new Vapor Fire 100 with very poor heat

[JRHAWK9]

I guess I should have said my peak plenum temps occur at 2, sometimes 3 hours... depending on the load...I would think with a full firebox that 2 hours would do it...
@JRHAWK9 ?

It's been so long since I ran the stock blower setup I don't remember for sure. With the furnace on high with a full firebox, I'd think anywhere around the 2-5 hour area would work.

 

[SpaceBus]

What's a "normal" burn time coals to coals for a VF100?

 

[JRHAWK9]

I will defer to those who know better, but that just doesn't seem like much heat is being put out with those temps in the ducts.

Kuuma's heat with lower, consistent, plenum temps. Even with my slowed down blower speeds, I'm still only seeing max plenum temps of ~125° when running full bore.. When very cold out and I'm running it harder, my plenum temps stay between the 117ish to 125ish area at all times, even between aggressive loadings. This has heated our not-so-efficient place in below zero temps (-37 one night) 5 days in a row last winter. There's the other thread in this forum section of a Max Caddy owner wanting 140°+ plenum temps......if I was seeing those kind of plenum temps this furnace would completely heat us out of the house most of the time. I don't get why there is such a huge difference in plenum temps between these two good furnaces, which, the end result, heat most homes just fine. @brenndatomu went from a Tundra with higher plenum temps to a Kuuma with lower plenum temps but yet he says the Kuuma has heated his home a little easier even after he added a bit more volume to the space he's heating compared to when he was using the Tundra. So I get why you see things the way you do. Maybe the blower on the Kuuma moves more air...? I really have no idea. Two good furnaces heating homes two different ways I guess.

 

[JRHAWK9]

What's a "normal" burn time coals to coals for a VF100?

All depends on how much fuel you add and how far the computer is turned up and how many coals you want to load on. In my case during mild weather I want to load on minimal coals but on very cold days I load on a fair amount of coals and start pulling them forward an hour or so before loading to get them to burn down faster so I can load faster.

What I use:
4-5 lbs/hr on low
5-7 on medium
7-9 on high.

Just this last weekend we were gone again and I loaded the furnace full (85lbs) right before we left and set it to minimum burn to keep the LP from running. I got 20 hours of blower run time out of that single load. Past experience tells me when the blower shuts off there are just enough coals left to reload on.

 

[gary38532]

All depends on how much fuel you add and how far the computer is turned up and how many coals you want to load on. In my case during mild weather I want to load on minimal coals but on very cold days I load on a fair amount of coals and start pulling them forward an hour or so before loading to get them to burn down faster so I can load faster.

What I use:
4-5 lbs/hr on low
5-7 on medium
7-9 on high.

Just this last weekend we were gone again and I loaded the furnace full (85lbs) right before we left and set it to minimum burn to keep the LP from running. I got 20 hours of blower run time out of that single load. Past experience tells me when the blower shuts off there are enough coals left to reload on, but not an excessive amount

That never happens for me my blower shuts off all the time and it's not ready for wood... Then again mines always cold

 

[SpaceBus]

All depends on how much fuel you add and how far the computer is turned up and how many coals you want to load on. In my case during mild weather I want to load on minimal coals but on very cold days I load on a fair amount of coals and start pulling them forward an hour or so before loading to get them to burn down faster so I can load faster.

What I use:
4-5 lbs/hr on low
5-7 on medium
7-9 on high.

Just this last weekend we were gone again and I loaded the furnace full (85lbs) right before we left and set it to minimum burn to keep the LP from running. I got 20 hours of blower run time out of that single load. Past experience tells me when the blower shuts off there are just enough coals left to reload on.

85 lbs of wood would last me three days if weather is above 30df

 

[JRHAWK9]

That never happens for me my blower shuts off all the time and it's not ready for wood... Then again mines always cold

constant cold return air and faster blower speed will do that

 

[JRHAWK9]

85 lbs of wood would last me three days if weather is above 30df

yeah, the house got up to 79° that day, but I was aiming at keeping the LP from running, hence I loaded way more than I normally would have for the outside temps. I knew it was going to overheat the house.

 

[Woodman1]

Is it possible to slow the blower down while at the same time having the furnace set for max output or are they tied together?

 

[brenndatomu]

Is it possible to slow the blower down while at the same time having the furnace set for max output or are they tied together?

Not tied together at all...unless the plenum temp gets so high that it automatically kicks the blower to high...don't think there is much danger of that here right now...

 

[Woodman1]

I think that would be my next step then. Somehow get that plenum temp up. Way up if possible.

 

[JRHAWK9]

That would require speed controlling it and I'm not sure it would help in his case. He already tried running the blower on low to increase is plenum temps and it didn't heat the house any better.

 

[gary38532]

That would require speed controlling it and I'm not sure it would help in his case. He already tried running the blower on low to increase is plenum temps and it didn't heat the house any better.

