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Wireless heating controls comparison guide

17/11/2019

 

Which is the best wireless programmable thermostat? Which controls are complaint with the new Boiler Plus regulations?

In this guide we have researched wireless programmable thermostats and smart controls from boiler brands, including Worcester, Vaillant and Baxi, and ‘third party’ models from Nest, Tado, Hive, Honeywell, Danfoss, Siemens, Drayton, Horstmann and Heatmiser. Our findings are presented together in easy to read tables so you can compare compatibility, function, price and warranty periods. We have also identified which wireless models are Boiler Plus complaint. Boiler Plus is new energy efficiency standard that requires you to fit advanced temperature controls with all new combi boiler installations and ‘time and temperature controls’ with new heat only and system boiler installations.

Find your Boiler Plus compliant heating control via our easy tables:

Boiler Plus requires that a minimum standard of heating control is fitted with your new boiler. We guide you on compatible products for Boiler Plus.

Options for installing a boiler branded wireless thermostat:

Worcester, Baxi, Vaillant, Ideal, Viessmann and Glow Worm all produce Boiler Plus compliant wireless programmable room thermostats and smart thermostats.

Combi boiler or hot water tank?

If you want your hot water tank to be controlled you will either need a separate hot water control or a ‘twin channel’ product. We guide you on Boiler Plus complaint products for heating and hot water systems below.

How to use this guide

Which thermostat is suitable

Compare thermostats

Review boiler branded options

More on Boiler Plus

What is a programmable room thermostat?

All programmable room thermostats are made up of a room thermostat, to control the temperature of your house, and a programmer, so you can pre-programme when the heating comes on and off. Standard wireless programmable room thermostats are operated from within the home whilst smart controls allow you to control your system remotely. Building regulations have long required that you fit a programmable room thermostat with any new boiler. Under the new Boiler Plus regulation (described in more detail below) you must now fit an ‘advanced heating control’ with any new combi boiler. Both standard and smart programmable room thermostats are available with advanced heating control functions.

Programmable thermostats for combi boilers.

A programmable thermostat for a combi boiler need only control the heating, as the hot water is instantaneous. This is what the trade refer to as a ‘single channel’ programmer. The single channel (as in radio channel) is for the thermostat to send a signal to the boiler to come on and off or modulate its output (See On/Off & Modulating Boilers section below). NB these can also be used for heat only and regular boilers however a separate hot water control will be needed.

Programmable thermostats for heat only and system boilers (to work with a hot water tank)

For a programmable room thermostat to operate both the heating and hot water functions of your system it will require two channels: one to communicate with the boiler and one to control the hot water. NB It is common to have a two-channel programmer and separate thermostat, although we have only considered combined heating and hot water units below.

Which control do I need to comply with Boiler Plus?

The comparison tables below show which thermostats are Boiler Plus compliant. Slightly different minimum requirements apply depending on boiler type (combi, heat only or system) and whether the heating control is being fitted to an existing installation or fitted as part of a new boiler installation as follows:

New installations of a heat only or system boiler:

require time and temperature controls, i.e. a programmable room thermostat or a thermostat with separate programmer. It is still possible to use advanced controls but they must be compatible, we guide you below.

New installations of a combi boiler:

require the same time and temperature control but with an additional ‘advanced’ energy saving feature, i.e weather compensation, load compensation or smart controls that combine automation and optimisation features (see Focus on Boiler Plus below).

Existing boiler installations:

have no minimum requirement for heating controls. It is advised that a programmable room thermostat is fitted as a minimum, however it is not mandatory. You can opt to use an advanced heating control on an old boiler and we guide you on compatible products below.

Using the comparison tables

The tables below consider standard and smart wireless programmable room thermostats from third party producers such as Honeywell, Tado and Danfoss and boiler brands such as Worcester, Vaillant, Baxi and Glow Worm. The tables below show which are compatible with Boiler Plus according to boiler type.

Compatibility!!!

Unfortunately it is not quite as simple as matching any boiler with any advanced heating control. Most advanced heating controls need to use the same ‘language’ as the boiler in order to communicate; this is known as the ‘communication protocol’. Providing boiler and control speak the same language, the advance control can tell the boiler to adjust its output in order to meet the desired room temperature most efficiently. Most boiler manufacturers use a language that is unique to their products. Only 28% of boiler manufacturers use the Opentherm protocol. Opentherm is a common language that can be adopted by any boiler or control manufacturer so that they can speak to each other. With such a small percentage of take up, it means that the number of compatible advance controls capable of working with a specific boiler is very limited. We guide you below.

