Solar Thermal


Other Parts

Assembly Guide

Installation Guide




Other Parts

Installation Guide

LED Lighting

Heat Pumps

Rainwater Harvesting

Solar Overview












What parts do I need?  Click here.

Flat Roof Stands

Stainless steel stands suitable for flat roof or ground mounting of panels.

ECO 47-1500-12 14.00 + VAT (16.80)
ECO 47-1500-20 20.00 + VAT (24.00)
ECO 58-1800-20 22.00 + VAT (26.40)
ECO 58-1800-30 30.00 + VAT (36.00)

Fitting Bolts

For fixing collector to roof.  Available in two lengths, stainless steel bolts 7mm dia with M8 thread at one end and coach screw thread at the other.  The maximum distance from top of the rafter to roof surface may be no more than 50mm for the short bolts or 90mm for the long bolts.  Includes 2 nuts, two stainless washers and two rubber washers.  See here for installation instructions for both fitting methods.

140mm overall length
1.95 + VAT ea (2.34)

180mm overall length
2.15 + VAT ea (2.58)

Fitting Straps

For fixing collector to roof.  Stainless steel strap 1m x 27mm punched with 9mm holes on 20mm centres.  Includes 2 M8 x 20 bolts and nuts per strap to fix to the panel frame.  These are an alternative to the fitting bolts above.
2.36 + VAT ea (2.83)

Flashing Kits

Lead or aluminium "slates" which can be formed to match the shape of the tile, incorporating a high temperature silicon boot (suitable for temperatures between -60C and +240C) with provision for a sensor wire.  Makes for a neat job, resolves weatherproofing issues, and keeps the building inspector (should you be involved with one) happy.  Recommended for roof pitches up to 45 degrees and pipe diameters between 5 and 40mm, suitable for both copper and corrugated stainless steel pipe.  One flashing per pipe required, except for twin entry version..

Lead flashing 410mm x 490mm
28.56 + VAT ea (34.27)

Aluminium flashing 450mm x 600mm
20.72 + VAT ea (24.86)

Twin entry aluminium flashing 450mm x 600mm
31.10 + VAT ea (37.32)

Spare Tubes

Spare Tubes assemblies are available from stock.  They include the internal fins and heat pipes, and are ready to slot into the manifold.

47 x 1500 Tube 13.00 + VAT (15.60)
58 x 1800 Tube 17.00 + VAT (20.40)

Heat Pipes

These are the copper pipes used in the centre of the collector tubes.  They are sealed and contain fluid at low pressure which vaporizes (boils) at low temperature.  When placed sloping upwards, the vapour rises to the top of the tube and transfers heat to whatever is attached to the top, then condenses and runs back down the tube to restart the cycle.  Useful for science projects and various applications such as using heat from a compost heap.  Suitable for moving heat at temperatures between about 40C and 220C

1500mm Pipe 4.50 + VAT (5.40)
1800mm Pipe 5.50 + VAT (6.60)

Differential Temperature Controllers

Solar controllers compare the temperature of the water in the collector header with that in the hot water cylinder.  If the temperature of the former exceeds that of the latter by more than a preset amount, typically 6C, it switches on the circulation pump.  We stock controllers from market leaders Resol. 
See http://www.resol.de/en/english.shtml?Produkte/Solarregler/Solarregler.html for more information about these controllers.  All of the following controllers are "full kit" products including temperature sensors.  Two sensors in the AX, three in the BS3, BS4 and 12v B, four in the BS Pro, and six in the ES.

