back boiler set up...

[lee b]

hi all,i am thinking of buying a multi fuel stove with a back boiler and was wondering the best way to set it up?...i have heard of gravity feed but dont like the idea of having chunky pipe running along the side of my boat,i would prefer all the pipes boxed in along the floor level...i will actually build the boxing in so where there are t-junctions for rads etc i will have a access lid for any leaks that may spring up,not that i'm planning on having leaks but shit happens so better to have easy access than cutting wholes and ripping walls to get to the problem...

thanks for any ideas...

[blackrose]

i have heard of gravity feed but dont like the idea of having chunky pipe running along the side of my boat,i would prefer all the pipes boxed in along the floor level...

 

In which case you will need a pumped system...

 

Personally I'm of the opinion that if a CH system can be made to circulate without a pump and without any external power input then that's advantageous on a boat, but if aesthetic concerns are of primary importance to you then so be it.

 

The only advice I can offer is to install the pump between two gate valves and always carry a spare on board. That way when the pump fails in the middle of winter you won't have to drain the entire system and it will be simple to replace.

Edited June 1, 2013 by blackrose

[Trento]

Hi Lee.

For a pressurised system you need the following

Danfoss, or similar circulation pump (240ac), or if no ac use Jabsco 8-24 volt d.c. 'ecocirc' pump, non-self-priming, for hot water circulation(details on Jabsco website)

6lts Accumulator

Pressure Relief Valve (PRV) with dump to overboard.

0-2bar pressure gauge.

Auto Bleed air valve

1/4 turn valve

System drain valve.

Various "T" pieces and fittings to suit your pipe work.

 

I assume you have radiators and calorifier.

 

The assembly is better shown as a sketch or drawing. However, I'm unable to post one on here.

I suggest we meet in the chat room later tonight to discuss, or you send me email address and I will send drawing/sketch

Trento.

[blackrose]

Hi Lee.

For a pressurised system you need the following

Danfoss, or similar circulation pump (240ac), or if no ac use Jabsco 8-24 volt d.c. 'ecocirc' pump, non-self-priming, for hot water circulation(details on Jabsco website)

6lts Accumulator

Pressure Relief Valve (PRV) with dump to overboard.

0-2bar pressure gauge.

Auto Bleed air valve

1/4 turn valve

System drain valve.

Various "T" pieces and fittings to suit your pipe work.

 

I assume you have radiators and calorifier.

 

The assembly is better shown as a sketch or drawing. However, I'm unable to post one on here.

I suggest we meet in the chat room later tonight to discuss, or you send me email address and I will send drawing/sketch

Trento.

 

What's the advantage of a pressurised system over a non-pressurised exactly? I can think of several disadvantages.

[Trento]

 

What's the advantage of a pressurised system over a non-pressurised exactly? I can think of several disadvantages.

Several.

No header tank to run dry,

No complicated fill ball valves,

Smaller dia pipework than a " thermosyphon" set up when using radiators

Neater smaller foot print.

[MtB]

Several.

No header tank to run dry,

No complicated fill ball valves,

Smaller dia pipework than a " thermosyphon" set up when using radiators

Neater smaller foot print.

 

What's a "complicated fill ball valve"?

 

 

MtB

 

 

 

Edit to fix typo

Edited June 2, 2013 by Mike the Boilerman

[blackrose]

Several.

No header tank to run dry,

No complicated fill ball valves,

Smaller dia pipework than a " thermosyphon" set up when using radiators

Neater smaller foot print.

 

I think I top up my header tank about once a year.

 

What's a complicated-fill ball valve?

 

I was asking about the advantages of a pressurised pumped system over a non-pressurised pumped system, not a thermosyphon system (because we already know that Lee doesn't want a thermosyphon system).

 

How does a pressurised system have a smaller footprint then a non-pressurised pumped system?

 

Edited June 2, 2013 by blackrose

[smileypete]

A multifuel back boiler must be run unpressurised as it's an uncontrolled heat source.

 

The main choice is to go for gravity or pumped circulation, or a combined 'best of both' approach. Then it's designing a decent layout which admittedly is a lot easier for fully pumped.

