Nest v3 Install with Ideal Istor HE260 and HE325

Prime Day on July 11th saw a big drop in the price of a Nest v3 system to £135. I’d been thinking of getting one for a while, so this discount was too good to refuse – especially as I’d received a £20 Amazon voucher from work, so it ended up being £115 of my own money.

It arrived yesterday.  I had a quick look over the instructions that evening and searched Google for help setting it up for my boiler, but I didn’t find anything helpful.  I know they say it’s meant to be installed by a pro, but from reading it seemed it was quite simple once you understood what activates what on the boiler.  It took me a while to get that understanding – but once I’d looked at the back of the existing programmer that’s built in to the heating system it fell into place.

Given I’ve worked it out and successfully installed it I thought I’d share what I did for anybody else who struggles to find the help they need.

My existing system is an Ideal iStor HE260 and HE325 system boiler, and it turns out installation is pretty simple, particularly in my case as I’m using the Nest thermostat on a stand, rather than replacing my existing thermostat in the hall.

This wiring diagram from the manual shows how the thing puts power to the boiler, which is essentially what the heat link will do; it’s a glorified power switch:

The Link on the right brings in the mains to the Programmer.  The programmer then provides the power to the Central Heating and Hot Water as it’s a switch that activates according to the programmed schedule.

Remove the link and the programmer has no power to provide, instead your wire the Heat Link to the CH and DHW terminals so it controls the power provided.

As mentioned, I didn’t remove my old thermostat from the equation, so the caveat above is that the Central Heating power can still be interupted by the old thermostat breaking the circuit.  In my case I’ve just turned the thermostat to maximum, so it will never break the circuit.  The alternative is joining the wires that go to the thermostat, but it’s a bit awkward to get to so I didn’t bother; leaving it as is also makes it simpler to reverse the installation in future.

Tools for the job

Make sure you’ve got everything ready… you’ll need some additional 2-core cable as that isn’t supplied with the Nest system.

  • Everything from your Nest system’s box
  • 2-core cable to wire the heatlink to the mains, and to connect it to the boiler inputs which activate Central Heating and Hot water (DHW or Domestic Hot Water in the iStor manual)
  • Philips screwdriver for removing panels and attaching the Heat Link to the wall
  • Small flat-head screwdriver for electrical junctions
  • Small Philips screwdriver for electrical junctions
  • 55-60mm rawlplugs (they’re not supplied with the screws in the Nest box)
  • Drill with 55 or 60mm drill bit.
  • Wire cutters and wire strippers.
  • Pencil
  • Spirit level.

Installation Steps

  1. Switch off the mains fuse for the boiler and switch it off at the wall too, just to be sure!
  2. Take the cover off the heat link.  Using a pencil mark where you need to drill screw holes on your wall where you’ll be attaching the Heat Link.
  3. Drill the holes using a 55mm or 60mm drill bit and insert your rawlplugs.
  4. Fully-loosen the screws inside the Heat Link on the following junctions:
    – N (neutral)
    – L (live)
    – 2 (Common – the live in to Heat Link to control Central Heating)
    – 3 (Call-for-heat – the live out from Heat Link to your Central heating)
    – 5 (Common – the life in to Heat Link to control Hot Water)
    – 6 (Call-for-heat – the live out form Heat Link to your Hot Water)
  5. Connect the neutral terminal and live terminals on  the Heat Link.  Neutral goes to “N” while live goes to “L”, “2” and “5”.
  6. Connect the output terminals “3” and “6”.  I bought 10m of 2-core cable so used the same one.  Remember which you’ve wired to where, and it’s a good idea to label these at the other end as Live, given the blue isn’t neutral as it might be expected.  I used blue for the Hot Water here, because blue = water, so easy to remember.  I didn’t trim the cable at this point, so as to ensure there was enough to threat it into the boiler as required.
  7. Attach the heatlink to the wall.
  8. Wire the Neutral and Live cable from the Heat Link into your mains switch (also shown above).
  9. Open the top section of your boiler by removing the top two screws at the front on the left and right.  Lift it off.
  10. Unclip the bottom section of the boiler.  Unscrew the screw at the bottom of the plastic control panel, then push the panel up to unclip it and remove it.  (not shown here, as the screw wasn’t attached to mine so it just unclipped).
  11. It’s not necessary, but it simplifies the next bit of wiring if you unclip the plastic wiring clip that connects the panel to the boiler.
  12. Remove the loop wire (the red wire below) from the input terminals.  This was what took the mains feed into the built-in programmer.

  13. Now connect the Central Heating and Hot Water live feeds from your Heat Link; in my case blue was Hot Water, brown was Central Heating.  I’d threaded the cable into the boiler so cut the cable to an appropriate length as I did this.
  14. Reconnect the panel to the boiler wiring clip, then slot the panel back into place.
  15. Reattach the boiler panels.
  16. Attach the front panel to the Heat Link.
  17. Turn the boiler socket on, then flip your mains fusebox switch to power up the boiler.
  18. The Heat Link should power on.  Push the central button to “boost” both Central Heating and Hot Water to confirm it works.
  19. Now set up your Nest thermostat following the instructions on screen.







Mac Mini surgery

My late-2009 Mac Mini has been playing up for a while, running Mountain Lion, so just before Christmas I decided to try and get it working thinking it just couldn’t cope with Mountain Lion.  I got a Lion USB stick and tried to install it – but on boot up the computer threw a tantrum because the hard drive was failing.

