Keeping it in

[Supertramp]

Simple thought, - does a pumped back boiler make it harder to keep a fire in overnight?

 

I'm guessing the water will cool the stove, and burn the fuel faster? - or is that too simple....

 

ETA - I'm looking at a Puffin with b/boiler.

Edited September 1, 2011 by Supertramp

[blackrose]

Simple thought, - does a pumped back boiler make it harder to keep a fire in overnight?

 

I'm guessing the water will cool the stove, and burn the fuel faster? - or is that too simple....

 

ETA - I'm looking at a Puffin with b/boiler.

 

It's not too simple - I think it's too complex! It assumes that the rate of fuel burned depends on the size of the heat sink - a demand driven rate of combustion? I'm not sure if that's true? Isn't the rate of fuel burned driven by the amount of oxygen available for combustion? (Supply driven.)

Edited September 1, 2011 by blackrose

[alan_fincher]

Interesting question.

 

I have no experience, but my gut feel is that it may be as you say.

 

If there is water in the back boiler, it will boil unless kept circulated, so heat will be taken away by that, faster than if it were just a solid back with fire brick, so possibly resulting in needing more fuel to be consumed.

 

But I can see Mike's take on it too!

 

It's worth noting that the Puffin is one of the smaller stoves, so you can't really start a night with as much fuel in as maybe some larger stoves. They will keep in easily, but getting the rate of burn right takes a bit of skill - just a bit too much air, and you awake to a blazing fire in the middle of the night. Throttle them back a tad too far, and in the morning you may no longer have a fire, finding instead a lot of unburned fuel.

 

Most solid fuel stoves involve a degree of practice, and experimentation with different fuels, before you get the art of keeping them in at night right every time, I think.

[blackrose]

Interesting question.

 

I have no experience, but my gut feel is that it may be as you say.

 

If there is water in the back boiler, it will boil unless kept circulated, so heat will be taken away by that, faster than if it were just a solid back with fire brick, so possibly resulting in needing more fuel to be consumed.

 

 

Well, assuming the ventilation is equal, does the same stove burn its contents faster in a larger room (bigger heat sink) or a smaller room?

Edited September 1, 2011 by blackrose

[mrsmelly]

Simple thought, - does a pumped back boiler make it harder to keep a fire in overnight?

 

I'm guessing the water will cool the stove, and burn the fuel faster? - or is that too simple....

 

ETA - I'm looking at a Puffin with b/boiler.

 

No experience of the puffin but my squirrell with 3 rads a few boats ago would still stay in 24 hoors if needed so you should be alright.

[bizzard]

A good way of keeping a stove in overnight is to.-Clean the grate,bank up with coal,make sure its burning through,then cover with ash liberally,shut controls down as normal.-Morning open bottom air control,fire will come alive,then a good poke or riddle more coal ect. bizzard

[Supertramp]

Some good ideas to try, - thanks to all.

I still cant work out if having a back boiler will force the fire to work harder by cooling it? - but Blackrose has a good point,

Any experts want to put their twopeneth worth in?

 

Tony

[blackrose]

Some good ideas to try, - thanks to all.

I still cant work out if having a back boiler will force the fire to work harder by cooling it? - but Blackrose has a good point,

Any experts want to put their twopeneth worth in?

 

Tony

 

I'm no expert in thermodynamics so this is just an educated guess, but I don't think the fire will respond to being cooled by working harder. However, I think what you can say is that a stove with a backboiler will have to work harder and burn more fuel (or take a longer time), in order to heat up the larger heatsink to the required temperature - compared to the same stove without a backboiler. Once they are up to operating temperature the difference in fuel used between the stoves will reduce, but I guess the stove with the backboiler will also have to burn slightly more fuel to maintain that temperature. (But it's the stove operator adding fuel and oxygen who achieves and maintains the stove temperature - not the fire.)

 

Anyway, personally that wouldn't be my criteria on whether to get a stove with a backboiler or not.

 

Is it a narrowboat? How long is it and where is the stove going to be positioned in the boat?

Edited September 3, 2011 by blackrose

[alan_fincher]

Personally that wouldn't be my criteria on whether to get a stove with a backboiler or not.

 

Is it a narrowboat? How long is it and where is the stove going to be positioned in the boat?

Agree entirely.

 

If I could easily move our Heron, (basically the same as the Puffin), from the front towards the middle of out 50 foot boat, I would have done so.

 

It's not a big stove, and the only heating we have on our (non liveaboard) 50 foot boat, but I'm convinced it would keep us warm in even the coldest weather if better positioned, with no radiator or other heat requirements.

