Water Heating

[yachtorion]

I'm looking to install heating on hot water on my old Horizon 26. She's got a 1GM (therefore direct cooled) in good condition.

I was thinking the best option was going to be to install a water heater to use with a calorifier, as I have doubts about the direct cooled engines ability to heat it. The heater would then also supply a matrix heater.

But now I'm thinking perhaps I should buy a conversion kit to make the engine indirect cooled and use that with a calorifier and install an air heater for heating.

The air heater and engine+calorifier solution would be a little bit more expensive including the conversion kit, but would use less power and provide instant heat. Run the engine for a bit in the morning and you have a charged battery and hot water for a clean up in theory...

What do others think?

 

[David2452]

It will certainly be far more efficient than raw water cooled as the fluid temperature will be higher, it will have the added advantage of making your engine more efficient as it will also run at a higher temperature more suited to diesels. However the cost seems very high and you could install a small diesel boiler for your calorifier and matrix at much lower cost. Of course that will not help with increasing your engine temperature. One or two people have been "happy" with just the raw water cooling supplying calorifier but I am very sceptical as I have larger samples to work from and a matrix is bad enough when supplied by an 85 deg fluid temp let alone the lower temperature given from a raw water cooled motor.

 

[yachtorion]

Thanks David. To add more information to the thread, some example costs look like this...

Air solution:

1gm conversion kit... £690
Mikuni £1314
Total: £2084

Water solution:

Mikuni £1256
Matrix Heater £140
Total: £1396

So you're right David - the conversion kit makes it an expensive option!

 

[planteater]

Is there enough waste heat form a single cylinder Yanmar to make this worthwhile? Mine doesn't seem to kick out much.

 

[yachtorion]

One Webasto dealer told me he wouldn't recommend a water heater on my boat because it would end up cycling a lot with it being such a small boat... anyone got any thoughts?

planteater - it seems to heat up the cooling water it kicks out pretty quick and well - I imagine up to the spec of an entry level water heater - but I don't really know....

David... if it was your boat what would you install?

 

[David2452]

On something the size and layout of your yacht I would not go for a water heater over 4kw and would make sure it was well loaded above that rating so that would exclude the Mikuni MX40 which is, confusingly, 5kw, The MY16 air heater which is again confusingly 2kw would cope well provided the duct was well lagged, both your prices quoted again seem high, certainly more than I sell them for. The old cycling problem was an issue with high sulphur diesel but with ULSD and if set up correctly so the burn is correct at the lower levels this is far less of an issue than it was. Both options are a material investment so care is needed to make sure you are satisfied, if it were my boat I would be very careful to select an efficient and large enough matrix and if that was not achievable would probably go for the air + conversion option but only if I was satisfied that the waste heat from your motor would be sufficient. Cost aside the disadvantage would be the necessity to run the motor (unless an immersion is fitted and power available) for a while to get hot water. If I was satisfied I could fit a large enough matrix it would be a wet system every time and that is what I will be installing on my next boat. Also consider the other attendant costs of each install, ducting, pipework etc, it can add up, though probably less so on a small boat. If you PM me an email address I can send you a PDF of a nice marine install manual that discusses various types of wet system in some depth.

 

[vyv_cox]

Usual advice is that there is insufficient heating from a single cylinder engine to run a calorifier. You risk lowering the coolant temperature to a level that the engine will suffer increased wear rates and inefficiency. There is a lot on my website about calorifiers, which you may like to read.

 

[yachtorion]

Thanks All.... small water heater it is. Considering Webasto Thermo Top E.

 

[onesea]

My tip, boil a kettle, its not that big a hard ship.

Sounds daft but if you have hot running water you will use more water, if you do not have access to a hose the increase is noticeable. I know its no help and you have decided you want but in my mind its more money you will not get back when it comes to sell and you have another thing onboard to break down.

Not much help in the thread but depends on your budget/ and or other restrictions.

 

[pvb]

My tip, boil a kettle, its not that big a hardship.