Very true I would need higher temps with a high amount of air movement

 

[Woodman1]

And that equals more btu's

 

[Woodman1]

We keep going in circles here. Most forced air systems are designed for register temps between 120-140. I just remember when I was looking at geothermal systems I was told expect register temps in the 85-90 degree range. The system was designed to basically maintain, it would take many hours to recover from a temperature set back of a few degrees. Even with very well insulated homes some form of back up was required when temps got down near zero.

Hopefully something gets figured out here real quick before it gets cold and you actually need some heat. No doubt the rim joists and basement walls will help. Anything you do to insulate and seal will help

 

[gary38532]

Hopefully something gets figured out here real quick before it gets cold and you actually need some heat. No doubt the rim joists and basement walls will help

yup the way it is now this stove wont do anything come jan/feb thats what Ive been worried about all along

 

[Woodman1]

I feel for you. I still think the furnace is excellent by design. I'm sure can be made to work. However, time is not your friend right now.

If laampa says this is way the furnace is designed to operate at these low output temperatures, your going to need to do a lot more work to your house than simply insulating the rim joists.

I would be looking for some type of cheap backup plan. Somewhere you could find a inexpensive wood stove that could use that 6" chimney. It could sit right where the kuma is and would buy you some time to get your house in shape. Of course this is worse case senerio, but at this point with what has been gone through, this is where my mind is thinking. I like backup plans. Good luck

 

[JRHAWK9]

Most forced air systems are designed for register temps between 120-140.

Don't know of a single Kuuma owner who sees that high of plenum temps, much less register temps. I see into the 120's at the plenum simply because I'm speed controlled and run a very slow blower speed. Heck, my 75KBTU LP furnace only produces 125° duct temps at around 6' from the plenum......and it's using the slowest tap on the blower motor. 120°-140° at the registers would require a monster wood furnace will a HUGE appetite to be able to convert ~6,500 BTU's/lb of wood into the BTU's required for that kind of register temp.....assuming similar blower speeds/air volume movement.

Gary's house may indeed need more BTU's than the Kuuma is capable of, all we are trying to do is optimize/figure out things to see if this is the case for sure. I was able to optimize my Kuuma for my house by making some simple return/supply air changes, the furnace was always producing the BTU's, I just needed to more effectively get them into the house. Although where I started from was much better than where Gary is starting from.

 

[Woodman1]

Don't know of a single Kuuma owner who sees that high of plenum temps, much less register temps. I see into the 120's at the plenum simply because I'm speed controlled and run a very slow blower speed. Heck, my 75KBTU LP furnace only produces 125° duct temps at around 6' from the plenum......and it's using the slowest tap on the blower motor. 120°-140° at the registers would require a monster wood furnace will a HUGE appetite to be able to convert ~6,500 BTU's/lb of wood into the BTU's required for that kind of register temp.....assuming similar blower speeds/air volume movement.

Gary's house may indeed need more BTU's than the Kuuma is capable of, all we are trying to do is optimize/figure out things to see if this is the case for sure. I was able to optimize my Kuuma for my house by making some simple return/supply air changes, the furnace was always producing the BTU's, I just needed to more effectively get them into the house. Although where I started from was much better than where Gary is starting from.

I understand, and I don't disagree. However Gary has been given a early Christmas gift with this beautiful warm weather. It may not last all winter. I think it is time to quit sugar coating this and call it for what it is. Unless he can find a way to raise his plenum temperature I think he may be in trouble come winter.

 

[gary38532]

I do not claim to be a cardboard engineer... is it safe? well it is held together with zip ties and duct tape so I would say yes!

 

[maple1]

I can't see a woodstove doing any better than the VF. If one could be added, that would no doubt help.

 

[gary38532]

120°-140° at the registers would require a monster wood furnace will a HUGE appetite to be able to convert ~6,500 BTU's/lb of wood into the BTU's required for that kind of register temp

I bet my clayton could come close it was set to shut off at 125 plenum temps. As in the forced draft would shut down after 125 was reached

 

[gary38532]

I can't see a woodstove doing any better than the VF. If one could be added, that would no doubt help.

I was going to get one and everyone told me not too... I missed the rebate on the stove now so now it would be like 6500

 

[SpaceBus]

View attachment 254096
I do not claim to be a cardboard engineer... its it safe? well it is held together with zip ties and duct tape so I would say yes!

I hope this helps. I've seen elsewhere on the forums where folks have rigged cardboard for temporary ducts to try and pull warmer return air.

 

[gary38532]

I hope this helps. I've seen elsewhere on the forums where folks have rigged cardboard for temporary ducts to try and pull warmer return air.

yeah I have my doubts.... the air on the floor of the basement was 66 this morning and thats what it was in the living room also... its not much warmer up high is what I am getting at.