Plumbing in a back boiler

[Doorman]

 

As for the eber being reliable - im sure theres plenty of posts on here about this For the first 3 years the eber was the only source of heating and with a 'new born' got a right battering. I know about the gas oil debate and its completely unreliable using this fuel. We had a lovely run just using paraffin/kersone until the local garage closed down. Been using ultra low gas oil since, and hasnt been to much of an issue other than a blower motor dying and new glow plug. The burner got coked up last winter, i actually cut the fuel pipe off the burner and got a friend to weld/braise the pipe back onto chamber.

 

 

It would appear that unreliability is not just isolated to your Eberspacher. A fellow moorer has just returned to his 18 month old boat from home, only to find that the Mikuni MX40 had failed to operate during the big freeze, causing his shower mixer block to crack open. Cause; replacement glow plug failure!

 

Mike

[Fuel__2001]

It would appear that unreliability is not just isolated to your Eberspacher. A fellow moorer has just returned to his 18 month old boat from home, only to find that the Mikuni MX40 had failed to operate during the big freeze, causing his shower mixer block to crack open. Cause; replacement glow plug failure!

 

Mike

 

Thanks for uploading those pictures, I managed to have a look at the pics on my phone. Is it possible you can upload those pictures again so i can have a better look at them on my PC? I find tinypic a much better hosting service than image shack.

 

The diesel heaters have their place but as for relying on them full time like a normal domestic heating -

[Doorman]

Thanks for uploading those pictures, I managed to have a look at the pics on my phone. Is it possible you can upload those pictures again so i can have a better look at them on my PC? I find tinypic a much better hosting service than image shack.

 

The diesel heaters have their place but as for relying on them full time like a normal domestic heating -

 

Hi,

 

can't understand why 'imageshack' have barred my pictures. It's not as if I have stolen them from someone else's copyright!

 

I'll upload them again and then try 'Tinypic' as you suggest. The main problem is that it's taken me ages just to understand the imageshack set-up

 

 

Mike

[Doorman]

I've kept these photo's at full size for clarity. Hope it doesn't take till next year to upload!

 

Mike

 

 

 

This diagram illustrates how simple our present central heating system is. Although there is no method of isolating either the Mikuni, or, the Morso when either one is in operation, this does not have an adverse effect to the efficiency. Also, as previously stated, the two heating sources can be run simultaneously, to our advantage.

 

Mike

 

 

This diagram illustrates the rear view of the back boiler indicating where the bleed & pressure relief valve are positioned.

 

 

 

Edited January 3, 2011 by Doorman

[smileypete]

The questions i have

 

what equipment(pump/valves/pipework etc) will i need, what makes/type?

 

Best way to isolate a system when the other is operational?

 

Safety considerations/BSS?

 

Where on the current system would be the best place to plumb in a water pump?

 

Where on the system would the best place be to hook into the flow/return?

If you want a system that's safe (and works well) it would be best to seek the advice of a competent heating engineer.

 

For starters a back boiler must have an adequately size vent pipe (with no valves of any sort) between back boiler and header tank.

 

Google 'open vent central heating' for more info.

 

cheers,

Pete.

Edited January 3, 2011 by smileypete

[MtB]

If you want a system that's safe (and works well) it would be best to seek the advice of a competent heating engineer.

 

For starters a back boiler must have an adequately size vent pipe (with no valves of any sort) between back boiler and header tank.

 

Google 'open vent central heating' for more info.

 

cheers,

Pete.

 

Yep, I wholly agree with that. Trouble is, where to find this mythical 'competent heating engineer'. Most (although not all) heating engineers I encounter are of the knuckle-dragging Neanderthal variety and considerably less competent than many of the lay-people who post on this site.

 

Some people allege that I'm a competent heating engineer but I'm not so sure. I've learned enough however over the years to avoid getting involved in the design of other people's multiple-source heating systems. They always end up being an ovecomplicated compromise with just too many things unanticipated to go wrong and stick a spanner in the works.

 

All I can say is pipe it up how you like, see how it performs, then make changes to address the problems you encounter. There will be things that one boat owner regards as a minor drawback easily dealt with that another owner would regard as a major issue and deal-breaker.

 

 

Mike

[Doorman]

If you want a system that's safe (and works well) it would be best to seek the advice of a competent heating engineer.

 

For starters a back boiler must have an adequately size vent pipe (with no valves of any sort) between back boiler and header tank.

 

Google 'open vent central heating' for more info.

 

cheers,

Pete.

