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Webasto and Calorifier sizing


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8 hours ago, Sea Dog said:

Well yes, I see your point, but you have to allow that, when people ask for the moon on a stick, others might be tempted to suggest something rather more easily achieved. 

 

It's unclear to me whether he's replacing a perfectly good calorifier specifically to achieve something more or because its a duffer that needs to be replaced anyway so he's looking at whether something more is possible (where, as you say, a larger calorifier might well help). I suspect this is why there are many who suggest it may be more expeditious to explore how he might best use his current set up rather than rip out what works well for most.

 

Personally, I don't think that matters too much: I think I'd be happiest with the a mix of suggestions and discussions so I could chose the way forward that best achieved the outcome I was seeking, rather than proposals which only told me how I might achieve my own first thoughts.

(Any red text entirely unintentional - no idea where that control is!)

 

 

I'm sorry but this post is utter bollocks! Asking for calorifier recommendations is hardly the moon on a stick, and the problem isn't a mix of suggestions - it's more a lack of suggestions. If you don't have any calorifier recommendations you don't HAVE to use your keyboard - you can always walk away and let someone else answer. Just a suggestion - try it next time?

 

Just to add I've clearly stated it needs replacing - not that that should matter

Edited by Colin Brendan
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7 hours ago, Loddon said:

For 20 years whilst I was a live aboard boater the diesel heater was my alarm clock. It would fire up I would get up and  make a coffee and take the coffee  back to bed. Half hour later I would get up to a warm boat, shower, dress and go off to work. In the summer I would turn off all the rads except the bathroom one and surprisingly it still worked 🤭

It's all surprisingly simple to do 😱

Very simple - yet webastos are called webastards for a reason - they short cycle and coke up - people have no end of trouble with them - so yeah - this post was about getting it right - and your comments once again remain so useless they only make me worry for humanity.

Edited by Colin Brendan
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10 hours ago, Colin Brendan said:

Very simple - yet webastos are called webastards for a reason - they short cycle and coke up - people have no end of trouble with them - so yeah - this post was about getting it right - and your comments once again remain so useless they only make me worry for humanity.

I obviously have it right as it works and has done for years. Since the introduction of low sulphur diesel some 20 or so years ago most of the problems have gone away.

I could easily help you with info on system design but since you seem to only want to hear answers that you have already decided on I won't waste my time.

Bye 

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This was a useful thread - (aside from the bickering... stay focused folks!) - and I am in the same situation in terms of thinking through sizing, rads, etc for my new build. 

 

Our situation is that we don't have room for an instantaneous gas boiler in the cabin space so that is a firm decision taken.  We can only fit the calorifier in the engine bay - again, because space inside is tight.  But, it's 10ft wide so the engine bay is large - I need to work out how physically large a calorifier I can actually get in / out if needed past the engine, mindful of if there is a disaster in the future. 

 

I want to use a calorifier to provide all domestic water.  I also want morning/evening supplementary heating prior to us lighting the stove.   But, with only 45ft of length, I think I can only have a small bathroom towel rail and then at the most three small radiators, possibly only two due to available wall space. 

 

We have shore power and for 6 months are stuck on the mooring (Thames flood channel) - so there is option for immersion - albeit pricey at present.  When we cruise during the rest of those months, we are not daily movers. Instead we tend to travel somewhere and lay up for a week or so then move on etc.  (Towpath shufflers?!) 

 

On the capacity of that calorifier - the other half has stipulated that the current boat's 55lt vertical calorifier, heated for several hours by its immersion, is not enough for her long hair-washing shower each week (short daily showers are fine, but apparently the long ones are not!!).    I think as long as I can fit it in, 75lt vertical but potentially even the Surecal 90lt is where I will end up.

 

 

I also want to ensure that the Webasto is running under load enough...

 

In the winter - laid-up on shore power - I was anticipating having the Webasto on a timer so it heats the water tank, fires up the rads for an hour to take the edge off etc - so not too worried about the short-cycling.   We can also turn on the immersion if we need to give it a rapid blast if for whatever reason we have used a lot of water.

 

In the summer - no heating requirement but could leave the towel rail radiator on, turn the others off.  I would expect that what with at least one of us having a shower and the washing up, there will always be a requirement for the webasto to come on. So i was thinking maybe an hour in the morning may be all that's required to heat the 75lt calorifier.  If we cruise, then we turn webasto off. 

 

What's the general view on just using the immersion heater off 240 for all domestic water - not sure whether the 240 is that much more expensive than diesel?