Find a compatible advanced heating control

Remember, it is only mandatory to fit an advanced heating control on a new combi boiler. However owners of older combis, or those having a new system or heat only boiler fitted, may still want to benefit from the energy savings of an advanced heating control or the functionality of an internet control. For those energy savings to be maximised however you must pick a compatible control for your boiler. Find the scenario that matches your requirements (1-4 below) and then use the the product comparison tables to find the right control.

 

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Options for new combi boilers

  • Pick the boiler manufacturer’s advanced control control and compatible boiler – Table 4 for standard controls and Table 5 for smart controls.
  • Pick a boiler and control that both use Opentherm protocol – find Opentherm controls in Tables 1 and 2 or see our Guide to Opentherm products for more detail, including Opentherm boilers.
  • If all else fails, pick an advanced control with optimisation features such as Nest or Tado – find optimisation controls in Tables 1 and 2 below. Or try our Guide to Best Smart Controls for more detail.

Options for new heat only or system boilers

  • Pick the boiler manufacturer’s smart control and compatible boiler – Worcester, Vaillant and Glow Worm manufacture smart controls that include hot water controls. See Table 4 for standard controls and Table 5 for smart controls.
  • Pick a boiler and control that both use Opentherm protocol – find Opentherm controls in Table 3 or see our Guide to Opentherm products for more detail, including Opentherm boilers.
  • Pick an advanced control with optimisation features such as Nest or Tado – find optimisation controls in Tables 1 and 2 below. Or try our Guide to Best Smart Controls for more detail.

Options for existing modulating combi boilers under 20 years old

  • Check to see if the manufacturer’s smart control is compatible with your old boiler, if yes use Tables 4 and 5 below.
  • Check to see if your old boiler uses the Opentherm protocol - find Opentherm controls in Tables 1 and 2 or see our Guide to Opentherm products for more detail, including Opentherm boilers.
  • If all else fails, pick an advanced control with optimisation features such as Nest, Tado or Danfoss TPOne - see Table 2 or try our Guide to Best Smart Controls for more detail.

Options for older on/off boilers

  • Pick an advanced control with optimisation features such as Danfoss TPOne, Nest or Tado - see Table 2 or try our Guide to Best Smart Controls for more detail.
  • Pick a control with TPI – see Table 6

Jargon Buster

OpenTherm is a form of digital communication that is not restricted to one manufacturer, i.e. it is a standardised technology that can be adopted my different manufacturers to make their products compatible with each other. Pairing two Opentherm products together will ensure you achieve the highest efficiencies from your heating system, for example a Honeywell or Tado Opentherm control with a Baxi Opentherm boiler. For more, view our in-depth Guide to Advanced Heating Controls or check compatible products in our Guide to Opentherm Boilers and Controls.

Third Party Wireless Programmable Thermostats & Smart Thermostats

Most mainstream control manufacturers produce a Boiler Plus compliant wireless programmable thermostat and smart thermostat. Honeywell, Danfoss and Drayton all offer quality smart thermostats alongside more familiar products such as Nest and Hive. Their functionality is compared in the tables below so you can find Opentherm, TPI and optimisation controls suitable for most boiler types.

Standard wireless programmable room thermostats

wireless thermostats with programmers (non smart control) Honeywell RF CM927 7 day wireless programmable room thermostat Honeywell T4R 7 day programmable thermostat Drayton Digistat +3 RF 7 day programmable room thermostat Salus RT520 RF programmable thermostat Horstmann C-Stat 17-ZW 7 day programmable room thermostat Heatmiser slimline-RF Programmable room thermostat Danfoss TPOne-RF programmable room thermostat Neomitis 1 day programmable room thermostat RT1 RF
 
