mascip

OK, I will use a plain color cable to the solenoid then. Clear heatshrink, that's a good tip! Thank you.

Thanks ditchcrawler! More eBay search then... I'm still going to find one shop where I'll be able to find all wire I might ever need in the future. Richard, I was thinking of following a standard, whichever it is, so I can always recognise all cables by sight. But I guess labeling could go quite a long way in this direction. I want it tinned, because all the wire around my engine is corroded and has very stiff PVC insulation. I'm hoping to avoid this happening too quickly again.

Thank you! Yes, the red with yellow stripe one is very hard to find tinned. I'm still hoping someone will know

Hi, I'm looking for coloured tinned cable for re-wiring my engine bay. For example red wire with yellow stripe between ignition and solenoid, as recommended here: http://www.marinewireandcable.com/p/marine-wire-color-codes.html?m=1 But I can't find any shop online who sells it. Any idea? Or a shop in London. PS: the difficult part is finding it tinned

Nice one, thanks Alan! It's a friends birthday soon, I might offer him that =)

£30 for a 400A DC clamp meter? I have just bought a 200A one for £80, I couldn't find any cheaper. Many clamp meter which are sold as "DC AC" do DC voltage readings, but only AC current reading, not DC current.

How do you calculate the current that might pass between two batteries? Do you consider the battery as a generator and a resistance, and use this for calculations? Or is there a simpler way? If they are already wired you could measure it with a DC clamp-meter with sufficient rating (expensive if it's over 200V), but calculating would be better really. So calculating the maximal load if everything was on, and checking the alternator output. That should tell you what is safe. Maybe that 25mm2 cable is required, in case you would change to a bigger alternator for example?

Good question! About 5.6mm diameter for the copper: http://www.sengpielaudio.com/calculator-cross-section.htm

Are you speaking about cable to the starter motor? I'm speaking about cable between batteries

I guess you are right. "Approximately" means "or a very close measurement, like 24.5mm2", not "as long as you think it's safe". Thank you for a clear answer Paul :-)

Thanks a lot for your input, springy and smileypete! I will add it all in the document when I work on my system again. I've had other life emergencies to take care of, so will get back to it in a few weeks. Then I will copy paste part of the document here in a new thread, because I cannot Edit the first message of this thread anymore. Oh! And smileypete, I saw this diagram too, but because I am not going to connect a calorifier to my system, I didn't keep any calorifier-related information. Even with the simplest system, I manage to get into too many details If you or anyone wants to modify the text and add things about calorifier, I can give you writing access.

I think you're write, this battery was tired. I'm reconditioning it now, let's see what happens... It is a 4TR regulator, and I do get 14.4v sometimes, event 14.5v. Maybe the regulator is a bit old and tired? What is the trimmer?

Hi, the BSS says that cables between a battery and - another battery, or - an inverter over 1000W, or - a master switch, - etc, should be "sufficiently" big: "must be approximately 25mm2". To me, "approximately" means "as long as it's really safe". With two leisure batteries of 110Ah in parallel, is it safe to have a 16mm2 cable between them? I have seen 16mm2 cables on several of my friends boats. I am wondering whether I should propose to change their cables to 25mm2. Also, if a cable to the master switch is 16mm2 and has a 50A fuse, that should be safe and hence pass BSS, right? PS: Woops, I cannot change the title anymore, it should be "25mm2". Mistyped.

Oh, that makes sense. Thank you. So I should always search "open thermosyphon" rather than simply "thermosyphon".

I'm definitely overthinking it ;-) The good thing is: I'm also getting active and making it happen on my boat. It's going to take a while though: I need to move the water tanks, remove some benches, etc. No filling ratio then. Maybe it's only useful for more finicky applications. Thanks for the info :-) I'll remove it from the document.

Sometimes I get less than 14.0v output though. It can be 13.0v or 13.5v. I'm guessing this might be caused by the lack of warning light. It depends, sometimes I do get the full 14.4v. But it might also be caused by a high resistance in the circuit (I know where it is, I need to re-wire it).

I have updated the document with more information, in particular about the "equivalent length of pipe" of various fittings: bends, tees, valves, etc. Which gives you an idea of the amount of friction that you are adding in your system. Or that you could remove from your system by changing fittings. I have also answered a few of my own questions, but for some reason I cannot edit my first post anymore. Any idea why?

This was quite a long time ago, I forgot to feedback: it all works without the warning light :-)

By reading more scientific litterature, I found that the Filling ratio is important: how much water do you put in the system? If you don't put enough, then there is less contact between water and backboiler, so it's harder for the system to start. If you put too much, then it creates large bubbles and film at the bottom of the backboiler, which hinders performance. Has anyone here noticed a difference depending on the amount of water that you put in system?