 

Am i making any silly assumptions here? 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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15 minutes ago, TandC said:

Am i making any silly assumptions here? 

 

 

The only one really is planning to put the calorifier in the engine room - it will be very cold in there and even a well insulated calorifier will leech heat away and you will need to do much more water heating to get warm (hot) water - and - your water in the morning will probably require re-heating before use.

 

I reckon you'll use 30% more diesel / electricity trying to keep an engine room calorifier hot. 

You could always try double or treble insulating the calorifier, but it will still lose the heat but, a little bit slower. The cold WILL percolate thru to the cylinder.

 

You will use much less Diesel / ELectricity if you calorifier is fitten withing the confimes of the insulated part of the boat. Under the bed, in a wardrobe etc.

 

On our current boat our calorifier is in the engine room - A big mistake, and one that'll never be made again.

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Alan - that is a problem indeed but one I will have to live with.  There is just no room for a decent size calorifier inside though - not with the layout (and windows are all cut etc) - there's no going back unfortunately. 

 

Layout is - engine bay - bathroom - kitchen - living room - bedroom.   So with the calorifier in the engine bay there is a simplicity / proximity in the plumbing - moving it to the bedroom makes things much more difficult and decimates the planned bedroom area. 

 

Increasing the insulation is probably the best I can hope to do.... 

 

At least we never freeze over (small temperature gain!) 

 

 

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3 minutes ago, TandC said:

Alan - that is a problem indeed but one I will have to live with.  There is just no room for a decent size calorifier inside though - not with the layout (and windows are all cut etc) - there's no going back unfortunately. 

 

Layout is - engine bay - bathroom - kitchen - living room - bedroom.   So with the calorifier in the engine bay there is a simplicity / proximity in the plumbing - moving it to the bedroom makes things much more difficult and decimates the planned bedroom area. 

 

Increasing the insulation is probably the best I can hope to do.... 

 

At least we never freeze over (small temperature gain!)

 

 

You can get calorifiers with extra-thick insulation as well as bigger coils, as I mentioned earlier. Mine's in the engine bay too, next to the diesel boiler and generator...

 

https://www.coppercylinder.co.uk/customise-your-hot-water-cylinder.html

Edited by IanD
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2 minutes ago, TandC said:

Alan - that is a problem indeed but one I will have to live with.  There is just no room for a decent size calorifier inside though - not with the layout (and windows are all cut etc) - there's no going back unfortunately. 

 

Layout is - engine bay - bathroom - kitchen - living room - bedroom.   So with the calorifier in the engine bay there is a simplicity / proximity in the plumbing - moving it to the bedroom makes things much more difficult and decimates the planned bedroom area. 

 

Increasing the insulation is probably the best I can hope to do.... 

 

At least we never freeze over (small temperature gain!) 

 

 

With no wall space for radiators have you considered blown warm air heaters similar to this

image.png.d819c5230a51b1c7aee98a4fa1dad724.png

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2 hours ago, TandC said:

This was a useful thread - (aside from the bickering... stay focused folks!) - and I am in the same situation in terms of thinking through sizing, rads, etc for my new build. 

 

Our situation is that we don't have room for an instantaneous gas boiler in the cabin space so that is a firm decision taken.  We can only fit the calorifier in the engine bay - again, because space inside is tight.  But, it's 10ft wide so the engine bay is large - I need to work out how physically large a calorifier I can actually get in / out if needed past the engine, mindful of if there is a disaster in the future. 

 

I want to use a calorifier to provide all domestic water.  I also want morning/evening supplementary heating prior to us lighting the stove.   But, with only 45ft of length, I think I can only have a small bathroom towel rail and then at the most three small radiators, possibly only two due to available wall space. 

 

We have shore power and for 6 months are stuck on the mooring (Thames flood channel) - so there is option for immersion - albeit pricey at present.  When we cruise during the rest of those months, we are not daily movers. Instead we tend to travel somewhere and lay up for a week or so then move on etc.  (Towpath shufflers?!) 

 

On the capacity of that calorifier - the other half has stipulated that the current boat's 55lt vertical calorifier, heated for several hours by its immersion, is not enough for her long hair-washing shower each week (short daily showers are fine, but apparently the long ones are not!!).    I think as long as I can fit it in, 75lt vertical but potentially even the Surecal 90lt is where I will end up.

 

 

I also want to ensure that the Webasto is running under load enough...

