tundra/heatmax owners

[bedrock1]

With my Kuuma I have my low limit button switch placed high up in my bonnet and have it set at 110/90 (put it at 105/85 when it gets very cold). Even with the computer set at minimum burn the blower pretty much runs constantly from the time it turns on till there are a handful of coals. Minimum burn will get me ~95°-100° vent temps. Max burn will get me ~110° vent temps all with the blower running the whole time. I did have to create more positive pressure in my duct though, as I seem to have over-sized ducts which would move too much air too fast not allowing the air to get properly heated. Wonder if this could be an issue as well........?

I have 8 inch duct and reduce to 5 inch I try decrease and increase the blower SBI is sending me a new snap disc that cut in at low temp hope that its a faulty one.

 

[JRHAWK9]

if yours currently cuts in at 140....then the new one should do the trick. I believe I've read they now cut in at 110.

 

[bedrock1]

I have 8 inch duct and reduce to 5 inch I try decrease and increase the blower SBI is sending me a new snap disc that cut in at low temp hope that its a faulty one.

here are some pi

With my Kuuma I have my low limit button switch placed high up in my bonnet and have it set at 110/90 (put it at 105/85 when it gets very cold). Even with the computer set at minimum burn the blower pretty much runs constantly from the time it turns on till there are a handful of coals. Minimum burn will get me ~95°-100° vent temps. Max burn will get me ~110° vent temps all with the blower running the whole time. I did have to create more positive pressure in my duct though, as I seem to have over-sized ducts which would move too much air too fast not allowing the air to get properly heated. Wonder if this could be an issue as well........?

Have some pictures this is with drafter closed this is open drafter

 

[bedrock1]

if yours currently cuts in at 140....then the new one should do the trick. I believe I've read they now cut in at 110.

Yeah the one they are sending cuts in at 110 hopefully that is the problem

 

[laynes69]

Did you reduce the 8" ducts to 5"?

 

[bedrock1]

Did you reduce the 8" ducts to 5"?

Yep I reduce to 5 inch

 

[JRHAWK9]

Yeah the one they are sending cuts in at 110 hopefully that is the problem

if yours is currently 140, the new one will make a big difference. Where is it located in the bonnet? It's best to move it as high up in your bonnet as you can. I moved my low limit button thermostat from where it was on the side of the furnace to up in my bonnet. I also added another identical one to act as a backup and to just serve as another temperature sample. One is mounted on the bonnet front/center as you face the furnace, about 24" up from the top of the furnace and the other is mounted as high up on the bonnet as I could get on the right side. I now have them both set at 110° normally but change it to 105° when it gets cold out. Doing this made a HUGE difference in the consistency of when the blower turns off/on. It will turn on whenever the first one senses 110/105 and off whenever the last one is to sense 90/85. I get more consistent heat this way as well. Before it seemed like the blower would not kick on when there were still decent coals. I don't have that issue any more. The blower runs with just a handful of coals extracting as many BTU's as possible.

Keep in mind I have a different wood furnace than you but I'd think you'd have similar results by re-locating it.

 

[bedrock1]

if yours is currently 140, the new one will make a big difference. Where is it located in the bonnet? It's best to move it as high up in your bonnet as you can. I moved my low limit button thermostat from where it was on the side of the furnace to up in my bonnet. I also added another identical one to act as a backup and to just serve as another temperature sample. One is mounted on the bonnet front/center as you face the furnace, about 24" up from the top of the furnace and the other is mounted as high up on the bonnet as I could get on the right side. I now have them both set at 110° normally but change it to 105° when it gets cold out. Doing this made a HUGE difference in the consistency of when the blower turns off/on. It will turn on whenever the first one senses 110/105 and off whenever the last one is to sense 90/85. I get more consistent heat this way as well. Before it seemed like the blower would not kick on when there were still decent coals. I don't have that issue any more. The blower runs with just a handful of coals extracting as many BTU's as possible.

Keep in mind I have a different wood furnace than you but I'd think you'd have similar results by re-locating it.

I just check the snap disc with a ohm meter and a heat gun its cutting in and out. Im is on back of the furnace when I check where it is located u have to have to have some heat to cut it in. Can u send me a picture where u have yours mounted

 

[brenndatomu]

Can u send me a picture where u have yours mounted

I think JR has a Kuuma with a plenum, completely different animal. Most wood burners would creosote up at the low fan temps that the Kuumas can get away with

 

[laynes69]

Why would you reduce the opening like that? You've reduced area of the openings by over 50%. With the 2-5" ducts, you have the equivalent of less than 1-8" opening. Not only do you overheat the firebox, you reduce your heat output of the furnace. Not to mention the blower up to 1400 cfms.

