The Drayton product range offers a solution to meet all of these except flue gas heat recovery as this is provided by the boiler manufactures. If you use the boiler manufacturer's own smart TRVs you only have to deal with one manufacturer for all your heating system products Have to systematically work through the zones reducing set points by at least 2 deg's to establish which area the heat demand is actually coming from, usually the area where actual temperature is very close to, within 1 deg of the set point, very annoying! require a combined programmer and thermostat with an ‘advanced’ energy saving feature. Namely: weather compensation, load compensation or smart controls that combine automation and optimisation features. (Or you can fit a flue gas recovery unit.) New installations of a heat only or system boiler: Honeywell Evohome gives more flexibility, with its custom actions and IFTTT channel. Its radiator thermostats are also more fully featured, letting you set the temperature you want from the room. If you want the most powerful and flexible multiroom heating system, then, we’d recommend Evohome.

Smart Radiator Thermostats are quite similar in appearance to traditional TRVs. Both are installed simply by attaching to an existing radiator valve, and both offer temperature control by manually twisting their caps. Smart TRVs also work like regular TRVs by controlling the hot water flow into radiators and use sensor-based systems to maintain a pre-set temperature. In addition, each room can have Open Window Detection turned on. This uses an algorithm to detect when a draft is detected, suggesting an open window or door. The heating is then turned off to conserve energy. Although the TRVs make a small humming noise while operating, I found that they were very quiet in operation. Once I was used to them, I could easily sleep while they operated. Yes, for a combi boiler there’s no need to control the hot water as it’s on demand so you will typically use a single channel controller. A conventional boiler stores hot water in a cylinder, so this also needs to be controlled for time and temperature, typically using a two channel controller. Ref the comments in this post about utilising existing Danfoss TRV bodies, most of my system uses old Danfoss RA's which I have converted to smart using the supplied adapters.

Zonal heating control on a budget

However once set, it did work, and other than sun through bay windows, which no system can correct, the temperatures in rooms were within 0.5°C once set. Have achieved mixed results with the Danfoss conversions, some work well, others produce results much the same as reported in this post despite re-calibration, valve free-up & lubrication and smart head substitution, have come to the conclusion that the only long term solution for these devices is replacement of the valve bodies. The Drayton Wiser system lets you set a schedule for each thermostat, indicating a desired temperature for each room in your home at different times of the day. For example, you can set the bathroom to warm up first thing in the morning and last thing at night, if you don’t use it during the day. As already mentioned, you can override a set schedule at any time by manually twisting the top of the radiator thermostat (turning the heating on in that room for 30 minutes) or from the app, where you can choose for the heating to remain on for between 30 minutes and three hours.

To control your heating, the Drayton Wiser system has a wireless heating relay that connects to your boiler to turn it on and off. There are two versions of the kit available. The first has a single-channel control that’s designed for combi boilers, turning the heating on and off only. Smart TRVs take the place of a traditional thermostatic radiator valve and close the valve using a motor that’s driven by batteries that will need to be changed periodically. These offer greater accuracy and have the ability to stop the call for heat when set point is achieved. They can also directly call for heat in individual rooms avoiding energy waste.It’s really easy to adjust heating schedules on the go using a smart control, which means you can reduce energy consumption by tailoring heating periods to fit in with your lifestyle and routine. I slightly prefer the Tado and Honeywell Evohome TRVs, which show the current temperature on their display and let you set a new target temperature.

The third-party smart TRVs reviewed here all do much the same thing, it is the control thermostat that is the most important choice. The Honeywell EvoHome is suited for much larger properties. All six other thermostats are compatible with the vast majority of heating systems (old and new boilers) and will operate the boiler efficiently based on a learned pattern of when you need heat. Radiator thermostats enable your Wiser system to enter a whole new level of smart. With a direct connection to the boiler they enable you to control the on/off times and temperatures of individual rooms via the intuitive app, even with no internet connection while at home. Building on the iconic design of the Drayton TRV4, the Wiser Radiator Thermostat maintains the simplistic style and builds on years of success as a leading TRV manufacturer with a host of additional features. Works with all Drayton Wiser kits. Further features include a digital boiler interface for efficient control using OpenTherm technology (only with OpenTherm supporting boilers) There’s also an Away mode, where your heating is set to a reduced temperature (configured by you). This mode is handy when you’re out or on holiday. There’s only manual operation of this, but you can use the IFTTT channel to build your own geolocation service, either for one device or, with a service such as Life360, for your entire family.Drayton has a range of time controls that give you different levels of flexibility. Some allow you to set a 24 hour programme that will be repeated on a daily basis, others offer a 5 day/2 day programme which enable you to set different programmes for the week and weekend, and some allow you to set a different programme for each day.