Boatman stove backboiler number of rads

[Rivelin]

Hi all,

I am looking at installing Boatman stove with a back boiler in my 38ft narrowboat.

 

I was proposing to power a calorifier and a single rad at the back of the boat (the stove will be at the front).

Do you think the back boiler will be too much for this arrangement?

Thanks in advance,

Nick

 

[peterboat]

I think it should work ok, however is it going to work on gravity or be pumped? if gravity put in 28mm pipe it will work better.

[alan_fincher]

2 minutes ago, peterboat said:

I think it should work ok, however is it going to work on gravity or be pumped? if gravity put in 28mm pipe it will work better.

if the boat sits like most do with its bows higher than its stern, and (as stated) the stove is at the "high" end and the radiator (and calorifier?) at the "low" end, then it will be hard to do with gravity!

[peterboat]

I have installed on my mates boat a rayburn Royal, its at the bow the cauliflower is in the middle and the big rad at the stern it all works fine the pipes all run up hill

[rusty69]

Ours is a 70ft boat with stove at front running three rads with gravity fed 28mm pipes.

 

It may be more difficult to achieve with a shorter boat, but not impossible I would think.

[Rivelin]

Thanks for your quick replies folks.

 

I was hoping to use gravity but the stove will be at the "high" end, so sounds like it would need to be pumped.

 

Do you think the 4kw output of the Boatman boil the water if I only had the calorifier and 1 rad?

[rusty69]

Probably not if you sized the rad and calorifier correctly.

[peterboat]

4 KW I thought was the total output for water and space heating. We have one in the house and it does very well on a good day it will heat every room 

[Boater Sam]

Relying on a pump on a solid fuel stove is a bad idea IMHO. It is possible to do a gravity system, just takes a bit of design and planning.

[Alan de Enfield]

7 minutes ago, peterboat said:

4 KW I thought was the total output for water and space heating. We have one in the house and it does very well on a good day it will heat every room 

I may be putting words into the OPs mouth but I believe his  concern is just the opposite :

 

"Will it be too big, Will I be able to get rid of the heat or will it boil the water with just one rad and a cauliflower"

Edited November 1, 2018 by Alan de Enfield

[Rivelin]

Yes, it's as Alan says, will the heat generated be too much for 1 rad and a cal?

[rusty69]

The question should be . "What size radiator(s),piping and calorifier do I need to install to match the output of a Boatman stove"

Edited November 1, 2018 by rusty69

[Rivelin]

What size radiator(s),piping and calorifier do I need to install to match the output of a Boatman stove? ?

[alan_fincher]

We have a fairly massive Much Wenlock stove which from memory is 6kW, so 1.5 times the output of a Boatman,

 

It s often run, (as it is being currently), with all the radiators turned off, so only the calorfier is being heated, and has never shown any tendency to boil when only heating a calorfier.

 

In my limited experience most back boilers do not take that large a percentage of the output from the stove, far more being radiated from the stove than ends up in the back boiler circuit.

Unless the Boatman puts a much higher percentage of its heat into the water circuit than stoves I'm familiar with, I think the chances of problems with both a calorifer and a radiator in the circuit are likely to be minimal.

[ditchcrawler]

You also need to take into account how long at a time its going to be running at maximum

[alan_fincher]

3 minutes ago, ditchcrawler said:

You also need to take into account how long at a time its going to be running at maximum

Or whether you actually ever need to run it at anything like maximum output.............................

[peterboat]

Of course we could always look at the site 1 x cauliflower and 3 rads is the answer so if it was a single rad it would need to be substantial  http://r.search.yahoo.com/_ylt=AwrCwOXbc9tbtkAAb2YnnIlQ;_ylu=X3oDMTByOHZyb21tBGNvbG8DYmYxBHBvcwMxBHZ0aWQDBHNlYwNzcg--/RV=2/RE=1541137500/RO=10/RU=http%3a%2f%2fboatmanstove.co.uk%2f/RK=2/RS=GLeCTe8KzIRO0n.fFFhhuDJNCu

[MtB]

5 hours ago, nickhindle said:

Do you think the 4kw output of the Boatman boil the water if I only had the calorifier and 1 rad?

