Kuuma VF100 arrived

[brenndatomu]

A nice dwyer from Ohio.

LOL, Yeah. I'm sure that is your favorite one...but I was referring to that pic (now that you can load it here) of your new Dwyer with all his buddys

 

[STIHLY DAN]

This one?

 

[brenndatomu]

There it is...the guy is as big of a tool hound as me!

 

[DaveH]

In response to some of the other posts, I have not been able to get the house above 68 with outdoor temps being at 32 or lower... Now matter where I put the control knob or thermostat.

I'm having the same struggles as you. What is your home sq. footage? It's been bitter cold here, single digits. Yesterday morning the home was about 66 when I left for work with a half load of wood in. I came back 12 hours later and my home was at 59. I reloaded but the house crept up to 61 after a load of Black Locust. With the fire roaring last night, I turned the computer from low to medium when the damper was in pilot (c). This opened the damper to a 1, stoked the fire and caused the furnace to alarm. I had to turn the computer down to just below medium in order for the damper to stay closed. Woke up and still at 60. I'm not getting the long burn times no matter what wood I load.

 

[JRHAWK9]

I'm having the same struggles as you. What is your home sq. footage? It's been bitter cold here, single digits. Yesterday morning the home was about 66 when I left for work with a half load of wood in. I came back 12 hours later and my home was at 59. I reloaded but the house crept up to 61 after a load of Black Locust. With the fire roaring last night, I turned the computer from low to medium when the damper was in pilot (c). This opened the damper to a 1, stoked the fire and caused the furnace to alarm. I had to turn the computer down to just below medium in order for the damper to stay closed. Woke up and still at 60. I'm not getting the long burn times no matter what wood I load.

I would not expect a half load of wood to heat a home for 12 hours in single digits. A half load for me in my Kuuma is about 30-35lbs. Wood has about 6,000 BTU's per pound @ 20% MC. If you are burning, say, 35lbs in 12 hours. Assuming 80% efficiency you are only averaging 14,000 BTU's per hour over that 12 hour span. Unless your home is small and/or VERY well insulated, 14,000 BTU's per hour will not be enough to heat in cold weather. You can't create BTU's......wood only has so many to give. The more wood you burn the more heat you will get out, assuming constant efficiency. For me in my in-efficient house, in sub zero temps, all my effort goes into trying to get the furnace to burn as much wood as I can. It seems to burn, max, about a full load every 8 hours or so. It's not capable of burning much more than that. Back when I was looking at purchasing the Kuuma and speaking with Daryl, I told him what we used for propane over the years and the area and style house we have. He pretty much told me I'm lucky the house was not any bigger. I knew going in I was at around the max heat load for the Kuuma.

The Kuuma is a very efficient, well built furnace, however it's not a miracle heater and can't create any more BTU's than the wood offers.


My advice, try to get the house up to temp and keep it there. It's a snowball effect once it starts to cool. You have colder air in which will mean colder air out. It will take a lot of BTU's to recover a cold house in cold weather. There were times last year when it was -17° in the morning and at the end of the burn the house would drop to 64°. I reloaded the wood furnace and then also kicked the LP on to get the house up to temp ASAP. I would have both furnaces running for about an hour to get the house temp back up and once it was I shut the LP off and the Kuuma maintained it throughout the burn cycle, until it reached the end of the burn.

 

[lampmfg]

I just spoke with my dad and he said if anyone is having issues to call him at the shop 1-800-358-2049. Most of the time it's only a handful of things that it could be and he's more than happy to help you out.

Remember, it's nearly impossible to burn wood more efficiently, but's it's not a miracle worker if you have poor insulation and a huge house in subzero temperatures, especially if your set-up hasn't been fine tuned yet.

Thanks!

 

[DaveH]

I haven't been able to fill the furnace without an alarm. I'm going to get the house up to 66 with LP and try to keep up with it. Half the issue is being out of the house for 10+ hours a day, combined with not trusting a full load not to alarm.