 

A forum search on 'back boiler' will turn up loads of threads with useful info. Maybe the OP could post a diagram for comments of the layout they plan to do.

 

cheers, Pete.

~smpt~

Edited June 2, 2013 by smileypete

[bizzard]

As Smiley Pete says solid fuel stoves are an uncontrolled heat source unlike most oil, gas, or electric boilers which are more or less instantly controllable or indeed most have some kind of fail safe overheat device. Ideally a large piped in caloriifier working on the thermo-syphon principle and mounted higher than the stoves boiler will act as a bit of a safety heat sink until the stoves heat can be reduced in the event of boiling, ''chucking salt on the fire'' is one way of doing it. The smaller bore radiator circuit can be T'd into the primary thermo-syphon calorifier circuit and pumped.

Relying on a pump or pumps to circulate the whole system is decidedly dodgy with a solid fuel boilered stove, if the pump fails for whatever reason the whole lot could erupt and go off bang.

[blackrose]

A multifuel back boiler must be run unpressurised as it's an uncontrolled heat source.

 

I knew there was something wrong with the idea!

 

Relying on a pump or pumps to circulate the whole system is decidedly dodgy with a solid fuel boilered stove, if the pump fails for whatever reason the whole lot could erupt and go off bang.

 

True, that's a huge disadvantage of entirely pumped systems compared to full or part thermosyphoning.

 

Part of the trouble is that people want to fit out their boats as if they're flats. I knew a bloke fitting out a boat and his partner insisted on a deep butler style sink. Once he'd fitted it in the galley near the stern, the skin fitting for the drain was almost on the waterline. I asked him if that sink was the best choice and he just shrugged his shoulders "It's what she wanted".

 

I think a boat should be fitted-out according to boating practicalities, not only aesthetics.

Edited June 2, 2013 by blackrose

[lee b]

cheers for the advice,i am looking at alternatives to a webasto or similar diesel heater to produce hot water via a calorifier tank, for two reasons,one is i like the idea of using all the heat from a multi fuel stove ''almost free hot water as the stove is already on when its cold'',and also i have heard from several boaters that diesel heaters can be temperamental and if its gona cost £1400 for i temperamental item then i'd prefer to leave it alone...i lived in france and my soul heat source for my house was a wood burner,although my hot water was from a gas heater but i don't want to have a gas heater on a boat.

so is it dangerous to install a pump system with a back boiler on multi fuel stoves?...how did back boilers on old houses cope?they run on a pump...i know pumps can pack in,i have replaced them but in my experience you hear a warning sign normally,usually a ''pinking noise'',which tells your pump is on the way out.

i will be fitting a surecal calorifier which i believe has a built in safety valve and self bleeding valve...?

could you please explain why a gravity system wont over heat but a pump system will? or is it just if the pump fails?

also i have been reading on several sites about a gravity system and they say the radiators can only run on one side of the boat? this makes no sense to me as a radiator system needs a pump to circulate the water...?

perhaps planning to do a gravity feed to the calorifier but boxing in the pipe work might work for me...its a sail away so if i design it in the build then would this be a option? i can always conceal the boxing in with shelve,book case etc...thanks for the tips and i will most likely be in the chat room later...

[blackrose]

cheers for the advice,i am looking at alternatives to a webasto or similar diesel heater to produce hot water via a calorifier tank, for two reasons,one is i like the idea of using all the heat from a multi fuel stove ''almost free hot water as the stove is already on when its cold'',and also i have heard from several boaters that diesel heaters can be temperamental and if its gona cost £1400 for i temperamental item then i'd prefer to leave it alone...i lived in france and my soul heat source for my house was a wood burner,although my hot water was from a gas heater but i don't want to have a gas heater on a boat.

so is it dangerous to install a pump system with a back boiler on multi fuel stoves?...how did back boilers on old houses cope?they run on a pump...i know pumps can pack in,i have replaced them but in my experience you hear a warning sign normally,usually a ''pinking noise'',which tells your pump is on the way out.

i will be fitting a surecal calorifier which i believe has a built in safety valve and self bleeding valve...?

could you please explain why a gravity system wont over heat but a pump system will? or is it just if the pump fails?

also i have been reading on several sites about a gravity system and they say the radiators can only run on one side of the boat? this makes no sense to me as a radiator system needs a pump to circulate the water...?

perhaps planning to do a gravity feed to the calorifier but boxing in the pipe work might work for me...its a sail away so if i design it in the build then would this be a option? i can always conceal the boxing in with shelve,book case etc...thanks for the tips and i will most likely be in the chat room later...

