Constant Call for Heat


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Old 10-27-19, 12:06 PM
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Constant Call for Heat

A Lennox Pulse21 Model: GSR21 Q3 80-1 will run all the time with the thermostat off. This condition inadvertently started after last heating season. I've replaced the ignition module, thermostat and the thermostat wiring with the same condition present. I think the Access Panel may be at fault?
 
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Old 10-27-19, 01:05 PM
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Welcome to the forums.

Keep a good eye on that furnace as most of them have been recalled and removed from service to design issues involving the heat exchanger. A checkup every other year is highly recommended.

Remove the thermostat wires from the board. If it still continues to heat..... the board is bad.
As far as I know..... new parts no longer exist for this furnace.
 
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Old 10-27-19, 01:51 PM
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Please, don’t randomly change parts without diagnosing things first. All the things you checked can be easily tested. Your just costing yourself money without fixing anything.
The Pulse has a very specific testing policy regarding the heat exchanger. It’s actually pressurized to test for integrity.
Most of the old Pulse furnaces have been sent to the scrap pile due to heat exchanger issues and low parts availability.
Before spending money on that furnace I’d test the heat exchanger first. If it fails the furnace is effectively dead.
 
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Old 10-27-19, 01:54 PM
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Pressure test that needs to be done

https://m.youtube.com/watch?v=pBttclAIyKA&t=391s
 
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Old 10-27-19, 03:11 PM
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When the "new" thermostat module is removed from the thermostat base, the condition is no longer present.
 
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Old 10-27-19, 03:16 PM
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Ok...... and what does that tell you ?
 
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Old 10-27-19, 03:29 PM
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Is it a Nest?
This doesn’t mean that furnace doesn’t need to be tested.
 
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Old 10-27-19, 03:32 PM
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That is why I'm asking for help.
 
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Old 10-27-19, 03:35 PM
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See my previous post just above
 
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Old 10-27-19, 05:52 PM
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OP?
Did you get the issue fixed?
 
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Old 10-28-19, 06:21 AM
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The heat exchanger test is a completely separate independent topic.

But if the heat exchanger test fails, you have a carbon monoxide hazard and the furnace must be shut down and replaced and the thermostat issue and all other issues become academic.
 
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Old 10-28-19, 07:02 PM
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When the "new" thermostat module is removed from the thermostat base, the condition is no longer present.
You have a thermostat problem.
You didn't post the make and model of it so we can't offer much help in the diagnosis of it.
 
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Old 10-29-19, 05:16 PM
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The thermostat is a Honeywell Model: CT87N. I have replaced the ignition module, thermostat and the thermostat wiring with the same condition present.
 
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Old 10-29-19, 05:35 PM
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Ok, check the terminal board with your meter and see if there’s a constant call for heating or not.
Your comment about removing the thermostat suggests you have a thermostat problem but we need to diagnose before replacing parts.
 
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Old 10-31-19, 05:50 PM
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Any luck op?
Have you made any plans to get the heat exchanger tested?
 
 

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