Price £140.00 £127.00 £141.00   £110.00 £72.00 £135.00 £72.00
Display Digital Digital Digital Digital Digital Digital Digital Digital and Dial
No of days 7 day 7 day 7 day 7 days 7 day 7 day 7 day 1 day
Smart phone app No No No No No No No No
Combi only or all boiler types All boiler types All boiler types All boiler types All boiler types All boiler types All boiler types All boiler types All boiler types
S & Y plan compatible Yes Yes Yes Yes Yes Yes Yes Yes
Integral hot water control No No No No No No No No
Warranty 1 year 1 year 1 year 5 years 2 years 2 years 1 year 3 years
Advanced control features: Weather compensation, load compensation or smart automation and optimisation Load compensation Load compensation Load compensation Load compensation None None Smart automation and optimisation None
TPI software Yes Yes No Yes Yes No Yes Yes
OpenTherm Yes Yes No Yes No No No No
Boiler Plus compliant for combis? No Yes Yes Yes Yes No Yes No
Boiler Plus compliant for heat only and system? Yes Yes Yes Yes Yes Yes Yes Yes
Heat zone capabilty 1 heating zone 1 heating zone 1 heating zone 1 heating zone 1 heating zone 1 heating zone 1 heating zone 1 heating zone
1 channel or 2 channel 1 channel 1 channel 1 channel 1 channel 1 channel 1 channel 1 channel 1 channel

Smart programmable room thermostats

wiresless thermostats with programmers (smart controls) Nest thermostat E Netatmo - Smart Thermostat Honeywell Lyric T6 Wireless Smart Thermostat Drayton Wiser thermostat Kit 1 Salus internet thermostat it500 Siemens RDS110 Tado smart thermostat Starter Kit V3+ Hive - Active Heating
 
Base unit/thermotat - suitable combi boilers £199.00 £132.00 £204.00 £135.00 £95.00 £155.00 £200.00 £180.00
Additional costs for separate hot water control Included NA NA NA £39.00 Included Included Included
Combined costs for heating and hot water £199.00 NA £242 for Lyric T6R HW model £149.99 Kit 2 - heating and hot water control £134.00 £155.00 May require an extension kit - £89.99 £180.00
Warranty/guarantee 2 years 2 years 1 year 1 year 5 years 1 year   1 year
Heating controls Yes Yes Yes Yes Yes Yes Yes Yes
Hot water time/boost Yes Yes No Kit 2 model with multi zone kit Yes Yes (possible extension kit) Yes
Advanced control features: Weather compensation, load compensation or smart automation and optimisation Load compensation and smart automation and optimisation Weather compensation and smart automation and optimisation Weather and load compensation Load compensation and smart autmoation and optimisation Load compensation and smart automation and optimisation Load compensation Load compesation w/Opentherm boilers and Smart automation and optimisation Smart automation and optimisation
Works with Smart TRVs Yes - Energenie Yes Netamo NAV-UK No Yes - Drayton Wiser Smart TRV No No Yes - Tado Smart TRVs No
TPI software Yes No Yes No No Yes Yes No
OpenTherm Yes No Yes No No No Yes No
Boiler Plus compliant for combis? Yes Yes Yes Yes Yes Yes Yes Yes
Boiler Plus compliant for heat only and system? yes Yes Yes Yes Yes Yes Yes Yes
Heating zone capabilities 3 zones with pipework adjustment or more with Egenie smart TRVs with Netamo Smart TRVs 1 1 (Kit 2 gives 2 channels - 1 heating and 1 hot water) Multi zone kit gives one extra zone - can be used for heating zone or hot water 0 1 3 zones with pipework adjustment
Geo location features Yes Yes - via IFTTT Yes Yes - via IFTTT Yes No Yes Yes
compatible boiler types Combi, heat only and system Combi, heat only and system Combi, heat only and system Combi, heat only and system Combi, heat only and system Combi, heat only and system Combi, heat only and system Combi, heat only and system
Not compatible with N/A on/off boilers N/A on/off boilers on/off boilers N/A N/A on/off boilers

Programmable room thermostats for heating and hot water

If you have a separate hot water cylinder then and you want to control the times it comes on then you will require a ‘2-channel’ programmable thermostat – one for heating and one for hot water. Other components may be required and it is best you check with your heating engineer (or find one on our network of heating companies). In the table below we have pulled together standard and smart programmable room thermostats with an integral hot water control.

