Integrate or replace old Heatmiser UFH system
Hi all,
I just asked this in the technical section, but have sen that maybe this is the most appropriate place. Forgive me if not.
I have two circuits on my heating system. An old Heatmiser system that controls the under floor heating on the ground floor (8 zone with a UH1 valve http://www.thermsaver.co.uk/wp-content/uploads/2015/07/Heatmiser-UH1-Wiring-Centre.pdf) and a Honeywell CM927 wireless thermostat that controls the radiators for the top floors (with some dumb TRV's for individual room control).
Both of these connect to a honewell programmer/timer (ST9400C) next to the boiler - which has to be on 'constant' heating so that the heatmiser and honeywell can both call for heat when they want it.
I get a crappy link between the honeywell wireless stat and the receiver next to the boiler, so want to change. I have bought the wireless V3+, and a bunch of Tado TRV's which I'm told is what I need to get the top floor up and running. So my question is
1) Does anyone know the easiest way to integrate the Heatmiser UFH into the Tado system? The existing heatmiser stats are 12V so I assume I can't replace heatmiser wired with tado wired. But can I simply replace the wired Heatmiser stats with tado wireless? (But I'm not sure how would they communicate with the UH1 valve). There will be decorating issues with replacing the stats, but I think I can persuade my wife of the benefit....
2) If it's not possible to replace the Heatmiser system with Tado, does anyone know how to wire it into the wireless receiver (which I'm told replaces my existing programmer/timer).
I may have totally misunderstood what I need to do, so if that is the case and my questions are irrelevant, please let me know!
Thank you!
Answers
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Did you get anywhere with this, I am in the same boat?
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I know this is an old post resurrection but it came up in my pre-installation search too so I'm going to update it....
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I'm in the UK and have just done this with a John Guest (rebranded Heatmiser) system using a John Guest UH3 Wiring Centre (very similar to the OP's in principle) and PRT-E (240v) room controllers (the same model number regardless of branding). Whilst the principle may be the same PLEASE BEAR IN MIND THAT MY ROOM CONTROLLERS ARE 240v SO YOUR WIRING WILL BE DIFFERENT if 12v! I suspect that the installation logic will be the same though - others may be PRT-N or even different manufacturers and Tado will instruct how to connect these on install.
Downstairs I have 6 individual UFH zones now successfully installed and using Tado Wired Smart Thermostats in Standalone mode (no zone controller assigned to the rooms that they are installed to otherwise they will fire other things too, e.g. upstairs - see below!). These wire to channels 1 through 6 of the wiring centre and fire the boiler, run the pump and open the UFH circuit valves individually.
Despite being wired for their relay connection, I believe that the Tado wired smart thermostats are still battery power for their internal power (the mains ones instruct to connect the mains neutral wire to parking terminal P1) so I suspect that the 12v power connection(s) currently running to your existing room controllers will be unused and also connected to parking terminals) but the Tado installation instructions in the app (or someone else reading this with a 12v UFH system) will be able to confirm this for the individual product being replaced.
No other wiring changes were necessary for the UFH - the valve, boiler and pump all switch/fire as before. That's the easy bit! These can also be purchased/done one at a time and tested as you go but you'll need an internet bridge which will affect your choice of starter kit (see below) .
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The OP doesn't mention hot water control or whether they have a combi or system boiler but I'll describe my hot water installation (system boiler with hot water tank) next and as part of my upstairs scenario in case it helps others reading this.
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Upstairs I had another PRT-E controlling a radiator loop to 3 bedrooms and 2 bathrooms. This PRT-E was connected to Zone 8 on the UH3 wiring centre to fire the boiler etc. Also, a separate Honeywell single-channel ST9100C in the airing cupboard wired as a simple relay with timer control for hot water.
I used the Tado UK-specific 2-channel wireless receiver for upstairs. For hot water, this was a straight swap for the Honeywell hot water programmer onto the Tado Wireless Receiver (must be the UK version with hot water) hot water relay side - the included Manual for Professional Installers is helpful here!
However, for the upstairs heating loop, I had to recable the wired PRT-E to connect the cable directly to the heating relay side on the Tado wireless receiver so that it controls Zone 8 (upstairs heating loop with valve and boiler firing) instead of the old wall controller. Fortunately, this was easy for me as the old PRT-E was on the wall of the airing cupboard so I could extend the cable back inside the cupboard and use the (now bypassed) wall box to neatly mount the wireless thermostat. This wireless receiver now manages upstairs the heating zone (bizarrely, it was in the upstairs hallway where there are no heat output devices so never worked well with passive TRV's in the bedrooms) and the hot water manual switching.
Finally, I added three Tado Smart Radiator Thermostats (TRV's) in each of the three bedrooms with their zone controller set to the Wireless Receiver. This enables each bedroom to call for heat individually, with their own schedules, and with the other TRV's closed if there's no call for heat from those. The 2 bathrooms have heated towel rails with no valves so they provide a bypass loop and come on with any call for heat upstairs. I may add additional wireless temperature sensors in these areas so that the bathrooms can call for heat if colder than the bedrooms at a later date.
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As far as the OP's installation goes, I can only guess that the existing Honeywell 2-channel programmer is only acting as a dumb connector box if set to always on, and it's not clear whether both heating zones are on the same channel or if the other channel is used for hot water. Either way, I would imagine that the Tado wireless receiver could easily replace one or both of these functions as it only works as a "call for heat" relay in any case...
I hope this makes sense and is of help to anyone finding it in the future - of course this is based on my own experience and existing installation so any work you do is at your own risk, I accept no liability, etc. etc. 😉
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