Size of Multifuel Burner

[steve_gts]

Hi All,

 

I'm having a bit of trouble deciding on the multifuel burner I'll need, I'm getting a 60x10 in January and am planning to have a burner with back boiler to feed 4 rads and hot water. Once I have a bit more money I may add a webasto, but that's definitely not in my immediate budget.

 

The question is, what size burner would you suggest? I'm thinking a 12k, on the basis that it should tick over quite nicely at about 6-8k most of the time with scope to crank it up a bit in mid winter if necessary, or does that sound like overkill?

 

Thanks,

Steve

[Paul C]

There's a guideline figure for kW per m2 floor area but it varies widely on how much insulation you'll use. So, the first question is....how well insulated will the boat be?

[steve_gts]

Probably pretty standard to be honest, The cabin is spray foamed and then will be boarded out too, I understand the floor is ballasted but not insulated and only single glazed windows, but I have the option to add clip on secondary later (again this decision has been made because of budget constraints)

[Grace and Favour]

Another key issue to your question is determining where your stove will be sited.

 

If it's at one end of your boat - you'll need an higher output than if it's sited centrally.

 

(We've a 60 x 12 and are perfectly happy (and warm) with a 5Kw stove located centrally. (Though we do have 75mm sprayfoam and double glazing)

[steve_gts]

it's as central as is practical with the planned layout, probably about a third of the way in. my concern is about keeping the bedroom and bathroom warm too though, that's why I'm going for some radiators too. Does your 5k have a back boiler and how do you find the other rooms in mid winter?

[Pembroke]

We have just fitted a 5kw stove to the house and the heat that produces is incredible.

 

I can't help thinking 12kw will would melt the steel the boat is made from

[steve_gts]

So do you think a 5-6k would be more suitable then? bearing in mind that it would probably feed over half of that heat to the rads and hot water?

[nicknorman]

Our 59 x 7 has a 5kw that spends most of its time shut down really low, with smoked glass a consequence. So I would say 8 kw would be plenty. We don't have a back boiler but I believe it can be harder to keep a back-boiler stove alight burning very slowly, due to the difficulty of keeping the combustion area hot enough (big slab of relatively cool steel/water adjacent).

 

Woodwarm fireview will be our next stove, they do a 6kw one with various back boiler options. Worth a look.

Edited December 16, 2013 by nicknorman

[PaddingtonBear]

I am on a full length boat and had to get up last night and douse the fire and throw open the windows as I was too hot.......................in the middle of December!, it is a squirrel with a back boiler btw.

[Stilllearning]

Our 59 x 7 has a 5kw that spends most of its time shut down really low, with smoked glass a consequence. So I would say 8 kw would be plenty. We don't have a back boiler but I believe it can be harder to keep a back-boiler stove alight burning very slowly, due to the difficulty of keeping the combustion area hot enough (big slab of relatively cool steel/water adjacent).

 

Woodwarm fireview will be our next stove, they do a 6kw one with various back boiler options. Worth a look.

It's hard to judge if the backboiler makes our stove harder to keep burning low, but I doubt it. The boiler is very hot , so is the water and the rads. We have a 6Kw Villager on a 55 ft portholed trad and regularly get too hot. Last night we slept with a pigeon box part open, but it was a warm night.

[canals are us?]

You really need to size the rad output required for the rooms size and the room heat required with the stove to get a better idea of the boilers size and stove heat output left to heat the space the stove is in. Less room heat is OK as you can install a rad in the same room as the stove but if the stove's room heat output is too much you will close the air supply down and have a smaller fire and hence not heat the rads and get black glass from the poor incomplete burn.

 

I have a 50ft narrowboat and have a woodwarm fireview 4.5kw stove heating 2 rads or the calorifier with it's 8,000btu boiler. I find woodwarm an excellent make.

 

 

I would probably buy the 6KW woodwarm as said with 20,000btu boiler (5.86kw) this leaves 3.7kw of heat left from the stove which should be plenty and leaves you nearly 6kw for rads and hot water.

http://www.woodwarmstoves.co.uk/_assets/pdfs/0031ft.pdf

 

 

James:cheers:

Edited December 16, 2013 by canals are us?