 

Ok, well, firstly a pumped system is not inherently dangerous - only if the pump packs up, the water can't circulate and it overheats. For this reason on a pumped system it's wise to have some part of it which can thermocycle (circulate without the pump) and that means bigger diameter pipes and not all at floor level.

 

The reason why a thermocycling (gravity) system can't overheat (if designed correctly) is that there is no pump and it circulates due to the forces of convection and gravity. The only way it can overheat is if you don't top up the header tank occasionally.

 

The difference between boats and houses is that on boats you don't always have shore power and that means that your pump will be 12v (or 24v) and less reliable than a mains pump. Even if you installed a mains pump and ran it off the inverter while cruising, it's still relying on batteries.

 

You may well hear your pipes overheating, or you may be out at the shops, or sleeping.

 

A radiator system doesn't necessarily need a pump - not if it's designed to thermocycle.

Edited June 2, 2013 by blackrose

[lee b]

i am having a trad boat''sail away'',the hot water cylinder will be at the rear end of the boat housed in the engine area,this would be higher than the radiators so i don't think a thermocycle system would work correctly,although i have never done a thermocycle system because my plumbing has always been done in houses,using pumps...

also i am not sure on radiator system running from the calorifier again with thermocycle because where my calorifier will be positioned and without a pump would gravity come into the factor?...cheers for any help

[smileypete]

Possibly a good way to do it would be to have a gravity circuit for the rads nearest the backboiler, then a pumped circuit for the calorifier and the more distant rads. The gravity fed rads must be large enough size (in kW or BTU) to accept what the back boiler is capable of putting out.

 

It'd be well worth using the search facility to read up and then making a diagram, it's easier to make changes to a diagram than have to make changes to installed pipework.

 

cheers, Pete.

~smpt~

Edited June 2, 2013 by smileypete

[lee b]

i don't want one running one way and one running the other,this in my opinion is a recipe for disaster,its best to do the set up from the start correctly and go for a pump or gravity feed or if needed a webasto and just the multi fuel stove without a back boiler.... the main draw back i can see about gravity feed is i would only be able to have rads on one side of my boat,as for the comments about some people want to kit their boat out as if were a flat or house couldn't be further from the truth in my case,for a start i don't want a washing machine on board...uses too much water and battery power and i'd prefer to spend the money what you'll be spending on a good inverter and low energy washer at a launderette and get it dried...in any case,£2500-£3000 for the inverter and washer would keep me in new clothes for years which i could wear and throw lol !! i will have a inverter for a few things like a oven fan,charging my lap top, but i wont have micro waves or sky tv,i like to read and most tv programs are crap any way...especially blood soaps !!!!

anyway,all i am trying to assess from comments is the best options for fitting my boat out for efficiency and am trying to go about things in the same manner as when i work building houses and barn renovations...'' measure twice,cut once'', in other words make sure you get it right first time round cause it saves a lot of pissing around....which costs money as well as time....

[blackrose]

Possibly a good way to do it would be to have a gravity circuit for the rads nearest the backboiler, then a pumped circuit for the calorifier and the more distant rads.

 

Agreed. It can be quite difficult to get a thermocycling system to heat a calorifier - unless the calorifier is fitted with wide bore coils and is close enough to the backboiler.

 

i don't want one running one way and one running the other,this in my opinion is a recipe for disaster,its best to do the set up from the start correctly and go for a pump or gravity feed or if needed a webasto and just the multi fuel stove without a back boiler.... the main draw back i can see about gravity feed is i would only be able to have rads on one side of my boat..