Programmable room thermostats for heating and hot water

wireless thermostats with programmers (non smart control) Honeywell RF2 Sundial Pack 2 wireless programmable room thermostat Myson Touch programmable room thermostat Vaillant VRC700F Wireless weather compensating programmable room thermostat Worcester Comfort II programmable room thermostat Nest thermostat E Honeywell Lyric T6R - HW wireless smart programmable thermostat Siemens RDS110 Drayton Wiser thermostat Kit 2
 
Price £160.00 £109.00 £195.00 £220.00 £199.00 £242.00 £155.00 £165.00
7 day programmer (set different times for each day) or 1 day (set same times every day) 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day
Smart phone app No No No No Yes Yes Yes Yes
Hot water temperature controls included? Yes Yes Yes Yes Yes Yes Yes Yes
Warranty 1 year 2 years 2 years 8-10 years when fitted with a new Worcester boiler 2 years 1 year 1 year 1 year
Compatible boiler types Heat only and system Heat only and system All current Vaillant boiler models All combi & system boilers and 27 and 30Ri heat only boilers All boiler types All boiler types All boiler types All boiler types
Advanced control features: Weather compensation, load compensation or smart automation and optimisation Load Load Weather and load Load Load compensation and smart automation and optimisation Weather and load compensation Load compensation Load compensation and smart autmoation and optimisation
TPI software Yes No No No Yes Yes Yes No
OpenTherm Yes No No No Yes Yes No No
Boiler Plus compliant for heat only and system? Yes Yes Yes Yes Yes No No Yes
Zones 2 heating zones 1 heating zone 2 heating zones 2 heating zones 3 zones with pipework adjustment or more with Egenie smart TRVs 2 heating zones 2 heating zones 2 (kit 3 can give 3 zones)

Boiler branded wireless programmable thermostats

Some boiler manufacturers produce their own wireless programmable thermostats and smart thermostats that work exclusively with their range of boilers. There are many benefits to fitting a boiler branded model with your new boiler, not least of all because the boiler warranty or guarantee is often extended to cover the heating controls. This means some controls come with up to 10 years of cover from the manufacturer, which is impressive when many third party products only offer one year.

To get the highest efficiencies from your boiler you will need to use controls that can communicate with your chose boiler (use our ‘Find a compatible advanced heating control’ guide above).

The tables below show both standard and smart programmable thermostats and indicate when they are Boiler Plus compatible for new installations. We have compared them alongside Nest and Honeywell’s Lyric for your ease of reference.

Boiler brands’ standard programmable room thermostats

wireless thermostats with programmers (non smart control) Vaillant VRT350F 24 hour Programmable room thermostat Vaillant VRC700F Wireless weather compensating programmable room thermostat Glow Worm Climapro2 RF wiresless programmable thermostat Baxi 7 day programmable room thermostat Worcester Comfort II programmable room thermostat Ideal 204789 Rf wireless programmable room thermostat Vitotrol 100-W RF 2 channel 7 day room thermostat
 
Price £146.00 £195.00 £132.00 £120.00 £220.00   £140.00
7 day programmer (set different times for each day) or 1 day (set same times every day) 7 day 7 day 7 day 7 day 7 day 7 day 7 day
Smart phone app No No No No No No No
Hot water temperature controls included? Yes Yes Yes No Yes No Yes
Compatible boiler types Combi, heat only & system Combi, heat only & system Combi and system Combi Combi, heat only (with a wiring centre) and system Logic, Logic +, Independent, Independent +, i-mini C, Vogue Combis Combi, heat only & system
Compatible boiler ranges All current Vaillant boiler models All current Vaillant boiler models Energy Combi and Energy System Baxi combis All combi & system boilers and 27 and 30Ri heat only boilers Combi boilers only 100-W 100-W compact
Not compatible with NA NA Heat only boilers System and heat only boilers Other heat only boilers System and heat only boilers 050-W boilers
Advanced control features: Weather compensation, load compensation or smart automation and optimisation Load Weather and load Weather and load None Load Load Weather (probe now supplied as standard with boiler ranges)
TPI software No No No No No No No
OpenTherm No No No No No Yes Yes
Boiler Plus compliant for combis? Yes Yes Yes Yes when paired with weather compensation kit from Baxi Yes Yes Yes (when fitted with weather compensation probe)
Boiler Plus compliant for heat only and system? Yes Yes Yes NA Yes (where compatible) Yes Yes
Warranty 2 years 2 years 2 years 2 years 8-10 years when fitted with a new Worcester boiler 1 year 1 year

Boiler brands’ smart programmable room thermostats

Product Worcester EasyControl (replaces the Worcester Wave). Vaillant Vsmart Ideal Touch Baxi Usense Smart room thermostat Glow Worm MiGo Nest thermostat E Honeywell Lyric T6R - HW wireless smart programmable thermostat Tado smart thermostat Starter Kit V3+
 