 

Hi Pete,

 

I believe your advice to be sensible, depending on the competence level of the person who reads it.

 

I have read many posts on this forum, from members of varying levels of experience, who look to install a diverse array of components on their boats, without the usual skills required. This doesn't mean that they are incapable of effecting such installations, as there is now a wealth of technical information available on the internet (as you know), enabling most people of reasonable intelligence, the opportunity to learn the skills involved.

 

Conversely, there are also people, who will attempt an installation that is beyond their skill level and not seek to learn the correct procedures. It is the people from this group whom I believe, should take your advice in earnest.

 

The key issue is where they gain their advice from!

 

Mike

[smileypete]

Yep, I wholly agree with that. Trouble is, where to find this mythical 'competent heating engineer'. Most (although not all) heating engineers I encounter are of the knuckle-dragging Neanderthal variety and considerably less competent than many of the lay-people who post on this site.

Well they're not heating engineers then, although they may claim to be. If they've done at least a couple of similar systems that work very well, chances are they're the real deal.

 

Another way for the OP could be to do lots of research into open vent, gravity, and pumped systems, then come up with a design, and ask specific questions.

 

But reading this thread and this thread it seems very few (any?) people don't want to go to that kind of trouble.

 

cheers,

Pete.

Edited January 8, 2011 by smileypete

[MtB]

Well they're not heating engineers then, although they may claim to be. If they've done at least a couple of similar systems that work very well, chances are they're the real deal.

 

But that's what the question was. HOW does once find a heating engineer who has a track record of successfully designing and installing dual-heat-source (one uncontrolled) heating systems, as opposed to one fits combi gas boilers and four rad systems in ex-council flats in Basingstoke (no matter how competently)? I'd suggest a HETAS member might be a good place to start. They are more likely to understand the issues.

 

http://www.hetas.co.uk/nearest_member

 

Another way for the OP could be to do lots of research into open vent, gravity, and pumped systems, then come up with a design, and ask specific questions.

 

Yep.

 

But reading this thread and this thread it seems very few (any?) people don't want to go to that kind of trouble.

 

And that thread only attempts to deal with the problem of boiling in a single 'uncontrolled heat source' system. This thread is about dual heat source systems, including an uncontrolled heat source for installation by a lay person. A recipe for unexpected consequences in my opinion.

 

Mike

 

(Edited to remove duplicated content.)

Edited January 8, 2011 by Mike the Boilerman

[Fuel__2001]

Most (although not all) heating engineers I encounter are of the knuckle-dragging Neanderthal variety and considerably less competent than many of the lay-people who post on this site.

 

All I can say is pipe it up how you like, see how it performs, then make changes to address the problems you encounter. There will be things that one boat owner regards as a minor drawback easily dealt with that another owner would regard as a major issue and deal-breaker.

 

Mike, you do manage to paint a very funny picture in my mind with your descriptions

 

That aside, if i was to tackle this job then thats partly how i can see this unfolding, by installing a system and then some tweaking.

 

I believe your advice to be sensible, depending on the competence level of the person who reads it.

 

The key issue is where they gain their advice from!

 

Im totally in agreement - Not only will i get my advice from here, but i will also be seeking from elsewhere - i do find this forum extremely knowledgeable and the input on this thread so far has been brilliant. No way am I put off tackling this installation and if at any time i feel overwhelmed then I would call in the experts. As this thread is progressing, i do have more questions which i will follow up with in another post.

 

I do engines, electrics, small scale pipework (bathroom installation) and gas, but i dont do wood - i hate wood and cant work with it, the only thing wood is good for after i finished with it is burning Knowing my limits is vital for a safe installation

 

Another way for the OP could be to do lots of research into open vent, gravity, and pumped systems, then come up with a design, and ask specific questions.

 

This thread is really the starting point for the installation. I see this stage of the work as the most important part of the process, as it will dictate the type of installation, what i buy and how i lay the pipe work. Im taking my time and am in no hurry to get the job done, as I would like to do it and get it right first time.

 

You may have noticed by the pictures i posted earlier, how the design has changed as im getting to grips with what I would like the installation to accomplish and what it actually needs to achieve this.

 

But that's what the question was. HOW does once find a heating engineer who has a track record of successfully designing and installing dual-heat-source (one uncontrolled) heating systems, as opposed to one fits combi gas boilers and four rad systems in ex-council flats in Basingstoke (no matter how competently)? I'd suggest a HETAS member might be a good place to start. They are more likely to understand the issues.