I'm

 

[JRHAWK9]

I get the alarm on occasion when I fill the firebox on a lot of coals from all the outgassing that happens. I'd contact Daryl to be sure, but in my situation he told me not to worry about it. The alarm is more or less there to alert you if you'd leave the ashpan door open, have way too high of draft or something of that nature. It's not like the furnace will melt when the firebox reaches that alarm temp. Talk to Daryl to be sure, as you may have a different situation and I don't want to tell you something wrong and/or un-safe. Make sure both your doors are sealing and make sure your draft is in check.

 

[STIHLY DAN]

I haven't been able to fill the furnace without an alarm. I'm going to get the house up to 66 with LP and try to keep up with it. Half the issue is being out of the house for 10+ hours a day, combined with not trusting a full load not to alarm.



I'm

@DaveH did you get a new low limit? Also how high is your Hi limit installed above the plenum. I will put money on your low limit is not accurate, have lamppa replace it, Seems to be a bad batch out there.

 

[DaveH]

I did not get a new low limit. I'll call as soon as I have some time. I brought up my high limit height whe I spoke with Daryl last , he said it was fine. About 5 inches up. Might move it a bit

 

[STIHLY DAN]

DaveH, Looked through the install pics, There were many questions on the ductwork and sizing. Did you ever install back draft dampers in the gas furnace.? Did you increase the size of that 14 inch round 154 sq inches return duct with a larger size?

 

[JRHAWK9]

DaveH, does your blower run all the time when in the middle of a burn like it should or does it act like garnford's did before he installed the new low limit? You really should look into some sort of temp gauge for your plenum, makes troubleshooting easier when you know what your fan kick-on/off temps are. A manometer would also be handy for checking your draft and static pressures.

Dan has a point with his questions, as I assumed your ductwork sizing was correct and had the correct back draft dampers in place. You may be short circuiting your Kuuma supply air by not having any back draft dampers in place. Hot air from Kuuma back feeds the cold air from the LP and then gets sucked back into the cold air of the Kuuma. This would be possible, right Dan?

The high limit shouldn't be an issue, as he's talking about the firebox alarm/overtemp and not the plenum overtemp.

 

[DaveH]

I have dampers installed, so air shouldn't be getting into the LP furnace. I'm in the process of new duct work. I have some 160 in duct work that has to go.

I need more return for sure. Going backwards from the blower is 14 in round, 8ft run of 196 sq in duct, then it chokes down to 160. This will get done very soon.

Do you guys step down the duct work? how long is your runs of 180-200sq in. ? My furnace is in the corner, back to the short wall of a center hall colonial. The main supply trunk runs the entire length of the basement. I get minimal air pressure by the end of the run.

As far as the blower cycling, today with the thermostat calling for heat and the computer on pilot, the fan shut down. I grabbed the phone to call Daryl but after maybe 10 minutes it kicked back on and has stayed on for the past hour or so.

 

[JRHAWK9]

As far as the blower cycling, today with the thermostat calling for heat and the computer on pilot, the fan shut down. I grabbed the phone to call Daryl but after maybe 10 minutes it kicked back on and has stayed on for the past hour or so.

I'm guessing the blower was on high (the thermo calling for heat) and then the air jacket temp dropped below what the low limit was set at, therefore turning off the blower circuit. Having some HVAC thermometers would help you verify this by monitoring your plenum temps and comparing the actual temp to what the low limit is set at.

IMO, the stock location of the low limit button switch is not the greatest. It's on the side and is susceptible to cooler air, especially when doing a cold start. The air is blowing up from the bottom and the air which passes over it does not even include any heat coming off the heat exchanger or even all the radiant heat off the full main part of the furnace. If you mount it higher up in the plenum it will see hotter air from the whole furnace plus the heat exchanger. Hot air rises, it doesn't go sideways ;-) Daryl knows this but it's a UL listing thing, as he has to have it mounted and wired in order to get UL listed I guess.

 

[Monaco]

I just got off the phone with Lamppa. They're really nice people and boy are they helpful.

They sent me a new computer and button temp sensor, and I have them installed. He advised I move the button sensor high up into the bonnet, which will make the sensing more accurate.

Over temp alarm:
When I installed the new sensor, I left it at 105. My fan shut off a good two hours before what it would with it set at 100-102F - giving me only about 8 hours of fan time. This morning there were a LOT of coals, so I loaded over top of them. About 3 hours later, the high temp came on. Daryl said the right idea is to always scrape the back of the firebox clean, down to the stone. Leaving coals there underneath a load of new wood messes up the front-to-back burn, causing excessive gassing.

