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Back boilers in solid fuel burning stoves


kevinm

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Hi Guys,

I am new to the forum and looking for my first live aboard Narrow-boat.

I would like to hear any feedback from anyone who has a back-boiler fitted in their solid fuel stove.

Do you run your radiators off it or does it heat the water in your calorifer tank or both?

how does it perform? What are the pros and cons of such a system?

Much thanks,

Kev.

 

 

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Welcome.

I think that 99.99% of boat SF stoves are fitted with a back boiler to drive radiators &/or hot water via the calorifier.

It would be a 'waste' not to utilise it.

 

I'd suggest it would be the norm to find liveaboard boats with a back boiler, 'leisure equipped boats' may well be found without back boilers.

 

When looking at boats there are a few pointers as to their suitability as a liveaboard :

SF fire with back boiler

Battery bank size

Battery monitoring equipment

Alternators (size and number of) - or installed generator

Water tank size

Toilet type - (cassettes being the best)

 

Other things such as a washing machine, are down to personal preference but would be indicative of at least a 'high usage' boat.

 

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Back boilers provide a way of spreading heat along the length of a narrowboat. Without, then a longer boat with a stove at one end will be too hot by the stove and freezing at the other. Generally if there is a calorifier in the system there will have to be radiators too so that enough heat is released when the cauliflower is up to temperature. Without this there is a risk of the water in the back boiler boiling.

Thefre are two basic circulation systems. Pumped and gravity. Gravity needs big bore pipes and very careful layout of the system to work as the pumping force of water differential density with heat is tiny. I have this on my boat and it works very well.

Pumped circulation means smaller bore pipe can be used and stove, rads and calorifier can be placed wherever they fit best. Disadvantages are electricity consumption to run the pump 24 hours a day. This can be an issue if you are off grid. I find the pump noise irritating when I have stayed on boats with it. If youforget to switch the pump on, or if it fails, then you will boil theback boiler, possibly damaging it.

 

Solid fuel heating and back boiler are on my essential list for a live aboard boat. Cheapest fuel, cheapest to install and maintain. Best reliability. Disadvantages are dust and filth, especially with smokeless coal, hauling 25Kg sacks around and storage space for said sacks. Wood is cleaner, but takes up much more space and is hard to keep in overnight.

 

Jen

Edited by Jen-in-Wellies
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27 minutes ago, Jen-in-Wellies said:

Back boilers provide a way of spreading heat along the length of a narrowboat. Without, then a longer boat with a stove at one end will be too hot by the stove and freezing at the other. Generally if there is a calorifier in the system there will have to be radiators too so that enough heat is released when the cauliflower is up to temperature. Without this there is a risk of the water in the back boiler boiling.

Thefre are two basic circulation systems. Pumped and gravity. Gravity needs big bore pipes and very careful layout of the system to work as the pumping force of water differential density with heat is tiny. I have this on my boat and it works very well.

Pumped circulation means smaller bore pipe can be used and stove, rads and calorifier can be placed wherever they fit best. Disadvantages are electricity consumption to run the pump 24 hours a day. This can be an issue if you are off grid. I find the pump noise irritating when I have stayed on boats with it. If youforget to switch the pump on, or if it fails, then you will boil theback boiler, possibly damaging it.

 

Solid fuel heating and back boiler are on my essential list for a live aboard boat. Cheapest fuel, cheapest to install and maintain. Best reliability. Disadvantages are dust and filth, especially with smokeless coal, hauling 25Kg sacks around and storage space for said sacks. Wood is cleaner, but takes up much more space and is hard to keep in overnight.

 

Jen

To add to above, many manufacturers suggest that some gravity capability is built into a back boiler system as a safety measure in the event of a pump faliure, making a gravity system a better bet to start with. 

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The last post says it all really, a gravity system really is the way to go and you will soon get used to pipes taking slightly 'diagonal' runs. On a freezing dreary February day you will really bless the day you did it.

