Seeking advice re Multifuel stove – feeling duped?!

[Loobyloo]

Three years ago I had a DEFRA approved Multifuel stove fitted (Gallery Collection Classic Clean 5).

 

I noticed within a few days of using it that it had poor heat efficiency and seemed to roar through the logs (kiln dried), which seems wildly uneconomical. I also noticed that I couldn't fully close the top valve, so I rang the installers who came round to look, and told me that that was a design feature of this type of stove, to not be able to fully close that valve – this is what makes it a clean burn stove they said.

 

So I accepted my lot and got on with it, but every year as winter approaches and I start using the stove again, I can't help feeling it's a bit pointless – it doesn't give out half the heat that my parents stove does (also a 5kw), and I spend £££ on logs. And yes I'm building/starting the fire correctly, fully closing the bottom valve, and the door seal seems tight.

 

I have just downloaded the stove instructions (the installers didn't leave me any), and there is no mention of one of the valves only half closing as a particular feature. Wondering if I've been duped?!

Any thoughts very much appreciated :)

[ProDave]

Mine is also a "modern" stove like this with a limit to how much you can close the air intake.  It takes a bit of getting used to, and the key to getting a good burn in our case is not load it up too much.

 

And I am very happy with the heat output and efficient burn ours gives.

 

Is your problem just a cold house that needs a lot of heat?

[Alan Ambrose]

That’s odd. Ours puts out so much heat we often have to open the windows to cool the place down. We’re fairly tiny at 85 m^2 though. We’re an EPC E on paper, although it’s possible we’re actually a C or D. This is a Rais Viva 100L. Pretty much the only heating we use.

[Loobyloo]

  On 24/09/2024 at 21:14, ProDave said:

Mine is also a "modern" stove like this with a limit to how much you can close the air intake.  It takes a bit of getting used to, and the key to getting a good burn in our case is not load it up too much.

 

And I am very happy with the heat output and efficient burn ours gives.

 

Is your problem just a cold house that needs a lot of heat?

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 Ah ok, so it is actually a 'thing' to not be able to fully close one of the valves? I am in an old property (built 1860), but it's small! The stove heats up the living room eventually if I keep the door closed.... I think I'm just really disappointed with the heat efficiency

[Loobyloo]

  On 25/09/2024 at 06:26, Alan Ambrose said:

That’s odd. Ours puts out so much heat we often have to open the windows to cool the place down. We’re fairly tiny at 85 m^2 though. We’re an EPC E on paper, although it’s possible we’re actually a C or D. This is a Rais Viva 100L. Pretty much the only heating we use.

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Thanks Alan – is your stove a DEFRA-approved 'clean burn'? This is what seems to be making the difference. My parents have one of the older stoves (before it became mandatory in my area to get the clean burn ones), and like you they have to open windows/doors as their house gets too hot! I'm envious!

[ProDave]

  On 25/09/2024 at 09:18, Loobyloo said:

 Ah ok, so it is actually a 'thing' to not be able to fully close one of the valves? I am in an old property (built 1860), but it's small! The stove heats up the living room eventually if I keep the door closed.... I think I'm just really disappointed with the heat efficiency

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That's how they can keep the emmissions down by ensuring there is always enough air for proper combustion.  I do recall reading on my stove it is possible to remove the restriction that stops you closing the input air fully, but it is not recommended.  I take it yours takes combustion air from the room?

 

The stove is definitely different to use than our previous old one, like you mentioned if you load it up fully, you can't turn it down enough and it roars away probably getting too hot.  You soon learn how much wood to put in at time.

 

Have you got a flue thermostat, if not get one, and use that to keep the flue temperature within limits, too low and it's not burning properly, too high and well that is not good news.

 

I would do a crude heat measurement for your room.  I am guessing from the model number your stove is a 5kW output?  Are you sure 5kW is enough for your house?  A crude test would be turn on a 3kW electric convector heater, one of the cheap plug in ones, and see how long that takes to heat the room up.  If that too takes ages then the issue is not your stove but the heat loss from the house.

