Smaller Calorifier?

[BD3Bill]

Hello all, new here so be kind!

 

I am new to NB ownership and so finding my way.

 

Our 45ft Tug has currently got a 70 litre ish, ( estimated on measurement ) calorifier with a single coil from the engine, plus a 3kw immersion (useless as we have no hook-up at the home mooring).

I don't want to run the engine for ages to heat up the water, wastes diesel, bad for the motor, annoying, blah-blah...

 

So what I am contemplating is this;

 

Change to a 30 litre horizontal Surecal ( under the bed, instead of cluttering up the engine room ).

 

Use the 700w inverter (feeble I know, but we are trying to stick to 12v, not run a Generator etc) to power a 500w immersion in the Surecal.

 

By my calculations running the inverter/immersion for about 2 hours will raise the temperature of the water by 20-25 degC

and discharge the batteries by 50% ( 2x 110 Ah) using up about our daily allowance of WattHours .

In summer this should provide a warm shower once per weekend?

I have fitted a 40w solar panel to recharge the batteries during the fortnight we are away from the boat, and it works rather well so far ( but that's another topic eh?).

 

This is a weekend boat, NOT a liveaboard btw.

 

Obviously if I run the engine for half an hour or so the temperature will rise quicker and effectively reduce the battery use.

 

If we start with full batteries and run the engine ( single 70amp alternator) how much does that reduce the battery requirement by? ( That's another thread really isn't it?)

 

Cheers

Bill

 

 

[Paul C]

I think you're on the right track with using a smaller calorifier. It will warm up quicker, at the expense of less total capacity of hot water obviously.

 

I'd forget about 700W inverter and 500W immersion heater - trying to heat water by electricity is going to hammer those two batteries, and the amount of solar power you have is well short of what you'd need to make a significant contribution to keeping them topped up. I'd not worry too much about having a single 70A alternator, which is on the small side these days, because charging batteries or supplying power off of the engine is kinda 20th century technology. Get more solar - its the way to go! If you want to use an immersion heater, think of getting MUCH more solar, eg 800W of panels or more. Even then, only in the summertime will any of that be a good contribution to heating water.

[ditchcrawler]

Why not go boating?

[bottle]

Welcome to the forum.

 

As I started typing, a flash popped up saying a new post had been made, looked and it said exactly what i was going to say.

Edited April 11, 2013 by bottle

[Paul C]

Why not go boating?

 

Its a good answer/suggestion but there's plenty of reasons not to. People use their boats in different ways - some do high mileage and go far, which has the side effect of hot water all the time, batteries nicely charged, etc etc (ie use their boat somewhat similar to a hire boater's typical usage). Some people tootle around and do 2-3 hours cruising per day, which might need alternative sources of power (such as solar) and/or running the engine when stationary. And others spend long times not moving anywhere. I think its a little simplistic to say "why not go boating" and we shouldn't be imposing a particular style/way of using a boat, onto people, when there's other ways to solve the original issue. For example, we are on a holiday at the moment and do about 8-10 hours cruising per day. But we went onto the Monty for 2 days, and both of those did about 3 hours driving - should we have done more?

[Dave_P]

I can't quite make sense of what you're saying. Say you visit your boat once a fortnight and arrive to find your batteries fully charge by solar, then you turn on your new immersion long enough to heat water and discharge your batteries by 50%. Your solar panel is going to take a fair while to bring the batteries back up so what are you going to do now? Surely you're going to have to recharge your batteries? The easiest way to do this is to run the engine, which would have heated your water anyway! All seems rather pointless to me. As ditchcrawler has said, you could always take your boat out, after all that's what it's meant for! If you can't or don't want to and you don't want to run your engine for hot water, you need another way of getting it. Your options are:

 

1. via the back-boiler on a solid fuel stove - except in the warmer months you probably don't want your stove on.

2. diesel or gas fired central heating - which would be expensive and a bit over the top just for the sake of hot water.

3. a gas instant water heater like a morco.

 

I'd go for number 3. they're pretty cheap and will do exactly what you're after. You can keep your big calorifier for 'free' hot water when cruising and use the morco/rinnai/paloma when you're not.

[BD3Bill]

Thanks for the interest & answers folks.