Base unit/thermotat - suitable combi boilers £210.00 £160.00 £160.00 £160.00 £190.00 £199.00 £242.00 £200.00
Additional equipment/ costs for separate hot water control £132 integral gas valve Different vSMART controller NA NA £67 hot water control Included Included Included
Combined costs for heating and hot water £332.00 £225 for vSMART control with hot water function NA NA £257.00 £199.00 £242.00 May require an extension kit - £89.99
Warranty/guarantee 8-10 years when fitted with a new Worcester boiler 2 years 5-10 years when fitted with Ideal boiler (matches boiler warranty length) 3 years Upto 7 years when fitted with a new Glow Worm boiler 2 years 1 year 2 years
Heating controls Yes Yes Yes Yes Yes Yes Yes Yes
Hot water time/boost Yes Yes - with hot water control model No No Yes Yes Yes Yes (possible extension kit)
Weather compensation, load compensation or smart automation and optimisation Weather and load compensation Weather compesation and load compensation Load compensation and smart automation and optimisation Load compensation Weather compensation Load compensation and smart automation and optimisation Weather and load compensation Smart automation and optimisation
Works with Smart TRVs Yes - Bosch Smart TRVs Yes - AmbiSENSE No No No Yes - Energenie No Yes - Tado Smart TRVs
TPI software No No No No No Yes Yes Yes
OpenTherm No (e-BUS) No (e-BUS) Yes Yes No (e-BUS) Yes Yes Yes
Boiler Plus compliant for combis? Yes Yes Yes Yes when paired with a compatible boiler Yes Yes Yes Yes
Boiler Plus compliant for heat only and system? Yes Yes Yes Yes Yes yes Yes Yes
Heating zone capabilities Yes with Bosch Smart TRVs 1 + plus hot water 1 heating zone 1 heating zone 2 + plus hot water 2 zones with pipework adjustment or more with Energenie smart TRVs 1 heating zone 1 heating zone (more with smart TRVs)
Geo location features No No No Yes No Yes Yes Yes
Compatible boiler types Combi and system Combi, heat only and system Combi Combi Combi, heat only and system Combi, heat only and system Combi, heat only and system Combi, heat only and system
Compatible boiler ranges Combi Greenstar i range: Junior, Si, CDI compact and Cdi Classic. Systen Greenstar: 12i-24i, 27i-30i and Cdi Classic System All ecoTEC boilers Logic Combis, Vogue Combis, Logic Max Combi and Vogue Max Combi Baxi 600, 400, 200 and 100 (Duotec and Platinum require flue weather compensation in addition to uSense control) All Glow Worm boilers All (check manufacturer's website for small number of exceptions) All (check manufacturer's website for small number of exceptions) All (check manufacturer's website for small number of exceptions)
Not compatible with: Heat only boilers ecoFIT range System and heat only boilers System and heat only boilers NA NA NA NA

Focus on: TPI software

TPI stands for Time Proportional Integral. TPI controls can work with older on/off boilers to only fire the boiler for shortest amount of time in order to meet the desired room temperature. For example, if the heat demand for the property is only 5kW in one hour, but the boiler’s rated output is 15kW, then a TPI heating control will fire the boiler for a third of the time, i.e. 20 minutes on and 40 minutes off. Research commissioned by BEAMA showed that a TPI control can save up to 13% on fuel bills.

TPI programmable room thermostats

wireless thermostats with programmers (non smart control) Honeywell T4R 7 day programmable thermostat Honeywell RF2 Sundial Pack 2 wireless programmable room thermostat Danfoss TPOne-RF programmable room thermostat Neomitis 1 day programmable room thermostat RT1 RF Nest thermostat E Honeywell Lyric T6 Wireless Smart Thermostat Siemens RDS110 Tado smart thermostat Starter Kit V3+
 