 

[maple1]

I think he tried that to increase his duct pressure at the suggestion of SBI?

 

[laynes69]

When the Tundra came out, I believe SBI said to disregard static pressures due to the 2-8" restrictions. On the Caddy, pressures need to be followed due to the large plenum opening. With 2-5" ducts, your around 40 sq inches. At 2-8" ducts, your at a little over 100sq inches. That's a huge reduction. Our Caddy which has the same firebox is pushing 144 sq inches off the plenum. You can't heat a house with little air volume. The fireboxes on these furnaces are capable of pushing alot of heat.

 

[bedrock1]

Why would you reduce the opening like that? You've reduced area of the openings by over 50%. With the 2-5" ducts, you have the equivalent of less than 1-8" opening. Not only do you overheat the firebox, you reduce your heat output of the furnace. Not to mention the blower up to 1400 cfms.

I have 8 inch coming from my furnace and the length of my house and branch off with 5 inch ,I put damper in because SBI said my furnace might be to much static pressure

 

[maple1]

I would quite likely agree with that - but was under the impression it was a temporary troubleshooting experiment.

(Edit: Replying to Laynes last post...)

 

[maple1]

That Dwyer manometer mentioned earlier can also be used to measure your duct pressures along with chimney draft. Would be a pretty handy tool to have.

 

[laynes69]

There's s reason why the comany is putting the lower sensors in their furnaces, they recover much more heat. I've ran high and low settings on ours, and I keep ours at 95 off 125 on or around there. I personally don't see a difference in the burn rate from one or the other, but I do see an increase in btus recoVered over the life of the burn. We don't accumulate creosote and we keep the house warm for many hours.

 

[bedrock1]

There's s reason why the comany is putting the lower sensors in their furnaces, they recover much more heat. I've ran high and low settings on ours, and I keep ours at 95 off 125 on or around there. I personally don't see a difference in the burn rate from one or the other, but I do see an increase in btus recoVered over the life of the burn. We don't accumulate creosote and we keep the house warm for many hours.

Where can I get a lower one I call around today no luck

 

[laynes69]

Use the one SBI is sending you. Your ductwork sounds like it's hurting you.

 

[bedrock1]

Use the one SBI is sending you. Your ductwork sounds like it's hurting you.

Why u say that

 

[bedrock1]

if yours is currently 140, the new one will make a big difference. Where is it located in the bonnet? It's best to move it as high up in your bonnet as you can. I moved my low limit button thermostat from where it was on the side of the furnace to up in my bonnet. I also added another identical one to act as a backup and to just serve as another temperature sample. One is mounted on the bonnet front/center as you face the furnace, about 24" up from the top of the furnace and the other is mounted as high up on the bonnet as I could get on the right side. I now have them both set at 110° normally but change it to 105° when it gets cold out. Doing this made a HUGE difference in the consistency of when the blower turns off/on. It will turn on whenever the first one senses 110/105 and off whenever the last one is to sense 90/85. I get more consistent heat this way as well. Before it seemed like the blower would not kick on when there were still decent coals. I don't have that issue any more. The blower runs with just a handful of coals extracting as many BTU's as possible.

Keep in mind I have a different wood furnace than you but I'd think you'd have similar results by re-locating it.

Sorry mine is 120

 

[bedrock1]

When the Tundra came out, I believe SBI said to disregard static pressures due to the 2-8" restrictions. On the Caddy, pressures need to be followed due to the large plenum opening. With 2-5" ducts, your around 40 sq inches. At 2-8" ducts, your at a little over 100sq inches. That's a huge reduction. Our Caddy which has the same firebox is pushing 144 sq inches off the plenum. You can't heat a house with little air volume. The fireboxes on these furnaces are capable of pushing alot of heat.

I have the damper open all the way now. SBI told me I was losing to much heat

 

[bedrock1]

i was looking where they have the snap disc to goes it funny they have it there because u have brick and the steet of stuff that lay on top of the pipe with the hples in it there is more heat in the front then in the back of the furnace. does that steet of stuff lay right on top of the pipes and pusth to the back.

 

[DoubleB]

I have the damper open all the way now. SBI told me I was losing to much heat

Doesn't matter if you opened the duct dampers, if you still reduce the 8" to 5" ducts, nothing will get better until you increase duct size and airflow.

 

[brenndatomu]

I have 8 inch coming from my furnace and the length of my house and branch off with 5 inch ,I put damper in because SBI said my furnace might be to much static pressure

So if I understand this right, you have two 8" "trunk" lines running the length of the house, and then 5" runs off of that going to the registers?

 

[bedrock1]

Doesn't matter if you opened the duct dampers, if you still reduce the 8" to 5" ducts, nothing will get better until you increase duct size and airflow.

But the floor vents are 5 inch