Replacing Honeywell ST9400C with Tado
In my 3-bedroom semi-detached house, I currently have a conventional central heating system comprising of:
- a MAIN HE Condensing boiler (located in lounge)
- a Honeywell programmer ST9400C (located in lounge beside boiler)
- a Honeywell HCW80 (Y6630D1007) Battery Powered Wireless Room Thermostat (located in hallway)
- a Honeywell relay/receiver HC60NG/R6660D (located in a bedroom cupboard beside the hot water tank, zone valves, and pump)
- a wiring box (located in the same bedroom cupboard where the hot water tank is)
- I believe I have a S-Plan setup with 2 x 2-port motorised valves controlled by the room thermostat and hot water cylinder thermostat (photo attached)
I am looking to replace this with the Tado Wireless Smart Thermostat Starter Kit V3+ with Hot Water Control so that I can control the central heating and hot water remotely.
Assuming the Tado Wireless Thermostat Starter Kit V3+ is compatible, is it fairly straight forward to remove the Honeywell set-up and replace it with the Tado system?
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All sounds fine. You’ll probably put the Tado box near the tank and valves.
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thanks @Montage. Do you mean placing the Tado extension box near the tank and valves? I thought the extension box would replace the Honeywell programmer ST9400C, and therefore the Tado box would be in the lounge beside the boiler?
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@Tonygrewal1 Hello Tony. We replaced the same setup in 2022, it's straightforward for competent DIYer. The Tado V3+ wireless receiver replaces the Honeywell ST9400C. In the Honeywell wireless receiver, you'll join the wires on A and B (call for heat) with a Wago connector from the starter kit.
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In principle, that’s how it works. If they wired it back to the programmer, it’s a drop in replacement. Perhaps I’m overly cautious in suggesting you might find it differs, especially as you have a receiver/relay by the tank and valves.
I’m not suggesting it’s a barrier. Just go in with the possibility in mind.
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thanks @Montage
@wateroakley - thanks. So am I right to assume that I:
- follow the instructions from the Tado app on how to wire the Tado v3+ wireless receiver using the wiring currently going to the Honeywell ST9400C ?
- from the wire going to the Honeywell wireless receiver, I join the wire going to terminal A with the wire going to terminal B using a Wago connector?
One thing I have read elsewhere is that some people have experienced problems in the Tado wireless thermostat staying connected with the Tado hub (which is connected to a router). Have you experienced any loss of connection between the hub and your Tado wireless thermostat?
Some people have mentioned that the schedules are not kept locally (are kept on the Tado server) so you can wake up sometimes to find the heating hasn't switched on, or hasn't switched off.
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@wateroakley - I received an email today at 7:45pm to say you had left a comment but from this post, I can’t see any comment following my last reply at 5:15pm.
Did you leave a comment around 7:45pm today?0 -
- Hello @Tonygrewal1 Sorry, the post was deleted while I was editing remotely. Reposted …
- 1. When you start the install, Tado support should give you wiring instructions. The Tado wiring guides are also on the main Tado web site. Alternatively, the Tado Professional app has details.
On the ST9400C, IIRC it's a 1-1 wire move. L to L. N to N. CH NO (4) to CH NO. HW NO (3) to HW NO. Add two purple links: L to CH Com to HW Com. Obviously, do this with the power off.
- https://www.free-instruction-manuals.com/pdf/pa_458238.pdf
- 2. Carefully open the Honeywell thermostat receiver. IIRC, it's a clip-on front cover. There should be four wires: L + N to power the receiver; and A + B for the relay. Disconnect the wires on A and B and join them with a Wago connector from the starter kit. Obviously, do this with the power off.
- 3. The V3+ 'internet dongle' and Tado devices talk wirelessly using IEEE 802.15 and 6LowPan standards, not the usual 802.11 home wifi. 802.15 is low power IEEE standard for IOT devices, with a design specification range of circa 10 metres.
Most 3-bed semis are less likely to experience the V3+ range issues that some have seen in larger homes or thick stone construction. Here, a 4-bed 1960s home, we have one rad outside range in the conservatory. We kept the dumb TRV.
There are workarounds for range issues by using e.g. an ethernet cable, wifi dongle, or powerline adapter. Our rellie with a 3-storey 5-bed Edwardian Villa uses a cheap Tp/Link wifi extender with ethernet port.
4. Offline scheduling.
- Hope this helps.
- EDIT: Reposted.
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Many thanks @wateroakley, greatly appreciated.
My main reason for wanting a Tado system (or alternative) is for my rental property. I’m going to spend a few months renovating it so I want to have the ability for controlling the heating & hot water remotely during this period as a minimum.
I also need to get broadband set up along with a WiFi router so that I can plug the Tado internet dongle into it as well as use the WiFi router so that I can connect a WiFi camera to it. I just need to find the cheapest broadband deal available.
Which Tp/Link wifi extender did you get?0 -
Our rellie connects to their Virgin router with one like this:
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