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Jenwil

Backboiler question

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Hi guys I have a boatman stove with a back boiler I want to instal with the help of a handy friend who is prepared to have a go.

I have read another thread and looking at doing things as in the attached picture but I have a newbie question.

In the pic it shows smaller pipes going to the rad valves why is this?

I have bought a small rad from b and q which has no valves, are all valves the same size or do I use a converter to get from the valve to the 22mm copper pipe I will be using?

should I have a pressure release valve on the system and if yes where?

thank you guys x

IMG_0198.PNG

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If it is to be thermosyphon system, you may be better off with 28mm pipe (the smaller pipe, usually 15mm will then connect to the rads)., depending on the length of your pipe run.

Edited by rusty69

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1 hour ago, Jenwil said:

Hi guys I have a boatman stove with a back boiler I want to instal with the help of a handy friend who is prepared to have a go.

I have read another thread and looking at doing things as in the attached picture but I have a newbie question.

In the pic it shows smaller pipes going to the rad valves why is this?

I have bought a small rad from b and q which has no valves, are all valves the same size or do I use a converter to get from the valve to the 22mm copper pipe I will be using?

should I have a pressure release valve on the system and if yes where?

thank you guys x

 

Because the main runs should be in 28mm and it will be a sod to get 28mm into a radiator. ( as above)

No valves in my view on a gravity system to maximise the circulation. If you must just one lockshield valve per rad that is probably left fully open.

One radiator on solid fuel stove? I hope its a small stove otherwise you are libel to get boiling when you need a high fire.

Wit a sold fuel stove I would fit the header tank more or less above the stove feeding into the lowest point in the pipework and then where the header tank is in the diagram and vent to the outside. That should make the system more or less self bleeding and may stop steal spraying rusty water all over the cabin.

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I'm sure someone will correct me if I'm wrong but I believe at least one rad should be fitted without valves (probably rad 2) so it can't be turned off and the system therefore always syphons and circulates. If for some reason all rads get turned off then the system can't circulate and the water will boil.

 

Edited by Bewildered
Tony beat me to it

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7 minutes ago, Bewildered said:

I'm sure someone will correct me if I'm wrong but I believe at least one rad should be fitted without valves (probably rad 2) so it can't be turned off and the system therefore always syphons and circulates. If for some reason all rads get turned off then the system can't circulate and the water will boil.

 

In the above diagram,if the rads are turned off, the water can still circulate through the pipework, although potentialy it could still boil I suppose if it was a short pipe run.

Edited by rusty69

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The set up on the diagram should be fine, I would put some sort of pressure relief valve in the top run though, near the boiler. A bit belt and braces but if the system ever got refilled with plain water and froze in the pipes somewhere and you lit the fire it would not melt the ice plug for ages by which time it could all go horribly wrong.

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The flow and return on my system is in 28mm, the connections to the rads 15mm. For each rad I used a single full flow ball valve. In reality these valves are left in the fully open position all the time. The system works fine.

The system won't freeze as it has antifreeze in it at all times, can't imagine anyone wouldn't use it.

Edited by Slim

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Sorry if I was unclear I'm actually having 3 small single rads.

2 hours ago, Tony Brooks said:

Because the main runs should be in 28mm and it will be a sod to get 28mm into a radiator. ( as above)

No valves in my view on a gravity system to maximise the circulation. If you must just one lockshield valve per rad that is probably left fully open.

One radiator on solid fuel stove? I hope its a small stove otherwise you are libel to get boiling when you need a high fire.

Wit a sold fuel stove I would fit the header tank more or less above the stove feeding into the lowest point in the pipework and then where the header tank is in the diagram and vent to the outside. That should make the system more or less self bleeding and may stop steal spraying rusty water all over the cabin.

I was going to use 22mm due to budget Tony.

So I use a valve at the bottom then the top coming from a 22mm to 15mm or just use no valves as you say meaning I just go through the rads in a circle?

 

Edited by Jenwil

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We know that 28mm will work in the vast majority of cases but with 22mm its much more "suck it and see". If you use 22mm and it does not work how much extra will it cost to do it again in 28mm?

My boat had no valves for the radiators and it seems other have told you they are not necessary as well but if you must fit them for some reason please make sure they      produce minimal restriction to flow and leave them turned fully on.

The more you restrict the flow the more likely it is that the system will boil easily.

 

  • Greenie 1

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I wouldn't fit any valves at all. I would want to keep flow restriction to a minimum. No sharp bends, all swept  I am not sure about even using 4 connections to each radiator so increasing the flow to them.

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2 minutes ago, Jenwil said:

But don't you have to have valves in order to connect the pipes to the radiator?

No.Other fittings are available.

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Hate to be negative but personally I feel a backboiler system is only worth the hassle for year round off grid live aboard, or long term winter boating. Though it is a very nice idea.

How much experience does the handy friend have of installing backboiler systems on boats? It's quite a bit different to normal domestic plumbing which is almost plug n play these days...

Edited by smileypete

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43 minutes ago, rusty69 said:

No.Other fittings are available.

So like  compression fittings coming from the radiator itself?

13 minutes ago, smileypete said:

Hate to be negative but personally I feel a backboiler system is only worth the hassle for year round off grid live aboard, or long term winter boating. Though it is a very nice idea.

How much experience does the handy friend have of installing backboiler systems on boats? It's quite a bit different to normal domestic plumbing which is almost plug n play these days...

None hence why I'm asking some questions here.

im a full time liveaboard.

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51 minutes ago, Jenwil said:

So like  compression fittings coming from the radiator itself?

None hence why I'm asking some questions here.

im a full time liveaboard.

Yes. I believe SP has also mentioned in the past it may be possible to screw a 15mm compression fitting directly into a rad tapping, although I have never tried this, please jump in if i got that wrong @smileypete

 

 

 

Edited by rusty69

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1 hour ago, rusty69 said:

Yes. I believe SP has also mentioned in the past it may be possible to screw a 15mm compression fitting directly into a rad tapping, although I have never tried this, please jump in if i got that wrong @smileypete

 

And slow bends are better than elbows I believe. 

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Just now, rusty69 said:

Not if you play the fiddle  :)

You shouldn’t fiddle with it. You’ll go blind. 

  • Haha 1

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1 minute ago, WotEver said:

You shouldn’t fiddle with it. You’ll go blind. 

I would never fiddle with someone else's plumbing without prior permission. 

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Having just installed a pumped radiator system in my boat, I can confirm that rads come with 1/2 bsp female threaded inlets and outlets, and therefore can easily be connected to without proprietary valves. Any 1/2bsp threaded fitting will work (nb: 15mm compression uses 1/2bsp thread so you could use a normal 15mm fitting without the olive and collar.

Reason for smaller pipe in the diagram is mostly dictated by the inlet size on the rads (as indicated above, 15mm is ideal) but also, even if total flow from backboiler is through 28mm pipe, each rad only uses a portion of that flow, so 15mm should be adequate. Lastly, 15mm much easier to make fiddly connections to rads, and can be made to look much nicer.

  • Love 1

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So the pipe goes in at the top right, out the top left in a kind of circle then back in at the bottom left and out the bottom right and so on if not using valves?

thanks guys.

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5 minutes ago, Jenwil said:

So the pipe goes in at the top right, out the top left in a kind of circle then back in at the bottom left and out the bottom right and so on if not using valves?

thanks guys.

Where did that come from

 

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