Buying Advice for a Wood-Burning Furnace

[maple1]

There is so much variability in measuring flue temps that it could be borderline dangerous - it seems to be the one thing that gets my BP on the rise. You need to make sure you are comparing apples to apples in how & where you're measuring them, and what you're comparing them to.

I have a magnetic guage right beside a probe guage, and the magnetic reads 100°c less than the probe when burning. IMO if you're seeing 500f on a magnetic, that's too hot.

Is there a recommended flue temp & measuring procedure in your manual?

I think it is also quite important to tune your chimney draft into what the manufacturer specs, and keep it there, with a barometric damper.

 

[sloeffle]

I rarely see flue temps over 200F with my magnetic thermometer on my Caddy. 500F is way too high. I also have a barometric draft damper that probably makes them somewhat cooler. As maple suggested I think you need to check your draft speed with a menometer. The manual should have the correct amount of WC to set your damper with.

Until you get you draft speed under control I would try to burn smaller fires. Smaller hotter fires create less creosote also. I generally only fill mine up about a third of the way unless we are in the middle of a polar vortex.

 

[laynes69]

500 degree surface temps on the flue is way too high. Usually with a very hot fire, I see 250 degrees external, maybe 300 if the damper is wide open. I suspect your not running a barometric damper.... How tall is your chimney? You can't use recommended flue temps with the Caddy compared to other stoves. That's because the secondary heat exchanger picks up a lot of heat that otherwise would go up the chimney. If your seeing up to 500 degrees external, I would suspect that's close to if not overfiring. Did you get the draft speeds measured, and how are you loading and operating the furnace, and what is your blower speeds. Sorry for all the questions, just trying to get a feel for your setup.

 

[Jonathan Stroble]

I may have overfired it for 5-10 minutes last night during first operation. The magnetic flue temperature gauge, placed about 18"-24" from the exhaust port on the back of the furnace, touched about 500 F which was just on the upper border of the "safe operation" zone of the thermometer and just on the lower border of the "too hot" zone. (The "too cold/creosote" zone runs from 0 F to about 250 F.) The firebox was loaded about 1/2 full, a roaring fire, and the air inlet was all the way open. When I saw the flue temperature at 500 F, I closed the air inlet completely and the temperature quickly dropped below 400 F. Since then, I have not filled the firebox past about 1/3, and the highest flue temp I've seen is 420 F.

maple1: I don't recall seeing a recommended flue temperature in the operating manual for the PSG Caddy. The recommended draft is 0.04" to 0.06" with a barometric damper recommended if the draft is higher than 0.06".

laynes69: The chimney runs from the basement through two stories and an attic, so I estimate it's about 30-35 feet. I have not had the draft speed measured with a manometer, and I am not using a barometric damper. I am burning relatively dry, seasoned hardwood about 18" long; since last night I have been cautious not to put more than 2-3 sticks of wood on at a time. I don't know the blower speed, it's currently at factory setting. I'm going to check it out tonight when I get home. The fan limit control is also at factory setting, which looks to be about 100/off, 150/on. There's another limit at about 250 which I haven't figured out yet; safety limit?

 

[PassionForFire&Water]

400-500F with a magnetic temp gage seems way to high.
That means inside the flue pipe it's 700-800F.
This is all lost heat
I think you need to slow down your draft

 

[maple1]

I would have to say that you definitely have too much draft with a chimney that tall & no barometric damper.

Mine is about 30' tall & it pulls 0.1" easily when the fire is burning, with my baro closed, and with no effort made at sealing any of the pipe joints. That's with no wind blowing. Wind gusts can pull it way up to 0.3" - which is a very dangerous situation to leave unchecked. You definitely need a barometric damper, and I would also get a Dywer manometer to set it up with. They are cheap insurance.

And I think I've beaten around the bush long enough on the other issue & just come right out with it - I think magnetic flue temp guages are garbage, bordering on dangerous. I think some have used probe BBQ temp guages (the dial kind that go on the BBQ cover) that you can insert into a hole drilled into your pipe - but I got my temp guage from my boiler vendor.

