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.

 

[R Henderson]

Today I decided to take a look at the vapor fire 100s internals, it had been burning 24/7 for 3 weeks when I left it go out yesterday to adjust the door after break in of gasket. The chimney liner itself was clean actually still somewhat shiny, however my stove pipe did have some build up that I'm not sure about. I'll put some pics up and get your alls take on if this is alright or should I make any adjustments.

First pic is in rear of furnace, 2nd is chimney thimble, 3rd and 4th is furnace end of stove pipe, 5th is chimney end of stove pipe, 6th is furnace outlet. As a whole the top side surfaces are more shiny black? Creosote? The bottom sides have the debris I can brush most loose its more like fine dust black and brown color. Heat exchanger did have a good dusting of white fly ash.

 

[brenndatomu]

I don't see anything that would bother me...

 

[R Henderson]

I don't see anything that would bother me...

The main thing I was concerned about was in the last picture the glossy stuff at the top, but it seemed odd that it was more gunk closer to the furnace and the chimney which I assume would be cooler was clean all the way to the top. This picture is what came out of the stove pipe.

 

[R Henderson]

I think I may have a faulty low limit switch (the one mounted on the front up high on plenum) I had a fire going from Thursday till Sunday afternoon and was going to let it go out with temps in 60s for a few days. Yesterday my blower stayed running long after the fire was out and coals and turned to dust, plenum was cool to the touch top and bottom, computer was still on "3" but I suspect because the firebox holds heat so well. I lifted the front good off and it wasn't all that warm so I shut the breaker off went back a couple hours later turned breaker back on and blower kicked on instantly. Tried breaker again about 6am this morning and when turned on the blower didn't run this time.


Do you all think the switch may have reset itself after being off awhile or is the switch on its way out? I did read on here of some experiencing trouble with them. Other than that though the furnace is still running along nicely with plenty of heat ( only needed low so far) and get pretty good times between reloads.

 

[brenndatomu]

Do you all think the switch may have reset itself after being off awhile or is the switch on its way out?

Sounds like a bad one...not switching at the temps it should, but does work at extremes...

 

[R Henderson]

Sounds like a bad one...not switching at the temps it should, but does work at extremes...

Alright I figured it was I am going to call and see if they'll send me another should be a warranty part as I ordered it in July. I do however still have the Honeywell fan limit switch with the spring and probe off my old furnace would likely have to readjust it.

Is there any real hazards with refiring the furnace with the blower running constant or should I get a fire going and just plug into the current switch to turn the blower on? Or just wire nut it together while I'm using it.

Will probably have to build fire by Thursday or Friday were getting big temp swings here 66 today high of 36 on Friday.

 

[brenndatomu]

Alright I figured it was I am going to call and see if they'll send me another should be a warranty part as I ordered it in July. I do however still have the Honeywell fan limit switch with the spring and probe off my old furnace would likely have to readjust it.

Is there any real hazards with refiring the furnace with the blower running constant or should I get a fire going and just plug into the current switch to turn the blower on? Or just wire nut it together while I'm using it.

Will probably have to build fire by Thursday or Friday were getting big temp swings here 66 today high of 36 on Friday.

I'm sure they'll send you a new one...but I don't regret installing the Honeywell on mine.
I'd say you could bypass the switch for a day or two if needed...can't imagine how there'd be any real danger in that...

 

[R Henderson]

Just spoke with Dale about an hour ago and they are sending out a new switch, will just bypass the switch if I need a fire before it comes in.

Thank you again for the information, I'm going to save my old fan limit switch and will probably take that approach if it needs it again after the warranty is out.