Solid flue vs decorative

[Wodez29]

Hi
I had a neo 1.6 free standing installed early last year. I wasn’t very impressed with the heat output during last winter.
My house is 135m2 or 14.5 squares and the heater is rated for 250m2. But after it burning for 5+hours I am lucky to get a 4*c increase in temperature in the lounge room it is in, and maybe a 2*c increase in the furthest part of the house.

House Has good ceiling insulation

Only has insulation in top half of walls. I installed this myself pushing batts through the brick cavity from above, but could not get passed the noggin in the middle of the wall.
Timber floor boards.
Standard single glazed windows.

I am wondering if changing the current solid flue to a decorative flue would make much difference.
I would appreciate any advice

 

[begreen]

This is not a large stove. Heating 250 sq meters is optimistic at best and under ideal conditions. Where is that claim made? I haven't found that statement on the Pacific Energy website.

What was the room temp before starting the fire? It takes a lot of BTUs to raise the temperature of a room many degrees. This is because the stove is not just heating the air in the room, but all the mass within it and the walls, windows, etc.

What is meant by a decorative flue? The flue will not change heat loss from the house.

How well seasoned is the firewood? Good dry wood will make a large difference.

 

[jetsam]

Fixing the wall insulation is job one.

I am not familiar with the construction there, but even with no access to the walls you can drill holes (inside or outside) and spray in polyurethane, or blow in fiberglass or cellulose. If this is impossible because the lower half of the wall isn't hollow, you can stud out the inside and add insulation, or just add rigid foam board.

After that, look at the windows and doors. If you have a lot of airflow through bad windows and/or a lot of radiant loss through single pane windows, any stove will struggle.

After that, go up to a bigger stove and you should be all set. A 2.5cf stove shouldn't struggle at all. You may even be happy with the old 1.6 if you are around to reload it frequently.

If you just want advice on getting heat out of what you have, tell us about your wood and how it is stored and dried, and tell us how exactly the stove is vented, with photos. (In fact, you may as well tackle this part now, since if this is your problem, you will have the same problem with the new stove also.)

 

[Wodez29]

Thanks for the quick replies.
The heater is rated to 250m2 on Australian websites... not sure why the big difference but I do remember there being a different in m2 and burn time... I asked both my local website and pacific energy about the burn time, my guy saying it’s because in Australia we have much better wood to burn... pacific energy kind of agreed but couldn’t be sure.
I didn’t question m2 with pacific energy.

room temp is around 15-18*c when I light the fire

by decorative flue I mean the outer skin that is seen within the house has many small holes which allows radiant heat to transfer from the inner skin flue into the room. With the solid skin(no holes) I currently have I am thinking a lot of heat would be trapped inside that solid skin, not getting direct radiant heat from the inner flue into the room.

I did get a quote on getting blow in wall insulation but it was 4 times the price of getting the ceiling done well with oversized batts.

Wood is stored in a shed. Most of it is sitting in there for a year. When I questioned my supplier about not being happy with the output he said to make sure the wood is at around 15% moister content.... not too dry. I did check my wood once last year and it was at 17%

I mainly burn redgum 100mmx100mmx450mm stumps from old house stumps or fence posts. I do have some split logs but I can’t recall what type of tree. Yellow box maybe... some type of hardwood. Once it’s burning hot I leave the vent barley open and overnight I leave it shut.

 

[jetsam]

Square footage ratings are rubbish made up by the marketing department. Can a heater do the same job in 250m3 of super-insulated new construction and 250m3 of leaky old uninsulated barn? Ludicrous.

Wood should be checked on a fresh split at 21C, parallel to the grain. Moisture meters screw a lot of people up because people assume it has an elf inside who measures moisture content on whatever the meter is pointing at using elf magic. In fact, contact meters are is ohmmeters. Many things affect the resistance that the meter sees; moisture content is only one. Temperature, wood species, whether the probes are parallel or perpendicular to the grain, and probe spacing are all factors. (I also suspect that crappy meters are common.) Further reading: https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr06.pdf


I'd suggest googling to see if you can find a table of correction factors for local wood.

One good way to see if wood is your issue is to get some very dry construction scraps (go to a lumberyard and buy a few 2x4s if you need to), and burn a small hot load or two that way. Be careful, that stuff can really take off on you. If your heat problem goes away, your wood is likely the issue.

 

[begreen]

Technically the 250 sq mtr claim could be true, but that would be in a very well insulated house and might be when it's 10ºC outside. It's just marketing jargon. Raising the interior temp 8º in a modestly insulated house is going to take quite a bit of heat until the interior has fully warmed up and stabilized. That could take hours if a good portion of the heat is heading outside when the temperature is cold outdoors. The single-pane windows are a big cause of heat loss too. How much ceiling insulation is there? Is there a basement or any insulation under the floors?