Resol AX

Basic differential controller with maximum temperature setting to switch off pump in the event of overheating.
68.25 + VAT (81.90)

Resol BS3

Controller with graphical display and ability to operate diverter valve heat dump circuit to avoid overheating.
105 + VAT (126.00)

Resol BS4

As BS3 with additional ability to control variable speed pump
118.13 + VAT (141.76)

Resol BS Plus (formerly designated BS Pro)

Adds the facility to control two pumps for East/West panels, used when only East or West facing collectors can be installed (the East facing panel is used in the morning and the West facing in the afternoon).
150.94 + VAT (181.13)

Resol ES

Includes 10 sensor inputs and 6 relay outputs, variable pump speed control and East/West collector configuration.  Most usually specified for systems with 2 stores, typically a hot water cylinder and a preheat cylinder, used when there is a requirement to retain the original cylinder.
229.69 + VAT (275.63)

Resol E

Includes 13 sensor inputs and 7 relay outputs, of which up to three are for variable  pump speed control.  Supports 30 layout schemes including East/West collectors with up to 3 stores or a single collector field with up to 4 stores.
243.75 + VAT (292.50)

Resol SP10 sensor protection device

Device to prevent voltage surges on the sensor lines caused by nearby lightning damaging the controller.  Placed in the cable between the collector sensor and controller.
11.00 + VAT (13.20)

Additional sensors, all PT1000 thermistors

FKP6  This is the sensor supplied with the Resol controllers to install in the collector manifold, with a high temperature silicon insulated cable.
17.50 + VAT (21.00)

FRP6  As supplied for temperature sensing at the hot water cylinder.
12.50 + VAT (15.00)

FRP21  Sensor with flat end and pipe clip, for sensing the temperature of fluid in a pipe.
18.25 + VAT (21.90)

Electrical Flowmeters

These allow accurate power delivery figures to be derived, by combining flow volume and temperature change figures.

Resol V40/0.6

Max flow 600litres/hr.  2 x 3/4" BSP male connections.  Readout in m3, and signal output for automatic data logging.
112.50 + VAT (135.00)


Pump Stations

Note: Flowcon A pump stations have been discontinued, and replaced with the Flowcon AS

A pump station comprises a number of components required in a solar circuit assembled in a neat insulated package.   Flowcon AS pump stations include a flowsetter, pump, differential temperature controller, non return valve, pressure relief valve, pressure gauge, and fill and drain valves.  Flow direction is upwards, and connections are 3/4" BSP female for the flow, return and pressure relief valve output, 3/4" BSP male and 1/2" BSP female combined for the fill and drain valves, and 3/4" BSP male for an additional connection which may be used for an expansion tank or part of a heat dump circuit etc, or may be blanked off.
For more information about these, go to the Resol link above, and choose Pump Station from the product menu on the left.

Resol Flowcon AS
Wilo 3 speed pump, pressure relief valve, pressure gauge, flowmeter/setter, non return valve, fill and drain valves and differential controller.

With BS4 controller 299.00 + VAT (358.80)


ITT Lowara EBV 15-1/65 low energy 230V bronze circulation pump.  These super pumps have a variable power setting of 2 - 8W and are suitable for closed loop solar circuits.  Maximum continuous temperature rating 95C, built in electronic temperature protection shuts the pump down at 125C.   
These pumps are also suitable for use as hot water recirculation pumps which maintain the temperature of water in the hot water pipes to give instant* hot water at the taps.  The hot water supply is plumbed in the usual way, but at the last take off point, the pipe loops back, through the pump, to the hot water cylinder, thus keeping the water in the pipe hot.  The energy use ramifications of a scheme like this are a bit more complex than it seems at first sight.  Obviously the down side is the energy cost of running the pump (easy to calculate and low in the case of this pump), and heat losses from the hot water in the pipework (difficult to calculate as the same heat losses occur for a time after each use of hot water in a conventional system).  However, set against this is the fact that during the period of running the hot tap before the water runs hot, cold water is being introduced into the hot water cylinder, so the cold water from the tap is actually priced as if it were hot water.  Well insulated hot water pipes and the use of a low energy circulation pump mitigate the energy cost of the convenience of more or less instant hot water at the tap.

*The taps are spurred off the hot water loop.  There will be a small amount of cold water in the spur which will cause a second or two delay before the water runs hot.