 

Absolutely agree that using the boat is the way forward you Chaps.

 

But I am, so to speak, steering with a spanner in one hand and a saw in the other at the moment.

 

For now I am going to invest time in insulating the hot tank better.

 

During our collection trip, down from Wolverhampton to the South Oxford at the beginning of March, the tank was cold in the morning after a whole day's cruising.

Yes, it was exceptionally cold weather, but surely the water should stay warm overnight?

 

Ditchcrawler, does Harnser still have a BD3 engine?

If so, is your calorifier fed from the front of the cylinder head or on a manifold tank I wondered?

 

Cheers Bill

[arpeeuk]

On my BD3, the calorifer is fed from the front of the cylinder head. I get hot water in about an hour of gentle cruising but a full tank would take a bit longer.

 

My calorifier will stay hot enough for a morning shower provided I don't use it for washing up etc. the night before. I find if I use some of the hot during the evening then it's still warm but makes for a rather chilly shower. Answer, shower in the evening or eat out, preferably both!

 

Rik

[David Mack]

During our collection trip, down from Wolverhampton to the South Oxford at the beginning of March, the tank was cold in the morning after a whole day's cruising.

Yes, it was exceptionally cold weather, but surely the water should stay warm overnight?

 

In some boats once the engine is not running there can be a convection current from calorifier to engine, which keeps the engine nice and warm for a few hours, but cools the calorifier. It won't happen with the right pipe layout, but an easy fix is to put a valve in the pipe from engine to calorifier to stop the flow. Just remember to open the valve again when you start the engine.

[BD3Bill]

Thanks for the sage advice Rik

 

That confirms I'm not daft, mad, imagining things, or there is anything wrong with the existing set up, always a good starting point !

 

My better half has already got used to doing the dishes with water from the kettle heated up by the woodburner.

Many thanks David

 

The calorifier in/out sits much lower than the inlet & outlet from the engine so I can see that being a factor, and the BD3 is a big old lump too.

So running an immersion would also heat the engine up as well......

 

This is just the kind of info I need, marvellous!

 

Cheers Bill

Edited April 12, 2013 by BD3Bill

[ditchcrawler]

Thanks for the interest & answers folks.

 

Absolutely agree that using the boat is the way forward you Chaps.

 

But I am, so to speak, steering with a spanner in one hand and a saw in the other at the moment.

 

For now I am going to invest time in insulating the hot tank better.

 

During our collection trip, down from Wolverhampton to the South Oxford at the beginning of March, the tank was cold in the morning after a whole day's cruising.

Yes, it was exceptionally cold weather, but surely the water should stay warm overnight?

 

Ditchcrawler, does Harnser still have a BD3 engine?

If so, is your calorifier fed from the front of the cylinder head or on a manifold tank I wondered?

 

Cheers Bill

I will go and look and report back.

 

I will go and look and report back.

One pipe goes into the head inline with No1 injector just under the inlet manifold. the other is T'ed into the waterpump with the pipe to/from the oil cooler.

 

In some boats once the engine is not running there can be a convection current from calorifier to engine, which keeps the engine nice and warm for a few hours, but cools the calorifier. It won't happen with the right pipe layout, but an easy fix is to put a valve in the pipe from engine to calorifier to stop the flow. Just remember to open the valve again when you start the engine.

My pipes come from the engine and turn through 90° down to floor level, 90° through the bulkhead, round the bathroom under the bath and then up to the calorifier and about a foot higher than the top of the engine.

[BD3Bill]

Brian, very many thanks indeed for the description.

 

The engine end layout is the same as mine, however having the calorifier up higher strikes me as a much better arrangement than down on the baseplate ( albeit on some ply... minimal insulation).

 

I can see there may even be some positive benefit from having the calorifier raised up in terms of improving the circulation from the engine when running.

 

The things we inherit from previous owners eh?

 

My earlier idea of a new calorifier horizontal under the bed would present the same convectional loss problem, so I am really very glad I asked now !

 

You chaps have saved me from wasting a good deal of time, effort and money. For which I thank you most sincerely.

 

Cheers Bill

 

P.S. As an aside could I be a real pest and ask about your alternator arrangement?