We have gum and eucalyptus trees here too. They are high oil content and tend to burn quickly compared to some other hardwoods. But it sounds like the wood is not the problem. House heat loss and a bit too small stove as a match for the loss is the issue. Adding the decorative flue (aka stack robber) is not a good idea. It can lead to creosote buildup in the flue system. The stove is the source of heat, not the flue. There are two choices, either get a bigger stove or greatly reduce the heat loss of the house. I suspect the house because your outdoor temps are generally fairly mild. What is the primary heat for the house? What have the heating bills been like in previous winters?

Do you have a thermometer on the stove top? If so, what temperature is it running at when hot?

PS: Can you provide a link to the Pacific Energy website in Australia where this marketing info is posted? I am only finding links to the company site in Canada.

 

[Wodez29]

Technically the 250 sq mtr claim could be true, but that would be in a very well insulated house and might be when it's 10ºC outside. It's just marketing jargon. Raising the interior temp 8º in a modestly insulated house is going to take quite a bit of heat until the interior has fully warmed up and stabilized. That could take hours if a good portion of the heat is heading outside when the temperature is cold outdoors. The single-pane windows are a big cause of heat loss too. How much ceiling insulation is there? Is there a basement or any insulation under the floors?

We have gum and eucalyptus trees here too. They are high oil content and tend to burn quickly compared to some other hardwoods. But it sounds like the wood is not the problem. House heat loss and a bit too small stove as a match for the loss is the issue. Adding the decorative flue (aka stack robber) is not a good idea. It can lead to creosote buildup in the flue system. The stove is the source of heat, not the flue. There are two choices, either get a bigger stove or greatly reduce the heat loss of the house. I suspect the house because your outdoor temps are generally fairly mild. What is the primary heat for the house? What have the heating bills been like in previous winters?

Do you have a thermometer on the stove top? If so, what temperature is it running at when hot?

PS: Can you provide a link to the Pacific Energy website in Australia where this marketing info is posted? I am only finding links to the company site in Canada.

Ceiling has the original blow in and r5 batts ontop.
No basement and no floor insulation. It would be an easy and cheaper option to changing windows to double glazed or getting insulation in the bottom half of the walls. But with heat rising I’m not sure if it’s worth it. But I guess if it’s the next easiest step then it’s worth a try.

This is my primary heating for the home. There is a small split system air conditioner in the same room. I was only in this house for 10 months before putting the wood heater in, so not sure on previous costs of heating. Didn’t use the split system much the first year.

I did check the wood heater temperature over the weekend. The top was at around 45c.
I also Stuck my thermometer inside the vent to touch the next layer of metal down where the fan flows air out and it was 53c

Here’s an Australian website showing the 250m2 and 12+hour burn time. I did my research and this wasn’t the only Australian website stating this.

Pacific Energy Neo 1.6 Wood Heater

The Neo is the latest in High Efficeint Wood Heating. The Neo burns less wood, burns longer and cleaner than traditional wood heaters

pivotstove.com.au

I was hoping swapping to the decorative flue with many holes would give out some more heat. You said it causes creosote issues. It wouldnt bother me if I had to get the flue cleaned once a year instead of every second year. Or is it a bigger issue than that? Obviously don’t want a flue fire.

while doing a bit of research on this problem I have seen flue heat exchangers that branch the flue into 2 or 3 flues within the room, making more surface area of flue I guess.
But they don’t look great.

 

[bholler]

Ceiling has the original blow in and r5 batts ontop.
No basement and no floor insulation. It would be an easy and cheaper option to changing windows to double glazed or getting insulation in the bottom half of the walls. But with heat rising I’m not sure if it’s worth it. But I guess if it’s the next easiest step then it’s worth a try.

This is my primary heating for the home. There is a small split system air conditioner in the same room. I was only in this house for 10 months before putting the wood heater in, so not sure on previous costs of heating. Didn’t use the split system much the first year.

I did check the wood heater temperature over the weekend. The top was at around 45c.
I also Stuck my thermometer inside the vent to touch the next layer of metal down where the fan flows air out and it was 53c

Here’s an Australian website showing the 250m2 and 12+hour burn time. I did my research and this wasn’t the only Australian website stating this.

Pacific Energy Neo 1.6 Wood Heater

The Neo is the latest in High Efficeint Wood Heating. The Neo burns less wood, burns longer and cleaner than traditional wood heaters

pivotstove.com.au

I was hoping swapping to the decorative flue with many holes would give out some more heat. You said it causes creosote issues. It wouldnt bother me if I had to get the flue cleaned once a year instead of every second year. Or is it a bigger issue than that? Obviously don’t want a flue fire.

while doing a bit of research on this problem I have seen flue heat exchangers that branch the flue into 2 or 3 flues within the room, making more surface area of flue I guess.
But they don’t look great.

