Recent content by hertsboilers

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Check the smaller head tank for water in the loft if you don't have a pressure gauge and filling loop.

105e or Instant 105e?

Providing the new boiler isn't far away from the cylinder. It is a good choice but there is nothing wrong with Vaillant vSMART which is a weather compensated control to modulate heating.

I referred one for Vaillant fixed price repair early this week, the customer was told the same thing as OP, it is a contract with Domestics and General. It seems better than Vaillant own package, so the customer went to 6 month contract by £50. The local Vaillant engineer turned up on the second...

More like a circulation problem.

Viessmann 200-W, a flagship boiler with 20/1 modulation ratio, is beyond most of heating installers. As far as I know it will work with Tado radiator TRVs but don't know others. Do some home work and call a Viessmann expert installer.

@Gasguru and @muggles dose this model have a filter in? F9 is the same as F75 on Vaillant.

Well, you wish to get a help from scratch?

His wiring is still working.

975 3 to 715 1 975 1 to 715 3 975 4 to 715 4

Yes. Can't set pre heat from Nest

"ATC on the right, numbered 3(NO) - 1 (Com) - 2(NC) + earth (also left to right)" Should be the same connection, ie, 1 to 1, 2 to 2 and 3 to 3.

I am going to spend some time to read Evohome now.

More about comfortable heating than gas bill saving. Also from the internet some installers suggested Nest isn't good on Opentherm.