 

I have but one on a singe vee-belt. I'm changing the original 55amp one for a 70amp but it would be good if I could use the 55amp for the engine battery and dedicate the 70amp to the leisure batteries. I am after some inspiration as to how to arrange this.

Edited April 13, 2013 by BD3Bill

[smileypete]

If there's a gas supply aboard then definitely consider getting an instant water heater like a Morco. And as others say, make sure the calorifer and connection pipes are very well lagged and not thermosyphoning when the engine is off.

 

Nevertheless, if you only want to run heat part of the calorifer when running the engine, this'll do it:

The way it works, while the engine is warming up the water on the calorifier side of the heat exchanger circulates in a loop, because the thermostatic valve only takes water from the left side until the outlet temperature reaches 65°C

 

As the temp of the water going round rises above 65°C, the thermostatic valve starts drawing water from the right side too and so draws cold water out of the bottom of the calorifier which in turn draws hot water into the top. The calorifer then 'fills up' with hot water from the top.

 

Needs about £100 worth of plumbing bits but may be easier and definitely cheaper than buying another smaller calorifier, plus it allows the engine to heat up quicker and frees up the calorifer heating coil for other things, like a back boiler.

 

Don't normally share these plumbing ideas but well, the weather this afternoon is rubbish and it's something to do.

 

But lagging and possibly a Morco (hot water heater) should be the first port of call!

 

cheers, Pete.

~smpt~

 

[BD3Bill]

Smiley Pete,

 

WOW! *tries not to swear with excitement*

 

That's my kind of system indeed, absolute inspiration !

 

Could I ask where you would source the Exchanger and TMV from ?

 

All my plumbing has been done in HEP, is that suitable?

 

You spent a rainy afternoon very well Chap!

 

I hear what you are saying about a Morco & insulation, but my longer term plan is to go gas-free, with a Refleks/Sigmar or Dickinson stove c/w back boiler. Your plan frees up the Cal.-coil to adopt that system with out an investment in a two coil calorifier, oh happy days!

 

You see my aim is to modernise the boat systems with diversity and economy in mind. Your idea fits right in with that ethos.

 

Cheers and many thanks

 

Bill

[ditchcrawler]

P.S. As an aside could I be a real pest and ask about your alternator arrangement?

 

I have but one on a singe vee-belt. I'm changing the original 55amp one for a 70amp but it would be good if I could use the 55amp for the engine battery and dedicate the 70amp to the leisure batteries. I am after some inspiration as to how to arrange this.

 

I have a 24 volt alternator fitted to a bracket on the left hand side of the engine looking from the flywheel/gearbox end. The bracket was fabricated to bolt onto the engine mounting rail. There is a Taperlock pulley on the engine crank in front of the existing alternator pulley. When I bought the engine it had been fitted with two alternators but the owner kept the second one, I fitted a much bigger pulley on the tapperlock hub to improve charging at low speed.

[smileypete]

Smiley Pete,

 

WOW! *tries not to swear with excitement*

 

That's my kind of system indeed, absolute inspiration !

 

Could I ask where you would source the Exchanger and TMV from ?

 

All my plumbing has been done in HEP, is that suitable?

 

You spent a rainy afternoon very well Chap!

For a circulation pump I think a few people have the first one and found them fine, I'd only use the second one if on a really tite budget or as a spare:

 

http://www.ebay.co.uk/itm/12-Volt-Hot-Water-Pump-6W-12v-Solar-Panel-Brewing-Aquarium-Boat-/130875510167

http://www.ebay.co.uk/itm/High-Quality-DC-12V-Magnetic-Electric-Centrifugal-BF00-Water-Pump-Hot-Sale-New-/400422979430

 

And for a plate heat exchanger this sort of thing will do, again I think one or two people have the first one and they're fine: (There are also loads of heat exhangers for combi boiler but only a few have threaded fittings)

 

http://www.ebay.co.uk/itm/Stainless-Steel-Heat-Exchanger-Plate-Heat-Exchanger-10-Plates-22-kW-/360635994653

http://www.ebay.co.uk/itm/Plate-HEAT-EXCHANGER-biofuel-veg-vegetable-cooking-oil-SVO-WVO-biodiesel-UCO-/121091659436

 

And for the TMV look for one that's adjustable up to 65°C or more, some only go a lot lower:

