Lennox 7 wire to Honeywell RTH6580wf


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Old 05-30-17, 06:31 PM
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Lennox 7 wire to Honeywell RTH6580wf

Hello All, first post... be nice. I'm not sure what the normal practice is on this forum, keep old threads running or start new ones. anyway here goes...

i have a Lennox Fuelmaster 21 that is controlled directly from an old mercury thermostat. Lennox heat pump and propane furnace.

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i have read the below post and followed its advice with setting the 'program' and wiring it up but its only cooling (i'm in Minnesota) which is of limited use to me. i'm unsure about the brown (emergency heat) which is wired with the white (heat call). when i call for heat the the condenser clicks and thats it.

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any help would be much appreciated...

program =
1 = 5
2 = 0
6 = 5
12 = 0
13 = 1
14 = 0
if you need more i can provide.

p.s. Honeywell help line suggested i need a different thermostat, one with external temp input. but as the Fuelmaster 21 has this and the old thermostat didn't, i don't agree with them. plus i didn't have confidence when i was speaking to them.

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all help gratefully received as my wife says i have too many unfinished projects already, you might be hearing more from me...

Regards Steven


Separated from.... http://www.doityourself.com/forum/th...rth6580wf.html
 

Last edited by PJmax; 05-30-17 at 06:56 PM.
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Old 05-30-17, 06:57 PM
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Welcome to the forums.

I moved you to your own thread to eliminate confusion. I'll look over what you've posted.

The outdoor temperature sensor is important so that the stat knows when to shut the heat pump down and run just the furnace. The heat pump and furnace cannot run at the same time.
 
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Old 05-30-17, 07:22 PM
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i should just add i am fairly technical but everything i know about thermostats and HVAC i have learnt in the last 24 hours, most of that time online. also heat pumps e.t.c. are completely new to me.
 
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Old 05-30-17, 07:31 PM
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The Fuelmaster looks to be a dual fuel control.
Is that staying..... it may need to ?

Don't know if you burn propane or natural gas but where I am it's much cheaper to use nat gas then propane or a heat pump for heat.
 
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Old 05-30-17, 07:44 PM
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yes the 'manager' will stay i believe that is what allows me to have a simple thermostat, problem is it isn't working. it is propane and it automatically switches over from the heat pump, but not sure at what temperature.

problem is i can't get the heat to work correctly, i did try it without the brown wire (emergency heat) but i think the heat pump and furnace came on together so i quit messing with it. i'm pretty inexperienced with heat pumps but a quick learner.

i'd like to get this thing working if i can, but the Honeywell call centre weren't much help and the internet seams oblivious to the existence of the Fuelmanager 21.
 
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Old 05-30-17, 08:13 PM
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There isn't too much difference between a heat pump and a standard split A/C.
The biggest difference is that there is a reversing valve that changes the refrigerant path for heating or cooling.

Since the heat pump is running in the winter it will get iced up and need defrosting. When this happens the valve is changed back to cooling. The heat pump takes heat from the house to defrost the outside condensor. Since this will cause cold air to be delivered into the house.... electric backup coils are usually used to heat the air until it goes back to heat mode.

In your case the furnace will need to come on to heat the air.

What must be avoided is the furnace running when the heat pump is in heat mode as the compressor can overheat.

I'll look over your application.
My forum partner, Houston, will probably stop by too.
 
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Old 06-02-17, 11:01 AM
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so after some more reading it sounds like to get heat the thermostat calls for cooling and switches the reversing valve. and the Emergency and Auxiliary heat are the same thing...? or i keep hearing people say wire them together. below is the circuit board for the Fuelmaster 21. i think i am going to get my multi-meter out and test the old thermostat and check its outputs.

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of course it may be working fine its just that i am panicking and shutting it down when i see the heat pump and the furnace working together, maybe this is just a temporary thing when it starts up...?

p.s. the cooling is working and its summer so i'm not in dire need of a solution just yet.
 
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Old 06-02-17, 04:26 PM
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The "emergency heat" mode shuts down the heat pump and only the furnace runs.
The stat switches to Aux heat when needed automatically

With a straight heat pump setup.... emergency and aux are the same electric coils.

In your case.... the emergency mode will be the furnace only and the aux mode will shut down the heatpump and start the furnace automatically. In addition... the fuelmaster will shut down the heat pump based on outside temps.

At least, that's what is supposed to happen.

I'm looking into the fuelmaster parameters.
 
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Old 06-05-17, 10:41 AM
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so looking through the Fuelmaster 21 manual if the FM21 was smart enough it could determine between auxiliary heat and emergency heat by the differences in input between the two even if the Aux and Emergency heat were wired together this would be because the 1st stage heat and blower are being activated.

or am I expecting too much?

I think I'm going to leave the brown Emergency Heat wire off for now and look it it when it gets cold.

p.s. when it comes to the outdoor thermostat, how cold is cold?

many thanks for the help so far.
 
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Old 06-05-17, 05:57 PM
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I'm thinking the output of the fuelmaster, aux and emergency would be tied together because there is only one furnace.

The outdoor temp, switchover point, is adjusted to shutdown the heatpump and run just the furnace. This setting is the lowest point the heatpump can operate and still make usable heat. If the heatpump is struggling and the room temp gets to 3 under the set temp... the aux heat will be activated turning off the heatpump and turning the furnace on. When the room temp approached setpoint... the heatpump would restart without the furnace.

There are a lot of things that contribute to that setting. You may know where it's currently set or you could pick an arbitrary point like 20 and run it from there.
 
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Old 06-08-17, 05:02 AM
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sounds good, so last night i checked the inputs and outputs of the fuelmaster with a multi-meter and set the indoor temp to 80 it was 72, i was kind of surprised the furn ace switched on, but from what you say below this would have been because of the 3+ degree difference?

i'm starting to find this fun...
 
 

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