Carrier Performance Boost 90 58MEB Gas Furnace Review

The Carrier Performance Boost 90 Gas Furnace comes with an AFUE rating of up to 93% AFUE. What separates this gas furnace from another gas furnace is the Boost name and the efficiency range.  Carrier calls it Boost and describes the name Boost as: when this furnace is combined with a Carrier heat pump or air conditioner and you are using it in cooling mode the furnace blower will circulate cool air throughout the house. This has the ability to increase efficiency of selected 13 and 14 SEER air conditioners and heat pumps by 1.5% SEER points. Carrier is a member of GAMA (Now AHRI) which is a respected organization that certifies manufacturers claims with efficiencies. Of course it is my duty to be skeptical of different claims manufacturers make and I would like to see the technicalities of this claim before I am a firm believer and can offer a professional opinion one way or the other on this feature listed with Carrier. I am guessing Carrier gives the blower a longer run-time after the condenser shuts down to offer more dehumidification and to take advantage of the cold evaporator coil while it is still cold however many manufacturers do this by having delay control of the blower. After the condenser shuts down the blower will continue to run because the evaporator coil is still cold. Why not take advantage of the cool evaporator coil and use it to offer a little more cooling? This is a common feature with all air conditioning systems but it is not clear what Carrier is doing to offer this higher Boost in SEER for an air conditioning or heat pump system coupled with this gas furnace.

Features listed for the Carrier Performance Boost 90 58MEB Gas Furnace are:

• Up to 93% AFUE rated - this is high AFUE but not the highest for gas furnaces. If you want a higher AFUE rating then you will have to go with the Carrier Infinity series gas furnace.


• 5 year parts warranty with a 20 year warranty on the heat exchanger - this is different from some other manufacturers who typically offer lifetime warranties on heat exchangers.


• Meets the Energy Star guidelines for energy efficiency.


• The Carrier 58MEB gas furnace will support a thermidistat and a thermostat - I would hope that all Carrier Gas Furnaces would support thermostats and the thermidistat is a combination thermostat and humidistat. A thermidistat will offer temperature control along with controlling a humidifier if a humidifier is installed with the system.


• Diagnostics are listed as on board diagnostics which means the control board in the gas furnace has the ability to help an HVAC technician diagnose problems with the furnace.


• Capacity range for this gas furnace runs between 38,000 and 128,000 BTU/H.


• The blower is listed as single-stage electronically controlled blower. This is slightly confusing as listed by Carrier because in the same listing it says it is an Programmed ECM. ECM to me is an Electronically Commutated Motor which is a variable speed motor. Carrier doesn't mention variable speed anywhere in the specs for this gas furnace except to say it is a programmed ECM.


• A polypropylene-coated heat exchanger - polypropylene is a thermoplastic polymer and Carrier must be telling us that the secondary heat exchanger is coated with polypropylene because I can't see plastic standing up to the temperatures in the primary heat exchanger. The secondary heat exchanger runs much cooler and needs something tough that will stand up to the corrosive effects of combustion by-products that are made in the process of combustion. The polypropylene will do this in the secondary heat exchanger where the corrosion is a big factor.


• Natural gas and convertible to propane - this is industry standard