 

http://www.ebay.co.uk/itm/15MM-Caleffi-Mixcal-OEM-TMV-2-Thermostatic-Mixing-Valve-TMV2-Approved-/160995117531

http://www.ebay.co.uk/itm/22mm-Caleffi-TMV-/281090719664

 

Lastly it might be good to run the pump from a voltage regulator to make it adjustable and give it a clean supply:

 

http://www.ebay.co.uk/itm/DC-DC-Converter-Power-Supply-with-Voltmeter-1-25-36V-Output-Real-UK-Stock-/300879529926

http://www.ebay.co.uk/itm/DC-To-DC-Converter-Step-Down-Buck-Module-With-Voltmeter-4-5-24V-To-0-93-20V-2A-/271042711263

 

Changing the existing Hep plastic pipe should be fine, get the matching inserts then use more push fit or compression fittings, and the straight pipe is easier to deal with.

 

Try and route the pipes on the calorifier side so any air that comes out of solution can 'run uphill' and out of harms way. And best fit the exchanger and pump in the cabin space away from the risk of frost if poss.

 

I'd stick to copper or braided rubber hose for the connections from engine to heat exchanger, and fit a couple of full bore isolation valves, maybe a Y strainer too, like:

 

http://www.toolstation.com/shop/Plumbing/Valves/Full+Bore+Isolating+Valve+CP+15mm/d20/sd2696/p11495

http://www.toolstation.com/shop/Plumbing/Valves/Inline%20Y%20Filter/d20/sd2696/p79459

 

cheers, Pete.

~smpt~

Edited April 14, 2013 by smileypete

[BD3Bill]

 

 

I have a 24 volt alternator fitted to a bracket on the left hand side of the engine looking from the flywheel/gearbox end. The bracket was fabricated to bolt onto the engine mounting rail. There is a Taperlock pulley on the engine crank in front of the existing alternator pulley. When I bought the engine it had been fitted with two alternators but the owner kept the second one, I fitted a much bigger pulley on the tapperlock hub to improve charging at low speed.

Cool, thanks Brian

So a 4:1 or 3:1 ratio on the pulleys?

Now I know what to look for, and again many thanks.

 

Cheers Bill

 

For a circulation pump I think a few people have the first one and found them fine, I'd only use the second one if on a really tite budget or as a spare:

 

http://www.ebay.co.uk/itm/12-Volt-Hot-Water-Pump-6W-12v-Solar-Panel-Brewing-Aquarium-Boat-/130875510167

http://www.ebay.co.uk/itm/High-Quality-DC-12V-Magnetic-Electric-Centrifugal-BF00-Water-Pump-Hot-Sale-New-/400422979430

 

And for a plate heat exchanger this sort of thing will do, again I think one or two people have the first one and they're fine: (There are also loads of heat exhangers for combi boiler but only a few have threaded fittings)

 

http://www.ebay.co.uk/itm/Stainless-Steel-Heat-Exchanger-Plate-Heat-Exchanger-10-Plates-22-kW-/360635994653

http://www.ebay.co.uk/itm/Plate-HEAT-EXCHANGER-biofuel-veg-vegetable-cooking-oil-SVO-WVO-biodiesel-UCO-/121091659436

 

And for the TMV look for one that's adjustable up to 65°C or more, some only go a lot lower:

 

http://www.ebay.co.uk/itm/15MM-Caleffi-Mixcal-OEM-TMV-2-Thermostatic-Mixing-Valve-TMV2-Approved-/160995117531

http://www.ebay.co.uk/itm/22mm-Caleffi-TMV-/281090719664

 

Lastly it might be good to run the pump from a voltage regulator to make it adjustable and give it a clean supply:

 

http://www.ebay.co.uk/itm/DC-DC-Converter-Power-Supply-with-Voltmeter-1-25-36V-Output-Real-UK-Stock-/300879529926

http://www.ebay.co.uk/itm/DC-To-DC-Converter-Step-Down-Buck-Module-With-Voltmeter-4-5-24V-To-0-93-20V-2A-/271042711263

 

Changing the existing Hep plastic pipe should be fine, get the matching inserts then use more push fit or compression fittings, and the straight pipe is easier to deal with.

