Log burner stove for large open plan room but MVHR

[readiescards]

Yes I know from ebuild threads that many people have installed log burners fired them up once, cooked themselves and never used them again in super insulated houses. 

As my house will be well insulated but not super insulated and I have a free source of wood, I've tried and failed to find a log burner BOILER stove that limits the heat to the room, is direct air, room sealed, found one but SWMBO rejected it.

So I'm now looking for a DRY stove that is:

• low output (sub 5kW say)
• square
• black
• "traditional looking" - what ever that is
• direct air feed

 

Question: does it have to be 'room sealed' to be allowed by building control in a property with no trickle vents and a MVHR? Or can the 'secondary air' be taken from the room?

 A local guy in a well insulated house with a MVHR, just uses the MVHR fresh air to feed his log burner and seems quite happy with that!

[Siochair]

Hi, I came across Hwam stoves a while ago. They have a wireless temperature sensor that can be used to automatically control the stove output. You can see them at www.hwam.com. I have no experience of the stoves apart from reading about them on the web. 

[Mikey_1980]

We have the HWAM electronically controlled stove in our MBC build, we have lit it a couple of times and seems to work well, I am not sure if they would fit with the traditional design requirement though.

[ProDave]

Springdale 3KW stove with room sealed kit, traditional look. It's what we are planning to use http://www.stovesareus.co.uk/burley-springdale-wood-burning-stove.html

[Crofter]

21 minutes ago, ProDave said:

Springdale 3KW stove with room sealed kit, traditional look. It's what we are planning to use http://www.stovesareus.co.uk/burley-springdale-wood-burning-stove.html

No boiler on that though.

[reddal]

12 hours ago, readiescards said:

low output (sub 5kW say)

I wouldn't worry about what the rated output of the stove is. A bigger stove can always be run at much lower output by just using less wood.

The rated output is a maximum - assuming the stove is somehow completely full and all at optimal burning temperature (hard to achieve). In practice trying to achieve the maximum output is likely to lead to some of the wood burning at too low a temperature - which is bad. Its much easier to get correct burning using less wood. I would guess you are unlikely to ever run a stove at more than half its rated output - and its easy to run it much lower than that.

The minimum output of a stove is determined by how small your logs are, and how much control you have over the airflow. I would guess that you could run any stove at 1kW by only using a couple of smallish logs at a time.

- reddal

[Crofter]

Respectfully disagree with some of the above.

Rated output is not maximum output. e.g. a 4kW stove may actually produce 5kW flat out.

Secondly, running any stove too low is a bad idea- just as it is a bad idea to run a IC engine on idle for prolonged periods. Running a stove very low means lower temperature combustion, therefore incomplete and inefficient combustion with volatiles deposited up the chimney instead of burned off. Higher risk of CO production, more ash, much more sooting up of the stove glass.

 

One of the commonest mistakes people make is to specify too large a stove and then try to run it throttled down.

[reddal]

1 hour ago, Crofter said:

Running a stove very low means lower temperature combustion

Two seperate issues here :

1. The temperature the stove burns at. I agree running a stove at too low a temp is bad.
2. How much wood you burn at once. Its very possible to burn a lot less than the maximum capacity at the correct high temperature - easier in fact.

Once a stove is burning at the correct (high) temperature - you can restock it with just one or two logs - and get low output - or pack in loads of logs and get high output.

The size of the stove doesn't make a lot of difference to the minimum output I think.

I agree that plenty of people will use a big stove incorrectly - and pack it full of loads of logs - and then close off the airflow to try to reduce the output - leading to low temp burning. However once you know not to do that - its not a problem to run a stove at a fraction of its max output.

 

Edited June 16, 2016 by reddal
typo

[Crofter]

Yes I see the difference, fair enough. But it's a damn sight easier to keep a small, compact, fire nice and hot than one that is unavoidably spread out along the bottom of the stove.

[DeeJunFan]

What about this yoke.

