Kuuma VF100 arrived

garmford said:

My fan goes in and off too. I've contacted Daryl and he gave me a few pointers. I am burning good wood. Even when the furnace is in pilot mode it still does it. So I finally set the low limit to 100 and it's been better but time will tell. Other than that I love this furnace so far!

Click to expand...

Is the T-stat calling for heat when you start up? If so the fan is on high and I can see this doing that. Try it without the T-stat calling then after well hot turn it on. If it is still doing it turn the computer to medium or 1/2.

I've turned the t-stat down to avoid the higher blower speed and have thought about setting the computer higher for the first hour or so. I'll have to try that next time. My dilemma is even if I reload over hot coals after the fan starts cycling due to the cooling firebox, it never stops short cycling. For example, Sunday morning I reloaded over hot coals and the fan was short cycling because it was towards the end of the burn. After 1 1/2 hours I came back in the house to a hot fire, computer in pilot mode, and the fan still short cycling. The low limit was set at 105. So I turned the low limit down to 100 for a few seconds then back to 105 and the the fan stayed running for the rest of the burn. Since then I talked to Daryl and I set the switch to 100. So far it's been a little warm in these parts so I've let the fire burn out during the day, so I haven't had a chance to really test it out.
Sorry for the rambling. I just like to give as much info that I can.
Thanks for all of the advice! That's what makes this forum so great!!

Mine will cycle at the end of a burn like it should, but doesn't short cycle. However, I moved my low limit switch up much higher in the plenum instead of on the side of the firebox per Daryl's recommendation for more consistent kick in/off temps. I also have it set at 115°. It turns off at 95° on the nuts every time like clockwork according to my HVAC thermometer.

When I have just coals left I'm normally towards the end of a burn and the coals are concentrated in the back of the firebox due to the front to back burning.

garmford said:

My fan goes in and off too. I've contacted Daryl and he gave me a few pointers. I am burning good wood. Even when the furnace is in pilot mode it still does it. So I finally set the low limit to 100 and it's been better but time will tell. Other than that I love this furnace so far!

Click to expand...

Is the T-stat calling for heat when you start up? If so the fan is on high and I can see this doing that. Try it without the T-stat calling then after well hot turn it on. If it is still doing it turn the computer to medium or 1/2.

garmford said:

I've turned the t-stat down to avoid the higher blower speed and have thought about setting the computer higher for the first hour or so. I'll have to try that next time. My dilemma is even if I reload over hot coals after the fan starts cycling due to the cooling firebox, it never stops short cycling. For example, Sunday morning I reloaded over hot coals and the fan was short cycling because it was towards the end of the burn. After 1 1/2 hours I came back in the house to a hot fire, computer in pilot mode, and the fan still short cycling. The low limit was set at 105. So I turned the low limit down to 100 for a few seconds then back to 105 and the the fan stayed running for the rest of the burn. Since then I talked to Daryl and I set the switch to 100. So far it's been a little warm in these parts so I've let the fire burn out during the day, so I haven't had a chance to really test it out.
Sorry for the rambling. I just like to give as much info that I can.
Thanks for all of the advice! That's what makes this forum so great!!

Click to expand...

I have had my unit set on 100 for a few years now, I find I get the most heat at that spot. I do remember now that in the beginning that the fan didn't seem to come on at the right time, and when I moved the temp dial to 100 then to 105 the fan came on and stayed on. In the end I found that I had the high limit in the wrong spot so even tho the T-stat wasn't calling the fan started in high. After I moved the High limit up stream some it didn't happen any more. Also I have found that I only need the T-stat if it gets below zero outside.

I do turn the t-stat down so the blower stays at the lower speed. I also put my low limit higher in the bonnet like jrhawk did. How far did you need to move the high limit?

My ceilings are not near as high as yours. My issue was, to get the ductwork the way I wanted it I had to go from square to round back to rectangle. So it was not possible to place it at their suggested location. The high limit is about 18" now. I also happen to have a string from a pull string light that hangs in front of my basement vent, that lets me know what the fan is doing. I think I went the whole year before I noticed the high fan on, at start up. Not reload.

