Greg2
Well-Known Member
Ah, so 80 degrees is unlikely to be sufficient. Thing is that this is the operating temp of our engines so it seems as though it will never work properly then
De-mister Heater Matrix
- Thread starter Greg2
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David2452
Well-Known Member
At river speed loading probably not, wind it open a bit and the temperature may well be enough.
LittleShip
Well-Known Member
Providing heating on a boat is akin to sticking your finger in the air and trying to gauge the wind speed.
Correctly designed heating will have to take into consideration the heat losses of the boat, that will include the loss through glass canvas walls ventilation ect. Remember, that the volume of air in a car is substantially less than that of a boat and the car will probably have a heat loss much smaller than the interior of a boat.
Because of this a best guess at what size rad or matrix is all that one can do. In short, nobody can design a heating system for a boat that will be guaranteed to be correctly sized for the heat requirements and remember the colder it is outside the more heat will be required inside.
I have a wet system on board little ship that will provide heat water and or both but at best it is just some heat to prevent the interior from being cold. Trying to raise the temperature to "comfort" conditions in very cold weather would probably require far more heat than I have available from the thermo top.
Tom.
Correctly designed heating will have to take into consideration the heat losses of the boat, that will include the loss through glass canvas walls ventilation ect. Remember, that the volume of air in a car is substantially less than that of a boat and the car will probably have a heat loss much smaller than the interior of a boat.
Because of this a best guess at what size rad or matrix is all that one can do. In short, nobody can design a heating system for a boat that will be guaranteed to be correctly sized for the heat requirements and remember the colder it is outside the more heat will be required inside.
I have a wet system on board little ship that will provide heat water and or both but at best it is just some heat to prevent the interior from being cold. Trying to raise the temperature to "comfort" conditions in very cold weather would probably require far more heat than I have available from the thermo top.
Tom.
Greg2
Well-Known Member
Yes, I quite agree Tom. I think the thing is that I expected the unit to put our warmer air than it does but it would appear that our normal engine operating temp of 80 degrees just ain't enough!
Spi D
...
True. If you consider the efforts done to make houses comfortable by insulation, humidity control, heat and light, a boat has a long way to go to get even comparable. A few boats are built for all year use in that respect but having cold water against your outer 'walls' is bound to affect inside comfort.
In a previous life I had to make trucks' cargo compartments temperature and humidity controlled while replacing the total air volume 30 times per hour. Trucks driving everywhere between Frankfurt and Umeå in northern Sweden - all year round. As an extra challenge the temp/humidity should be controlled also when drivers where at rest - up to 8 hours with engine shut off.
Admitted, different to a boat but still. Lesson learned was that a too small and too big heater both made problems. Heaters a bit too large and able to run hi/lo performance came closest to succes.
Engine as a main source of heat in a boat seems viable only if running the engine close to always.
In a previous life I had to make trucks' cargo compartments temperature and humidity controlled while replacing the total air volume 30 times per hour. Trucks driving everywhere between Frankfurt and Umeå in northern Sweden - all year round. As an extra challenge the temp/humidity should be controlled also when drivers where at rest - up to 8 hours with engine shut off.
Admitted, different to a boat but still. Lesson learned was that a too small and too big heater both made problems. Heaters a bit too large and able to run hi/lo performance came closest to succes.
Engine as a main source of heat in a boat seems viable only if running the engine close to always.
Barleycorn
Well-Known Member
I am thinking of fitting one of these to keep the cabin warm and demist to save wearing out the Webasto.
http://www.t7design.co.uk/index.php?main_page=product_info&cPath=65&products_id=301
My calorifier gets really hot, so I should think it will work OK
I would not worry too much about mounting the matrix above the engine. In some farm machinary the heater is mounted in the top of the cab feet above the engine, and the pipes are never lagged.
http://www.t7design.co.uk/index.php?main_page=product_info&cPath=65&products_id=301
My calorifier gets really hot, so I should think it will work OK
I would not worry too much about mounting the matrix above the engine. In some farm machinary the heater is mounted in the top of the cab feet above the engine, and the pipes are never lagged.
Greg2
Well-Known Member
That is effectively what we have fitted albiet a different (and more expensive) make. That looks to be good value compared to the Isotherm model which are over three hundred quid as I understand it.
Interetsing what you say about mounting above the engine....I was following the installation instructions, which advise it to avoid the possibility of problems with coolant flow.
David2452
Well-Known Member
Simply not so, it is a matter of doing the calcs and specifying the correct heater(s) or A/C to suit and installing it correctly, equally importantly having the full knowlege of what it is expected to do.
David2452
Well-Known Member
Look at the spec. it goes back to what I wrote earlier, if you can get the coolant close to 100c it will give decent heat, but if you can't then it will not.
LittleShip
Well-Known Member
Show me where you get the "U" values for GRP walls, windows, doors, roof, floor and ventilation for specific boats which would enable you to design a correctly sized heating system and at what outside temperature.
Correctly sized and designed heating requires all of them and more. A best guess with boats is all that can be done.
I stand by my original quote.....
Providing heating on a boat is akin to sticking your finger in the air and trying to gauge the wind speed.
Tom
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Robg71
Well-Known Member
I would imagine that companies like webasto would have done the research and have that information....
LittleShip
Well-Known Member
No Chance..... the most they would be doing is working on heating a volume of air.
Tom
Tom
David2452
Well-Known Member
Indeed Rob, there is lots of information being used, Webasto's largest market is military and there is a lot of built up data, perhaps not the precise scince of domestic & commercial applications but far far from holding a finger in the air.
David2452
Well-Known Member
you could start here for GRP, there are values available for most material used in building boats, the OT is avariable.http://www.rtech-materials.co.uk/news/2013/08/09/thermal-properties-of-grp-panel/
LittleShip
Well-Known Member
And just how do you think that information is going to help design a correctly sized heating system on a boat.
Personally, I don't need to start anywhere..... My experience comes from designing correctly sized heating systems for almost 40 years and I know that I couldn't do it on Little Ship so I held an experienced finger in the air and picked something that would "hopefully" do the job in the temperatures I would be using her in.
Tom.
Barleycorn
Well-Known Member
On my previous boat a heater out of a series 2 Landrover mounted on the front bulkhead kept the wheelhouse lovely and cosy.
David2452
Well-Known Member
lynall
Well-Known Member
Surely any liveaboard or anyone that actually uses their boat in all weathers can tell you what works and what doesnt?
LittleShip
Well-Known Member
Trundlebug
Well-Known Member
Yes you're quite correct, but don't worry all is not lost!
If you remove the thermostat(s) from the engine and take one into a (decent) local motor factors, you are very likely to be able to find an identical 'stat with a higher operating temp, say 88 or 90 degrees.
That's exactly what I did, after I fitted a webasto madera 8kw matrix to my boat.
Finding it only blew luke warm I remembered what a huge difference fitting an 88deg thermostat made to the heater output of a Mini compared to a summer stat of 82.
I managed to find a 90 deg stat for the boat at very affordable cost, and it improved the heat output considerably.
Remember, it does then leave less margin for engine overheat, so I also have exhaust temp readouts fitted to aid early warning of any problems.
Try this before giving up!