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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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We have the same problem with our new rheem furnace that

Customer Question

We have the same problem with our new rheem furnace that shuts off before reaching the target temperature. This same question was submitted to you 6 years ago but there is no solution indicated. After about 4 cycles to increase the temperature from 62 to 70 degrees the furnace then operates properly for example it drops a degree and then increases back to the setting. When we take the bottom door off and hold down the safety switch we do not have the problem, the furnace runs without stopping until it reaches the desired temperature. When the door is off we can feel a strong pull from the vent returns even so much we can feel the air going over our feet into the furnace. We also added an additional air return cut-out grille in the hallway. It appears that when the door is closed the furnace gets too hot causing it to stop and start again. This is a new Rheem 80% single stage 100K BTU upflow furnace- The model number of the furnace is R801SA100521msa. When we first start the furnace from the off position there are codes that show. 22 for two or three times then code 57 once and the H for heat. The furnace manual shows the codes as follows, 22- MAIN LIMIT OR HALC OPEN, 57-PRESS SWITCH STUCK OPEN WHEN SHOULD BE CLOSED. PLEASE NOTE THAT WE HAD A LANGUAGE BARRIER WITH OUR INSTALLER. Our house is staying warm but we feel that if this continues to take place it can cause damage to our new furnace. Should be have our air ducts cleaned? It has been about 9 years ago that we cleaned them. I hope you have a simple solution. Thanks. Dave Fanselow.
Submitted: 1 year ago.
Category: HVAC
Expert:  Heath.M replied 1 year ago.

Hello my name is ***** ***** will be my pleasure to assist you. It sounds as if the furnace is oversized for the application. Is it running two stages of heat is there a wire connected to the w2 terminal in the furnace? There may be a solution without replacing the problem. rutting in another return grill in the return duct near the furnace may help. Make sure all the dampers to the heat runs are open to the house.