Strettonman

Richard. Is the header tank a couple of inches above the top edge of the calorifier or the highest coil inlet for the coolant ?

I plan to fit a calorifier in the engine bay but I’ve just seen something saying the calorifier coil needs to be below the engine coolant tank. I have a cruiser back with a 1.5 BMC diesel with a metal water reservoir across the top of the engine about 20cm below the deck. The side platform I want to put the calorifier on means it is touch and go whether the coil will be below the engine water height. Firstly, is it right that the coil needs to be lower then the engine water height ? I presume air will always find the highest point so would end up in the coil and water would come out of the engine coolant filler cap when you open it. Secondly, can you buy/fit a tank on top of the existing one or fit a different tank to lift the level up the near deck height.

Cheers all. Looks like calorifier in the engine bay with loads of lagging and invertor under the bed and hope it doesn’t find its magic smoke. Hopefully over night the fan won’t kick in. Roland - the only link between the invertor and the calorifier is that I am fitting them at the same time. I’m not going to run the immersion off the invertor. Who would think up such a numb idea (see my question a few weeks back ?)

I am tight for internal space on my 40 ft cruiser back so want to utilise the engine bay as much as possible. With the sleeping compartment at the back I want to miximise space and want to avoid if possible anything noisy under the bed. I plan to heat the calorifier from the engine and install a big inverter and battery set. I gather inverters can give a bit of a hum so want to put it in engine bay but do they cope with a winter with sub zero temperatures ? also do most people put calorifiers in the engine bay and just lag them well or am I advised to sacrifice under bed space ?

Oldgoat, thanks for the pointer. I’ll have another search on the forum for the topic you mentioned from some years ago.

Thanks. You are right about how much heat we need. The current stove gets the front of the boat pretty toastier but I need to move the heat down to the back. We plan to have a full width bathroom arrangement so even one of those stove fans won’t move enough hot air to the back. The bedroom rad is to take the chill off when going to bed and getting up so 1KW may be fine. I will make sure I investigate back boiler output when we replace the stove. Cheers

Just done a rough calc and assume both rads would produce 3-4KW output.

I don’t know. I need to work out radiator sizes and I am also looking to change the current stove for one with back boiler connections. The boat is only 40ft so I won’t need a big stove and the bedroom at the back will be the typical 6ft square (ish) so not masses of volume to heat. I will also put a small rad in the bathroom. Assume it is 2 rads of 4sq.ft total connected with 2 25ft runs of 22mm copper. I presume when buying the stove I can look at the output from the back boiler. At this stage I am just looking for a rough idea of how long it takes to get the hot water circulating fully through the rads so I can decide whether gravity will be good enough.

I’m trying to keep it simple by avoiding having to fit an additional heat source which will require a link to an energy source (gas or diesel) an exhaust system, a burner and a pump. Clearly from an operator point of view flicking a switch to get hot radiators is easiest but I am trying to balance in my mind the compromise between that and the implications of simpler system which potentially might not even need electricity. In terms of radiator heat up rates I’ve no problem waiting for the stove to get fully up to temp before the rads kick in. What may be an issue is that if the stove is hot and I open up a radiator it then takes a long time for it to get warm with a gravity system. Any idea how long a hot stove will take once you allow thermo syphoning ? 10 mins would probably be fine but if it’s more like 30 mins I think I’d have to go for a circulation pump (which would mean the plumbing routes would be less critical).

My thinking is that as we will only be on the boat for cruising we will run the engine every day for a decent period. Therefore we should definitely use the engine to heat a tank of hot water for a couple of showers after a days boating and a bit of pot washing. If we need heat during the day or the evening we’ll fire up the stove so should use some form of radiators off this to distribute heat to the bathroom and bedroom (with or without a small quiet pump)That’s the basic obvious stuff. I guess the main question is whether I should use the second calorifier coil to top up the heat in the water tank during the cold evenings and over night. This coil I guess could be repurposed for a wabasto if we ever decide to live aboard. If I try to use the stove heat for either radiators or water heating am I a) going to compromise flow so much that I can’t hope to have a gravity system, b) is it appropriate to have a manual or powered diverter valve between Rads and tank (like home gravity or pumped CH systems) and c) is there a danger that if the stove isn’t on and I have a tank of hot water I will inadvertantly siphon out all the heat into the rads over night. The idea of heating the tank from the stove as a second source appeals for the odd occasion we don’t cruise or the calorifier doesn’t hold the heat too well over night but am I setting myself up for compromising performance for these occasional benefits. I also need to understand how quiet a pump I could get for the rads if I needed to. Need to think about disturbing those either sleeping in the bedroom or the lounge.

Maybe I WILL see how the fridge runs off gas rather than dismiss it totally. It will give me a chance to compare performance.

