With direct systems, and with indirect systems where water is the heat transfer fluid, all new work, and also the existing system, as necessary, should be thoroughly flushed out with water, pressurized if necessary, and suitably isolated from the mains to prevent back siphonage.
Indirect systems using non-aqueous and certain aqueous based heat transfer fluids have to be flushed out in accordance with the fluid manufacturer’s instructions. This stage of commissioning may afford an early opportunity to check that all unions and glands are watertight and free of weeps. However, some liquids are more searching than water and, particularly in systems where a circulating pump is employed, the circuits will require a second inspection when finally filled and with the pump operating.
The installer should ensure that all non-return valves and the pump are connected the right way round (usually indicated by an arrow) for the direction of flow, and that non-return valves and motorized or solenoid valves are operative.
The system should then be drained and refilled with the final charge of fluid, preferably when the collector is cold rather than hot.
It is important to ensure that air pockets are removed from sealed and vented systems, and special attention should be given to this at the time of commissioning. The design of the system should allow for subsequent automatic release of air.
13.2 Drain-down systems
Solar heating systems that are susceptible to freezing may be expected to incorporate in their design a frost sensing device that will monitor either freezing conditions at the collector, or the ambient temperature adjacent to the array, or both.
Frost control devices can be of a simple 'yes/no' logic or they can monitor the differential temperature irrespective of ambient temperature and drain the system when no temperature differential exists between the collectors and the preheat vessel.
Where drainback systems are employed, it is recommended that provision is made for the installer to test that the installation is operating correctly by the provision of a test button facility. Where no such provision is made, the manufacturer should provide instructions for overriding the control so that the arrangements for drainback may be tested.
13.3 Electrical and auxiliary equipment
Pumps of a lower wattage than domestic central heating pumps are available for solar heating installations. However, special attention to pump selection will be needed when non-aqueous fluids are used. The pump's setting will have to be made to suit the flow rate required. The installer should ensure that the pump is vented of air and that it operates quietly. If a flow meter is fitted to the circuit, the pump flow control should be adjusted to give the design flow rate.
Differential temperature controllers may be preset at a suitable differential at the factory, or they may require setting and testing on site in accordance with the manufacturer's instructions.
Correct functioning of all indicator lights and other electrical devices should be confirmed. Correct functioning of temperature indicators (if fitted) should be confirmed when the system is first filled and, if possible, at a later date when the system is hot.
FDUS 853: 2009
The manufacturer's instructions should also be followed for any frost protection equipment installed.
13.4 Thermal insulation for the system
It is recommended that all testing and inspection of the system is conducted before the system connections are thermally insulated in order to ensure that these are not weeping.
13.5 Making good
Before an installation can be regarded as being satisfactorily completed, the installer has to ensure that all damage to the structure caused by the fitting of pipes, tanks, mounting brackets, etc. is restored and made good.
Particular attention should be paid to repairing and sealing any damage to the roof lining, resulting from the installation of fixing brackets and pipes, etc. passing through the roof cover. Damage to guttering, walls, garden and lawn by ladders, scaffolding, hoists, etc. should also be made good.
13.6 Start-up and handing over
Once the installer has completed the installation, depending upon the time of year and on the instructions of the client, the system may be either switched on and left operating, or left in a safe condition for later handing- over.
In either event the installer should present an appropriate document to the client, certifying that the system has been installed and commissioned satisfactorily.
At handing-over, the client should be supplied with a user's information envelope, containing the following: a) The handing-over document described in paragraph 2 of 10.6.
b) Descriptive literature, prepared by the designer, relating to the operational principle of the system, and giving technical data on the main system components. This information may be provided on a data sheet, and a suggested format providing the minimum information is given in 10.7.
c) Warranties or guarantees issued by the manufacturers of the components, or by the installer.
d) A set of operating instructions, describing start-up, normal running and shut-down procedures in a form readily intelligible to the non-technical user. These should also include details of protection provided against overheating and frost.
e) A schematic diagram of the system and a circuit diagram of the electrical controls. A warning should be given against tampering with any of the electrical controls or other equipment.
f) A user's data sheet (see 10.7).
g) Details should be provided of any equipment that has been fitted to check system operation. The purpose of all indicator lights should be clearly explained. If a flow meter is fitted, the design flow rate (and permissible variations) should be stated. Information should be given on the expected normal behaviour of instruments and on how they may be used to detect incorrect system operation. Details of action to be taken in the event of apparent faults should be provided. If special additives are used in the heat transfer liquid, durable identifying labels providing the necessary information as to the formulation, solution strength, and specific hazards, source of supply and expected life of the liquid should be attached to the appropriate system components in a conspicuous manner for future reference. A separate label should also record the date of the installation and the name and address of the installer.
13.7 Recommended form of user's data sheet
System description
Instrumentation provided for checking system operation ………. Circuit design
*Direct system/Indirect system Heat transfer fluid in collector circuit
*Water and inhibitors/water and antifreeze/mains supply water/non-aqueous/other
Manufacturer's recommended replacement fluid………. Method of circulation
*Pumped (pump rating ……….W)/ thermosiphon Means of accommodating fluid expansion
*Feed and expansion cistern/pressurized accumulator/other………. Means of accommodating 'no-load' condition in summer weather
*Drainback/special fluid/pressurized system/other ………. Method of frost protection
*Antifreeze/special fluid/drainback/other……….. Method of system control
*Differential temperature controller/time clock/other………. *Other controlled functions………..m2
System performance
Aperture area of collector ………m2 Collector inclination to horizontal ……….degrees Collector orientation ………... degrees east/west of south Collector performance classification in accordance with BS 5918 *B/C/D/E/F1
Design hot water demand.…………./day Preheat storage tank volume………... Combined preheat/hot cylinder volume ………. Design hot water delivery temperature ……….°C
Estimated annual solar energy supplied………. (MJ per year) Maintenance
Recommended frequency for heat transfer fluid inspection ……….. Recommended frequency for heat transfer fluid replacement ………. Other servicing requirements ………
FDUS 853: 2009
13.8 Post-commissioning checks(see also Clause 16 (a) and (b))
Depending on the terms of contract agreed, a post-commissioning visit within a few weeks may be included in the supply and fixing cost, or it may form part of a maintenance contract, or be by arrangement with the installer. It is recommended that at least the following checks should be made:
a) that all unions and glands are free of weeps; b) that the glazing seals are weathertight and sound; c) that all air has been expelled from the collector circuit;
d) that the levels in cisterns are correct or that sealed systems are at the correct pressure and volume; e) that electrical controls and warning indicators are operating correctly, according to the manufacturer's test
instructions;
f) that the circulating pump (if fitted) is operating without undue noise; g) that all insulation is firmly attached;
h) that all cistern covers are properly in place,
i) that no condensation or damp spots are apparent, particularly around the pipes and fixings in the roof space;
j) that roof fixings are firm, and that the roof covering is free from cracks and abrasions beneath the collectors;
k) that the weathering is properly protecting the structure.
A suitable check list should be provided by the supplier for the inspection, and it should be signed and dated by the person making the inspection. A copy should be left with the client.