 

http://www.hetas.co.uk/nearest_member

 

Once again Mike your description is beautifully worded, i read your post out to a friend and we were rolling about the place

[smileypete]

This thread is really the starting point for the installation. I see this stage of the work as the most important part of the process, as it will dictate the type of installation, what i buy and how i lay the pipe work. Im taking my time and am in no hurry to get the job done, as I would like to do it and get it right first time.

OK, so where's your open vent pipe? Heat dump radiator?

 

Sorry, but I get the impression you're not quite as competent as you really should be, and some of the help you're getting, though well intentioned, isn't any better.

 

Edit: Try starting with simple diagram of a stove back boiler, single gravity fed heat dump radiator, header tank, cold feed and vent.

 

cheers,

Pete.

Edited January 9, 2011 by smileypete

[Fuel__2001]

OK, so where's your open vent pipe? Heat dump radiator?

I appreciate your concerns and certainly dont take offence to your comments. I actually welcome them.

 

The eberspacher header tank which im looking to use is something i need to investigate further. I was hoping the pressure cap on the header tank can deal with the venting as there is also a small over flow at the top of the header tank should the system over pressurise.

 

As for a dump rad - if the back boiler is rated a 3Kw and the minimum rad system that would ever be used is 3Kw, do i really need a dump rad on a pumped system?

 

What is your PRV rated to? Or the question should be, if the rad cap on the eber header is above 4 bar is this out of range and liable to cause over pressurisation?

Edited January 9, 2011 by Fuel__2001

[smileypete]

I appreciate your concerns and certainly dont take offence to your comments. I actually welcome them.

 

The eberspacher header tank which im looking to use is something i need to investigate further. I was hoping the pressure cap on the header tank can deal with the venting as there is also a small over flow at the top of the header tank should the system over pressurise.

 

As for a dump rad - if the back boiler is rated a 3Kw and the minimum rad system that would ever be used is 3Kw, do i really need a dump rad on a pumped system?

 

What is your PRV rated to? Or the question should be, if the rad cap on the eber header is above 4 bar is this out of range and liable to cause over pressurisation?

 

<Sigh!>

 

Again, try starting with simple diagram of a stove back boiler, single gravity fed heat dump radiator, header tank, cold feed and open vent.

 

cheers,

Pete.

Edited January 9, 2011 by smileypete

[Doorman]

<Sigh!>

 

Again, try starting with simple diagram of a stove back boiler, single gravity fed heat dump radiator, header tank, cold feed and open vent.

 

cheers,

Pete.

 

Hi Pete,

 

I am a little concerned why you keep advising the OP in referring to what can only be described as a household style central heating system, when his request for advice is all about a system confined to a wide beam boat. Surely, you must be aware of the height constraints involved here, together with the impracticalities of such a system on board a boat.

 

Simple diagrams of a working system have been provided, including a dump radiator (several), a back boiler, header tank and open vent. Why then, does he need much more?

 

Mike

Edited January 9, 2011 by Doorman

[Fuel__2001]

<Sigh!>

 

Again, try starting with simple diagram of a stove back boiler, single gravity fed heat dump radiator, header tank, cold feed and open vent.

 

cheers,

Pete.

 

Pete

 

You've stopped smiling!

 

I came here for information and help, hopefully for others to spot errors or concerns with the setup i want to use.

 

In fact, youve highlighted everything in red and repeated yourself. In getting me to jump through your hoops will this help me to achieve a safe a reliable pumped system from the information i have provided? If you think im going to blow my boat up and make it unsafe, then please say so.

 

Otherwise, lets keep this thread on topic.

 

As youve said nothing about me using the eber header and pressure cap can i take it this is ok?

[smileypete]

As youve said nothing about me using the eber header and pressure cap can i take it this is ok?

No!

 

A back boiler has got to be completely unpressurised under all circumstances, with a proper vent pipe that's always open to the atmosphere. (Hence 'open vent'...)

 

Why not have a look on the web at some gravity central heating designs, as suggested earlier. They don't have a sealed header tank with radiator cap, do they...?

 

cheers,

Pete.

[Pretty Funked Up]

This diagram illustrates how simple our present central heating system is. Although there is no method of isolating either the Mikuni, or, the Morso when either one is in operation, this does not have an adverse effect to the efficiency. Also, as previously stated, the two heating sources can be run simultaneously, to our advantage.

