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Solar thermal FAQs

I do not seem to get any solar gain

Please make sure that your boiler is timed to be off during times of peak summer sunlight.

Can I fill my solar system with water?

No. You need a glycol mix due to the high running temperature and for frost protection.

Will I get any solar gain during the winter months?

Yes. The solar panels will continue to collect even when the sky is overcast.

Can my solar blow off valve be piped to the outside of the house?

No. This is because glycol is involved and the blow off can be very hot. It has to be collected in a trapped container and we offer a suitable container as an optional extra. Your Account Manager will be able to provide more information.

Can I use copper pipework?

If the optional flexible stainless-steel pipe has not been chosen, then copper may be used. Be aware that any solder joints must be made with high temperature solder on the solar circuit.

Also, any threaded or compression joints should be sealed with a high temperature liquid PTFE sealant (such as Rocol 28022 Pipeseal PTFE Liquid). Brass olives must be used on compression fittings due to the high temperatures NOT copper olives.

The pipe runs must be insulated both to prevent heat-loss and risk of being burnt. Any material used for this must be capable of withstanding 150°C. High temperature nitrile rubber (e.g. Armaflex) is a proven material in this application.

What are the service requirements

The collector/s need to be serviced annually and the following checks undertaken:

  • Collector glazing is undamaged.
  • Collector glazing is reasonably clean.
  • There is no visible evidence of leakage on the roof.
  • Where visible, absorber paintwork or coating is sound.
  • The roof fixings are firm and the roof covering satisfactory by visual inspection.

In addition, certain checks need to be undertaken on the solar circuit:

  • The solar system pressure is correct according to the pressure gauge (1.5 bar +/- 0.2 bar).
  • There is no visible evidence of leakage.
  • Safety valve manually checked.
  • Antifreeze concentration checked. Should protect to -19°C.
  • Deaerator checked for air build-up.
  • Electrical controls and temperature sensors are operating correctly.
  • Flow rate remains at level stated on commissioning certificate.
  • The circulating pump is operating without due noise.
  • Pipework insulation is firmly in place.
  • There are no condensation or damp spots, particularly around the pipework and fixings in the roof space.
  • All safety and information labels are in place.

Need more help to resolve a solar thermal problem? You can contact our Technical Support Team via techsupport@nu-heat.co.uk or give them a call on 01404 540745 between 8am and 5pm, Monday to Friday.