Schwaa

Thanks very much Peter, I've sent you a PM. A chat would be excellent. Starting from cold will always take longer with any system of course but these are really good points, thanks. Just to clarify, the stove is in fact rated at 12kw total, with roughly 7 going to boiler. It is in the main living space and the main source of heat. The living room radiator is an afterthought in many ways, and a relatively small additional expense for greater flexibility. In reality, the stove would be run hard in the evenings, but still kept ticking over full time in the winter, as is conventional. and again, really good points and making me triple check all of my thinking, thanks. In reality, the rads will not be expected to do much during the day. They are primarily for putting some heat into the bedrooms in the evening and first thing. I've done loads of calculations for different scenarios and I'm more concerned about being able to dump enough heat in the evening when the store is at 90 and the boiler is still going strong! I can see why that would make sense (on the TS thermosyphon), great input, thanks. Do you not think a vent on the heat sink side would help to reduce the risk of knocking in an overheat situation? Hmm, now I'm tempted to do both.

I think perhaps I've not explained myself very well. Sorry if I'm failing to make sufficient sense. At no point will I be trying to heat 160l of water electrically or in one go. In the colder months, the body of water in the thermal store (let's call it thermal fluid to differentiate it from the DHW) will be heated by the wood burner. This thermal fluid will be used to heat DHW in a high efficiency coil through the store, like a reverse cauliflower, driven by the freshwater pressure pump and with a thermostatic mixing valve on the output to regulate the DHW temp.. The thermal fluid will also be circulated through the radiator system. When the engine is run, which it is regularly in the winter, there will be the option to feed thermal energy in via the engine's calorifier takeoff, to top up the store (ther reason for the heat exchanger is because of the distance from the engine to the thermal store). THe aim with a thermal store is to kkep it's contents at around 70 to 90degC as much as possible, in the winter anyway. In the summer, when demand for hot water is slightly less and heating is virtually nil, the water in the store (let's call it thermal fluid to differentiate it from the DHW) will be heated when the engine is run. It will not need to heat the whole store. THe idea is that the contents of the store is stratified as much as possible to keep the heat where it's needed, around the DHW coil. The immersion element is very much a secondary source for a short boost and an opportunity to collect any spill-over from the PV output on really good days. I was hoping for some help with the technicalities of the plumbing and control system, i.e the placing of stats and valves, more than anything else really. Thanks all for taking the time though.

Hi Tony, thanks, This system looks complicated but it's just combining the engine's heat output with the stove's in one place to serve both radiators and DHW. It is bringing together already very common boat systems and replacing the typical calorifier tank with a thermal store. Apologies if my diagram makes it look more complicated than it is! In the winter there will be no more electrical demand than in most boat heating systems, just the ch pump for a few hours each day, less than many boats I've known. the summer is trickier although it will only be providing DHW so input will nned to be considerably less. Haha, I'm not trying to offend. Why?? What do most people do for power in the winter on a boat?

Not in the summer, when the panels are outputting. In the winter i rely much more (entirely) on the engine for power anyway, it gets run for a full day every few days

Thanks, in the winter the solar wont be contributing to the heating system at all. the stove will be doing most/ all of the work.

Thanks for the input so far, its much appreciated. I'm pretty good with electrics, it's the plumbing I'm more concerned about, and the overall safety of the system. I havent given it too much thought to be honest, mainly because I've known others to try and be disappointed. I'll give that a read though, looks interesting. I dont really intend to rely too heavily on solar for DHW anyway and I'm happy to run the engine for an hour or so most days for hot water and a battery boost all year round.

The boat's got twin alternators, 75a and 175a. It has occurred to me that the starter alternator has a lot of spare power once it's topped off the battery, which could perhaps be diverted to a, say, 600w 12v element all of its own. Has anyone done or heard of such a setup? The cables would of course need to be huge in my case.

The pump on the engine calorifier circuit will only be running when the engine is, i'm thinking of putting it on the starter alternator/battery circuit (twin alternators). The ch pump will need adequate cable but the draw is not crazy, can't remeber exactly, around 2 amps I think, and the run is approx10m one way. It wont be on anything like 24/7. I dont think this is a real concern but thank you, I want to be thoroughly grilled as I want to make sure I havent missed anything!

Hi and thanks. I'm taking the weight of the store into account in the layout. Domestic alternator is 175a. I'm thinking of using a 240v 1kw element through a pure sine inverter, I figure I can spare the overhead as engine will be running or solar 'over-producing' when it is operating. I'm planning 1.2kW of solar (with an 880ah 12v battery bank). This is something I'm wondering about... willl it ever actually spill over? (I know it depends how much power i use)

They are 12v pumps. Yep, I move a bit and I dont have shore power on my permanent mooring, it's all off grid

Hello everyone, I'm new to the forum but been on boats for a while. I'm currently fitting out a sailaway widebeam and I'm on a search for some thoughts on my plan to build the central heating and domestic hot water system around a thermal store and boiler stove. Someone on a facebook boaters' group suggested this might be a good place to ask. On reading around, you seem to be a pretty friendly, helpful and knowledgable bunch so any advice or opinions on the attached diagram would be very gratefully received. For context, the stove, store and heatsink are all next to each other, in the middle of the cabin, with the bathroom bulkhead between them