Heat with the stove not the flue. With a modern stove being run properly there shouldn't be that much excess heat going up the chimney to salvage. Taking to much would mean creosote issues. Heat exchangers in the pipe are a horrible idea. They can create massive amounts of creosote in a short period of time. Those that insist on using them usually clean monthly

 

[jetsam]

You should definitely not go into wood burning with the idea that you will sweep the flue every year or 2 years.

Check the flue for buildup regularly. New burners often have wet wood. I tell people to sweep it every couple weeks at first, which quickly will let them get a handle on how often they actually need to do it. I personally sweep 3-4 times a year (basically every time the fire goes out).

If you are paying someone else to do it, at least inspect it often. Also consider that buying the equipment to do it yourself is probably cheaper than paying someone to do it one time. (It is here, anyway.)

Sweeping is not something that needs to be done a fixed number of times per year... it needs to be done when the flue is dirty.

Let's say you are doing fine with one sweep per year. The next year you finish off a woodpile at the beginning of spring. The new woodpile hasn't seasoned as long, and maybe the tarp had some holes in it, so the wood is wet and it has surface moisture. It's also warmer outside, so you burn this wood on a lower setting. Your 1 year between sweepings may have just turned into 1 month.

 

[bholler]

You should definitely not go into wood burning with the idea that you will sweep the flue every year or 2 years.

Check the flue for buildup regularly. New burners often have wet wood. I tell people to sweep it every couple weeks at first, which quickly will let them get a handle on how often they actually need to do it. I personally sweep 3-4 times a year (basically every time the fire goes out).

If you are paying someone else to do it, at least inspect it often. Also consider that buying the equipment to do it yourself is probably cheaper than paying someone to do it one time. (It is here, anyway.)

Sweeping is not something that needs to be done a fixed number of times per year... it needs to be done when the flue is dirty.

Let's say you are doing fine with one sweep per year. The next year you finish off a woodpile at the beginning of spring. The new woodpile hasn't seasoned as long, and maybe the tarp had some holes in it, so the wood is wet and it has surface moisture. It's also warmer outside, so you burn this wood on a lower setting. Your 1 year between sweepings may have just turned into 1 month.

They aren't burning a bk. Burnt correctly with a good setup their stove can probably go 2 years. Every modern stove I have used until this one easily went 2 years. The bk needs a mid season cleaning.

That being said by the look of the glass on that stove it doesn't look like it is being run correctly. And you are correct until you know the setup checking often is a good idea

 

[jetsam]

They aren't burning a bk. Burnt correctly with a good setup their stove can probably go 2 years. Every modern stove I have used until this one easily went 2 years. The bk needs a mid season cleaning.

That being said by the look of the glass on that stove it doesn't look like it is being run correctly. And you are correct until you know the setup checking often is a good idea

My grandmother burned a smoke dragon, and she would have been a lot safer with this advice. I think she cleaned her flues exclusively with yearly chimney fires.

It only takes a few minutes to hop up and look, or run a camera through it. Those wifi inspection cameras are dirt cheap on Amazon now, cheaper than a brush.

 

[bholler]

My grandmother burned a smoke dragon, and she would have been a lot safer with this advice. I think she cleaned her flues exclusively with yearly chimney fires.

It only takes a few minutes to hop up and look, or run a camera through it. Those wifi inspection cameras are dirt cheap on Amazon now, cheaper than a brush.

Well that depends on the setup. For many people getting ontop to inspect is a big deal. And many of us never shut down during the season to check from the bottom.

But again I agree completely checking often is very important for new burners or even old burners with a new setup

 

[begreen]

I forgot that the top of the Neo is totally convective, still the temps reported sound quite low. How are they being measured? Do you have an IR thermometer? If so, can you remove the upper grille temporarily and get a reading on the actual stove top?

Note that the 250 sq mtr heating claim is being made by a stove sales company, not PE. This is marketing.

 

[Wodez29]

I used a digital meat thermometer.
I poked it through the grill to get the 54c
And the 45c was next to the grill.
Both touching the metal

I do run the fire with the air vent between 1/4 and closed to save burning through wood quickly. I only have it all the way open for the first hour to light it and build up coals.
Once I did try running it at 3/4 open for the hole day and it might have made a 1 or 2c better difference than vent at 1/4.

 

[begreen]

Try turning down the air sooner if the wood is burning well. If the draft is good, then after 10-15 minutes the air can be turned down at least 50%, or until the flames get lazy. Then wait for the fire to recover strength for 5-10 minutes and turn down the air again to 25%. That will encourage a hotter secondary burn. The temp reading method is not accurate. The stovetop is more likely around 260ºC, unless something is wrong.
Here are examples of starting a fire in a larger PE stove.

Starting a fire and running an EPA stove

Questions about starting a fire and avoiding a runaway stove come up so frequently I decided to document starting our stove. This is a Pacific Energy Alderlea T6 with about a 3 cu ft firebox. The stove is connected to a straight-up, 20' interior flue. The outside ambient temperature is 34ºF. The...

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