 

In the winter - laid-up on shore power - I was anticipating having the Webasto on a timer so it heats the water tank, fires up the rads for an hour to take the edge off etc - so not too worried about the short-cycling.   We can also turn on the immersion if we need to give it a rapid blast if for whatever reason we have used a lot of water.

 

In the summer - no heating requirement but could leave the towel rail radiator on, turn the others off.  I would expect that what with at least one of us having a shower and the washing up, there will always be a requirement for the webasto to come on. So i was thinking maybe an hour in the morning may be all that's required to heat the 75lt calorifier.  If we cruise, then we turn webasto off. 

 

What's the general view on just using the immersion heater off 240 for all domestic water - not sure whether the 240 is that much more expensive than diesel?

 

Am i making any silly assumptions here? 

 

Have you already bought a diesel heater? If not maybe you can spec it to the calorifier output (with maybe a bit extra for towel rail, and 3 small rads) - I'm not an expert though.

 

I feel like the problem with the 5.2kw webasto is that some people suggest surecal coils soak up about 1kw (not sure how correct this is) leaving it vastly overpowered/short cycling if you don't have significant rads on. Maybe IanD's suggestion of a bespoke one is the way to go if not - then you can spec the calorifier to suit the heater. I think he said £1000+ though....

I'd like to know if there are any off the shelf high output calorifiers out there - NautiQuick seem to say they are - but no stats to back this up

I'd also like to know if there are any high output rads out there - aluminium rads are supposed to have high output but feel like they may pose other dissimilar metal problems - copper boiler etc.

 

We have immersion heater - and if I was on shorepower and electric wasn't absurdly expensive I'd use that all the time

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6 minutes ago, Colin Brendan said:

We have immersion heater - and if I was on shorepower and electric wasn't absurdly expensive I'd use that all the time

 

Paying 'shore prices' for your electricty is probably 1/10th of the price of generating it yourself running the engine.

 

A year or two ago (before these silly prices for diesel) a forumite calculated the cost per Kw of electricity when using your engine - it was fully 'costed' and included things like engine servicing, engine wear and tear, depreciation etc etc as well as the diesel used.

 

It came out at over £5 per Kw

 

In our Marina we are currently paying 28p per Kw for a shore supply.

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2 minutes ago, Alan de Enfield said:

 

Paying 'shore prices' for your electricty is probably 1/10th of the price of generating it yourself running the engine.

 

A year or two ago (before these silly prices for diesel) a forumite calculated the cost per Kw of electricity when using your engine - it was fully 'costed' and included things like engine servicing, engine wear and tear, depreciation etc etc as well as the diesel used.

 

It came out at over £5 per Kw

 

In our Marina we are currently paying 28p per Kw for a shore supply.

Yep - this what I've always thought - less smelly too - and ever greener (esp. if they sort out proper storage for those windfarms rather than turning them off).

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14 minutes ago, Colin Brendan said:

Have you already bought a diesel heater? If not maybe you can spec it to the calorifier output (with maybe a bit extra for towel rail, and 3 small rads) - I'm not an expert though.

 

I feel like the problem with the 5.2kw webasto is that some people suggest surecal coils soak up about 1kw (not sure how correct this is) leaving it vastly overpowered/short cycling if you don't have significant rads on. Maybe IanD's suggestion of a bespoke one is the way to go if not - then you can spec the calorifier to suit the heater. I think he said £1000+ though....

I'd like to know if there are any off the shelf high output calorifiers out there - NautiQuick seem to say they are - but no stats to back this up

I'd also like to know if there are any high output rads out there - aluminium rads are supposed to have high output but feel like they may pose other dissimilar metal problems - copper boiler etc.

 

We have immersion heater - and if I was on shorepower and electric wasn't absurdly expensive I'd use that all the time

 

The 1.1kW figure for a standard Surecal came from actual measurements Dave Jesse made on a 55l twin-coil one.

 

If I could have found any calorifiers offering high-output coils as standard off-the-shelf I'd probably have gone that way, but I couldn't, hence the custom one. But I also have different requirements to most boaters since the coils connect to either a generator or a pressure-jet diesel boiler, and I want the generator to heat up the tank in less than an hour (expected running time per day) and to reduce boiler cycling (peak output abut 10kW) when that's being used, so I want really hefty (~5kW) coils -- most people don't need this.

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5 minutes ago, IanD said:

 

The 1.1kW figure for a standard Surecal came from actual measurements Dave Jesse made on a 55l twin-coil one.

