I want to build a panel to pre-warm the water entering the HW cylinder. It has to be a budget DIY job because at around £2000 for an off-the-shelf it would take many years to recoup the cost.
I have installed a 160 litre cylinder (£120 new, unused, off Ebay) in the attic in tandem with the existing HW cylinder and the water has been running through this for a year now, problem-free. Now I need to make the panel, this will be around 1.5 m2 made from a hardwood frame with rebates for a marine ply back and toughened glass front. The collector will be ali sheet, etch primed then painted black with 10, 12 or 15mm copper pipe in a serpentine shape clipped to the front, also painted back. Controls will be a Satchwell or equivalent water temperature detector in the top of the pipework and another on the cylinder, linked to a control unit giving a choice of range for the difference between the panel and the cylinder. The system will be filled with car anti-freeze and there will be a SS expansion tank at the top, covered to prevent evaporation. A small CH circulator will come on when the controller detects usable heat in the panel pipework and will pump the liquid through the panel and thence into the coil. My neighbour, a retired plumber, has been running a similar simple design of system for 20 years without any problems and reckons it saves him £60-£90 a year on hot water costs, though he has about 3m2.
I reckon I can do this for under £500. I will plumb it so that a second panel could be added later if I wanted to.
I plan to line the back of the panel with Kingspan, which will not absorb moisture but I'm concerned about the material at high temperature. Kingspan tell me it should be okay at up to 90 degrees - any thoughts? I'm reluctant to use glass wool because it will get wet with condensation, although the case will have drain holes.
I don't know how to decide the pipe thickness for the collector, or the pump capacity. I'd have thought 10mm pipework would be easiest with the lowest capacity pump possible but am open to persuasion to use 15mm or even 12mm if I can get some.
I plan to fix the panel to the roof using straps extended up under the tiles and screwed to a couple of battens. The panel will be at the edge of the roof so that the F&R pipes can double over the edge and straight in through the gable to the expansion tank and pump.
Any suggestions or experiences that might help me?
I have installed a 160 litre cylinder (£120 new, unused, off Ebay) in the attic in tandem with the existing HW cylinder and the water has been running through this for a year now, problem-free. Now I need to make the panel, this will be around 1.5 m2 made from a hardwood frame with rebates for a marine ply back and toughened glass front. The collector will be ali sheet, etch primed then painted black with 10, 12 or 15mm copper pipe in a serpentine shape clipped to the front, also painted back. Controls will be a Satchwell or equivalent water temperature detector in the top of the pipework and another on the cylinder, linked to a control unit giving a choice of range for the difference between the panel and the cylinder. The system will be filled with car anti-freeze and there will be a SS expansion tank at the top, covered to prevent evaporation. A small CH circulator will come on when the controller detects usable heat in the panel pipework and will pump the liquid through the panel and thence into the coil. My neighbour, a retired plumber, has been running a similar simple design of system for 20 years without any problems and reckons it saves him £60-£90 a year on hot water costs, though he has about 3m2.
I reckon I can do this for under £500. I will plumb it so that a second panel could be added later if I wanted to.
I plan to line the back of the panel with Kingspan, which will not absorb moisture but I'm concerned about the material at high temperature. Kingspan tell me it should be okay at up to 90 degrees - any thoughts? I'm reluctant to use glass wool because it will get wet with condensation, although the case will have drain holes.
I don't know how to decide the pipe thickness for the collector, or the pump capacity. I'd have thought 10mm pipework would be easiest with the lowest capacity pump possible but am open to persuasion to use 15mm or even 12mm if I can get some.
I plan to fix the panel to the roof using straps extended up under the tiles and screwed to a couple of battens. The panel will be at the edge of the roof so that the F&R pipes can double over the edge and straight in through the gable to the expansion tank and pump.
Any suggestions or experiences that might help me?