This is great stuff. Thanks for everyones help. I think I will spend my Sunday morning digesting all this with a cuppa and pen & pad in hand (if the misus will let me). It has already saved me a job. The boat has a 12v/240v/gas fridge onboard that we’ve not really tried to get going. When I strip the boat out I was going to try to get it working in my garage but it looks like the best place for it is the tip. Its triggered loads more questions (solar, fridge types, location of invertor, battery banks......) but I’ll try to absorb this lot first. Steep learning curve but Thanks again.

That’s some great advice. Thanks very much. Do people tend to put in 12v power outputs as well as 240v so you can run phone chargers etc without needing the invertor ? Also, I was planning to stick with a small caravan fridge that will run off 12v (and gas I think) but are they any good or should I plan for a 240v fridge. As I’m not going to live aboard there will be times when it is just all switched off.

Obviously I’m planning to use a calorifier (water tank) - just don’t want a gas boiler taking up precious interior space. I understsnd and most calorifier a come with twin coils and a small element so I can heat the water if I’m on elec hook-up (although that will be unlikely). The he plan is to use ine coil off the engine and the other off the stove but might need to think about how a wabasto might be plumbed in later. Thanks for the link. Sorry about all the typos- small phone and damn predictive text ?

Thanks. I take it you should not run the batteries down to less than 50% SoC. do invertor have a cutoff to stop over draining you batteries.

Can anyone point me to a good comprehensive guide to boat plumbing. I’m not going to fit a boiler but want to heat my water and radiators from the engine and a stove as we plan to use it for cruising rather than a live aboard (and i’m tight so always looking for something for free ?). I want to do it in a way that could add something like a wabasto at a later date.

I’ve just bought an old boat and about to start stripping it out for a refit. Can anyone recommend a good (performance and value) invertor. I am planning to fit a good bank of batteries so should be good for a high output unit. Also , where can I get hold of a good guide to narrowbat electrics. I heard somewhere that earthing has an impact on hull corrosion and I’m keen to understand how the invertor should be wired in relation to engine charging and external 240v supply.

Good days gentle boating - off the the pub now. Think the prop shaft bearing might be on the way out which might explain extra vibration causing the grub screw to work loose. There are 3 grub screw holes in the coupling and the shaft has a hole right through as well as the dimple but so far I’ve stock with using the dimple. Can I just bolt right through the prop shaft and coupling or is the grub screw a designed weakness for any reason ?

Damn website - was sure I’d hit submit this morning ——— Thanks all. Got it sorted this morning. Found the grub screw in the bulge water. Managed to push the prop on about 1/2 an inch using the pole as a lever and wiggling the prop at the same time. Started the engine and (very gingerly) put it into drive. The prop went all the way home straight away and the grub screw hole lined up perfectly. Fitted grub screw screw securely and tried reverse on tick over. No problems at all. AMAZING !!!!!! will still follow the advice about avoiding reverse. Thanks so much to you all. Hopefully another happy day of boating. Just need the sun to shine now???.

Not spending any money is the best bit of all. Will look at loctiting in the grub screw. Cheers

Thanks all. Got it sorted this morning. Found the grub screw in the bulge water. Managed to push the prop on about 1/2 an inch using the pole as a lever and wiggling the prop at the same time. Started the engine and (very gingerly) put it into drive. The prop went all the way home straight away and the grub screw hole lined up perfectly. Fitted grub screw screw securely and tried reverse on tick over. No problems at all. AMAZING !!!!!! will still follow the advice about avoiding reverse. Thanks so much to you all. Hopefully another happy day of boating. Just need the sun to shine now???.

Thought I’d posted this last night. ——- Thanks very much everyone. I’ll look for the grub screw in the morning. The shaft is petty well aligned as it goes into the coupling but too tight and I can’t get enough force on the end of the prop to push it further. I will try the pole idea (did try with a block of wood but couldn’t get enough purchase. If I do get it back in will try the jubilee clip and chug her home gently. Thanks again. Secretly I’m enjoying the challenge ?.

Thanks very much everyone. I’ll look for the grub screw in the morning. The shaft is petty well aligned as it goes into the coupling but too tight and I can’t get enough force on the end of the prop to push it further. I will try the pole idea (did try with a block of wood but couldn’t get enough purchase. If I do get it back in will try the jubilee clip and chug her home gently. Thanks again. Secretly I’m enjoying the challenge ?.

Sorry , 2nd photo failed to load (again). Probably not very relevent - it was only a picture of the key - 30mm square bar about 8-10mm thick.

Does this help. The wood underneath is just there to catch the key as I was trying to shove it all back together. Not sure if it is helpful but the 2nd photo is the key I recovered.