Everything Drolet Tundra - Heatmax...

[brenndatomu]

If I add one more duct will it increase my sp or decrease? I feel it seems kind of inefficient that most my ducts on the first floor are close so much to get the heat up stairs plus my sp where it should be

I agree completely.
Adding a duct will make it drop.

Not to mention I heard my fan jump into high mode today so I'm nervous.

I agree again...in my experience that is 50* higher than "normal" supply plenum operating temps with a Tundra.
As I mentioned before, I quit chasing the seemingly unachievable .2 SP.
Temp rise means much more to me than SP. If you can get a 40-50* temp rise, I'd call it good.
That should put your plenum temps in the 110* - 120* range, and that will heat your house. My Kuuma seldom runs over 120* in the plenum...spends most of the time in the 110-115* range honestly. I don't even know what my SP is (I'm sure its low, real low) not sure Lamppa even mentions SP in the manual either.
I'd open those ducts back up at least a little and run it! Adjust them for more or less heat where you want/need it, never mind the SP.

 

[brenndatomu]

Plus 125* air coming out of your plenum will pull more heat from the flue gasses than 175* air will...that means better efficiency. Better deltaT

 

[brenndatomu]

Mine switched to high mode automatically today and I checked the temp and it said 175.

Good info, thanks!

 

[Getwidit]

I thought u when u said 40 to 50 higher u meant at the far end of the duct work. Not what the actually plenum temp is. That makes more sense. My plenum is generally between 120 and 140. I was going to say I'm lucky if my air temp at duct is 85 90. Besides today and it only kicked into high mode for maybe 5 minutes max.

I'm thinking I might need to just bust my fan up one notch to strip alittle more heat from the plenum and to be able to open my first floor vents alittle more. Seem like the basement is the hottest room in the house.

 

[Getwidit]

Well the reason I thought I should close the ducts up some was because of low sp? Which was causing the over heat fan to kick on? Maybe I have this whole thing backwards.

 

[brenndatomu]

Closing the ducts off...or having less of them, will raise SP...and the plenum/duct temps too.
If you are running 120-140* plenum temps then that is plenty...you could speed the blower up one notch...or just open the ducts back up some...accomplish the same thing.
Personally, I like having the ducts open as much as possible so that the system has at least a shot at gravity heating if the power goes out with a full load in the firebox...heat going up the ducts into the house means the firebox is being cooled down, at least to some degree.

 

[Gbawol42]

SBI finally emailed me back with the specs for the blower speed vs plenum temps. Also the safety cut off for plenum temp. Here is what they said.

The blower modulates based on the plenum temperature. If the plenum reaches a temperature of 250 F then the unit will automatically close the air supply damper and put the blower on high (speed 4) until the temperature drops below 175 F. See KIP ( Kick In Point) and KOP (Kick Out Point) values below.

 

[brenndatomu]

SBI finally emailed me back with the specs for the blower speed vs plenum temps. Also the safety cut off for plenum temp. Here is what they said.

The blower modulates based on the plenum temperature. If the plenum reaches a temperature of 250 F then the unit will automatically close the air supply damper and put the blower on high (speed 4) until the temperature drops below 175 F. See KIP ( Kick In Point) and KOP (Kick Out Point) values below.

Excellent info!
Boy, 110* seems like a high KOP to me...losing some BTU's for sure!

 

[Gbawol42]

Excellent info!
Boy, 110* seems like a high KOP to me...losing some BTU's for sure!

This is exactly what I was thinking.

This also really makes me wonder about my wood because I don't think I have ever seen my plenum go above 150. I have seen 145 on a startup, but that about it.

 

[Mojappa]

This is exactly what I was thinking.

This also really makes me wonder about my wood because I don't think I have ever seen my plenum go above 150. I have seen 145 on a startup, but that about it.

Makes me wonder what I’m doing wrong, I hit 180 pretty easily though it cools down to 150 quickly and hangs out there for a while. Highest I’ve seen is 210. I thought maybe I was waiting g too long to close the primary air but if I do that much sooner the Fire seems to fizzle down within 5-10 minutes and I have to reopen the primary air until it’s going stronger.

 

[Gbawol42]

Makes me wonder what I’m doing wrong, I hit 180 pretty easily though it cools down to 150 quickly and hangs out there for a while. Highest I’ve seen is 210. I thought maybe I was waiting g too long to close the primary air but if I do that much sooner the Fire seems to fizzle down within 5-10 minutes and I have to reopen the primary air until it’s going stronger.

I also wondered if I had a lot of gravity flow in my system keeping some of the heat moving up while the blower was off. I have all 6 of my pipes off the plenum pointed up.

My flue warms up great, up to about 600-650 in usually under 20 minutes, front of the stove usually around 450-500 on the magnetic. But like I said the plenum only gets to around 140 in these conditions. I think I need to try a full load of for sure dry wood to see what it is supposed to burn like and let that be the judge of my woods current condition.

 

[brenndatomu]

I also wondered if I had a lot of gravity flow in my system keeping some of the heat moving up while the blower was off. I have all 6 of my pipes off the plenum pointed up.

Exactly what I was thinking...

 

[JRHAWK9]

man, I don't get why you guys are shooting for such crazy high plenum temps....?? Get that warm air up stairs. The way I see it, all you are doing by keeping that heat built up in your plenum is reducing your overall delivered efficiency and probably heating up the space where the furnace is located more than you should be.

Maybe I'm being ignorant though, as only experience I have is with my furnace.

 

[Mojappa]

man, I don't get why you guys are shooting for such crazy high plenum temps....?? Get that warm air up stairs. The way I see it, all you are doing by keeping that heat built up in your plenum is reducing your overall delivered efficiency and probably heating up the space where the furnace is located more than you should be.