Monaco, it does sound like a bad fan sensor. But looking back at your pics the high limit that sticks in the plenum about 10-12 inches, is mounted at an angle putting the tip of the probe very close to the HE. This may be putting the fan in high all the time. (even then it should run a lot longer than 1 sec) I would move that a ft higher. Also do you have supply registers in your basement? or an always open basement door? Thinking of neg press in basement. Also what is slightly green wood? what kind is it, and how long was it stacked for? When the fan is short cycling how hot is the bonnet?(sarcasm now) WE TOLD YOU NOT TO LEAVE THAT OUT IN THE RAIN

Have you checked for a good connection at the low limit? Those female adapters sometimes need a pinch to tighten them. Could be just poor connection.

cold air return temp? Bonnet temp? Static pressure in bonnet? MC of wood? Does the computer go to pilot during the middle of the burn or does it constantly go from pilot to '1'?

You may want to look into connecting your cold air return duct to the furnace if your basement is going to be staying that cool. It should warm up though as your house warms up. My basement is generally right around the same temp as my house when burning and I don't have any open supply registers down there. It's solely heated by the radiant heat off the Kuuma. I use an open staircase for my return air.

Last night I did a cold start too. T-stat down and the computer up. It cycled for about an hour and that was it. Ran until now. But now I just loaded it and have to leave for a few hours so I won't be able to watch it. But at least last nights start was promising!

Monaco said:

High limit sensor:
What I did was measure the height from the tip to the top of the burner and mounted it high enough to keep the same measurement.

My fan is never on high - so that part seems to work (I can control the fan speed with the thermostat.)

The intake seems to work properly, from C to 3,2,1, c and so on.

Basement has no supply registers but the temp is always the same as the house. 65-68 when I fire it up and it heats up fast from just being near the furnace. There's an open door right by the furnace, and the cold air return from upstairs is right above it.The room the furnace is in gets pretty warm when it's going good - close to 80F.

It's been better though since I turned the dial down to 100. I've only had the opportunity to cold-start twice though.

This morning I did another cold start with no fan cycling (the house was at 68). However: this odd thing happened twice: The control box turned off, then back on a few seconds later. By off, I mean the LED went out, the damper closed- then when it came back on on it did the single "beep" it does when it's turned on.

Click to expand...

That is the unit going out on high limit. (safety) High speed fan comes on by the high limit not just by the t-stat. I suggest you call Lamppa immediately and get a new fan sensor. You have a problem there.

Monaco, these are the same symptoms that I've been having since I've had it hooked up. Ive also had my computer go black and come back. It's happened twice at least, but I dont sit and watch it 24/7. Even tonight I started a fire, 2 1/2 hours later it's still cycling. That's with the switch at 100, fan on low, computer on medium. It's getting frustrating. He must have had a bad batch of switches! I'll email him tonight and see if I can get a replacement and try it out.

Mine has been sitting in the basement for several weeks, not hooked up yet. I'm curious if there is a sensor issue. I'll be watching this thread.

motoguy said:

Mine has been sitting in the basement for several weeks, not hooked up yet. I'm curious if there is a sensor issue. I'll be watching this thread.

Click to expand...

I think I would hook it up & get burning anyway. Or maybe there are other factors...

Yeah, this won't be a critical factor. Still need to get ductwork fabbed to tie it in.

Monaco said:

Just to clarify - this is not the same as the high temp error, where it does the continuous beep and gives the error code. It's more like the computer loses power.

Click to expand...

Did the fan keep running when the computer went blank?

Super curious to see what is going on there. Seems to be 2 separate issues going on. Unless the computer keeps blanking off causing the unit to not get to temp.

I've been keeping an eye on this thread. A big thank you to our current Kuuma owners for always trying to be so helpful on any type of questions or issues. I really appreciate you doing this! For anyone with questions or concerns please feel free to call or e-mail us directly, but sometimes it's easier to use this awesome forum. When contacting us it's great to first e-mail some pictures of your set-up before calling my dad directly at the shop the next day. He's much more detailed over the phone, especially if he has seen your set-up. He does only goes over e-mail once a day with my mom and it's usually later at night. Rest assured that we will get you taken care of because we want you to have a great customer experience. Please make sure that you follow the installation instruction in the owners manual, which can also be found on our website. The majority of issues we have ever had come from incorrect installation. From time to time we do receive defective parts from our suppliers, and if that's the issue it's very easy for us to get you out a replacement. My dad does a good test of a couple items before the furnace is shipped, but this can't catch everything.

To summarize We spend a ton of time helping people with questions. I couldn't even tell you how many e-mail chains we get going with some owners to ensure proper operation. So any that are solved here it's really appreciated!