1/2" BSP female connections.  Includes non-return valve.

115 + VAT (138)

12V DC Equipment

It is possible to use a 12V pump connected to a photovoltaic (pv) panel instead of using 230V equipment.  This has the advantage of not using any (albeit a small amount of) mains power.  Two strategies are possible.  The first is to connect the circulating pump directly to the pv panel.  The principle here is that when the sun shines, the pump will run and (hopefully!) the water in the collector will be hotter than the water in the cylinder (because the sun is shining).  An alternative approach is to use a 12v differential temperature controller and connect via a charge controller and battery, which will give better control, but be more expensive.  Don't make the mistake of undersizing the pv panel.  Bear in mind that the quoted output is always a peak figure for full sun, which as noted elsewhere on this site, may occasionally not be the case in the UK.

BP Solar SX30U pv collector
This is a high quality panel as you would expect from BP.  Spec as follows:

Pmax W Nominal voltage V Open circuit voltage V Current A Width mm Length mm Height mm
30 12 21 1.9 502 594 50

160 + VAT, (192.00)

Laing D5 SOL-38/7B Ecocirc low voltage pump.  Automatic voltage selection in range 8 - 24V.  Minimum startup power 1W, max power consumption 22W, current .25 - 1.46A.  Note that this pump is designed to be connected directly to a pv panel, it incorporates firmware which deals with a fluctuating supply.  The pump checks the power supply characteristics every 3 seconds, and adjusts its speed accordingly. 
178.40 + VAT (214.08)

Laing D5 vario-38/700 B low voltage pump.  Automatic voltage selection in range 8 - 24V.  This pump is for stable regulated power supplies.

136.45 + VAT (163.74)

Resol Deltasol B 12v differential temperature controller.  Similar to the Resol BS3 in specification, but 12V.
116.82 + VAT (140.18)

Expansion Tanks

Used to accommodate thermal expansion of the solar fluid.  Solar expansion tanks have a membrane which can withstand a higher temperature than regular expansion tanks.  Domestic installations usually require an 18 litre tank.  Connection 3/4" BSP male.

18 litre Expansion Tank
33.05 + VAT (39.66)

Fitting Kit comprising bracket, fixing screws, 500mm flexible stainless steel hose with 3/4" BSP female connection at both ends, and quick release valve (3/4" BSP male/female) (which allows removal of the expansion vessel without draining the solar circuit). 
24.38 + VAT (29.26)

Solar Fluid (Antifreeze Solution)

Ready mixed propylene glycol based antifreeze solution.  This is used neat, and 10 litres is sufficient for typical domestic installations.  See here for more information and details on calculating volumes.

10 Litres
25 + VAT (30.00)

5 Litres
15.00 + VAT (18.00)

Thermal Transfer Paste

Tube of thermal transfer paste as supplied with the solar collectors.  Used to improve the thermal connection between the heat pipe and collector manifold. 

3.00 + VAT (3.60)

Valves & Fittings

Resol VA32 3 port high temperature motorised valve (normally used to operate a heat dump circuit in conjunction with a BS3 or higher controller).  3/4" BSP female connections.
97 + VAT (116.40)

Resol VA22 2 port high temperature motorised valve.  3/4" BSP female connections.
86.25 + VAT (103.50)

Eco-nomical 3 port high temperature motorised ball valve.  No power consumption when heat dump not in use.  1/2" BSP female connections.
44.75 + VAT (53.70)

Thermostatic mixing valve.  Allows a higher temperature in the hot water cylinder by mixing the output with cold water to a safe level.  Effectively increases the capacity of the hot water cylinder.  Adjustable temperature.  Max input temperature 100C.  Three compression fittings for connection to copper.  Note that the maximum hot/cold or cold/hot pressure ratio is 2:1.

