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Category: HVAC
Satisfied Customers: 14863
Experience:  15yrs in the HVAC industry with certificates and degrees.
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I have a 10 year old Carrier Infinity Heat Pump. We've had

Customer Question

I have a 10 year old Carrier Infinity Heat Pump. We've had various issues with the system since we had it installed. I just had an electric bill of about $900. It works well in the summer and has been a savings on cooling costs but during the winter it has always cost more than the previous system we had. It's a 5-ton system with 3 zones using electronic dampers. After having a $900 electric bill last month, I've been reading posts on various HVAC forums and discovered that there is a setting to prevent electric heat from running unless it's below a certain temperature. I set it <30 per some of the recommendations on the sites I was reading. Without electric heat, the system is not able to warm the two upstairs zones. The temperature settings for those zones are set to 70, but the thermostats have been dropping throughout the night. It's shows that it's 45 degrees outside and we have about a 3400 sq ft house. Another thing to note is that in the Fault History on the Infinity Controller it shows "low pressure switch open", 255 events and they happen fairly consistently. These events have been happening for years but whenever the technicians have come out they've never done anything in regards ***** ***** events. I think one even stated it wasn't an issue. I've tried to research this error. I'm looking for some insight on whether my system is not sized properly or if there is likely an issue with it that prevents it from being able to warm the house without relying on the resistive heat?
Submitted: 1 year ago.
Category: HVAC
Expert:  HVAC Guru replied 1 year ago.

Hello and thanks for using this service, if you have been waiting do not worry or get upset I am just one of the techs on here and I try to get to as many customers as I can and I just picked up your question now.

The unit is likely sized right but, the electric heat is what is really killing your bill. Where do you live?

Customer: replied 1 year ago.
In the suburbs of Northern VA. I'm confident that the electric heat is what's killing my bill, I just don't understand what's wrong with my system that it needs to rely so much on electric heat. I found the setting yesterday to lockout electric heat above a set temperature. I set to <30 and over the night last night the outside temp was around 45 and the Heat Pump was not able to heat the house. The main floor zone was set to UNOCCUPIED and the upstairs zones lost heat throughout the night. They were set to 70 degrees but by 7:30am this morning the zones were at 61 degrees. I changed the electric lockout to <50 this morning to get the house warmed up.
Customer: replied 1 year ago.
Hmm, looks like my message above was chopped off...
Customer: replied 1 year ago.
Actually it chopped off over half of my response
Customer: replied 1 year ago.
I set the lockout to <30. That prevented the electric heat from coming on last night as it remained around 45 degrees outside
Customer: replied 1 year ago.
Oh, it's chopping off my messages because I used the less than symbol
Expert:  HVAC Guru replied 1 year ago.

The heat pump will likely not be able to keep up with temps that low no matter what. If you house is not super tightly insulated that can be a factor as well. The bot***** *****ne basically is if you want to have normal heating bills again you will have to get a regular gas furnace put in or this will be a continual issue. Heat pumps are good basically for 55 degree outside temps and above nothing too much below that or that will be an issue.

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Customer: replied 1 year ago.
I set the lockout to < 30 degrees. That prevented the electric heat from coming on but the Heat Pump couldn't warm the house. The outside temperature was around 45 degrees and the downstairs zone was set to unoccupied and the two zones upstairs were each set to 70 degrees. The electric didn't come on last night but the two zones upstairs lost heat throughout the night. They were at about 65/66 degrees when we went to bed and they had dropped to 61 by 7:30am. I increased the electric lockout to 50 degrees this morning.
Customer: replied 1 year ago.
On HVAC forums all over they talk that Heat Pumps should be effective down into 30s and below. I never had these types of issues with my previous heat pump and my electric bill had never been this bad. I appreciate you taking the time to answer but this didn't answer my question. I was look for advice from someone specifically with carrier infinity experience. My first time trying out this site. Thanks for your assistance but this wasn't helpful at all
Expert:  HVAC Guru replied 1 year ago.

Yes the issue is the temp outside, a heat pump can only produce heat and very little the colder it gets outside, at about 37 degrees the heat pumps basically produce little heat and has to run all the time to try and produce heat as that is the balance point. With a 3400 square foot house the size is too large for what that can put out at those temps. Your heat pump is working as it should but I would get a gas furnace and dump the electric if you want to cut the bill to about 1/4 of that amount. Read this article to better understand what I am talking about. I have family that live where you do and they got rid of the heat pump and put a gas furnace in due to the same issues, it would be different if you were in Florida