 

I actually think about of a third of the way back is best, (assuming "sitting room" at front, and "bedroom" at back, to keep sleeping quarters a bit cooler than living area).

 

But if that's a picture of Supertramp's boat in the Avatar, it also looks rather like it is "stove right at front", which I think is a common poor design feature in so many boats.

 

A problem in adding radiators to a front fitted stove, which would certainly apply on Chalice, is often boats sit "front end high", meaning that pipes would run downhill towards radiators further back in the boat - exactly the opposite of what would work best.

[nb Innisfree]

Interesting question.

 

I have no experience, but my gut feel is that it may be as you say.

 

If there is water in the back boiler, it will boil unless kept circulated, so heat will be taken away by that, faster than if it were just a solid back with fire brick, so possibly resulting in needing more fuel to be consumed.

 

But I can see Mike's take on it too!

 

It's worth noting that the Puffin is one of the smaller stoves, so you can't really start a night with as much fuel in as maybe some larger stoves. They will keep in easily, but getting the rate of burn right takes a bit of skill - just a bit too much air, and you awake to a blazing fire in the middle of the night. Throttle them back a tad too far, and in the morning you may no longer have a fire, finding instead a lot of unburned fuel.

 

Most solid fuel stoves involve a degree of practice, and experimentation with different fuels, before you get the art of keeping them in at night right every time, I think.

 

With our Puffin I knocked up a piece of steel plate to slot in behind the front fire bars, result - more fuel could be stacked up without it rolling forward, using Excel and turning to minimum we can keep it going for a day or two, once left it for 3 days and still still managed to catch it.

 

Also knocked up this little gadget to control and indicate vent setting more accurately, used a £1 coin as the cam as that was all I had to hand at the time.

 

[Supertramp]

Thanks Blackrose and Alan,

It's an existing pumped system with 3 rads and calorifier on a 58' NB using a diesel bubble stove.

I'm looking to change the bubble for a solid fuel, maybe the Puffin, or possibly one of Eddie Brooks 'Boatman' stoves as they have a higher boiler output.

 

Although both these stoves are small, - does anyone have experience of actually keeping them in overnight with a pumped back boiler taking away most of the heat, or will they simply burn too quickly and I need to look at a bigger stove?

thanks

Tony

 

ETA - Great picture innisfree, - !!

Edited September 3, 2011 by Supertramp

[bizzard]

As Blackrose has stated, the stove with back boiler,radiators and perhaps heating water? will use the corresponding amount of extra fuel ''burning more strongly''. No such thing as getting power and or heat for nowt.'I'd get a stove slightly larger than recommended for your size of boat whatever that is,as you can always put extra firebricks in to reduce grate area if too hot,and hook em out if the temperature gets very cold,as forcing a stove too much might crack the cast iron body. Try and get a steel bodied one,also one with a nice large and deep ash pan area as most are stupidly too small,for the sake of a couple of inches of extra stove height.

It depends on where your lounge area is going to be,as to where the stove is situated,avoid by the side of the front doors,try to mount it nearer the middle of the boat.bizzard.

[Supertramp]

As Blackrose has stated, the stove with back boiler,radiators and perhaps heating water? will use the corresponding amount of extra fuel ''burning more strongly''. No such thing as getting power and or heat for nowt.'I'd get a stove slightly larger than recommended for your size of boat whatever that is,as you can always put extra firebricks in to reduce grate area if too hot,and hook em out if the temperature gets very cold,as forcing a stove too much might crack the cast iron body. Try and get a steel bodied one,also one with a nice large and deep ash pan area as most are stupidly too small,for the sake of a couple of inches of extra stove height.

It depends on where your lounge area is going to be,as to where the stove is situated,avoid by the side of the front doors,try to mount it nearer the middle of the boat.bizzard.

 

Thanks Bizzard, - guess where the stove is already placed? - by the side of the front doors. - no real alternative in the existing setup.

The Boatman is a steel bodied stove with cast iron door, not sure if the ash pan area is larger or smaller than 'average'.

 

As an additional 'problem', the existing bubble is a corner stove, and I doubt I can find a replacement solid fuel corner stove in my budget, so a small square stove is my only option.

[nb Innisfree]

I would guess that a back boiler taking heat will lower fire temp and result in a slower rate of burn so reducing output to room and result in fuel burning longer (assuming vent is left at same setting)

[Supertramp]

I would guess that a back boiler taking heat will lower fire temp and result in a slower rate of burn so reducing output to room and result in fuel burning longer (assuming vent is left at same setting)

 

Interesting twist, - others have thought the reverse, - I hope your right !

[bizzard]

Thanks Bizzard, - guess where the stove is already placed? - by the side of the front doors. - no real alternative in the existing setup.