[Ryeland]

Another vote for Woodwarm. We have one at home and it's brilliant. 6KW warms a very large lounge from stone cold each day. I think their ratings are very conservative.

 

Cheapie (Valor Willow) on the boat not so good, though this could be lack of decent draw through short flue.

 

Richard

[canals are us?]

Another vote for Woodwarm. We have one at home and it's brilliant. 6KW warms a very large lounge from stone cold each day. I think their ratings are very conservative.

 

Cheapie (Valor Willow) on the boat not so good, though this could be lack of decent draw through short flue.

 

Richard

 

I really like mine too. Stays in no trouble and glass stays pretty clean even when burning housecoal.

Really like the built quality and the multi positional grate, set flat for wood and open for coal and that the door ropes fit into a channel and don't require gluing. Door handles adjustable by turning to get a tighter seal as rope seals wear.

I find wood the best for getting the stove heated up fast 10-15 minutes and it's belting the heat out. Smokeless fuel takes longer but once burning well blasts the heat out.

 

http://www.thehotspot.co.uk/Images/Woodwarm/Fireview/Woodwarm_Fireview_6_Profiled_Flat_Top_4_Legs_.jpg

 

James

Edited December 16, 2013 by canals are us?

[steve_gts]

Thanks for all the input, I'm starting to think I need to half my initial estimate and get a 6kw instead!!! I like the idea of feeding most to thee rads and just adding one in the same room as thee burner too if I need it, I hadn't thought about it that way.

 

I'll be back with many more questions over the next few months no doubt!

[blackrose]

http://www.stovesonline.co.uk/calculator.asp

[Ex- Member]

Another key issue to your question is determining where your stove will be sited.

 

If it's at one end of your boat - you'll need an higher output than if it's sited centrally.

 

(We've a 60 x 12 and are perfectly happy (and warm) with a 5Kw stove located centrally. (Though we do have 75mm sprayfoam and double glazing)

 

Agree partially on our 60 x 10 we keep plenty warm enough on a 4kw Bubble stove. It is at the front of the boat in the corner though, but runs 4 small rads and hot water.

 

Good insulation Is the key I think, I note your 75mm insulation, we have a mix of 50mm Rockwool and 10mm Cellotex so a 60mm mix. No double glazing but portholes with 50mm foam bungs for the winter.

 

A mild winter is helping too, even with the stove on minimum were here with side doors wide open and it's still 18c inside.

 

We've only used 90L of diesel so far this winter too, could have been a lot less if we bothered to turn the BB stove off.

Edited December 16, 2013 by Julynian

[blackrose]

 

Good insulation Is the key I think, I note your 75mm insulation, we have a mix of 50mm Rockwool and 10mm Cellotex so a 60mm mix. No double glazing but portholes with 50mm foam bungs for the winter.

 

A mild winter is helping too, even with the stove on minimum were here with side doors wide open and it's still 18c inside.

 

We've only used 90L of diesel so far this winter too, could have been a lot less if we bothered to turn the BB stove off.

 

Not to mention blocking your vents - that helps too.

[bizzard]

And don't forget you might not be able to put the stove exactly where you want to put it, Its precise position is determined by transverse steel roof beams and any other steel beams up there and possible electrical cables which will have to be dodged to allow adequate clearance away from them for the fitting of the stoves flue pipe and collar. And obviously window- flue pipe positions too.

[Ex- Member]

 

Not to mention blocking your vents - that helps too.

 

Adequate ventilation elsewhere as you well know but have difficulty in comprehending, still that's nothing new

[deckhand]

Ours is a 4kw Whitworth and when fire is going, we have to open windows. It is very hot. We do have excellent foam insulation but even so, still very hot.

We have 2 doors (bathroom through to bedroom) and leave these open. Fire warms the whole boat nicely.

We would not be able to stand anything bigger than a 4kw. We do not have any rads running off this though.

We have a 7kw at bricks and mortar but the house is very open plan but still heats nicely.

[pquinn]

57x 10 with an 8kw evergreen stove.does the job well.pretty much what canals or us said above.i also like the fact that i can cook on it too. paul

[smileypete]

Try a forum search on backboiler or "back boiler" and you'll have sufficient reading to last to the end of next winter!

 

cheers, Pete.

~smpt~

Edited December 17, 2013 by smileypete