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Somebody has to be the Devil's Advocate so here goes:  A back boiler is a good bodge for dealing with the problem of not having the right equipment in the right place, which is a centrally positioned stove and a Morco.  It introduces considerable extra complexity and stuff to go wrong, can take power to run if so designed, and must be well designed to run effectively.  Some stoves offer back boilers that on close examination can only output a tiny amount of heat eg 1Kw.  It could be said that a Morco introduce complexity because of the gas but then you need the gas systems in place anyway to run your gas fridge. :D

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52 minutes ago, Alan de Enfield said:

Welcome.

I think that 99.99% of boat SF stoves are fitted with a back boiler to drive radiators &/or hot water via the calorifier.

It would be a 'waste' not to utilise it.

 

I'd suggest it would be the norm to find liveaboard boats with a back boiler, 'leisure equipped boats' may well be found without back boilers.

 

When looking at boats there are a few pointers as to their suitability as a liveaboard :

SF fire with back boiler

Battery bank size

Battery monitoring equipment

Alternators (size and number of) - or installed generator

Water tank size

Toilet type - (cassettes being the best) composting being the best

 

Other things such as a washing machine, are down to personal preference but would be indicative of at least a 'high usage' boat.

 

I have altered it^^^^^^^ to read right ?

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28 minutes ago, system 4-50 said:

Somebody has to be the Devil's Advocate so here goes:  A back boiler is a good bodge for dealing with the problem of not having the right equipment in the right place, which is a centrally positioned stove and a Morco.  It introduces considerable extra complexity and stuff to go wrong, can take power to run if so designed, and must be well designed to run effectively.  Some stoves offer back boilers that on close examination can only output a tiny amount of heat eg 1Kw.  It could be said that a Morco introduce complexity because of the gas but then you need the gas systems in place anyway to run your gas fridge. :D

A centrally sited solid fuel stove, plus gas water heater is also a good live aboard combination. Works best with a relatively open plan boat. The more doors and bulkheads there are, then the colder the boat extremities will get. One end, or the other of the boat is likely to be your bedroom and there is only so much a thick duvet can do when the temperature drops, so consider this if looking at a boat with this combination.

Jen

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Thanks guys,

much appreciate all the feedback  :)

Midships SFB and gravity feed to calorifermejig and rads it is then.

I also read somewhere that, although cleaner, the diesel heating systems are heavy on house electricity (guess thats the pump).

I see most boats that I have seen on the internet have SFB at fwd end, 3 or 4 radiators along the length then the calorifer somewhere near the rear.

It seems that everytime I figure something out and decide on a specific feature, that kinda narrows my field of choice down, but I guess thats natural and you guys have all been through this with many a story to tell    ?  

Kev

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3 minutes ago, kevinm said:

 

I also read somewhere that, although cleaner, the diesel heating systems are heavy on house electricity (guess thats the pump).

 

 

Depends on the diesel heating system.

 

Boilers, like Webasto, Eberspacher and Mikunl, draw a couple of amps for the electric pump and more on start up, but drip feed diesel stoves like Kabola, Lockgate and Bubble don't need any electricity. They can also be combined with a water heating coil to supply a few radiators and/or calorifier, either by gravity or pumped feed.

 

At current diesel prices they cost no more to run than coal fired stoves, are much cleaner and easier to light & control.

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5 hours ago, Jen-in-Wellies said:

A centrally sited solid fuel stove, plus gas water heater is also a good live aboard combination. Works best with a relatively open plan boat. The more doors and bulkheads there are, then the colder the boat extremities will get. One end, or the other of the boat is likely to be your bedroom and there is only so much a thick duvet can do when the temperature drops, so consider this if looking at a boat with this combination.

Jen

What you get with a back boiler and a radiator system is heated towels in the bathroom :) No centrally sited stove, Morso or any other make, gives you that. Having had boats with both options, the best for whole boat heating is, IMHO, a stove at the front connected to a gravity system, running a rad or two to give even heat throughout, all the way to the back of the boat.

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17 minutes ago, kevinm said:

It seems that everytime I figure something out and decide on a specific feature, that kinda narrows my field of choice down,

 

7 minutes ago, cuthound said:

At current diesel prices they cost no more to run than coal fired stoves, are much cleaner and easier to light & control.

 

As with everything on boats, it is worthwhile having a 'fall-back' alternative, having a diesel fired system gives you the flexibility of 'instant heat' for the radiators on a chilly spring/Autumn morning when the fire has either gone out or not yet lit.