 

Try and route the pipes on the calorifier side so any air that comes out of solution can 'run uphill' and out of harms way. And best fit the exchanger and pump in the cabin space away from the risk of frost if poss.

 

I'd stick to copper or braided rubber hose for the connections from engine to heat exchanger, and fit a couple of full bore isolation valves, maybe a Y strainer too, like:

 

http://www.toolstation.com/shop/Plumbing/Valves/Full+Bore+Isolating+Valve+CP+15mm/d20/sd2696/p11495

http://www.toolstation.com/shop/Plumbing/Valves/Inline%20Y%20Filter/d20/sd2696/p79459

 

cheers, Pete.

~smpt~

Thank you very much Pete

 

All that is now in my watch list on eBay mate.

 

Connecting up the circulation pump to the ignition-on circuit, with the regulator in line ?

 

Cheers Bill

 

P.S. The 6w circulating pump is a gem !

[smileypete]

Connecting up the circulation pump to the ignition-on circuit, with the regulator in line ?

 

That's the one! Longer term you could also add a strap on cylinder thermostat right at the bottom of the calorifier, set it between say 65°C and 80°C. That way the pump will stop once the whole cylinder is heated, saving wear and tear.

 

BTW if you have non-thermostatic/manual shower mixer, to prevent scalding in the shower there should be a TMV between calorifier and the hot inlet limiting the temperature to say 45°C. Similarly to prevent scalding of hands ideally the kitchen and basin taps should limited to say 65°C either by a TMV or by the cylinder stat setting.

 

cheers, Pete.

~smpt~

Edited April 14, 2013 by smileypete

[arpeeuk]

Cool, thanks Brian

So a 4:1 or 3:1 ratio on the pulleys?

Mines got 2 90amp alternators running off 13mm single v belts. The 2nd alternator has a taper lock pulley as Brian describes 12" diameter which give a little over 4:1 I think. If I was setting it up myself (rather than inheriting it) I'd go for an even larger pulley, I think I could squeeze a 14" possible even a 15". This would give better output at the sort of speed I like to travel at.

 

I've also got a Smartbank setup to enable the two alternators to power my inverter for running the washing machine while cruising.

 

Cheers

 

Rik

[BD3Bill]

 

That's the one! Longer term you could also add a strap on cylinder thermostat right at the bottom of the calorifier, set it between say 65°C and 80°C. That way the pump will stop once the whole cylinder is heated, saving wear and tear.

 

BTW if you have non-thermostatic/manual shower mixer, to prevent scalding in the shower there should be a TMV between calorifier and the hot inlet limiting the temperature to say 45°C. Similarly to prevent scalding of hands ideally the kitchen and basin taps should limited to say 65°C either by a TMV or by the cylinder stat setting.

 

cheers, Pete.

~smpt~

Yes excellent advice, at home I have the combi boiler set to 45 deg for all hot taps, plenty hot enough. And this would save on the amount of hot drawn from the tank too I believe.

 

Thanks again

 

Cheers Bill

 

Mines got 2 90amp alternators running off 13mm single v belts. The 2nd alternator has a taper lock pulley as Brian describes 12" diameter which give a little over 4:1 I think. If I was setting it up myself (rather than inheriting it) I'd go for an even larger pulley, I think I could squeeze a 14" possible even a 15". This would give better output at the sort of speed I like to travel at.

 

I've also got a Smartbank setup to enable the two alternators to power my inverter for running the washing machine while cruising.

 

Cheers

 

Rik

Good to know that I can go up to a 90amp on a single vee without slippage, more batteries then.

Just got to source the taper lock hub and pulley to suit.

 

Many thanks

Cheers Bill

[Robbo]

Change to a 30 litre horizontal Surecal ( under the bed, instead of cluttering up the engine room ).

 

If your looking to move the calorifier to under the bed why not just add another and leave the one in the engine room? Get the big calorifier to feed from the hot water outlet to the cold water inlet on the smaller calorifier and get the engine to heat the smaller one first (or a three way valve, etc). This way if you go out for long period of time boating you'll have more hot water, but have the option of just heating the smaller calorifier if wished.

Edited April 15, 2013 by Robbo

[ditchcrawler]

 

Cool, thanks Brian

So a 4:1 or 3:1 ratio on the pulleys?