 

[brenndatomu]

I don't recall seeing a recommended flue temperature in the operating manual for the PSG Caddy. The recommended draft is 0.04" to 0.06" with a barometric damper recommended if the draft is higher than 0.06".

They have done extensive testing, with a -.04" to -.06" WC draft, they know that the flue temps will be right.

You definitely need a barometric damper, and I would also get a Dywer manometer to set it up with. They are cheap insurance.

I have now bought (2) Dwyer Mark II manometers from different sellers on fleabay (1 for me, 1 for sis/BIL) if you watch you can get 'em $20 (or less) delivered. I have mine mounted on the wall, hooked up permanently.

 

[laynes69]

In all reality, even just getting a barometric damper and setting it to high should put you within operating range. I've ran our furnace before at .08" with no problems, but .05-.06" is the magic number for efficiency.

What your doing now is dangerous, and I don't want to scare you but... The furnace operates via thermostat on the wall. If by chance you loaded up your furnace and went to bed and the damper opened for heat, your creating a forge inside your furnace. Who knows how long it will burn this way before the damper closes. By having the draft at recommended levels, there's less chance for issues like this. That and you'll be sending a lot less heat up the chimney and more heat will be going in the house. I made the mistake of not latching the door one night and went to bed tired. I didn't know about it until my wife found it in the morning. If I had draft like that, more than likely I might not still have my furnace.

 

[Jonathan Stroble]

No worries, I've taken the wood-burning furnace offline and I'm heating with the oil-burning furnace until I can have the draft measured. If the draft exceeds the recommended limit, I will install a baro before I use the Caddy again.

 

[maple1]

I would just buy a manometer & permanently mount it. It's cheap.

The problem with just having someone come measure it is that will only give you a snapshot. Draft can vary a lot depending on conditions - he might happen to catch the draft when it's lowest and think it's OK when it won't be when it's real cold out or there's a wind blowing. And he'll have to come back to tune in your baro with the manometer when you get it. Also, having the manometer mounted where you can easily see it when tending the furnace will allow you to tell at a glance if the baro by chance is sticking - they can do that on occasion.

 

[Jonathan Stroble]

A manometer like this one? http://www.dwyer-inst.com/Product/Pressure/Manometers/FluidFilled/SeriesMarkII

I found a YouTube video of a person demonstrating one of these:

What confuses me is that the manometer in a flue draft application seems to be using the negative end of the scale... which maxes out at -0.05. How do you measure beyond that with this manometer?

 

[maple1]

That's the one - Mark II Model 25.

You just hook the hose up so it pulls up the tube rather than down (don't hook it to the guage fitting he used but hook it to the other one - I think he used the left one, use the right one), which goes way up to 3". You can also use it to tune in your air ducts for static pressure balancing - but I've never done that so can't give any input on it.

Should be able to find one on Ebay - I got mine from DwyerDirect site last year, not sure if that's still available or not.

EDIT: you just hang it on screws on the wall, can leave it there all the time. I have a short piece of brake line I attached to my flue pipe, I just stick the other end of the hose on the other end of that.

 

[brenndatomu]

What he said ^^^. I've seen that video, he has it backwards, well, it's actually correct, but for our intended use it needs to go the other way. Just hook the line up to the other port.

 

[Jonathan Stroble]

Dwyer Mark II Model 25 ordered from www.dwyer-inst.com. Not sure if it comes with red fluid; I didn't see an option to order it separately.

laynes69, responding to your earlier question, here is a pic of the blower wiring:



In case it's not clear from the picture, positions 1 (white), 2 (red), and 5 (black) are connected on the right side. According to the manual, these are the positions for "Common," "Low," and "High," respectively.

The blower manual advises: "When connecting the blower, it is suggested to use the speed "LOW" (summer speed), «MED LOW» or «MED HIGH» in heating, depending on ventilation needs." So I need to decipher the wiring and figure out what it all means. I recall somebody (maybe earlier in this thread?) saying that he had best results with a lower blower setting.

 

[maple1]

It will come with fluid. You should also be able to buy it separately though.