I'm still trying to find out about Secondary air but looks much better traditional wise!

http://www.stovesonline.co.uk/wood_burning_stoves/Stratford-Ecoboiler-Stoves.html

D

[ProDave]

3 hours ago, Crofter said:

No boiler on that though.

OP asked for a "dry" stove which I took to mean a room heater only with no water heating capability.

[Crofter]

1 minute ago, ProDave said:

OP asked for a "dry" stove which I took to mean a room heater only with no water heating capability.

Apologies, I misread.

By the way I'm also going for the Burley... wonder if we could save on delivery costs by buying at the same time?

[reddal]

5 minutes ago, Crofter said:

But it's a damn sight easier to keep a small, compact, fire nice and hot than one that is unavoidably spread out along the bottom of the stove.

I'm not sure about that. With the firebox rammed full of logs its actually quite difficult to get it all burning at the right temperature - some parts of the stack inevitably don't get enough air and don't burn properly. However when burning a few logs in a big firebox there is lots of room for air to get to each log - and you can choose whether to spread them out or pack them together - which gives you more control on the output.

I have a stove thats rated at 8.5kW. I did some tests once to try to estimate what output I was actually producing. I ran the stove for a few hours - only adding 1 or 2 logs when needed - maintaining correct burning temp throughout - and measured the impact on the house temperature. I then repeated the exercise next day but using a 2.5kW electric heater instead.

The result was that the stoves output was a bit less than the 2.5kW electric heater. i.e. when using the stove in the way I found easiest to keep it burning properly - the output was only a fraction of the rated output (8.5kW) - probably only about 2kW. I could easily burn less wood that this test - maybe getting output down to 1kW - or more - maybe getting output up to 5kW. However I don't think it would be easy to get up to 8.5kW and keep good burning temp throughout.

The output rating of a stove is pretty much entirely determined by how big the firebox is - but you don't have to use it all - in fact I find it easier to get logs to burn properly when only using a fraction of the max capacity.

- reddal

[ProDave]

12 minutes ago, Crofter said:

Apologies, I misread.

By the way I'm also going for the Burley... wonder if we could save on delivery costs by buying at the same time?

Possibly.  I can get it locally from Highland Stoves at Cromarty, but I am sure they are more expensive than some of the on line suppliers.

What I found is the stove is the cheap bit. Twin wall flue's are about £100 per metre, so the flue and terminals etc will cost twice the cost of the stove or more.

[JamieM]

I have been considering this one when the time comes to get a stove. They do have a more traditional look.

http://www.clearviewstoves.com/stove-details/solution-400

don't know if anyone has any experiences with them?  though they might be in the dearer side of the market.

 

 

[Stones]

We had a 5kW Morso 'Badger' in our last house.  A nice little stove with external air feed.  I remember one occasion very early on when it was -15C outside, we lit the stove and filled it up.  The house rapidly overheated and we had to open all the windows to cool the house down.  Through a process of trial and error, we established the only way to use the stove was to burn one log at a time, and limit total burn time to no more than 4 hours.  The issue we found burning one log at a time was that it didn't seem to do it very efficiently, the fire inside was just too small.

We were planning (or perhaps more accurately I should say my wife was planning  a WBS in our new house, but after a lot of debate, feedback about the performance of local ICF built houses and the timely reports about the health problems related to burning timber, my wife has accepted that we don't actually need one.  

[PeterW]

18 minutes ago, JamieM said:

I have been considering this one when the time comes to get a stove. They do have a more traditional look.

http://www.clearviewstoves.com/stove-details/solution-400

don't know if anyone has any experiences with them?  though they might be in the dearer side of the market.

 

 

We looked at Clearview in Stow and even met one of the guys who make the hoods for them - they are very well made but are north of the £12-1500 mark for anything that is around the 5-8kw mark.