22mm compression connections
62.90 + VAT (75.48)

28mm compression connections, larger valve for higher flow
86.90 + VAT (104.28)

Automatic high temperature air bleed valve, to be fitted at the highest point of the solar circuit, usually on the roof next to a panel. 3/8" BSP connection.
20.62 + VAT (24.74)

Automatic air scoop.  This is a device which filters out micro air bubbles from the solar fluid and ejects them via a high temperature automatic air vent which is included in the item.  This does not need to be fitted at the highest point of the circuit, and may obviate the need for the external air vent.  The belt and braces approach is to fit them both.  Fits in horizontal pipe run via two 3/4" BSP female connections.
48.63 + VAT (58.36)

High temperature isolating valve for use with automatic air vent.  Two 3/8" BSP connections, one male, one female.
3.68 + VAT (4.42)

Pressure relief valve, 6 bar
9.50 + VAT (11.40)

Fill and drain blocks.  Makes filling the solar circuit easier.  Comprise 3 high temperature valves, 2 to air and one in the solar circuit between them.  Close the solar circuit valve, open the others, fill through top one.  When fluid emerges from lower valve close it, open the solar circuit valve and bleed and pressurise the circuit.  Already included with our Flowcon pump stations.

PAW monobloc fill and drain valve block.  15mm compression fittings to the solar circuit, fill and drain valves with 15mm OD barbs, 1/2" BSP female threads and 3/4" BSP male threads, and blanking caps.
32.75 + VAT (39.30)

Eco-nomical built up fill and drain block.  15mm compression fittings to the solar circuit, fill and drain valves with 1/2" BSP male threads
19.50 + VAT (23.40)

Flowmeter/setter 1-3.5litres/min. 
25.95 + VAT (31.14)

Flowmeter/setter 2-8 litres/min.  Two 15mm compression connections.
25.95 + VAT (31.14)

Non return valve.  1/2" BSP female threads.
4.90 + VAT (5.88)

15mm-22mm reducing compression fitting, used on return side of collector
2.78 + VAT (3.34)

15mm compression to 3/4" male BSP, for connecting 15mm pipework to pump station, air scoop etc.
3.25 + VAT (3.90)

22mm compression to 3/4" male BSP, for connecting 22mm pipework to pump station, air scoop etc.
3.25 + VAT (3.90)

15mm straight compression coupling
0.95 + VAT (1.14)

22mm straight compression coupling
1.42 + VAT (1.70)

15mm elbow compression coupling
1.05 + VAT (1.26)

22mm elbow compression coupling
1.68 + VAT (2.02)

Equal T compression fitting 15 x 15 x 15mm
1.42 + VAT (1.70)

Equal T compression fitting 22 x 22 x 22mm
2.25 + VAT (2.70)

Reducing T compression fitting 22 x 15 x 15mm (branch is last number)
2.48 + VAT (2.98)

Unequal T fitting.  One 22mm and one 15mm compression fitting with a 3/8BSP T leg.  Use on feed side of collector to connect 15mm pipework to 22mm collector manifold inlet with connection to automatic air vent.
6.44 + VAT (7.73)

PTFE Tape reel
0.50 + VAT (0.60)

Heat Exchanger

Flat plate heat exchanger, 4 x 3/4 BSP male connections, 5kW, 190 x 60 x 60mm, max pressure 12 bar.  Suitable for use as external heat exchanger for solar loop.

42.00 + VAT (50.40)

Swimming Pool Heat Exchangers

Because chlorinated pool water attacks the copper manifold in the solar collector, it is recommended to use an indirect system with a heat exchanger.  We offer Bowman cupro-nickel purpose built solar pool heat exchangers, incorporating thermostat pockets. 