The Boatman is a steel bodied stove with cast iron door, not sure if the ash pan area is larger or smaller than 'average'.

 

As an additional 'problem', the existing bubble is a corner stove, and I doubt I can find a replacement solid fuel corner stove in my budget, so a small square stove is my only option.

The bubble is a very good stove,but what with the increasing cost of oil a solid fuel if burning free wood say during the day,will be much cheaper to run.

I have had cast iron stoves, Torgem,Morso ect ok as long as you treat them gently ie bring them up to heat from cold slowly or are liable to crack. Welded steel is much much more reliable. The Boatman of which i've had two in different boats although not back boilered have been superb.The present one now 13 years old still as good as new,i only let it out about four times during the winter for decoking.Will keep in easily for 24 hours especially doing the ash trick on top of the coals.

If buying a back boilered stove make sure that the boiler has plenty of space on top and a gap between it and the back plate of the stove for clearing soot away.Some stoves are bad in this respect ''Morso''for example also cast bodies very thin. The ash pan area is big enough on the Boatman and is accessed by way of the main door not by a seperate lower door. bizzard.

 

With our Puffin I knocked up a piece of steel plate to slot in behind the front fire bars, result - more fuel could be stacked up without it rolling forward, using Excel and turning to minimum we can keep it going for a day or two, once left it for 3 days and still still managed to catch it.

 

Also knocked up this little gadget to control and indicate vent setting more accurately, used a £1 coin as the cam as that was all I had to hand at the time.

 

Jolly good mod,but not sure if its ok to drill a hole through the queens face. bizzard.

[Supertramp]

Just what I needed to hear Bizzard, - Thanks

 

The boatmans back boiler is welded into the rear space where the back fire bricks would have been (according to Eddie) so no loss of space in the combustion chamber, I guess this means I dont need to worry about checking spaces around it for cleaning? (the puffin has a 'clip in' stove and would be what you were warning of i guess.)

 

And as you confirm it stays in all night (with experience) it's my choice!

 

Tony

[bizzard]

Just what I needed to hear Bizzard, - Thanks

 

The boatmans back boiler is welded into the rear space where the back fire bricks would have been (according to Eddie) so no loss of space in the combustion chamber, I guess this means I dont need to worry about checking spaces around it for cleaning? (the puffin has a 'clip in' stove and would be what you were warning of i guess.)

 

And as you confirm it stays in all night (with experience) it's my choice!

 

Tony

Mmm,its usually best if the boiler stands off the back plate,not integral, to allow heat and flames to surround the boiler entirely and so transfer maximum heat to it.Maybe someone will come on here with experience of one.

[Supertramp]

Just when I thought it was sorted.......

[bizzard]

Just when I thought it was sorted.......

You see by being welded to the back plate the boiler will be losing a quarter or perhaps a third of its potential heating surface. Come on folks ,someone must have one!

[Supertramp]

You see by being welded to the back plate the boiler will be losing a quarter or perhaps a third of its potential heating surface. Come on folks ,someone must have one!

 

I see your logic, - however I'm sure i've read recently that welded in boilers have a higher ouput than clip in ones, - perhaps based on the fact the the heat is transferred from the whole stove (sides, top and bottom anyway) to the boiler. I will try and find the article.

 

Why is nothing ever straight forward...

[Supertramp]

Found the bit about clip in and manufacturer fitted,

 

Generally, integral back boilers (those fitted to the fire, or stove by the manufacturer) are the most efficient. They have a high heat output and are quite capable of handling hot water and central heating needs of a small to medium sized property.

 

Clip-in back boilers are also available, although they generally have a lower output than those fitted by the manufacturers.

 

from the British Gas website

 

I knew i'd seen it somewhere... - any thoughts on how it relates to boats?

[bizzard]

Found the bit about clip in and manufacturer fitted,

 

Generally, integral back boilers (those fitted to the fire, or stove by the manufacturer) are the most efficient. They have a high heat output and are quite capable of handling hot water and central heating needs of a small to medium sized property.

 

Clip-in back boilers are also available, although they generally have a lower output than those fitted by the manufacturers.

 

from the British Gas website

 

I knew i'd seen it somewhere... - any thoughts on how it relates to boats?

If the boiler is using the stove back as a wall of the boiler then i am surprised.Or is it welded in on stand off's to create a gap at the back.

Way back when houses had open fires and back boilers,there was a damper above the boiler which you could slide in and out. In to just warm the water and out to allow heat and flames to go up behind too and so surround it for hot or very hot water.bizzard

[system 4-50]

Bumped for Topcat.