I'd have to agree. I doubt that the OP is planning to put a shower in the heads, so the requirement for hot water must necessarily be small. Better just to concentrate on an air heater. Having a water heater (or indeed an air heater) will also impose a load on the 12v supply, so there are battery capacity and recharging considerations to bear in mind. Unless, of course, the boat has access to shorepower, in which case a calorifier with an immersion would be a cheap option.

 

[Heckler]

Thanks David. To add more information to the thread, some example costs look like this...

Air solution:

1gm conversion kit... £690
Mikuni £1314
Total: £2084

Water solution:

Mikuni £1256
Matrix Heater £140
Total: £1396

So you're right David - the conversion kit makes it an expensive option!

Or go to a scrappy, find a rover 75 diesel and buy the Webasto heater, dont forget the tick tick pump under the rear offside arch!
I bought one for £40. This one has a simple on off wire so a cheap thermostat can be used to control it.
Stu

 

[David2452]

Or go to a scrappy, find a rover 75 diesel and buy the Webasto heater, dont forget the tick tick pump under the rear offside arch!
I bought one for £40. This one has a simple on off wire so a cheap thermostat can be used to control it.
Stu

Far too heavy for this application, also wrong ECU to prevent excessive cycling and the premature coking up it brings.

 

[David2452]

Thanks All.... small water heater it is. Considering Webasto Thermo Top E.

Good choice, your target price is around 1k for a proper marine kit with the correct ECU

 

[yachtorion]

I'd have to agree. I doubt that the OP is planning to put a shower in the heads, so the requirement for hot water must necessarily be small. Better just to concentrate on an air heater. Having a water heater (or indeed an air heater) will also impose a load on the 12v supply, so there are battery capacity and recharging considerations to bear in mind. Unless, of course, the boat has access to shorepower, in which case a calorifier with an immersion would be a cheap option.

Actually I am planning to put a shower in the heads..... hence the requirement... admittedly it's a tight fit and it will definitely be for a quick wash rather than a great luxury... but I'm trying to set the boat up so I can avoid civilisation for a few days at a time without feeling too icky.

 

[Modulation]

And me too. this could be a case of huge spending for limited returns

I'd have to agree. I doubt that the OP is planning to put a shower in the heads, so the requirement for hot water must necessarily be small. Better just to concentrate on an air heater. Having a water heater (or indeed an air heater) will also impose a load on the 12v supply, so there are battery capacity and recharging considerations to bear in mind. Unless, of course, the boat has access to shorepower, in which case a calorifier with an immersion would be a cheap option.

 

[David2452]

And me too. this could be a case of huge spending for limited returns

Hardly huge, material yes, but not huge, that's all subjective anyway. Some people are quite content and even happy to spend money on something they want to have to increase their particular enjoyment of boating, others are not willing or are unable to do so or think that particular feature is not on their radar anyway. Depends on the importance one places on something. However in the OPs case technical challenges and eventual satisfaction are probably more important, just heating the calorifier which would obviously be quite small without other "loads" is going to lead to regular and not inconsiderable cost so I would not advise any of my customers with a similar sized boat to fit a Webo or other evaporator if that is their main requirement. It is achievable using a buffer tank or plate heat exchanger but the limitations of space available to fit one, not to mention cost would probably lead me to carefully re think how this could be achieved even if it cost me the job. Explanation for this is, a small volume of water in the circuit of a calorifier heats very quickly and the ability of a small calorifier coil to transfer heat to the domestic water at a fast enough rate to cool the fluid returning to the boiler (especially as the domestic water temperature increases) is not sufficient to keep the thing fired up properly, this leads to constant cycling down to low levels and even shut downs and re starts so apart from the coking issue extra current drain should be considered. The original design of these was to heat a large engine block with quite a lot of surface area only when the ambient temperature was below 5 deg and they were and are very efficient at that but despite modifications made to the ECUs for marine use they still need a decent load. Heating and hot water yes, hot water alone without a buffer load, no no, I promise you it will lead to disappointment. The type of exchanger where say 30 + litres of coolant is heated and the domestic water is passed through that on demand, a calorifier in reverse if you like but with a very large contact surface area would solve it but I know of none small enough. I wish I knew an accommodating boilermaker, I would love to knock something compact up with a header tank each end and a tube stack.

