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Philip

Additional heating for cruiser

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I'm thinking about a way to provide additional heat (already have a gas powered blown air propex) and potentially hot water for my boat, a Norman 24 GRP, by using the heat from the engine basically. This would be good in that it would keep the inside of the boat warm all day whilst the engine is running and be of particular use in helping to dry out clothes and remove condensation. I have heat exchanger cooled Beta 20 diesel engine, which has a wet exhaust and saildrive and uses raw water to cool the internal water, via the heat exchanger. I've had a look at a couple of options of indirect heating and the two I've seen are airtronic systems, which uses an air-air heat exchanger to burn combustion air from outside and then blows hot air through ducts into the boat and a forced hot water system; this uses an air-water heat exchanger and the cooling water is pumped around the boat using radiators and fans, like a car heater.

 

I'm just wondering if anyone would know which system would be more practical for the boat or easier to install, considering it is only 24 feet long? As I say it would also be good to have a means of hot water for the tap.

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I would suggest a small calorifier for the hot water and Finrad type things or small radiators in the return to the engine pipe plus a suitable valve to isolate the rads for summer.  The heat is essentially then free being waste engine heat.

 

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Thanks, Beta have an installation diagram for the hot water but it is only for their 'Green Line' engines which I don't believe the 20 is, I'm not totally sure what they mean by the 'green line'. 

Would copper be suitable piping to use?

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To be honest you can use whatever pipe suits you, even something like silicon reinforced pipe and jubilee clips which would make installing an easy job.

You say you have a sail drive but do you? does the prop feather and collapse when not under power  or do you have an outdrive, also known as a Z leg or even an Enfield drive.

Phil 

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I added a little wood/coal burning stove to my 22ft boat. It takes up a space of about 2ft/2ft. I removed one of my air vents in the roof to poke the chimney out of.

 

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27 minutes ago, Philip said:

Would copper be suitable piping to use?

What fittings would you be using with copper?  It is often said that soldered fittings are not suitable due to possible work hardening from the vibration of the boat. Compression fittings are preferred.

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12 minutes ago, Phil Ambrose said:

To be honest you can use whatever pipe suits you, even something like silicon reinforced pipe and jubilee clips which would make installing an easy job.

You say you have a sail drive but do you? does the prop feather and collapse when not under power  or do you have an outdrive, also known as a Z leg or even an Enfield drive.

Phil 

It's definitely a saildrive, a 110s model. Long story but the boat had a Volvo Pentre engine in it until last year and the 110s was fitted to the Volvo when installed. Beta can accommodate an old Volvo saildrive in their engines by means of a special adaptor plate and tailor made engine feet to suit the dimensions. We replaced the prop not long after the new engine was installed; it is a smaller diameter and pitch 2-blade prop which suits the higher revs of the Beta compared to the Volvo.

 

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12 minutes ago, philjw said:

What fittings would you be using with copper?  It is often said that soldered fittings are not suitable due to possible work hardening from the vibration of the boat. Compression fittings are preferred.

I was just thinking the link off pipe from the header tank to the calorifier which would have to go in the bilge (although space is limited as it is) and then the connection from the calorifier to the water pump and tap.

A stove would be nice for heating but because it's a small boat it may get too hot, plus I don't have the space to fit one.

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Greenline = marinised to suit canal boats (effectively keel cooled) but  it should make no difference.

Typically there will be a take off plug in the cylinder head where a cab heater would be connected in industrial applications. Apipe runs from here to the calorifier coil, from that to a 3 port valve so you can run any combination of calorifier only, rads only (but why would you), and both. From the vale to the radiators, then back via a T from the valve to a T in the pipe that connects your heat exchanger to the engine water pump inlet.

You do nothing to the raw water part of the circuit and if by chance it is not heat exchanger cooled as you said it was then this idea becomes very much more complicated.

You do not normally touch the header tank piping unless the manifold/heat exchanger is the header tank and then you only touch the pipe feeding back to the engine water pump.

As long a sit is well clipped you can use copper inside the boat if you wish but you must use "rubber" hose for all engine connections to avoid vibration failure. The whole lot could be hose if you wished or plastic but you may well be running close to plastic pipes maximum temperature.

 

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2 hours ago, Tony Brooks said:

Greenline = marinised to suit canal boats (effectively keel cooled) but  it should make no difference.

Typically there will be a take off plug in the cylinder head where a cab heater would be connected in industrial applications. Apipe runs from here to the calorifier coil, from that to a 3 port valve so you can run any combination of calorifier only, rads only (but why would you), and both. From the vale to the radiators, then back via a T from the valve to a T in the pipe that connects your heat exchanger to the engine water pump inlet.

You do nothing to the raw water part of the circuit and if by chance it is not heat exchanger cooled as you said it was then this idea becomes very much more complicated.

You do not normally touch the header tank piping unless the manifold/heat exchanger is the header tank and then you only touch the pipe feeding back to the engine water pump.

As long a sit is well clipped you can use copper inside the boat if you wish but you must use "rubber" hose for all engine connections to avoid vibration failure. The whole lot could be hose if you wished or plastic but you may well be running close to plastic pipes maximum temperature.

 

Thanks for your help. How big would the calorifier typically need to be in litres for this arrangement? I know I'll need two copper coils in the cylinder in order to provide heating for the boat as well as water.

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10 hours ago, Philip said:

Thanks for your help. How big would the calorifier typically need to be in litres for this arrangement? I know I'll need two copper coils in the cylinder in order to provide heating for the boat as well as water.

