Ideal iStor - Installing Nest 3rd Gen

13 Apr 2017
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United Kingdom
I have an Ideal iStor HE260 and have just purchased a 3rd gen Nest Thermostat. However, I'm a little confused as to whether the nest can control my boiler's hot water.

The Nest documentation (and customer services) state that the Nest cannot control DHW on combi boilers. However, my understanding is that the iStor is not a true combi. My question is, does anyone know if the Nest can be used to control the DHW by replacing the iStor's DHW programmer? If so, do you have any tips on installation?

I've included the Nest guide with wiring guide from page 20 if it helps.



  • 3rd-gen-Nest-Learning-Thermostat-Install-Guide-UK.pdf
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Hi Dan. Thanks for the quick reply. Any chance you can point me in the direction of the manual you're referring to please? Page 29 of the one I have is about connecting the flue to the boiler.
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Thanks. Though it's not entirely clear to me whether the Nest would be able to take control of the hot water as well as central heating.
I found this thread a bit ambiguous as there's no confirmation it was understood... but I've just done this install, albeit relocating the thermostat (so I've just left the old one "always on" so it never breaks the circuit). Basically what you do is remove that link loop as shown on page 29. It's on the back of the control panel (which the existing programmer is attached to) on the boiler. Once that's done wire up the neutral terminal (N) and the live terminals of the Heat Link (L, 2 and 5) then connect Heat Link terminal 3 into the the "CH" connection and terminal 6 into "DHW".

I've done a full guide here from my install: Nest v3 Heatlink install with Ideal Istor

Jesus the Nest is worth twice as much as an istor , horrendous boilers for breaking down

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