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Ask Daniel Plourde Your Own Question
Daniel Plourde
Daniel Plourde, HVAC Technician
Category: HVAC
Satisfied Customers: 327
Experience:  hvac technichian at performance plumbing and heating
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I have a 99 double wide that has a evcon mercury thermostat.

Customer Question

hey , i have a 99 double wide that has a evcon mercury thermostat. i want to change it to a honetwell rth6580wf. my problem is I have 7 wires . with the white wire feeding two different terminals a\\
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: i have a 99 double wide with a evcon mercury thermostat. i want to go with a honeywell wi-fi . rth6580wf . my thermostat uses 7 wires
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: it has a blue wire a green wire a orange wire a red wire a brown wire a yellow wire and a white wire feeding 2 termails
Submitted: 4 months ago.
Category: HVAC
Customer: replied 4 months ago.
white wire to e and w2.green to g.orange to o. yellow to y. red to r.brown to x. blue to L.
Expert:  Daniel Plourde replied 4 months ago.

hi i am dan i can help you with this. what terminal connections do you have on the new thermostat?

Customer: replied 4 months ago.
r,y,c,o/b,aux/f,l,k
Expert:  Daniel Plourde replied 4 months ago.

ok did you wire the terminals the same as the old thermostat?

Customer: replied 4 months ago.
on the old 1 . white goes to e and w2. green goes to g. orange goes to o. blue goes to L.brown goes to x. red goes to x.yellow goes to y
Customer: replied 4 months ago.
red goes to r. I should of typed
Expert:  Daniel Plourde replied 4 months ago.

ok the new thermostat should be wired the same except white is going to go to aux brown will go to C and blue is not used.

Customer: replied 4 months ago.
its blowing out hot air and cold air together. are u sure I don't need the blue wire fir common. its like EMERGENCY HEAT and cold air together
Expert:  Daniel Plourde replied 4 months ago.

the blue wire went to L on the old thermostat. that is just for a light on the thermostat. the brown X is your common. the air can not be hot and cold it is either hot or cold. are the pipes coming from the outdoor unit hot or cold? also what is the brand of unit you have?

Customer: replied 4 months ago.
the gas line coming into the hanger is hot
Expert:  Daniel Plourde replied 4 months ago.

ok that means the outdoor unit is in heating mode. that means it is a problem with the O and B wire. depending on the brand of your system depends on what setting you use. most systems use the O terminal. make sure your thermostat is set to use O on cooling changeover

Customer: replied 4 months ago.
can I switch 2 wires on the thermostat on the wall to correct that problem?
Expert:  Daniel Plourde replied 4 months ago.

if you connect the orange wire to R then the outdoor unit will only cool

Customer: replied 4 months ago.
ok. then how do I correct the problem so it will heat and cool
Expert:  Daniel Plourde replied 4 months ago.

by setting the thermostat correctly. in the parameter settings of the thermostat there will be a setting for using the O terminal or B terminal. or cooling changeover, heating changeover. also make sure the thermostat is set for a heat pump system in the parameter settings

Customer: replied 4 months ago.
I still don't understand not using the blue wire for its goes to a transformer
Expert:  Daniel Plourde replied 4 months ago.

it may have gone to the transformer and had a switch or relay in it too. all the l terminal does its power a light on the thermostat when the unit has a malfunction. that feature is not supported by modern systems and is not needed