Now I know what to look for, and again many thanks.

 

 

!

 

Cool, thanks Brian

So a 4:1 or 3:1 ratio on the pulleys?

Now I know what to look for, and again many thanks.

 

Cheers Bill

Sorry missed that amongst the heat exchanger. I can't remember exactly but something like 8-1 for domestics so it wont over rev the alternator when the engine is on max

Edited April 15, 2013 by ditchcrawler

[peterboat]

Hi I have a 12v 300watt immersion heater which runs from my solar panels in the summer (if we get one this year) it provides hotish water. In the winter the wispergen stove with back boiler does its stuff.

The surprise for me is that in my last boat I had a large calorifier which was upright and remained hotter longer than my current horizontal and small calorifier the workings of boats eh?

 

Peter

[BD3Bill]

Time for an update then,

 

I fitted the heat exchanger system that smileypete suggested and it now works very well indeed !

 

I get enough water for two showers and washing up after running the engine for an hour or so.

 

What teething troubles I had were the engine thermostat being knackered (& circulating the keel tank at 40 - 45 C ) AND my engine not actually getting up to 65 C ...ever.

 

So I adjust the TMV to its minimum setting and draw the cold water from the bottom of the tank immediately and keep the engine running until the tank is hot, which as I say takes an hour, this gives a legionella safe 62 C.

 

Now I have fitted the new thermostat ( 82 c) the keel tank seems to do very little, I almost wonder if I need it connected at all ! ????

 

I think that I could give the TMV a miss altogether ( and re-use it close to the shower mixer).

 

The calorifier tank turned out (once removed for inspection) to have twin calorifier feeds. anyway ( so fitting the exchanger allows 3 hot water systems in the future! ) .

 

My question to the Team ( esp smiley pete ) is should I make better use of the engines output by supplying one of the calorifier coils from the return pipe from the exchanger to cylinder head??

 

Cheers Bill

Edited August 24, 2013 by BD3Bill

[smileypete]

Glad it's working well!

 

I think that I could give the TMV a miss altogether ( and re-use it close to the shower mixer).

 

The TMV should come into it's own in very cold weather, allowing the engine to heat more quickly until the temp reaches the TMV setpoint, after which any further heat is siphoned off as it were to heat the calorifier.

 

Since much engine wear occurs when starting from cold, minimising the warm-up time should help reduce engine wear.

 

Now the main thermostat is sorted, maybe try adjusting the TMV set point upwards to 50-60°c to help with faster engine warmup. You can verify this by feeling the pipe going into the top of the calorifer, it should stay cold until the pipe from the engine is nearly hand hot (you can hardly keep your hand on it) beyond which the calorifier pipe soon reaches the same temp and the calorifer heats from top down.

 

BTW if cruising in a hard water area it may be good to fit a thermostat low down on the calorifier to switch off the pump when the calorifier is heated to 60-65C This is because above this temp, limescale can form in the heat exchanger and reduce it's performance. It would also help protect the TMV if it's not rated for water above this temp.

 

My question to the Team ( esp smiley pete ) is should I make better use of the engines output by supplying one of the calorifier coils from the return pipe from the exchanger to cylinder head??

Would expect that the plate heat exchanger can transfer heat much better than a calorifier coil. Also adding a coil in this way would slow the engine warmup from cold, which isn't so good.

 

Might be better if the calorifier coil can be switched out, someone mentioned there's a solenoid heater valve for Fords that can be had quite cheaply:

 

http://www.ebay.co.uk/itm/Ford-Fiesta-KA-Puma-NEW-HEATER-CONTROL-VALVE-/180948961093

 

Once the engine has warmed up it could give the choice of boosting the calorifier from say 65°C to 82°C without causing limescale problems and so on.

 

Not sure how the valve works but with 4 pipes it looks like it simply bypasses the heater output when not energised, which would be ideal. Hopefully the valves and pipes are big enough not to reduce flow thought the plate exchanger too much.

 

Overall though I'd prefer to 'keep-it-simple' and only consider adding a calorifer coil and valve if it's really needed.

 

cheers, Pete.

~smpt~

Edited August 24, 2013 by smileypete