New Solar Water Heating gadget

[thenightowl]

Just found this, hope the link works, looks like the perfect device for heating water on the boat?

Your thoughts?

 

Peter

 

Just found this, hope the link works, looks like the perfect device for heating water on the boat?

Your thoughts?

 

Peter

 

Sorry trying to correct the fact I forgot the link!

 

http://cgi.ebay.co.uk/swimming-pool-solar-..._Pools_Hot_Tubs

[twbm]

Possibly, but you'd need a circulating pump and hot water storage tank, and not sure it'd ever get hot enough not to need finishing off with conventional fuels.

[parasal]

http://cgi.ebay.co.uk/NEW-40L-CAMP-CAMPING...DefaultDomain_3

 

I just bought one of these! Bag on the roof, tubing down the vent and shower away! Not exactly a power shower but free, well on a hot day at least!

[thenightowl]

Possibly, but you'd need a circulating pump and hot water storage tank, and not sure it'd ever get hot enough not to need finishing off with conventional fuels.

 

 

That is the worst case senerio, best one being, plumbing it into the existing system and it works on a thermo syphon principal. If not maybe a solar powered pump. It has too meet the needs for the bulk of the summer months I would of thought.

 

Regards

 

Peter

[Gibbo]

That is the worst case senerio, best one being, plumbing it into the existing system and it works on a thermo syphon principal. If not maybe a solar powered pump. It has too meet the needs for the bulk of the summer months I would of thought.

 

It won't work on thermosyphoning if it's the highest part of the water system which, being on the roof of the boat, it will be. Therefore a pump will be required.

[matty40s]

........unless you site it on a canoe ......

[sueb]

http://cgi.ebay.co.uk/NEW-40L-CAMP-CAMPING...DefaultDomain_3

 

I just bought one of these! Bag on the roof, tubing down the vent and shower away! Not exactly a power shower but free, well on a hot day at least!

Does yours work? I never managed to get warm water out of mine but it was slightly different.

Sue

[id_rather_be_welding]

It won't work on thermosyphoning if it's the highest part of the water system which, being on the roof of the boat, it will be. Therefore a pump will be required.

Having had a really good thermosyphon boiler for 15 years in our old boat that sits in a old dedicated woodburner, I have plans on the new boat to have a second coil linked up to heat exchangers formed by copper pipes pushing against the cabin sides of an unlined engine room. Anyone done this? I think as well as having enough rise to power the thermosyphon, getting a really good contact between steel and copper would be key. I know someone who was planning to use his handrails as heat exchangers for hot water - big volume and nice easy rise all along the length to power a thermosyphon, but I don't know if it actually worked. Should have done.

[Gibbo]

Having had a really good thermosyphon boiler for 15 years in our old boat that sits in a old dedicated woodburner, I have plans on the new boat to have a second coil linked up to heat exchangers formed by copper pipes pushing against the cabin sides of an unlined engine room. Anyone done this? I think as well as having enough rise to power the thermosyphon, getting a really good contact between steel and copper would be key. I know someone who was planning to use his handrails as heat exchangers for hot water - big volume and nice easy rise all along the length to power a thermosyphon, but I don't know if it actually worked. Should have done.

 

But he'd have to put his hot water tank on the roof above the handrails.

[id_rather_be_welding]

But he'd have to put his hot water tank on the roof above the handrails.

 

Maybe. Perhaps a little pump would be needed with that system. But I dont think that it is that the tank has to be above the heat source (there are many boilers that sit partly higher than the tanks they heat) but that there needs to be a clear rise in the pipe work above the heat source where some cooling can occur, to create the pump that powers the thermosyphon.

[Smelly]

Possibly, but you'd need a circulating pump and hot water storage tank, and not sure it'd ever get hot enough not to need finishing off with conventional fuels.

 

On a sunny day the coolant would get rather hot I'd imagine, especially with a pump that only kicked in when it was blinkin' hot. On our installation; with no instantaneous hot water, one of these in the summer, when most of our electricity is via PV and hence we don't want to run the engine, could be ideal. Darker months we'll be running the engine/genny/immersion & solid fuel to keep it all topped up.

 

I've asked for a data sheet...

 

I wonder whether a "solar pump" is feasible? Using the timer function on the PV controller would work.

 

Maybe. Perhaps a little pump would be needed with that system. But I dont think that it is that the tank has to be above the heat source (there are many boilers that sit partly higher than the tanks they heat) but that there needs to be a clear rise in the pipe work above the heat source where some cooling can occur, to create the pump that powers the thermosyphon.

 

I thought it was the cooling at such as the Radiator with a significant cooling and descent that did that? Hot water rises through the cooler water higher up, aiding the intial warming with a significant amount of radiation over convection, then it hits a cooling plane such as a calorifier or rad and starts dropping significantly there as it cools; reducing the local pressure and hence inducing the "syphon" around the circuit.

 

I'm no expert mind but I'd reckon trying to run a thermosyphon from the bottom of a boiler would be doomed to failure; all the hot water would be hiding at the top.

Edited August 17, 2010 by Smelly

[id_rather_be_welding]

I'm no expert mind but I'd reckon trying to run a thermosyphon from the bottom of a boiler would be doomed to failure; all the hot water would be hiding at the top.

You are right, and this is not what I suggested. Imagine a boiler in a stove on a narrow boat with a copper pipe coming out of the boiler through the wall of the stove, and then and going vertically up till it meets the gunwhale lining. The pipe then turns through 90 degrees and runs downslope along the boat to wherever the water cylinder or radiator is - this might be some distance away eg 7 or 8 metres away.

The pipe then passes through a coil within the cylinder or a radiator (so losing most of its heat), exits the cylinder/radiator near the base and then is routed at floor level back to and up into the boiler.

In my book the foot long piece of pipe that sticks up above the boiler is the pump, as everything else is down slope. The hotter water in the boiler has got somewhere it wants to go in this short length of pipe, and this pipe is not as hot as what it is inside the stove - so there is a thermal difference, a potential which causes the circulation. The longer this piece of pipe, the greater the volume, the better the pump.

[Smelly]

You are right, and this is not what I suggested. Imagine a boiler in a stove on a narrow boat with a copper pipe coming out of the boiler through the wall of the stove, and then and going vertically up till it meets the gunwhale lining. The pipe then turns through 90 degrees and runs downslope along the boat to wherever the water cylinder or radiator is - this might be some distance away eg 7 or 8 metres away.

The pipe then passes through a coil within the cylinder or a radiator (so losing most of its heat), exits the cylinder/radiator near the base and then is routed at floor level back to and up into the boiler.

In my book the foot long piece of pipe that sticks up above the boiler is the pump, as everything else is down slope. The hotter water in the boiler has got somewhere it wants to go in this short length of pipe, and this pipe is not as hot as what it is inside the stove - so there is a thermal difference, a potential which causes the circulation. The longer this piece of pipe, the greater the volume, the better the pump.

 

It might not be quite so pretty, but the 2m long pipe that rises from our backboiler to the first rad heading "down" the gunwhale (our fire's in the middle of the boat) works a treat. "Up" the boat isn't so much of an issue...

 

I'd be interested to know how many folk have such a "straight up" arrangement as it'd save me a headache. I've never seen such a creature, although tbh I've not looked that hard.