I have answered one of my questions and added information about the pipe slope. Found by searching "thermosyphon angle". The keyword "thermosyphon" returns a lot more relevant results than "gravity fed", in particular, many scientific articles. And added a question: - can you use tap water, or should you use distilled water? Why?

In the first post of this thread I have listed all the questions that need answers. Any help would be very appreciated. Answers will be added to the document, so everyone benefits from them.

Ok, I have done modifications: - the Intro section says enough that people can get a rough idea of what they must do - in Key principles they should find enough info to get started - and in Design there is more information for geeks who like to understand it all, or for people who need to debug I have removed the text from the original post, because it's much more readable in the link I think: if you only read the words in bold it gives you a good overview of the content. Plus, folding/unfolding makes for easier reading. And I can't be bothered to copy-paste it all here every time I make a change. Any feedback, well appreciated. Any answers to questions, very welcome please ;-)

I wrote this for myself, so it wasn't written as an introduction to the subject. More like an overview of all information to have in mind, when either designing or debugging. Someone on London Boaters told me that it made them realize that heat dissipation in the pipes is the cause for their last rad to be lukewarm. So it has been useful already :-) I am modifying the text right now to add an introduction. The "Design" section is only useful once you want to debug, or if you like to know everything on the subject before getting started; which is the case for me but not for everyone. So this "Intro" section should be enough for people to get started, hopefully. I will post here to say when I've finished doing it. I probably need an hour or so.

I'm happy to improve the text if some parts are unclear or ambiguous, just let me know.

Hi, here is all the information that I could find on this subject: Gravity fed systems for heating with a backboiler - the Intro section says enough that you can get a rough idea of what you must do (Added on the 18/09/2015) - Key principles is enough to get you started - and in Design there is more information for geeks who like to understand it all, or for people who need to debug I am designing a simple system which does not include a calorifier, so I have not included any information on this subject in this Summary. If you would like to add it, let me know and I will let you modify the text. There are still some questions that have not been answered. I have copied all of them here, below. If you have a short and clear answer to any of these questions, please post it here and I will add it to this summary. I might start discussion threads for some of these questions, if it turns out that the answer is complex and needs further discussion, or if no-one answers the question in the next few days. Important questions: Slope: - Why is the return pipe often straight-ish? Is the slope on the top pipe more important than the slope on the return? If yes, why? Pipes: - do you anneal copper pipes yourself, or do you buy them annealed? - could I use plastic hose to connect both the top pipe and return pipe to the radiators? That would save a lot of copper pipe bending. What would be the drawback, apart from appearance? The hose would have to tolerate boiling water temperature, too... Header tank: - is it a good/bad idea to have the top of the header tank outside of the boat? Radiators: - how can I know whether a radiator has a suitable bore, or whether it will cause too much friction? Coolant: - can you use tap water, or should you use distilled water? Why? Fiiling ratio: - how much water / coolant do you put in your system? (read the relevant part of the document, for more info) Geek questions: Thermostat: - is a thermostat only useful if you have a pump, or also for gravity-fed systems? (to prevent the water from flowing below 30C, for example) And where would you put it? On the return, on the top pipe, or on both? Pump: Apparently a centrifugal central heating pump would allow water to circulate via gravity when it's not running. Is that true? How would you choose such a pump? (how much power, etc) Anti-freeze: - Why do you need to premix anti-freeze and water before? (what difference does it make?) - How much anti-freeze do you put, with water? 50%? But Anti-freeze does not flow as well as water, and does not transfer heat as well, so less anti-freeze might be better? Is 30% alright in the winter? Pipe size: - Why do people recommend a 22mm pipe to the header tank, instead of a 28mm pipe which would make it easier for hot water to escape? - Is it better to have 28 to 15mm adapters on the rads, or to have 15mm pipes Tee-ing to the rads? The second options enables to have a tighter bend, which causes friction, but enables the radiators to be higher. Misc: - SmileyPete said this in an old post, and I don't understand the word "lagged" in this context, any idea? Here is the text: "a good way of doing it is to have an adequately sized gravity 'heat dump' rad(s) near or next to the stove, then more distant rads and/or calorifier on a pumped circuit connected by 15mm pipes, ideally lagged. That way the gravity rads can be shut off and all the heat directed to the furthest rad." ------------ I wrote this by reading, organizing and summing up all of the relevant information discussions threads that are mentioned in the Index of common topics on this forum, plus a few other sources of information on internet.