Bowman 4825-5 heat exchanger, suitable for pools up to 91000 litres, 20000 gallons.  Connection to the solar circuit via two 3/4 BSP female connectors, and to the pool water circuit via two 11/2" BSP female connectors.  For larger pools, please contact us.
265 + VAT (318.00)

Armaflex Duo Solar Corrugated Stainless Steel Flexible Pipe

Preinsulated with Armaflex HT, comprises feed and return pipes in corrugated stainless steel, insulation, and sensor wire.  The two pipes are joined by the insulation, but easily separated where required.  This is used in place of copper pipe, and is generally favoured by professional installers because of its speed of installation and reduced possibility of leaks (no pipe bending, fewer joints).  No special tools are required to make the joints.  Nominal ID 16mm, insulation thickness 14mm.   Stocked in 10m coils (20m of pipe, 10 feed and 10 return).  Other lengths available on request.

10m coil Armaflex Duo Solar DN16
162.75 + VAT (195.30)

Fittings for Armaflex Duosolar (note that fitting are sold singly, 4 are required for all pipe ends in one coil).

To connect a single pipe to itself
4.90 + VAT (5.88)

To connect a single pipe to 3/4" BSP female, eg to a Flowcon pump station
6.20 + VAT (7.44)

To connect a single pipe to 1/2" BSP female
6.20 + VAT (7.44)

To connect a single pipe to 22mm copper via compression fitting
6.20 + VAT (7.44)

To connect a single pipe to a 22mm compression fitting.  Used to connect
Duosolar to cylinders with 22mm compression connections.
6.20 + VAT (7.44)

T connector for 3 DN16 pipes, as for a heat dump circuit etc.
8.75 + VAT (10.50)

Pipe Insulation

Armaflex HT foamed HDPE high temperature pipe insulation from Armacell.  This is a top quality German product designed for the high temperatures that can be produced by evacuated tube collectors.  The pipe insulation is supplied in 2m unslit tubular form, either slip it over your pipe work as you go, or slit it yourself with a sharp blade.  We stock Armacell high temperature adhesive for joints and seams, resulting in a tidy job.  Good for 150C and waterproof and UV resistant (can be used outside without additional protection).  Thermal conductivity at 40C 0.045W/mK.   We stock it for 15mm and 22mm pipe in 13 and 19mm wall thickness. 

15mm pipe 13mm wall 1.35/m + VAT (1.62/m)
15mm pipe 19mm wall 2.85/m + VAT (3.42/m)
22mm pipe 13mm wall 1.72/m + VAT (2.06/m)
22mm pipe 19mm wall 3.20/m + VAT (3.84/m)
0.25 litre Adhesive 8.98 + VAT (10.78)
1 litre Adhesive 20.77 + VAT (24.92)

Installation tools

Five litre pump up sprayer for introducing the solar fluid into the system.  Includes adaptor to fit pump stations or fill/drain blocks.  Includes original lance, so may also be used as a garden sprayer.
21.75 + VAT (26.10)

Power filler/flusher, quickly fills and removes air from the solar circuit.  Solid German built professional tool with welded steel chassis, self priming centrifugal pump pump and large fluid reservoir.

Max Flow Rate 34 litres/min
Max Pressure 5.9 bar
Max Fluid Temperature 60
Size H x W x D 980 x 460 x 550 mm
Weight (empty tank) 28 kg
Tank size 30 litres

465.00 + VAT (558.00) 

Hot Water cylinders

We suggest you deal directly with the manufacturer for solar hot water cylinders (mainly because we have no room here to stock them!).

Companies which will deal with individuals and are knowledgeable in the solar field are:

Dedicated Pressure Systems Ltd.
0845 241 1441

Inventors and manufacturers of the Heat Bank range of thermal stores, specialising in the design of multifuel hot water and central heating systems


MacDonald Engineers
01592 611123

Newark Copper Cylinder Co Ltd
01636 678437

We accept payment by most credit cards, cleared cheque or cash.  Panels are collection or courier (not parcel company) delivery only, see here for the reason for this.  Other components can be sent to most destinations.  Small items such as differential temperature controllers can be sent by post, larger items by carrier.  Costs vary by consignment, please enquire when ordering.



Send mail to SW@eco-nomical.co.uk with questions or comments about this web site.
Last modified: 30-06-10