 

 

[Crofter]

@reddal That's very interesting indeed. One other factor of course is log size. If using actual split logs then yes a rammed full firebox is going to struggle to burn properly. Given that I don't have ready access to trees, the vast majority of what I burn tends to be smaller stuff and scrap building wood etc. Much of it is no bigger than kindling really. Consequently the fire needs attending every 20mins or so to top it up, but the benefit is a very hot and clean fire. I realise that this is not typical of most people's usage though (and most people do not want to spend their winter evenings sat beside the fire feeding tiny bits of wood into it).

[JamieM]

16 minutes ago, PeterW said:

We looked at Clearview in Stow and even met one of the guys who make the hoods for them - they are very well made but are north of the £12-1500 mark for anything that is around the 5-8kw mark.

 

 

when I talked to the guys in NI, they were around £950 and £1100 for the two 5KW models we looked at. Although all the extras added around £1500 including labour and delivery (though half of that price was the 8m of  steel flu)

[Crofter]

I haven't seen a Clearview in the flesh, they do seem awfully expensive! I really like my Charnwood which was a fraction of the price. Prefer it to the inlaws' Morso in fact.

 

My installation will use bog standard single wall flue from the stove right up to the vaulted ceiling, and then twin wall where it passes through the roof structure and above.

[PeterW]

Charnwood can be expensive too when you get up the scale ! BiL has one and wanted to swap for a Charnwood double sider and it came in at nearly £2k..!

[Stones]

58 minutes ago, Crofter said:

@reddal That's very interesting indeed. One other factor of course is log size. If using actual split logs then yes a rammed full firebox is going to struggle to burn properly. Given that I don't have ready access to trees, the vast majority of what I burn tends to be smaller stuff and scrap building wood etc. Much of it is no bigger than kindling really. Consequently the fire needs attending every 20mins or so to top it up, but the benefit is a very hot and clean fire. I realise that this is not typical of most people's usage though (and most people do not want to spend their winter evenings sat beside the fire feeding tiny bits of wood into it).

One of the reasons that my other half has seen sense over - no trees up here (or very few), so no ready supply of wood. 

[reddal]

3 hours ago, Stones said:

established the only way to use the stove was to burn one log at a time, and limit total burn time to no more than 4 hours.  The issue we found burning one log at a time was that it didn't seem to do it very efficiently, the fire inside was just too small.

Wood burning can be tricky. A few tips for anyone trying to run a smaller fire :

• Make sure the fire gets up to a proper temperature when lighting. Don't limit the airflow until it's burning nice and hot. Get a flue thermometer and an IR gun and obsess over them :).
• Make sure the flue/chimney has enough draught. You can get a fan installed to help it if not.
• Make sure the logs are properly seasoned - this means something like 15-20% moisture content. Most of the logs you buy from garages etc are rubbish - I've seen them at 35% moisture which is very hard to burn and will cause all kinds of problems.
• Its easier to burn 2 or 3 small logs than one bigger log - so if you want to only burn a limited amount of wood it's easier if you split your logs into smaller chunks
• Dont wait too long before refueling - e.g. don't wait until the fire is nearly out and has cooled down before putting on another log - do it when its still burning hot - so it will keep that temperature up.

[ProDave]

The one "issue" we have had with our stove is keeping the door clean.

The manufacturer tells us it has an "air wash" system to keep the glass clean etc but the reality doesn't really bear that out.

After much experimenting, the conclusion is with the primary air intake fully open and a roaring flame, it will keep the glass clear. But apart from the initial burn to get it up to temperature, we don't run it like that. As soon as you shut down the air intake, the door clouds up. So it is something we just accept now, and likely to be a similar problem in the new house.

 

 

[reddal]

29 minutes ago, ProDave said:

The one "issue" we have had with our stove is keeping the door clean.

I think that normally means its not burning hot enough. Apart from the cosmetic issue of the glass this can also lead to creosote build up in the chimney which can be dangerous.

Can you shut down the air intake a bit less to avoid it? Also check your fuel is properly seasoned (measure it with a cheap meter).