HHT part 4021-229B rev C

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Nh880

New Member
Dec 8, 2018
7
Maryland
A nearby lightning strike too out bunch of electronics. Fireplace fan wont turn on. I bypassed the fan plug and it runs direct from wall but won't turn on with the fireplace. Seems that the control switch is bad as the test button wont work either.
I have 4021-229-B Rev C control but unable to find it anywhere online. Is there a new part number as replacement for it? Will it be the 708 model?

Appreciate some help.
 

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Normally, one leg from the rheostat goes to the junction box under the unit. The other leg goes to the snap (aka Thermo) disk.
Coming out of the snap disk is a wire into the blower & coming out of the blower is a wire that completes
the circuit by being plugged into the Junction box. The snap disk actuates the system when the unit body
reaches a designated temperature & opens the circuit when the unit cools. Without seeing the wiring schematic
from your install manual, I would guess your is probably wired the same as what I described...
 
There are 3 wires (black, red and white) that go from the fan control in to the power strip for the fan.

There are two black wires that come out from the other end of the control switch. One wire is grounded and second goes into the main and into the fireplace.
[Hearth.com] HHT part 4021-229B rev C
[Hearth.com] HHT part 4021-229B rev C
[Hearth.com] HHT part 4021-229B rev C
 
If the blower is grounded, I think the wire from the rheostat is redundant.
I see no issue with replacing your rheostat with the two-wire version.
 
If the blower is grounded, I think the wire from the rheostat is redundant.
I see no issue with replacing your rheostat with the two-wire version.
let me try it I guess.

So one wire will go to the power strip to control the fan and other one with the main wire which is the green one in the picture.
 
Do you have the install instructions for the blower assembly?
You should. The blower is an OPTION for this unit & does not
come the factory with one in the unit.
That's where the wiring schematic is.