 

I'll be staggered if mine ever gets anywhere near 4kW output unless I have it fully banked up, glowing orange/yellow and virtually jumping off the hearth. 

 

Put less coal on if the water boils....

[Ex Brummie]

I have a Bubble stove with a nominal 5kw output. The backboiler capacity is nowhere near that, as it produces heat to radiate. I have a pipe thermostat on the boiler flow, set at 65oC that switches on a small pump to the forward radiator of about 2kw, but stops the pump when the boiler temp falls. If you rely on gravity and use 28mm pipes, remember the pipes are another radiator, and reduce the output to the cauliflower and radiator. I think your problem is likely to be under capacity rather than over capacity.

[sparrowcycles]

Ive done a good few gravity systems with the stove up the front, if you definitely get it running up hill, even when the water tank (if it's at the front) is empty, and there's not too many 90degree bends etc it'll be fine. 

 

Most rads have 1/2" bsp threads so Ive used 1/2" to 22mm compression fittings into and out of them so the pipework doesn't have to reduce to 15mm into the radiators. 

 

And I always start with the return pipe, to make sure it's got a nice flow back with no need to rise up to the back boiler. 

 

The only issue is that the rads can end up quite close to the gunwale due to the pipe angle. 

 

[Jen-in-Wellies]

You could always ask the manufacturer how many watts of radiator you need on the backboiler. They are difficult to get in touch with by phone. Too busy making stoves, but should get back by email eventually. Bought some spares for a neighbours stove last year.

 

Jen

[bizzard]

A gravity system will run much more reliably and better without wretched radiators. They can be a nuisance and are expensive, extra joints waiting to leak and often frequent bleeding. The only handy thing about them is one can turn the odd one off if needed and to drape washing on them to dry. Originally on boats when central heating from a coal stove or gas boilers folk rarely bothered with radiators, including hire boats, and they were all lovely and warm throughout. We have a couple of boats here, still running with just 28mm gravity pipework from multi fuel stoves and they're always as warm as toast and generally completely trouble free.  If the water in your area is hard and limey its wise not to use tap water in the system, nor in the engine.

[Alan de Enfield]

11 minutes ago, bizzard said:

We have a couple of boats here, still running with just 28mm gravity pipework from multi fuel stoves and they're always as warm as toast and generally completely trouble free.

A run of 30 metres (2 x 15 metres) of 28mm copper pipe will have a surface area of 2.64 metres squared.

 

That is equivalent to a big area of radiators.

[bizzard]

20 minutes ago, bizzard said:

A gravity system will run much more reliably and better without wretched radiators. They can be a nuisance and are expensive, extra joints waiting to leak and often frequent bleeding. The only handy thing about them is one can turn the odd one off if needed and to drape washing on them to dry. Originally on boats when central heating from a coal stove or gas boilers folk rarely bothered with radiators, including hire boats, and they were all lovely and warm throughout. We have a couple of boats here, still running with just 28mm gravity pipework from multi fuel stoves and they're always as warm as toast and generally completely trouble free.  If the water in your area is hard and limey its wise not to use tap water in the system, nor in the engine.

Around 1882 we hired a boat from Tony Matts at Foxton Boat services for a week in November £31 each.  He had a small fleet of Harborough Marine boats all with Foxy names and air cooled Lister engines., ours was Foxtail. They had Ald Comfort gas  boiler heating for hot water and just a gravity pipe circuit central heating, it was as warm as toast.  Tony Matts had a big hand in designing those Ald gas boilers, so he told us.

[rusty69]

5 minutes ago, bizzard said:

Around 1882 we hired a boat from Tony Matts at Foxton Boat services for a week in November £31 each.

Jeez Bizz, I knew you was old, but 136 plus?