It also gives you the option to continue with hot water when the SF stove has cracked, the chimney / flue corroded thru, or you have run out of coal.

 

Having alternatives or options is good on a boat.

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1 hour ago, Alan de Enfield said:

 

 

As with everything on boats, it is worthwhile having a 'fall-back' alternative, having a diesel fired system gives you the flexibility of 'instant heat' for the radiators on a chilly spring/Autumn morning when the fire has either gone out or not yet lit.

It also gives you the option to continue with hot water when the SF stove has cracked, the chimney / flue corroded thru, or you have run out of coal.

 

Having alternatives or options is good on a boat.

 

Indeed I agree, only having a solid fuel stove is a pain during spring and autumn, when  chilly mornings and evenings, but warm days make lighting the stove for an hour or two a pain in the proverbial. Having an easy and quick to fire up diesel boiler and radiators makes these chilly mornings and evenings much more comfortable.

 

The stove, whether solid fuel or diesel drip feed, is a much better option for leaving on days/weeks on end in the cold  winter months, when diesel boilers will coke up with prolonged running on a light load.

Edited by cuthound
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2 hours ago, kevinm said:

Thanks guys,

much appreciate all the feedback  :)

Midships SFB and gravity feed to calorifermejig and rads it is then.

I also read somewhere that, although cleaner, the diesel heating systems are heavy on house electricity (guess thats the pump).

I see most boats that I have seen on the internet have SFB at fwd end, 3 or 4 radiators along the length then the calorifer somewhere near the rear.

It seems that everytime I figure something out and decide on a specific feature, that kinda narrows my field of choice down, but I guess thats natural and you guys have all been through this with many a story to tell    ?  

Kev

Sorry if i'm stating the obvious but with a  gravity system it is simpler to have all the radiators on one side, so if you require heat in a bathroom or bedroom you would need to bear this in mind when installing your stove. Another issue that will ensure success, or a temperamental set up is the size of the pipework, 28mm is the correct size - any less and you will end up having to bodge a pump into the system. 

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5 minutes ago, tree monkey said:

Just to add a bit of balance,  15yrs liveaboard,  squirrel stove and no back boiler and never seen the need.

The cassette bog thing is right though

On an open plan boat of around 45ft, with a centrally mounted squirrel stove I'd agree. A back boiler does have the effect of lowering the heat in the area of the stove which I quite like. 

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38 minutes ago, BWM said:

Sorry if i'm stating the obvious but with a  gravity system it is simpler to have all the radiators on one side, so if you require heat in a bathroom or bedroom you would need to bear this in mind when installing your stove. Another issue that will ensure success, or a temperamental set up is the size of the pipework, 28mm is the correct size - any less and you will end up having to bodge a pump into the system. 

Agree. With a gravity system the layout of the boat has to be designed around it. Location of stove, calorifier, radiators, header tank and their relative heights. As near to 100% 28mm pipe as you can get. Mine has some lengths of 22mm in finrads and the calorifier coil. No valves, the minimum of bends. Everything on the same side of the boat.

On mine the stove is in the centre of the boat. The cauliflower is beside it in a cupboard, raised up on a platform. A rising 28mm pipe goes to the top fitting of the calorifiercoil with a vent to the header tank at the highest point. The height is arranged so the lower fitting of the calorifier coil is at gunwhale height, where it goes to the front of the boat through finrads. From there it turns 180 degrees, with a bleed point and heads back to the back boiler.

 

Je

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23 minutes ago, BWM said:

On an open plan boat of around 45ft, with a centrally mounted squirrel stove I'd agree. A back boiler does have the effect of lowering the heat in the area of the stove which I quite like. 

My boat is far from open plan, the L shaped corridor keeps the bedroom cool, which I like.

Tbh only twice have I felt cold on the boat and that was during a couple of bloody cold winters, approx -10+, with a wind chill, even then the front room was snug.

48ft boat

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There's lots of ways to heat a boat but anything that relies on electricity falls at the first hurdle, if you go away for the weekend and come back in the dark, with sleet coming at you horizontally and the butane frozen and then you find that the batteries are only half charged you really will be so glad that you can light the fire, warm the boat up, light the paraffin lamps and candles and do some toast on the fire.