 

Mike

 

 

The image shows the 2 CH pumps fighting each other. I'd be inclined to swap them at the mikiuni end so they compliment each other

[Doorman]

The image shows the 2 CH pumps fighting each other. I'd be inclined to swap them at the mikiuni end so they compliment each other

 

I've replaced the original drawing with this one, illustrating

the conclusion that I've come to, regarding the coolant direction of flow when both the Mikuni and Morso are in simultaneous operation.

 

 

Although not specifically designed to operate in sync by the boatbuilder, by adding a few modifications, the system does work very well, even without an open vent, as per original design.

 

Also, it can be seen that both circ pumps are positioned on the return side of each boiler, the one on the Mikuni as per design and the one on the Morso as per my specification. If you look to most household central heating systems, you can see that the engineer positions the pump directly after the flow side of the boiler, why? The pump fitted to the return does the same job, only at a far more efficient working temperature. In addition to this, you often see the 'T' from the flow circ leading to the open vent. If there is a constriction further down the line in the flow side, this will

create back pressure and potentially cause the open vent to overflow! That is why I placed the 'T' on the return circ of our system.

 

Mike

Edited January 10, 2011 by Doorman

[Fuel__2001]

No!

 

A back boiler has got to be completely unpressurised under all circumstances, with a proper vent pipe that's always open to the atmosphere. (Hence 'open vent'...)

 

Why not have a look on the web at some gravity central heating designs, as suggested earlier. They don't have a sealed header tank with radiator cap, do they...?

 

cheers,

Pete.

Thankyou Pete,

 

I see this is where the conflict arises, when some say you can use a 'pressurised system' and others say only 'open vent'. Looking at the suitability of the eber header its not a completely closed system, it will only pressurise to a certain level, then vent if the pressure gets too much. I assume this is where you see the danger arising.

 

I could just remove the rad cap from the eber header and run a vent back to it, which seems a very simple option as i wont be using the eber and stove at the same time. The only difference between this and a domestic setup is there is no cold feed.

 

In a typical open vent with header, how is this achieved on a boat as a domestic header is large, typically with a ball cock and cold feed.

[Doorman]

 

In a typical open vent with header, how is this achieved on a boat as a domestic header is large, typically with a ball cock and cold feed.

 

Precisely..!

[sharpness]

In a typical open vent with header, how is this achieved on a boat as a domestic header is large, typically with a ball cock and cold feed.

You dont need a large header tank, the system doesn't "comsume" any water and with perhaps 10 maybe 15 ltrs ciculating the expansion between cold & hot is minimal. My "feed & expansion tank", a much better description of what it actually does than "header tank" is a car washer bottle from a scrapyard. Cold to hot the water level rises perhaps 1/2 an inch. It is fitted as high as possible in the engine space, ie up against the roof so has about 4ft of head above the Mikuni, 2ft above the tops of the rads. You only need a head of water to be able to bleed the system so 2 ft above the rads is plenty. I dont see the problem, or the need to run a pressurised system. Theres more hot water circulating in the engine & skin tank & calorifier circuit & you dont have a header tank with a cold feed & ballcock on that. Agreed it runs pressurised but only to raise the boiling point of the coolant.

 

Steve

[Fuel__2001]

My "feed & expansion tank", a much better description of what it actually does than "header tank" is a car washer bottle from a scrapyard.

 

Steve

 

Cheers Steve

 

Does this 'feed and expansion tank' also act as your vent, or do you have a separate vent running back to the tank or elsewhere?

 

John

Edited January 12, 2011 by Fuel__2001

[sharpness]

Cheers Steve

 

Does this 'feed and expansion tank' also act as your vent, or do you have a separate vent running back to the tank or elsewhere?

 

John

 

The "vent" is simply to prevent a build up of pressure in the system (caused by the expansion as the system heats up) so the open top tank acts as the vent.

 

Steve

Edited January 13, 2011 by sharpness

[Doorman]

The "vent" is simply to prevent a build up of pressure in the system (caused by the expansion as the system heats up) so the open top tank acts as the vent.Steve

 

As does an Eberspacher header tank with a built in pressure relief valve. The sealed header tank helps prevent oxygen from in atmosphere from being absorbed into the coolant, with the potential to cause corrosion within the system. The free space (air gap) within the header tank allows for the expansion of the coolant when in normal operating mode.

 

Mike

[RLWP]

I'm asking this because I don't know.

 

Do you have to have an open vent in a solid fuel system because you have to take precautions against the water boiling? I know we accidentally boiled our domestic system twice when we had a Franco-Belge stove in our previous house. The volume of steam will be far greater than the normal expansion of the water.

 

Richard