Solar Thermal


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Graham Wise installed a 30 tube solar thermal system in his house.  The photos are in the order Graham refers to them in the text.  Graham writes:

This is a 30 58mm tube array with a BS3 pump station feeding a Newark Solar cylinder 1300 x 450. It is south facing but a large oak tree reduces midday sunshine.

Photo 134 Scaffolding to lift items to the roof, roof angle shallow enough to walk upon.  It took two people to get the larger items, one to pull with a rope and the other on the ground to steer to miss the projecting scaffolding poles. The reflectors were taken first and then the manifold as a separate item. The tubes were walked one at a time up the ladder.

The array is mounted on mounting frames that come from Covers in Chichester that has a "to order", environmental centre.  These are not in many Covers merchants.  The racks are very strong made of galvanised steel.  The roof fixings slide in slots so the bar can be raised or lowered.  The rack length 1.6m, was positioned to be between the manifold and first reflector and below the bottom reflector so that the fixings could be accessed. Photo 138 Roof fixing with tile removed showing tarred paper underneath.  Screws go through this layer and are covered in "roof and gutter seal" to ensure no water access.  The screws screw into noggins as shown in photo 161.  With the tile replaced Photo 140, covers fixings so not exposed to weather.  One frame shown in photo 142. Photo 143 shows the reflector part of the solar array mounted to the  3 mounting bars which was adjusted to be square and flat, the roof wasn't flat enough.  The frame is fixed to the bars with 12 right-angle brackets see Photo 155, drilling though the galvanised steel.  Cutting grease to aid drilling was used which covers the new surface and penny washers covered the hole so will not continue to rust.  The metal to metal contact will mean that the zinc galvanising will corrode to form a thin white surface to the zinc and stop.

Photo 151 shows the completed outside installation and the access window fitted in the rear.

Inside the attic the pump station was mounted near the access hatch, close to the bathroom, so the pipes had to cross over for the cylinder and the solar panel so longer pipe runs were involved.  Pump station, dump radiator valve, is shown in photo 156, the plastic container is to hold the fluid if it goes over pressure, the inverted cut down funnel stops dust getting in, to the right is the pressure vessel that store the liquid expansion which is wired into position, the two roof trusses were too close for the bracket to be used.  Looking from the pump station Photo 159 shows the pipe cross overs and heat dump radiator. The Armaflex was glued and the joints covered with self amalgamating tape to make neater finish.

 Solar controller is fitted above the heating controller Photo 160, conduit keeps the temperature sensors away from the 230V pump and dump valve cables. Photo 162 shows the "airing cupboard" with the bigger tank and the pipes for the heating and solar partly insulated.  The white bar across is the conduit on a support bar to extend the cables for the Pump and motorised valve to the source on the right-hand side. The tank is 450mm and a tight fit with the insulation in cupboard width of 630mm, a 500 would not fit.

The connection to the Automatic air vent near my pump station not the bigger vent on array proved troublesome in making it pressure tight, I was told 15 turns of PTFE was a good number.  I ended inserting two 1/2" tap washers, the washer hole lets the air pass, instead and no PTFE.  Compress the washers at the top isolating valve and screw until good enough.  I am slightly concerned if these will degrade with the high anti-freeze concentration over time.  In a similar method the pressure vessel aluminium tube I did not use fibre but used washing machine hose rubber washers.  Note if pressurising and then re-pressurising use the garden sprayer to receive the fluid back into it, lower the spray pressure and it will take most of the liquid back if low enough the below the pipework. take care not to pump air back in.  If you have a dump radiator then fit radiator valves so that it can be switched off at both ends, not needing to be filled and emptied each time. 

The radiator known for difficult connections was tested outside before installing in the cramp attic.  I purchased about 1 a lorry tyre air valve from a tyre fitters. Mounted it in copper fittings and used an air compressor and tested and changed the PTFE turns until the radiator survived the 6 bar. Used a pint brush with soapy water to leak detect for bubbles.

I made a temperature socket for S4 so that input power can be measured, KW seems OK but also has a counter for MW!  This is formed of plumbing parts, a short length of 10mm pipe is capped and then adapted to 15mm Picture 093, then another adapter 15 to 22 is put on the wrong way around, see photos 096. The whole sub assembly was silver soldered, needing a good blow lamp as the parts have to be pink hot before the silver solder flows.  This assembly is then mounted into a 22mm Tee piece so the water can flow around the inserted pin.  The photos 098 shows a short length of 8mm tube would make a better fit for the thermocouple and the Tee assembly 100, it practice I used a solder Tee as found the 22mm compression with 22 to 15mm not reliable under pressure.

So far some wintry sunny days have pre-heated the tank between 30 and 40C the sun not very high in the sky for long in mid December.

Thanks to Graham for this information.


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Last modified: 05-06-09