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Always wondered why so many boats are built with stoves at the front. Doesn't make sense but I guess it's probably easier to fit out a boat with it there. Mine is at the front which means my bedroom takes a while to warm up. Not always what you want. ?

 

I'm thinking of a back boiler for my squirrel, probably for this winter coming. Are they pretty effective? Could anyone give me a rough idea of the cost of fitting one?

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On ‎03‎/‎05‎/‎2018 at 08:07, kevinm said:

Hi Guys,

I am new to the forum and looking for my first live aboard Narrow-boat.

I would like to hear any feedback from anyone who has a back-boiler fitted in their solid fuel stove.

Do you run your radiators off it or does it heat the water in your calorifer tank or both?

how does it perform? What are the pros and cons of such a system?

Much thanks,

Kev.

 

 

  I have a woodwarm fireview with 8,000btu domestic hot water boiler heating 2 rads or the calorifier on gravity circulation on my 50 foot trad narrowboat. Never gets the rads really, really hot like a webasto, but heats the bathroom and bedroom to a good temperature in winter and stops my bedroom windows freezing up.

 

  My stove is at the bow doors and replaced an oil stove without boiler and is a gravity system with 28mm and 22mm copper.

I can also turn off the 2 gravity rads off on the lever valves and switch a pump on to heat the calorifier under the bed, pipes run from one side of the boat to the other under the floor to the calorifier under the bed hence needing a pump.

 

  It takes the back boiler at least 2-3 hours to get the water hot for a shower, so don't ever use it.

I'm Marina based and so for hot water use a 1.1kw immersion heater on a timer. 2 years ago I installed a used Webasto and linked it into my existing heating system and added 2 more rads in the salon and galley, to heat this space when stove isn't lit. This works really well, but only use it when not worth lighting the fire.

 

If cruising have engine heating water, or Webasto or SFS with backboiler. If land based immersion heater.

 

The only real disadvantage of gravity heating is it's not as neat looking with large 28mm pipes fixed along the side of the boat, but no electricity used!

I think secondary form of heating is important as if ill much prefer to flick the switch than mess about with fires. I have my Webasto timer in my wardrobe at the foot of the bed!

 

James:)

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A word of caution.

A live aboard friends'  squirrel back boiler has given up and started leaking. The stove and boiler are less than 5 years old but have seen a lot of hours use. On inspection, the boiler , supposed to be stainless steel, has corroded around the bottom and I guess is not repairable. It was a major task to disconnect the stove, remove from the boat( to avoid a mucky mess) and fit a new boiler. The replacement  boiler cost is about £220 plus, unless DIY, a lot of labour. You might consider a 5 year life for it is acceptable, I don't.

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3 hours ago, billh said:

A word of caution.

A live aboard friends'  squirrel back boiler has given up and started leaking. The stove and boiler are less than 5 years old but have seen a lot of hours use. On inspection, the boiler , supposed to be stainless steel, has corroded around the bottom and I guess is not repairable. It was a major task to disconnect the stove, remove from the boat( to avoid a mucky mess) and fit a new boiler. The replacement  boiler cost is about £220 plus, unless DIY, a lot of labour. You might consider a 5 year life for it is acceptable, I don't.

You do have to bear in mind it's in a very harsh environment what with sulphuric acid with burning logs and coal together, soot, tar coating, condensation formed while heating up on the boilers surface etc.

Mine is just a steel back boiler not stainless and is 4 years old. It's wasn't expensive at £140 from woodwarm.

 

It's a pain having to drain the heating system and refill but the only thing to really go wrong rather than heaters coking up etc.

Some factory integral fitted boiler stoves used to fail around 5 years like the old arrow stratford due to above issues, undersized boiler for heat load, no rust inhibitor etc and no pipe stat to prevent cold water being circulated back round the system when fire started and fire dying down.

I like woodwarm stoves as all of their boilers from 8-70,000btu are bolt in and are separate to the stove so that when it leaks you don't have to throw away the stove. Clearview do too.

 

James:)

Edited by canals are us?
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