 

If I could have found any calorifiers offering high-output coils as standard off-the-shelf I'd probably have gone that way, but I couldn't, hence the custom one. But I also have different requirements to most boaters since the coils connect to either a generator or a pressure-jet diesel boiler, and I want the generator to heat up the tank in less than an hour (expected running time per day) and to reduce boiler cycling (peak output abut 10kW) when that's being used, so I want really hefty (~5kW) coils -- most people don't need this.

 

For general discussion, not a direct reply to the quote

 

But one has to remember that as the calorifier heats up the transfer oh heat will drop, so whatever heating capacity the coil has it will gradually reduce. The question is, will you have enough and hot enough water before this reduction causes the boiler to start cycling up and down.

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22 minutes ago, Tony Brooks said:

 

For general discussion, not a direct reply to the quote

 

But one has to remember that as the calorifier heats up the transfer oh heat will drop, so whatever heating capacity the coil has it will gradually reduce. The question is, will you have enough and hot enough water before this reduction causes the boiler to start cycling up and down.

I'm aware of that, and there are things in the system design (e.g. thermal storage) to reduce the effect. The boiler is more akin to a domestic oil-fired boiler than a Webasto, it's designed to cycle on and off in exactly the same way.

 

It doesn't change the fact that if you want to heat the tank up faster and reduce boiler cycling, bigger coils are always better than smaller ones.

Edited by IanD
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40 minutes ago, nb Innisfree said:

2x smaller cals with auto or manual change over valve (assuming enough space & deep pockets)

Quick heat up for 1st one and 2nd one as extra heat sink if req. 

 

The capacity of the calorifier to absorb heat (in kW) is set by coil size; a smaller calorifier with the same size coil heats up faster (less water) but doesn't absorb any more heat.

 

You could get twice the coil capacity by using both coils of a twin-coil one if there's only one heat source, or use two smaller calorifiers in series -- but this will probably cost more than one bigger calorifier with bigger coils... 😉

Edited by IanD
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1 hour ago, IanD said:

 

The 1.1kW figure for a standard Surecal came from actual measurements Dave Jesse made on a 55l twin-coil one.

 

If I could have found any calorifiers offering high-output coils as standard off-the-shelf I'd probably have gone that way, but I couldn't, hence the custom one. But I also have different requirements to most boaters since the coils connect to either a generator or a pressure-jet diesel boiler, and I want the generator to heat up the tank in less than an hour (expected running time per day) and to reduce boiler cycling (peak output abut 10kW) when that's being used, so I want really hefty (~5kW) coils -- most people don't need this.

What does the temperature difference need to be to achieve a 5kW transfer? 

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1 hour ago, nb Innisfree said:

The answer is: There is no answer. 

Wash less often. 

 

Believe it or not I have not had a shower or a bath for a month. I'm fine with this and the kids seem happy enough. I do occasionally wash clothes in hot water in the sink with bio washing powder so as not to smell like a tramp. 

 

Needing hot water every day is one of those modern luxuries which is just not necessary. 

 

Imagine the carbon offset which could be achieved if people did not rely on having running hot water. Neither of my boats have hot water to the taps. The hot water is available (Paloma or calorifier) but rarely used. 

 

Humans don't need this sort of thing. The sooner people realise this and act the better. It won't happen. 

 

Burn more wood and wash less. It will offset itself. 

 

Lynx deodorant no thanks. 

 

 

It is crazy how humans have been conditioned over the yars to believe they need things which they actually don't need purely to fulfil the goals of a greed based capitalist economic system. 

 

Then when something comes along that you actually DO need, like burning things to keep warm, suddenly it gets banned or made more difficult. 

 

Something wrong here I think. 

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You could use a heat exchanger-be cheaper and more versatile.

Advantage being is that in the summer time it would load the boiler and heat the calorifier rapidly.

Winter time you wouldnt need to use it as I assume you would have the heating on anyhow so using the standard coil would be enough.

You would need an additional fitting in the bottom of the calorifier as the calorifier cold feed will be fitted with a one way valve preventing you circulating the water. Unless of course it has a drain? Just pump it through the heat exchanger and back in the top where you hsve the PRV fitted.

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3 hours ago, Colin Brendan said:

Yep - this what I've always thought - less smelly too - and ever greener (esp. if they sort out proper storage for those windfarms rather than turning them off).

Has anybody suggested these guys yet?

 

https://www.bobilvans.co.uk/product-page/bobil-air-xchange

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