New furnace ( kuuma vapor fire 100) and new member here.

[Micdrew]

Wonder if your low limit switch is bad? I remember mine was bad right out of the box, the plenum temp was hitting about 160-180 before it turned the blower on, dale had me wire nut the switch closed until the new switch came in the mail, no problems since.

 

[Micdrew]

Mine was cycling a lot through the whole burn and it ended up being the low temp switch being bad. I had it turned all the way down to 105 (I think) and the when I put a temp probe in my plenum it appeared to cycling at 140-160. I was skeptical it was a the switch though, but i changed it anyway. With the new switch set at 110 the blower comes on and stays on for hours. Temp probe in the plenum is reading more in line with the switch now too.

Beat me to it 😂

 

[brenndatomu]

Mine was cycling a lot through the whole burn and it ended up being the low temp switch being bad. I had it turned all the way down to 105 (I think) and the when I put a temp probe in my plenum it appeared to cycling at 140-160. I was skeptical it was a the switch though, but i changed it anyway. With the new switch set at 110 the blower comes on and stays on for hours. Temp probe in the plenum is reading more in line with the switch now too.

I had a string of bad switches...the original, the one lamppa sent to replace wasn't really any better, the one I got off eBay was crap too...I replaced it with a Honeywell FLS (fan limit switch) that I had laying here and that was the end of it.
Lamppa said they got a bad batch of switches at one point there...I think I recall they ended up switching brands then...that's been a few years back though

 

[Erichomeowner]

Mine was cycling a lot through the whole burn and it ended up being the low temp switch being bad. I had it turned all the way down to 105 (I think) and the when I put a temp probe in my plenum it appeared to cycling at 140-160. I was skeptical it was a the switch though, but i changed it anyway. With the new switch set at 110 the blower comes on and stays on for hours. Temp probe in the plenum is reading more in line with the switch now too.

Was that the little snap switch that you replaced? Thanks

 

[burtman4]

Yes, it was the little snap switch.

 

[R Henderson]

I had a string of bad switches...the original, the one lamppa sent to replace wasn't really any better, the one I got off eBay was crap too...I replaced it with a Honeywell FLS (fan limit switch) that I had laying here and that was the end of it.
Lamppa said they got a bad batch of switches at one point there...I think I recall they ended up switching brands then...that's been a few years back though

Is the Honeywell fan limit switch you used more similar to the one that the VF uses for a high limit?

Mine seems to be working but it's only been burning a few weeks.

 

[brenndatomu]

Is the Honeywell fan limit switch you used more similar to the one that the VF uses for a high limit?

Mine seems to be working but it's only been burning a few weeks.

Yes.