 

A thermocycling system can be designed to circulate the way you want it to. Making a hybrid system using both thermocycling and a pump for the calorifier and/or distant rads is certainly not a recipe for disaster - lots of people do it very successfully.

 

Why would anyone need rads on both sides of a narrowboat (assuming it's a narrowboat)? I only have rads on one side of my boat and it's 12ft wide. If you must have rads on both sides then consider what Pete suggests and use thermocycling for one side and a pump for the other side + calorifier.

Edited June 4, 2013 by blackrose

[Pete & Helen]

After reading this thread I must admit to being a little worried about the system that's fitted to my narrowboat, in particular the comment about the back boiler being an uncontrolled heat source.

I have a multi fuel burner which feeds 2 radiators at the back end of the boat and then on to the calorifier which sits at the same height as the burner. The pipework is 22mm copper set low level and the system is pumped by a 240v domestic pump. the system is also pressurised with an expansion tank and pressure gauge in the engine bay. There is a blow off valve fitted to dump excess pressure overboard.

Does anyone else have anything like this?

[smileypete]

If the backboiler of the multifuel IS being run pressurised, do NOT use the stove until it's converted to a 'open' system with header tank with feed and vent pipes, better still find a way to prevent the stove being used until it's done.

 

A competent boatyard with experience of fitting narrowboat heating should be able to convert it, or a reputable domestic plumber with decent experience of backboiler heating systems, a plumber with a HETAS qualification would be ideal.

 

cheers, Pete.

~smpt~

Edited June 4, 2013 by smileypete

[Pete & Helen]

I am also assuming that if its a pumped system then the pump needs to be on all the time the stove is fired up to prevent boiling. With a 240v pump I would think that this would cause some battery issues if not on land power

[lee b]

the radiators on both sides of the ''narrowboat'', would be a few on one side for the bedroom and mid area of the boat and one in the bathroom the otherside of the boat,the design i want is to have the bathroom to help reduce humidity after showers etc...i am trying to design the inside so weight is distributed to both sides,i have viewed a few boats that's got fixed floors so you cant re distribute ballest and it feels as though your capsizing because everything was on one side of the boat... i know your on a boat and you will never be completely level but i would go insane sleeping on a hill...''well,more insane than i am already anyway''lol.... i would go with a diesel heater for my rads and hot water but quite a few people have told me they can be unreliable...it seems like a lot of money for something unreliable and fiddly,i want a multi fuel stove on my boat so if i can run my rads and hot water calorifier and it will be more reliable than a webasto or similar then it would be better for me....i am having a 57ft narrow boat so i think i will need rads,even if the heater is around the middle of my boat,i have been told if i have it at the front without rads the back of the boat will be cold...i am designing my boat with no doors other than the bathroom door,would the heat travel around ok without rads or would it be better with them? cheers for your help...much appreciated, some people including family members think i am a loony case buying a narrowboat without ever having any experience...i have met a few people that says they were like myself and taken to it like a duck to water,i have given a hell of a lot of thought into buying a narrowboat to live on for years so i am going into it open minded...time will tell ! lol

[canals are us?]

Hi,

 

I bought a 50ft trad 6 months ago now to live on and had never been on one or knew anything about them.

I installed a 4.5kw woodwarm multifuel stove which is at the front and then later installed a backboiler to heat the calorifier. I also only installed rads on gravity to absorb the heat from the boiler and pumped the circuit to the calorifier under my bed.

 

To be totally honest if I knew how well the stove heated the boat I personally wouldn't of bothered with installing the rads or linking the calorifier as I'm mostly Marina based and so could use the immersion for showers etc. I bought the stove and boiler together and with plumbing in etc cost around £700 inc backboiler, pipes, rads etc installing myself.

The bedroom is at the rear and even in the cold spell must of been around 18 degrees. I left the bedroom door open.

I find you can't beat the engine at heating the water quickly and much hotter than the backboiler.

 

My boat is a 1999 liverpool trad with sprayfoam insulation and found it really warm with just a good 4.5kw stove.