So I'm going to move the button sensor off the side of the furnace up to the spot I have marked in green, turn it down a little, and will see what happens.

I think I prefer the 12 hour fan time. Even though air feels more lukewarm at the very end of the burm, it's still way warmer than outside, and it's still considerable, continuous BTUs going into the house - unlike when the fan is off.

 

[Monaco]

IMO, the stock location of the low limit button switch is not the greatest. It's on the side and is susceptible to cooler air, especially when doing a cold start. The air is blowing up from the bottom and the air which passes over it does not even include any heat coming off the heat exchanger or even all the radiant heat off the full main part of the furnace. If you mount it higher up in the plenum it will see hotter air from the whole furnace plus the heat exchanger. Hot air rises, it doesn't go sideways ;-) Daryl knows this but it's a UL listing thing, as he has to have it mounted and wired in order to get UL listed I guess.

That is exactly what Daryl just told me - he said it should absolutely go higher onto the bonnet - if you can. He said if they sold the bonnet with the furnace, it would be installed higher by default.

 

[JRHAWK9]

I would move the sensor to the back side of where you show. This way the sensor is actually over the top of the furnace due to the angle of your plenum and it will see a better representation of the temp coming off the furnace. As Daryl already probably mentioned, you will most likely need to raise your low limit as well, as you will notice the fan running almost all the time with it set at 100°. I have mine set at 115° with my sensor moved. May put it down to 110° when/if we get some real cold weather though.

 

[Monaco]

I would move the sensor to the back side of where you show. This way the sensor is actually over the top of the furnace due to the angle of your plenum and it will see a better representation of the temp coming off the furnace. As Daryl already probably mentioned, you will most likely need to raise your low limit as well, as you will notice the fan running almost all the time with it set at 100°. I have mine set at 115° with my sensor moved. May put it down to 110° when/if we get some real cold weather though.

Thanks - very good points - I'll move it to the back side. I'll enjoy being able to access the thing without a pocket mirror and double-jointed elves :D

 

[STIHLY DAN]

This morning there were a LOT of coals, so I loaded over top of them. About 3 hours later, the high temp came on. Daryl said the right idea is to always scrape the back

How could you not do this Mr. There is even pictorial Directions on the front of the unit, along with the provided tool. I thought they put that there for the wives.

 

[JRHAWK9]

How could you not do this Mr. There is even pictorial Directions on the front of the unit, along with the provided tool. I thought they put that there for the wives.

lol.....someone had to say what all of us Kuuma owners were thinking ;-)

 

[Monaco]

How could you not do this Mr. There is even pictorial Directions on the front of the unit, along with the provided tool. I thought they put that there for the wives.

Duly noted

I had never seen so much coals before. Presented with the unknown, I shrugged and raked "most" of them forward thinking "well, I'm sure it doesn't have to be EXACTLY like the illustration

 

[STIHLY DAN]

The low limit at a lower temp will allow you to get more heat from those coals so you can reload later. I get it when it doesn't get as cold at night as the weather men say and load to much wood in. I load for time, especially at night because the morning is up and out. No dilly dallying.

 

[JRHAWK9]

Had our first cold spell of the winter on Saturday night and all day Sunday. It made it down to -1° Saturday night and never got above 1° on Sunday. The house was 72°-74° the whole day Sunday. Sat around in my skibbies watching football all day....lol It was -4° by 10pm Sunday and by midnight it was -7° and when I got up Monday morning at 6:30am it was -14°. The house was 71° at midnight and was 65° when I got up Monday morning with coals in the furnace and the blower cycling. This is with my relocated low limit switch set at 115°. I dropped it to 110° this morning in order to get a bit more heat out of it at the end of the burn cycle.

 

[STIHLY DAN]

What time did you load it on sunday night.

 

[JRHAWK9]

I almost always load for the night around 9:30 - 10pm. I knew what the temps were at midnight because my digital indoor/outdoor thermo I have clears the highs and lows for the day at midnight.