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Solar Tank - Installation

A personal record of my green initiatives for Solar Hot water - further information on the installation of the Solar Twin Coil Tank


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One Copper Twin Coil Tank 300 Litres (54 Gallons approx) standing 1850 mm high (just over 6 foot)

I purchased my Solar Twin Coil Tank as part of the original kit before upgrading the system in general. I went for what was then the largest commercially available one for three reasons.  I knew that I would expand the collectors at some stage so needed a  good store size to match. I also wanted to store hot water through the autumn, winter and spring and wanted to buffer as much hot water as possible when skies were very cloudy, taking full advantage of the good sunny days. And lastly I did not just want to "top up" my hot water usage but wanted it to be the main source without resorting to the boiler.  Though I would concede in the height of winter with multiple days of heavy cloud cover I will at least need to bring the temperature up from the already pre-heated state.


Solar Twin Coil Tank

 The Installation

I was lucky enough to have a very deep coat cupboard that I could use. The wall to the right is an external wall, I battened this, insulated and plaster boarded  the wall  to assist in heat retention. The  house is 90 years old and has a quarry Tile floor Floor, I also insulated this by placing a false floorboard floor on top with more insulation and it made look a lot better. At the end of the cupboard, only where the tank stands I raised the floor 6" to give easier access for future maintenance, draining etc.  The tank fittings are very low to the base and it makes it that bit easier to access the fittings during the install and to drain or remove fittings in the future. As the tank is so tall, I also pre installed some builders strapping, securely screwed to the wall behind the tank to keep everything tight and safe. (good practice or peace of mind I'll let you decide.)
Since taking this photo, I have further insulated the top portion of the tank with a  purpose  made spare tank blanket that I had left over from my loft insulation project. I have also packed some standard loft insulation, glass fibre type into large bags to contain it and packed the around the rear of the tank.



Most of the connections are of the compression type. These  are used particularly on the flow as this can get very hot though generally these are used in close proximity to the panels where the heat is at its peak. The main reason if have used compression fittings , is that as space is tight and to safeguard on future maintenance I can relatively easily disconnect everything as re-assemble quickly (though I hope not to)
Pipe work.  Not strictly part of the tank but as its shown, the pressure relief valve on the Flowcon Pump station has a drain to the outside. this must have un-hindered access to drain, and in my case its a dead straight pipe to the outside, and where it is also safe to discharge should it ever come to it.

As with most normal non Solar tanks, the cold feed comes in to the very bottom (just off picture) and the heated water exits at the very top (both 22mm). The Solar Flow and Return are both 15mm, only expanding to 22mm when passing through the pump station and solar panels.

Sensors. There are four sensors in total, three on the tank and one on the panels all linked back to a Resol BS/4 solar controller.  The top Sensor as you may guess measures the hottest point and the controller takes this reading for its maximum temperature. The Sensor at the bottom essentially measures the coldest part of the tank, though as its Just above the Solar return it will eventually reach more  or less (just below) the temperature at the top of the tank due to stratification.  Therefore unlike normal tanks fed by a boiler , the WHOLE tank is used as a heat store. The last sensor  is clamped to the solar return pipe, this essentially measures the heat extracted by the tank and by knowing the solar panel temperature it calculates a KWH value for the energy used or extracted by the panels.


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