 

I would install the rad system as said, ie gravity one side, pumped other plus calorifier if you really do want rads.

 

 

James

Edited June 4, 2013 by canals are us?

[blackrose]

the radiators on both sides of the ''narrowboat'', would be a few on one side for the bedroom and mid area of the boat and one in the bathroom the otherside of the boat,the design i want is to have the bathroom to help reduce humidity after showers etc...i am trying to design the inside so weight is distributed to both sides,i have viewed a few boats that's got fixed floors so you cant re distribute ballest and it feels as though your capsizing because everything was on one side of the boat... i know your on a boat and you will never be completely level but i would go insane sleeping on a hill...''well,more insane than i am already anyway''lol.... i would go with a diesel heater for my rads and hot water but quite a few people have told me they can be unreliable...it seems like a lot of money for something unreliable and fiddly,i want a multi fuel stove on my boat so if i can run my rads and hot water calorifier and it will be more reliable than a webasto or similar then it would be better for me....i am having a 57ft narrow boat so i think i will need rads,even if the heater is around the middle of my boat,i have been told if i have it at the front without rads the back of the boat will be cold...i am designing my boat with no doors other than the bathroom door,would the heat travel around ok without rads or would it be better with them? cheers for your help...much appreciated, some people including family members think i am a loony case buying a narrowboat without ever having any experience...i have met a few people that says they were like myself and taken to it like a duck to water,i have given a hell of a lot of thought into buying a narrowboat to live on for years so i am going into it open minded...time will tell ! lol

 

To be honest, on a 57ft open-plan properly insulated NB you would probably be fine without any rads at all, as long as the stove is located in the middle of the boat. I have rads going from my (central) stove into the bathroom behind and then bedroom at the bow, I seldom close the bedroom and boathroom doors because I live alone, but I closed them once for some reason and was quite surprised some hours later when I went into the bedroom and it was quite cold. Usually the bedroom is warm with the stove on and bedroom door open, which meant that most of the heat must be getting into the bedroom by air convection down the corridor, rather than from the radiator. However, as a caveat to that, the corridor past the bathroom is quite wide (wider than most NB corridors), which may facilitate these air convection currents.

I am also assuming that if its a pumped system then the pump needs to be on all the time the stove is fired up to prevent boiling. With a 240v pump I would think that this would cause some battery issues if not on land power

 

Yes, you need to have the pump switched on all or most of the time while the stove is on. It could cause problems if the batteries aren't charged properly.

 

The problem with such systems away from shore power, is that they rely not only on the pump working correctly, but also on the inverter and then the batteries. That's too many links (to go wrong) in the system for me. This is why many boaters like thermocycling systems. They just work on their own - without any external DC or AC power inputs. Thermocycling has its limitations of course, like getting it to cycle over any distance and through calorifiers, so having thermocycling in conjunction with a pumped system for those difficult bits makes perfect sense.

Edited June 4, 2013 by blackrose

[lee b]

so if i put a thermocycling system in i would assume it would be better to do this just for the calorifier so the hot water is circling naturally,there for would it be better to put a pump for the rads or will those run from the calorifier with thermocycling too...?

if i run the rads on a pump and the calorifier on the thermocycling this would then meen i can have radiators on both sides of my boat,one towel rad in the bathroom and a few rads along the other side?...

cheers

[peterboat]

After reading this thread I must admit to being a little worried about the system that's fitted to my narrowboat, in particular the comment about the back boiler being an uncontrolled heat source.

I have a multi fuel burner which feeds 2 radiators at the back end of the boat and then on to the calorifier which sits at the same height as the burner. The pipework is 22mm copper set low level and the system is pumped by a 240v domestic pump. the system is also pressurised with an expansion tank and pressure gauge in the engine bay. There is a blow off valve fitted to dump excess pressure overboard.

Does anyone else have anything like this?

Hi yes I do and like yours it works well also have a bubble stove in the circuit plus a wispergen the advantage of the bubble stove is if the pump breaks it turns itself off clever eh

 

Peter