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BillyHvac
BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22347
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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Rheem Model RBHA-21J14SUAA Thermostat is calling, blower

Customer Question

Rheem Model RBHA-21J14SUAA
Thermostat is calling for heat, blower runs no heat
Problem has been intermittent, works sometimes for several months then problem reoccurs
is there a relay to turn on the 24VAC to the 240VAC staging relay or does that 24VAC come directly from the thermostat switching on calling for heat?
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
Any ideas on common faults for this intermittent problem?I kind of discounted the staging relays because there are 2 of them and i'm getting no heat so my thought is the 24AC to switch them on is not switching then on? Unlikely they would both simultaneously be intermittent that makes me think the 24VAC to turn them on is not working?If the 24VAC to turn on the staging relays is switched at the thermostat then it could be a thermostat problem?
Expert:  BillyHvac replied 1 year ago.

Hello,

my name is Billy.

The 24v starts in the air handler from the 24v transformer....goes to thermostat and waits to see what wire the thermostat is going to send it back on.

In heat it gets sent back on the W wire and goes to a sequencer. This sequencer is a stacked switch that turns on each level one at a time.

First is blower...then is stage heat and then if equipped 2nd stage heat.

If you get blower but no heat you likely have a bad sequencer.

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