Maybe I'm being ignorant though, as only experience I have is with my furnace.

I’m certainly not shooting for high numbers, it’s just what seems to happen at the beginning of a load, especially if the stove still has some heat to it from the previous load. Might also be because I only have 3 of the 6 ducts hooked up so far, hoping to have two more done on Sunday.

 

[brenndatomu]

Might also be because I only have 3 of the 6 ducts hooked up so far,

That'll do it.

 

[Gbawol42]

man, I don't get why you guys are shooting for such crazy high plenum temps....?? Get that warm air up stairs. The way I see it, all you are doing by keeping that heat built up in your plenum is reducing your overall delivered efficiency and probably heating up the space where the furnace is located more than you should be.

Maybe I'm being ignorant though, as only experience I have is with my furnace.

Well my issue is I feel I need to keep the plenum warmer so the blower stays on longer. I am doing a lot of cycling after the damper is closed. I feel the less the blower runs the warmer my basement is. I do kinda wish the blower was set up to continue running a little below 110, and maybe at a slower speed to accommodate it. To be honest the speed 1 is pretty fast imo. Maybe it was to be that way to maintain SP? Not sure.

 

[Mojappa]

Well my issue is I feel I need to keep the plenum warmer so the blower stays on longer. I am doing a lot of cycling after the damper is closed. I feel the less the blower runs the warmer my basement is. I do kinda wish the blower was set up to continue running a little below 110, and maybe at a slower speed to accommodate it. To be honest the speed 1 is pretty fast imo. Maybe it was to be that way to maintain SP? Not sure.

Maybe one of the veterans of the Drolet furnaces can correct me but I think the variable speed control mod is supposed help with that.

 

[JRHAWK9]

I also wondered if I had a lot of gravity flow in my system keeping some of the heat moving up while the blower was off. I have all 6 of my pipes off the plenum pointed up.

I have a completely open and very large plenum which ties into a 24x10 (?) main duct. This is done so there is gravity flow in case of a power outage.

Well my issue is I feel I need to keep the plenum warmer so the blower stays on longer. I am doing a lot of cycling after the damper is closed. I feel the less the blower runs the warmer my basement is. I do kinda wish the blower was set up to continue running a little below 110, and maybe at a slower speed to accommodate it. To be honest the speed 1 is pretty fast imo. Maybe it was to be that way to maintain SP? Not sure.

I bet the basement is warmer the less the blower runs as it's not delivering the heat up stairs....hence your delivered efficiency is low.

Slowing my blower down made a HUGE difference in our house. It's turning so slow at the 96° kickoff I can barely even feel it pull air into the furnace on the cold air side when I put my hand over the intake at the basement ceiling. Doubt I would be able to feel anything come out of the vents upstairs. Only way to find out if it will work for you is to speed control your blower. This is what I did to mine. Doing so made a difference, but the biggest difference was when I started to experiment with slowing the blower down. The more I slowed it down the better results I saw. I'm not so sure slowing the blower down as much as I did will work for all setups though. No idea why it worked so good for me. I never had an issue with the blower cycling, sure, it cycled at the end of a burn, but it always ran constant throughout most of it. It was just blowing higher volumes of cooler air compared to the lower volume of warmer air it does now.

 

[brenndatomu]

Maybe one of the veterans of the Drolet furnaces can correct me but I think the variable speed control mod is supposed help with that.

That it exactly why it was done...all that blower cycling drove me crazy...and I knew there was BTU's being lost at the end of the burn when the blower was off more than on. Blower speed control makes the blower speed follow the plenum temp...VERY little cycling...

 

[JRHAWK9]

Blower speed control makes the blower speed follow the plenum temp...VERY little cycling...

or in my case, zero cycling due to the slow blower speed. It's either on or off. When it turns off you pretty much need to do a matchless re-light to get things warmed back up before it will kick back on. The blower runs non-stop if there's any amount of fire and/or coals.

 

[Gbawol42]

or in my case, zero cycling due to the slow blower speed. It's either on or off. When it turns off you pretty much need to do a matchless re-light to get things warmed back up before it will kick back on. The blower runs non-stop if there's any amount of fire and/or coals.

This would seem like the ideal way to keep the most heat upstairs and not dumping into the basement.

I'm sure you guys are kinda getting hit by this cold snap, I believe it is dipping pretty low in the country. Want to just watch and run the furnace as is to get a little more data now that i can start putting bigger loads into the firebox.

Only 22 degrees right now. In the beginning of November, ugh.

 

[JRHAWK9]

I'm sure you guys are kinda getting hit by this cold snap,

yup! Was 8° Thursday morning and 2° this morning. Going to be 40° tomorrow though. Monday and Tuesday nights are supposed to be back down into the single digits. We actually have leaves accumulating on top of the snow. LOL

 

[sloeffle]

It's turning so slow at the 96° kickoff I can barely even feel it pull air into the furnace on the cold air side when I put my hand over the intake at the basement ceiling. Doubt I would be able to feel anything come out of the vents upstairs.

@JRHAWK9 we've might of discussed this before. Does your JRHAWK5000 have a DC or AC motor on it ?

 

[JRHAWK9]

@JRHAWK9 we've might of discussed this before. Does your JRHAWK5000 have a DC or AC motor on it ?

It's AC, but I have a ball bearing motor in it.

 

[brenndatomu]

JRHAWK5000

Its SpaceHawk1000©...

I have not converted to a ball bearing motor, but have turned it down really slow (while monitoring for motor overheat) and did not get the same results as JR did with the low CFM's.
On my system (and most I would guess) just running the blower slow enough to keep if from shutting off before the firebox is down to "just warm" is as much as I have to gain...keeping it running after that doesn't seem to help.