 

[maby]

We had one of those Martecs fitted to a 1GM10 on our Hunter Ranger some years ago. It works ok - thermostatically controlled, so if anything it brings the operating temperature of the engine up a bit. They are also reputed to improve the life expectancy of your engine because you can put corrosion preventer in the cooling water rather than pumping salty water through the engine. The heat output is not massive, but it was able to get a small calorifier up to a useful temperature.

 

[yachtorion]

If I'm already fitting air heating then switching to a water heater to get hot water as well isn't actually very expensive, and in my subjective judgement will make a big difference to comfort on-board. Being able to say there is hot water and a shower (of sorts) should make a difference to some potential crew as well!

It might be worth mentioning that my holidays quite often tend to fall in winter - and I want to be comfortable on the boat then!

I was wondering if fitting the Martec conversion and an air heater would in some way be better, but it sounds like a lot of financial outlay for no real benefit and in fact perhaps a worse system.

David has me pegged right, I don't mind spending money on the boat if I've got it and if I think it will give me a challenge (selecting/designing/fitting) and teach me something new, combined with a comfort/safety/whatever benefit when using her. That was why I bought a project boat rather than spent a little extra on a ready to go one.

I have considered the charging concerns... I've fitted a decent size battery and I don't mind running the engine for a bit to top it off when needed.

So I think I'm going to fit the water heater, to each their own

 

[Heckler]

Hardly huge, material yes, but not huge, that's all subjective anyway. Some people are quite content and even happy to spend money on something they want to have to increase their particular enjoyment of boating, others are not willing or are unable to do so or think that particular feature is not on their radar anyway. Depends on the importance one places on something. However in the OPs case technical challenges and eventual satisfaction are probably more important, just heating the calorifier which would obviously be quite small without other "loads" is going to lead to regular and not inconsiderable cost so I would not advise any of my customers with a similar sized boat to fit a Webo or other evaporator if that is their main requirement. It is achievable using a buffer tank or plate heat exchanger but the limitations of space available to fit one, not to mention cost would probably lead me to carefully re think how this could be achieved even if it cost me the job. Explanation for this is, a small volume of water in the circuit of a calorifier heats very quickly and the ability of a small calorifier coil to transfer heat to the domestic water at a fast enough rate to cool the fluid returning to the boiler (especially as the domestic water temperature increases) is not sufficient to keep the thing fired up properly, this leads to constant cycling down to low levels and even shut downs and re starts so apart from the coking issue extra current drain should be considered. The original design of these was to heat a large engine block with quite a lot of surface area only when the ambient temperature was below 5 deg and they were and are very efficient at that but despite modifications made to the ECUs for marine use they still need a decent load. Heating and hot water yes, hot water alone without a buffer load, no no, I promise you it will lead to disappointment. The type of exchanger where say 30 + litres of coolant is heated and the domestic water is passed through that on demand, a calorifier in reverse if you like but with a very large contact surface area would solve it but I know of none small enough. I wish I knew an accommodating boilermaker, I would love to knock something compact up with a header tank each end and a tube stack.

David
I f I had fitted it in to my boat, a big 2.0 litre diesel and a calorifier, adding a heater core and fan would have allowed me to use it as a cabin heater as well, it would have worked perfectly.
Now let me see, Rover 75, 2.0 litre diesel engine, check! radiator instead of calorifier, check! heater core and fan for the cabin, check! I run to the newspaper shop in the morning, so short journeys, check! Hmm doesn't seem to be any difference in the useage and heat soak in the Rover from my boat and for the princely sum of £40 notes and a bit more for the other bits, hmm! Plus the satisfaction of doing some Practical Boat Owning! taraaa!
Stu

 

[yachtorion]

I have heard it said that the Rover 75 handled like a boat anyway.