[JohnMo]

  On 24/09/2024 at 21:05, Loobyloo said:

Gallery Collection Classic Clean 5

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I take it you are using the primary and secondary controls. The user manual states 

 

"If you are burning only wood, the primary air control can be fully closed. If you are burning solid

fuel you will require some primary air. Your stove is burning with maximum efficiency when a bright fire is achieved using minimum air inlet and a Stove Thermometer. We

advise that stove thermometer is purchased in order to for you to monitor the operation of the stove. For best results the thermometer should register within the “Best Burn” range.

[Iceverge]

Do you have any video of it in operation? 

 

Sometimes if they're set wrong you can have a gale blowing up the chimney taking all the heat with it. 

 

What kind of timber are you burning? Dry spruce split into small pieces will evaporate up the chimney! 

 

I think these multi fuel stoves nominal heat output is for coal rather than wood. You could try a bag if you're ok with that kind of thing. 

 

[Loobyloo]

  On 25/09/2024 at 09:27, ProDave said:

That's how they can keep the emmissions down by ensuring there is always enough air for proper combustion.  I do recall reading on my stove it is possible to remove the restriction that stops you closing the input air fully, but it is not recommended.  I take it yours takes combustion air from the room?

 

The stove is definitely different to use than our previous old one, like you mentioned if you load it up fully, you can't turn it down enough and it roars away probably getting too hot.  You soon learn how much wood to put in at time.

 

Have you got a flue thermostat, if not get one, and use that to keep the flue temperature within limits, too low and it's not burning properly, too high and well that is not good news.

 

I would do a crude heat measurement for your room.  I am guessing from the model number your stove is a 5kW output?  Are you sure 5kW is enough for your house?  A crude test would be turn on a 3kW electric convector heater, one of the cheap plug in ones, and see how long that takes to heat the room up.  If that too takes ages then the issue is not your stove but the heat loss from the house.

Expand  

 

Yes it's a 5kw stove, and I was assured this was the right size (it's a one-bedroom 'lower colony' in Edinburgh – I was told a bigger one would be too hot! 😅)

I don't have a thermometer, but it sounds like I should get one - thanks.

[Loobyloo]

  On 25/09/2024 at 11:38, JohnMo said:

I take it you are using the primary and secondary controls. The user manual states 

 

"If you are burning only wood, the primary air control can be fully closed. If you are burning solid

fuel you will require some primary air. Your stove is burning with maximum efficiency when a bright fire is achieved using minimum air inlet and a Stove Thermometer. We

advise that stove thermometer is purchased in order to for you to monitor the operation of the stove. For best results the thermometer should register within the “Best Burn” range.

Expand  

 

Ah, interesting! Ok I'd better get a stove thermometer...

[Loobyloo]

  On 25/09/2024 at 11:56, Iceverge said:

Do you have any video of it in operation? 

 

Sometimes if they're set wrong you can have a gale blowing up the chimney taking all the heat with it. 

 

What kind of timber are you burning? Dry spruce split into small pieces will evaporate up the chimney! 

 

I think these multi fuel stoves nominal heat output is for coal rather than wood. You could try a bag if you're ok with that kind of thing. 

 

Expand  

 

I'll try and get a video of it later. It does seem like there's a strong draw up the chimney.

I've been burning kiln-dried birch logs – I'm in a smokeless zone, so I can only use that or smokeless 'coal' which may be worth trying.

 

Thanks!

[Loobyloo]

I Just found this in the stove installation instructions:

"The Classic 5 Eco must be fitted with a permanent stop to prevent closure of the secondary air control beyond 3mm open."

 

Mystery solved! Thanks everyone who chipped in to help. I now just have to get a thermometer and work out how to get the best burn with this stove.

 

Lucy

[Iceverge]

 

This is quite an enjoyable book in its own right despite being effectively a set of instructions.