]

80 BTU furnace and I believe 2300 square feet house. No skylights, or anything. New triple glass windows, over 20 inches insulation at the attic. Very well insulated all over. The Customer is ... an effeciency enthusiast, so he's doing a lot of things himself and does it 'very well'.  At the same time, I have to take his word for all of that, so if there's irrevocable fact that let's say there is just that much heat loss that the furnace has to be continuously on, then it's something. But if this were the case, then he'd be losing heat down to well below 20s. While his problems begin only after 22+. At 21-22, it works as intended.

The control board was changed, the plug was replaced from the old board onto the new one. The problem was happening before that, so that wasnt the case. But unfortunately when control board changes, the thermostat ceases to recognize model/serial of the furnace. It's even mentioned in the manual about that. At the same time, it does recognize it as a furnace 78 KBTU/H.  Like it have with a previous problem.

Few things I'd like to know if I understand correctly.

When you're using infinity control. The dip switches become mostly irrelevant correct? The Thermostat takes over all the settings and nothing you do with the dip switches take effect unless you set it up so at the thermostat as well. Am I correct in this assumption?

[Admin]

Could the original board have had the wrong model plug connector?  Are you able to confirm it is the correct one for your model of furnace?

Is there an OAT (Outdoor Sensor) installed?

Are there any stored error codes?

Is the system staging set to SYSTEM in the Infinity control?  You could try changing it to MED-HIGH or HIGH.  If the client has been playing around with the settings I might look at doing a factory reset on the Infinity Control.

When you're using infinity control. The dip switches become mostly irrelevant correct? The Thermostat takes over all the settings and nothing you do with the dip switches take effect unless you set it up so at the thermostat as well. Am I correct in this assumption?

Yes, that's correct.

I'm wondering if there's something in the infinity control that can be adjusted.  I don't have much experience using them.  I'd almost look at installing a standard single or 2 stage stat and use the dip switches and see if the cycling problem continues.  The problem might just be a result of using the infinity control, and may not be a problem at all.  It may just be a comfort setting that causes the heat to keep running on a low stage.  How is the client's gas bill?  If it's not higher than expected I would tell him everything is working as per design.

It might be worth calling Carrier Tech Support - 1-800-237-3005.

[Sergroum]

There is no OAT, but it does  have the type of Air conditioner that's communicating as well, it has a temperature sensor in it as well. It also has a Ventilator connected to the same infinity control through a NIM Module.

The staging system is set on System, yes. Interesting thing. The setting there are System, Furnace, Low, High. Doesnt have a Med-High, or I would've absolutely tried it.

I am wondering if the dip switches will become useable if I set it to 'Furnace' staging mode.


The client says his gas bill tripled in size since installation of the new system compared to a 90 effeciency furnace prior to this. He showed me the bills. He's ... not wrong. His consumption is way up.