Underfloor heating with Wired Smart Thermostat
I recently installed a Tado V3+ Wired Smart Thermostat (amongst other things) to control the wet underfloor heating in our dining kitchen extension. The UFH is on it's own zone valve, separate from the radiators in the main part of the house.
The issue I find is, Tado seems to wait until the temperature in the room has dropped a full degree below the set temperature before it brings on the heating. The room is about 7m x 4m with a concrete floor so it takes some time to warm up. Tado then won't turn off the heating until the room reaches temp, which means the now very warm floor continues to heat the room way past set temp for several hours. The old WarmUp 3ie standalone thermostat seemed to be able to keep the room about the right temperature at all times.
I gather I'm not the only user who's noticed this but I had a couple of questions I haven't seen answered elsewhere yet. First, is there anything in the paid subscription for Tado that would help with this? Second, our boiler seems to support OpenTherm (noticed wiring terminals for this), I've got the wireless receiver connected to the boiler but not wired to the OpenTherm terminals - can I do that with the Wireless Receiver and would that help here?
Answers
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To address that large drop in temperature, I would suggest you change the settings for that thermostat (go to Settings > Rooms & Devices, select the device, then choose Temperature Offset and adjust the value, saving the change), so that it maintains a higher temperature.
How long has it been since you fitted the Tado system? If it is inside the warranty period it is important. May need to swap the thermostat and the wireless receiver.
To answer your second question need to know:
- Whether your boiler is a combi (actually need to know the exact model as well)
- Do you have S Plan, Y Plan, etc . Do you have a hot water tank in place with its own thermostat? How many zone valves do you have and what do they handle specifically?
- Whether the wireless receiver is a UK version or the EU version. The latter handles Opentherm, the former doesnt (so if we conclude that it is viable to switch to opentherm it will be necessary to swap the wireless receiver- hence may need to have your retailer swap - and you have a simple case to have it returned - and then you can purchase a kit with an EU wireless receiver).
First, come back, will go through this step by step.
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Hi, thanks for the response.
Regards changing the temperature offset - I'm not sure how your suggestion helps my issue, the problem is not that the temperature is too cold, it's that the Tado system allows the temperature in the UFH room to fluctuate quite wildly, I want it to maintain a steady temperature.
I bought the components and installed them in January this year, so about two months old.
To your bullet points:
- Boiler is a Viessmann Vitodens 100-W WB1C combi.
- Not sure what you mean by S plan, Y plan etc.? There is no hot water tank of any sort. Two zone valves; one for the radiator loop in the main part of the house, the other for the wet UFH in the extension.
- The Wireless Smart Thermostat kit appears to be the UK version - certainly the sticker on the bottom of the box ends with -TC-UK-00 so I guess that means I'm out of luck with the OpenTherm thing then.
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You’d want to change the hysteresis, rather than offset, and I don’t think Tado expose that for users.
Presumably someone designed the system and you’d think they’d have a plan for control. My hunch is you’d be better off running weather compensation on the Viessmann 100W.
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Ok. Thinking through this, is it fair to conclude that:
1. The two central heating zone valves are individually triggered by Tado smart thermostats?
2. It is a Tado wireless receiver talking to the boiler, not a wireless sensor, or wired thermostat?
Would you take a photo of them and post them here, blurring out their serial numbers? Need to be sure about what's in place. Need a laptop for photographs to be posted.
Another thing: whats the blend temperature that's been set on the manifold? Is your ufh pump set to permanent pressure, or differential pressure?
And yes, would suggest you consider contacting your retailer and arranging a refund/ return with a parallel purchase of the bits you need for opentherm to work.0 -
1 - yes - the UFH zone valve is controlled by the wired smart thermostat in the kitchen and the main central heating zone valve is controlled by the wireless receiver. The kitchen 'stat is independent, all the smart TRVs are set to operate via the wireless receiver.
2 - Yes, it is the Tado Wireless Receiver from the Smart Wireless Thermostat starter kit which is connected to the boiler, I installed that to replace the old Honeywell timer/programmer which was installed along with the boiler. It's from this kit:
https://www.screwfix.com/p/tado-v3-wireless-heating-hot-water-smart-thermostat-starter-kit-white/141kt
The part number on the label on the box is V3P-SK-WTS01WRP01IB01-TC-UK-00.
Blend temperature and pump settings - absolutely no idea, sorry - how would I find that out?
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On the UFH manifold there is a blending valve, designed to ensure that the temperature of the fluid running underfloor is not so high that it forces the material covering the pipes to swell and break. It should be set somwhere between 32 degrees and 40 degrees- and the installers should have left instructions about this. The pump is usually built into the manifold. You need to study it settings from its manual.
Suggest the following. Get a replacement kit from Screwfix, with an EU wireless receiver. Carefully decommission the original kit. Remove its content from your app - and with the specific guidance for your boiler, identifying for them the model, the zones, etc, the fact of UFH - all that you have presented here - follow the specific instructions from sales support team at Tado to install the new kit in your home, this time with Opentherm engaged. It isnt difficult but you have to follow their instructions meticulously.
Once the new kit is working, return the old one and provide them with a printed letter identifying the fault. They are usually helpful and will refund it immediately.
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