Disk Utility wasn’t able to repair it so I wrote it off; until a spare 2.5″ 200GB drive was given to me for nowt.  It only had a 160GB in it already, so this was an upgrade regardless.  I also remembered I had a couple of 2GB SO-DIMMS spare from when I upgraded an old MacBook Pro – so that’d double the memory in the machine too.

I found a video guide to upgrading on MacWorld/YouTube:

and set about to opening it.  I didn’t have a putty knife, so I improvised – using a Stanley knife which did the job fine.

Opening the Late-2009 mac Mini
Opening the Late-2009 mac Mini

It makes a worrying crack sound when the catches come away, but it came apart with no troubles.

Case separating
Case separating

Once it’s prised apart, just lift the base (which all of the computer is attached to) out of the case carefully.


I detached the antenna but the cable for the front one (which I later found out is the bluetooth antenna) detached in the process.  The rest went according to the video, and I put the “new” hard drive in along with the replacement memory.

The new hard drive.
The new hard drive.

Lion installed fine, and then I upgraded it to Mavericks.

After resolving most of the problems in the next section it’s working well – quicker than it was on Mountain Lion, even with Mavericks on.  Admittedly I’m not pushing it beyond some basic streaming – as it’s just a box for under the telly.  I’m not sure Mavericks is wise for a late-2009 Mac Mini in heavy use.


I had a few problems after re-assembling the Mac Mini…


…in the sky.  Great song, if a little spiritual for me…  Anyway.

Somewhere along the way I’d managed to detach all the antennas from the main board, in addition to the damage to the bluetooth antenna joint.  This meant the wifi wasn’t working properly, I opened it up and re-attached them all.  It’s quite a small connection, so the slightest knock will cause it to disconnect.  The one below is the bluetooth connection.  The wifi aerials are to the left of this (two connectors).

Bluetooth connector
Bluetooth connector

Wifi was working but the bluetooth range wasn’t much beyond right next to the MacMini.  That wasn’t a big deal, but I did think i should have a go at fixing it.

Detached antenna
Detached antenna

The cable held in place by tape wasn’t doing the job, so I borrowed a soldering iron and set about trying to repair it.  I can’t say it’s the tidiest job…

Bluetooth antenna re-soldered
Bluetooth antenna re-soldered

…and it also hasn’t worked too well.  The range is about 1.5 metres, so a bit useless for using the bluetooth keyboard on my sofa which is beyond that range.

I’m wondering if the solder is bridging points it shouldn’t be, though I’m not sure how that would matter on an antenna, as it isn’t about forming a circuit but just getting the signal beyond the machine’s innards and to the top of the machine.  Does anybody know if that’d be an issue?

I may revisit it at some point – either to clean up the soldering job or swap antenna cables for the back wifi that isn’t broken.  For now I tend to use my MacBook Pro and screen sharing if I need to use a keyboard.

Turn it up…

…Bring the Noise!

On one of the occasions I took the Mac Mini apart again I forgot to re-attach the soundboard which has to be detached to get to the innards.  This manifested as no sound and the Mini complaining that it could’t find any devices for sound input/output.

Sound board connection
Sound board connection

Thankfully as the first step after cracking the Mac Mini open it took around a minute to open it up again and reconnect it and close it up again.

Sound board reconnected.
Sound board reconnected.

New Year, New Connection

I started the migration of my Broadband from Zen to Plusnet a couple of weeks ago – to make sure it was sorted before my employment officially terminates, so I don’t have to pay for the Zen connection.  Well, today the Plusnet connection went “live” – albeit a day early and with a minor hiccup.

I’ve been impressed with the communication from Plusnet – nice and clear emails and text messages with progress updates and clear instructions with the router they provide which arrived earlier this week.

This morning (barely morning really – my body clock is a bit skewed after New Year’s celebrations so I didn’t sleep well and then woke up late) I opened my laptop and there was no connection.  I checked my router and it was an authentication failure.  I tried the bt_test_user@startup_domain username and received a BT IP for DNS – so clearly I’d moved from Zen’s LLU equipment to BT Wholesale’s equipment.  Next up I tried and that had the same result, so BT were all setup for me to connect, but trying the Plusnet details for my own account failed.

The router from Plusnet is a TG582n, with TR.069 used to automatically configure it.  I swapped my old TG582n for the Plusnet one and saw it established a connection to Plusnet, which it would be using to pull down my connection details – sure enough after about 5 minutes it was populated with my new details but wouldn’t connect.  The same thing would happen at Zen if a connection was activated early – everything is set up up apart from the username and password on the ISP’s systems.  A couple of minutes on live-chat via their website on my iPhone and they added the details and I connected without a problem.

Early impressions continue to be good – a nice and fast response to an initial problem and the connection is working fine and at the same speeds (sync’d about 100 kbps higher than Zen, but it’s daytime so I expect it to drop a bit in the evening).

Plusnet connection summary
Plusnet connection summary

I watched the Bojack Horseman Christmas Special on Netflix to test it out, and no problems there – so altogether I’m happy so far.  I’m paying £2.50 per month for an unlimited Broadband service plus £12.99 (paid annually up-front which saved me a few quid) for the phone line which is due to migration on the 16th.  Total of £15.49 a month.  Not too shabby as the equivalent (500GB limit, rather than unlimited) from Zen would have been £48.04 a month, though I could probably have shaved a tenner off that by going for the 200GB service as it’s more than enough for me.