 

[laynes69]

When it was -14 with chills of -40 I was running the blower on high speed. Now that it's warmed back up, medium low seems to do just fine. We don't have a blower speed switch, so I just have my common and my blower.

 

[STIHLY DAN]

No need for the monometer. Just put in a baro, there like 25 bucks and install in minutes. Instructions MUST say you need one. Damn my furnace came with one.

 

[brenndatomu]

Dang dude, where you buyin your BDs stihly?! I couldn't find one for much less than twice that! Also, how the heck you set the BD w/o a manometer? I have found that those "ballpark" marks that they put on 'em are somewhat less than accurate! I 'spose better n nuttin though...

 

[STIHLY DAN]

I got mine at lowes, it wasn't till I came home that I found the one Kuuma sent. I have a monometer and have checked mine and many others. All the new installs are close enough, Its the older ones that get soot build up on the back of them. Whether it be fossil or wood fuels.

 

[Jonathan Stroble]

Manual says that the ideal draft is 0.04 - 0.06" WC. Rookie question: is that with a cold flue or a hot one? I measured both and got an average of 0.03" cold, and 0.08" with a heating furnace before the tubing melted. If the correct method is to measure hot, how do I connect the Dwyer manometer to a hot flue?

 

[laynes69]

You don't have to permanently mount it, just have it in enough to get a reading. Are those settings with the barometric damper?

You need to set the furnace when the flue is hot. That way it doesn't exceed your set point. I use a small 1/4" copper tube attached to the rubber tube so things won't melt.

 

[maple1]

Manual says that the ideal draft is 0.04 - 0.06" WC. Rookie question: is that with a cold flue or a hot one? I measured both and got an average of 0.03" cold, and 0.08" with a heating furnace before the tubing melted. If the correct method is to measure hot, how do I connect the Dwyer manometer to a hot flue?

Measure with fire burning. I used a 2' long piece of brake line between my flue pipe & manometer tubing. It's permanently mounted like that.

 

[jtheye]

I bought the hybrid 200 with 20k electric backup and the whole thing was mis-wired from factory. Electrical from factory was wired wrong in connection pigtails and ended up costing me a whole new blower... installation and blower replacement cost me another $2200. That doesn't include the huge scare we got when our house filled with smoke from the factory wiring that melted. Boy that was a scare, thought my house was on fire. I am sure mine was not the only furnace wired wrong, but according to the manufacturer they have never had that happen. This happen to anyone else? So that you understand what your getting into, total bill for furnace, installation, fixing Napoleon's defective product with new blower....$15800.... yes that was 15 thousand eight hundred U.S.D. Napoleon does not stand behind their product and I know for a fact that my unit could not have been the only unit sent out with connection pig tails wired wrong.

 

[jtheye]

I have a Napoleon HMF 200 wood furnace. It can be wood/oil/electric if you want or any combination. I have the wood/ electric as I got rid of the old oil furnace. This is my second winter with it and no complaints. I would recommend the Caddy too. The Napoleon is a copy of the Caddy. I am heating an old school house and it does well in the middle of winter.

I bought the hybrid 200 with 20k electric backup and the whole thing was mis-wired from factory. Electrical from factory was wired wrong in connection pigtails and ended up costing me a whole new blower... installation and blower replacement cost me another $2200. That doesn't include the huge scare we got when our house filled with smoke from the factory wiring that melted. Boy that was a scare, thought my house was on fire. I am sure mine was not the only furnace wired wrong, but according to the manufacturer they have never had that happen. This happen to anyone else? So that you understand what your getting into, total bill for furnace, installation, fixing Napoleon's defective product with new blower....$15800.... yes that was 15 thousand eight hundred U.S.D.

 

[brenndatomu]

total bill for furnace, installation, fixing Napoleon's defective product with new blower....$15800.... yes that was 15 thousand eight hundred U.S.D

That's like 3 Kuumas dude! Only if you bought 3 Kuumas all at once they'd prolly send somebody out to put 'em in for ya! Definitely not tell ya tough luck pal! That's rough, I have heard similar poor customer service and high price stories about Napolean before