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Tech support

Online support - solar thermal FAQs

We’ve collated a set of frequently asked questions to help you to diagnose any system issues. If you’re still experiencing any problems, please contact our technical support team via techsupport@nu-heat.co.uk or give them a call on 01404 540745 (available from 8am to 5pm, Monday to Friday).

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 use this system if there is partial shade?
We will be happy to perform a solar evaluation for free at quote stage

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 – Our solar panels will continue to collect even when it is overcast

Can my Solar blow off valve be piped to the outside of the house?
No – as glycol is involved and the blow off can be very hot. It has to be collected in a trapped container – we offer a suitable container as an optional extra – SSVDC-C – Eco safety valve discharge liquid recovery container with drain valve and SSVDC/2-A – Solar system safety valve discharge fluid recovery container assembly (19.6l).

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 needs 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 buildup
  • 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


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