Why will you need two copper coils? Twin coil calorifiers are used for two heat sources, in so far as we are talking you will only have one - the engine. The Propex you say is blown warm air so can not heat water.

The calorifier can be any size you want but on a cruiser space to fit it into is more likely to be a limiting factor than the amount of hot water you would like.  As you only have a small engine I would suggest you do not go for a large calorifier because the larger it is the longer it takes to heat up.

The way you pipe it goes like this:-

Engine > calorifier coil > 3 port valve > radiators > T for return from valve in summer > engine.

When the three port valve is set for winter the radiators will barely get warm for a while because the calorifier will be taking most of the heat from the water but after half an hour or so both water and radiators should be warming up nicely. IN summer the three port valve will be set so hot engine water can not get to the rads.

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You could use a slightly different circuit to give either hot water heating, boat heating or both combined. Either use a 3 port valve with a 'T' type flow rating ( ie p to a, p to a and b when central or p to b port) . Alternatively  use 2 on/off valves to select either or both circuits. Use full flow ball valves, they are available as manual lever valves or with 12 volt electric actuators ( look for solar power range). Fit the valving in the flow just after the engine. If you increase the coolant volume to much you may have to add an additional expansion reservoir or expansion accumulator with a low precharge. Don't  forget the antifreeze, premix at max 40%.

I have the 2 valve setup on a small kubota engine ( as beta) and find the engine water pump gives adequate circulation although I have used 22mm copper as much as possible to reduce friction losses. I have 2 heat sources, engine or mikuni suppling radiators only  controlled via thermostat and electric actuator valves, slightly complicated but it is what I do for a living! My hot water is from an instant gas heater.

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22 minutes ago, adrianh said:

...............slightly complicated but it is what I do for a living!

Doing 'slightly complicated for a living' must make life 'interesting', but I suppose its better than doing 'very complicated'.

Is there a big market for 'slightly complicateds' ?

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Yes, I have made a good living from this as well as the more complicated for the past 45 years. It keeps the brain working even when the body begins to struggle! Engineering is in my blood

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On ‎12‎/‎01‎/‎2018 at 07:58, Tony Brooks said:

 

I've ordered connections from Beta and a compact stainless steel 22 litre calorifier; should be ok for what I need it for, since I don't have a shower onboard!

 

Would the radiator model in the link below be suitable for a small cruiser?

http://aquafax.co.uk/product/n-29700-alde-aluminium-400mm-convector-radiator-inc-mnts

Edited by Philip

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1 hour ago, Philip said:

I've ordered connections from Beta and a compact stainless steel 22 litre calorifier; should be ok for what I need it for, since I don't have a shower onboard!

 

Would the radiator model in the link below be suitable for a small cruiser?

http://aquafax.co.uk/product/n-29700-alde-aluminium-400mm-convector-radiator-inc-mnts

At 400 watts per metre and knowing how poorly insulated most cruisers are plus thinking about how how much heat a 1000 watt electric fire produces I would suggest you may have a problem finding locations for enough. Plus you really need to box them in with well vented tops and sides. However so much depends upon your boat layout I suspect only you can decide.

As you will only get the extra heat when the engine is running and the batteries are being charged how about something like a car heater box and motor?

  • Greenie 1

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44 minutes ago, Tony Brooks said:

At 400 watts per metre and knowing how poorly insulated most cruisers are plus thinking about how how much heat a 1000 watt electric fire produces I would suggest you may have a problem finding locations for enough. Plus you really need to box them in with well vented tops and sides. However so much depends upon your boat layout I suspect only you can decide.

As you will only get the extra heat when the engine is running and the batteries are being charged how about something like a car heater box and motor?

This could be an excellent backup heating solution for a cruiser. A car style heater matrix with fan will be very compact compared with finrads and can chuck out a huge amount of heat with the fan on full. You can also duct air to where it is needed. They are designed for car cabins, so not dissimilarly sized and poorly insulated spaces. For summer, a diverter valve could prevent hot water going through the matrix, bypassing it, but that may not even be required. With the fan off, then little heat will go in to the cabin. The electric fan will use some current that would otherwise go to battery charging, but not much.

There are various ones you can buy new, or a trip to your nearest car breakers would get you one very cheaply.

Jen

Edited by Jen-in-Wellies

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The car heater matrix sounds a great idea - thanks! I want this secondary source of heat mainly for drying the boat out from condensation formed overnight and to dry wet clothes but it would be nice to walk into a nice warm boat after a long day's cruising in the cold or rain!

 

I'm frequently tempted by the somewhat more comfy and practical interiors of narrowboats, but on the other hand this thing now has an excellent new engine; new steering and throttle cables and a fairly recently refurbished saildrive so mechanically it's pretty sound. These works as well as hopefully a folding windscreen and a proper rewiring should bring it up to a good standard, with insulation and condensation being the biggest weaknesses, but not a huge amount we can do there, save ripping the interior out.

Edited by Philip

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Well I've bought a small hot water/car heater matrix from the website in the link above. I've gone for the one with the lowest power output at 2.2kw, since the engine is fairly small. I would think this should still provide plenty of heat and keep things toasty once the engine has been going for a bit. It's a small thing with only one outlet but the plan is to have this blow directly into the heater cupboard/wardrobe and then put a vent in the doors so that heat can also reach the cabin.

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