Price £127.00 £160.00 £135.00 £72.00 £199.00 £204.00 £155.00 £200.00
Display Digital Digital Digital Digital and Dial Touch screen Touch screen Touch screen Touch screen
No of days 7 day 7 day 7 day 1 day 7 day 7 day 7 day 7 day
Smart phone app No No No No Yes Yes Yes Yes
Combi only or all boiler types All boiler types Heat only and system All boiler types All boiler types All boiler types All boiler types All boiler types All boiler types
Integal hot water control No No No No Yes Yes Yes Yes
Heat zone capabilty 1 heating zone 1 + hot water 1 heating zone 1 heating zone 2 + hot water 1 heating zone 1 heating zone 1 heating zone (more with smart TRVs)
Weather compensation, load compensation or smart automation and optimisation Load Load Smart automation and optimisation Neither Load compensation and smart automation and optimisation Weather and load compensation Load compensation Smart automation and optimisation
TPI software Yes Yes Yes Yes Yes Yes Yes Yes
OpenTherm Yes Yes No No Yes Yes No Yes
Boiler Plus compliant for combis? Yes Yes Yes No Yes Yes Yes Yes
Boiler Plus compliant for heat only and system? Yes Yes Yes Yes yes Yes Yes Yes
Warranty 1 year 1 year 1 year 3 years 2 years 1 year 1 year 2 years

Our view on the best wireless programmable room thermostats

Our research into products for this page led to many technical helpline phone calls, web searches and scrutiny of technical data sheets. We found a correlation between the quality and functionality of a product, and the availability of technical information and knowledge levels of technical help line staff. Nest, Vaillant, Tado, Honeywell and Worcester offered great products and were easy to research. The technical helpline for Honeywell in particular was amazing – big thank you for your help. The product with the least amount of information available and the least knowledgeable staff, was Hive, and that reflected the functionality of their product. Hive also have the shortest warranty. Could do better Hive, we know you can up your game.

Focus On: Boiler Plus requirements for new boiler installations

In April 2018 new efficiency standards were introduced aimed at reducing the amount of fuel we use to heat our homes. As our environmental resources grow short it is important we conserve energy and a well-controlled heating system is central to that. It was all lower your fuel bills.

The three key requirements that all new boiler installations must meet are as follows:

  • Every boiler installation must have an ErP efficiency of at least 92% (not to be confused with boiler efficiencies which are 89-94% - see our Guide to Boiler Efficiencies).
  • All new boilers must be fitted with time and temperature controls e.g. a programmable room thermostat, if not already present
  • An additional energy saving measure must also be installed for combination boilers from the following list
  1. Weather compensation control Load compensation control
  2. Smart control with automation and optimisation functions scheme
  3. Flue gas recovery unit - this sits above the boiler and recovers heat from the flue. It is reported to reduce gas consumption by upto 4%.

Measures 1 and 2 are forms of advanced heating control designed to work modern ‘modulating’ boilers, i.e. they can be adjust their output to suit demand (see See On\Off & Modulating Boilers section below). Measure 3 uses AI to learn the most efficient patterns of use. Their common aim is to ensure the boiler is on for the shortest possible time to meet the room temperature. Standard controls tend to overshoot the room temperature by 1 or 2 degrees which is very inefficient. Advanced controls reduce the heat output of the boiler as it approaches the desired temperature to prevent overshooting. The net result is a reduction is gas use and lower fuel bills.

Focus on: How thermostats work

A thermostat is a device that controls the temperature of your room. It can have a simple dial, a digital display or a touch screen, but they all do the same thing. You can set your thermostat to your desired temperature, say 20 degrees, and your thermostat will send a signal to the boiler to come on when the room temperature drops below 20 degrees. Once the room temperature has been met the thermostat will send a signal to your boiler to turn off. Standard thermostats tend to overshoot the desired temperature by a degree or two, which is every inefficient.

Focus on: How programmable thermostats work

A programmable room thermostat combines a room temperature control with the ability to set the heating to come on at different times of the day. There are two main types: 1 day and 7 day (although some with a 5/2 day options). Most programmers will allow you set 2-6 time periods per day and also set different temperatures for each time period. If you do not have a programmer your thermostat will tell the boiler to come on and off all day unless 1) you turn the thermostat down when you out or 2) you switch the boiler off when you go out.

A ‘1-day’ thermostat will allow you to set different times, say 6am – 8am and 4pm – 8pm, but they will be the same for every day of the week

A ‘5/2’ thermostat will let you set different times for two days of the week. i.e. the weekend. For example 6am – 8am and 4pm – 8pm Mon – Fri and 10am – 6pm Saturday and Sunday

A ‘7 day’ thermostat offers the most flexibility as it will let you set different times on each day of the week. These are useful if your work shift patterns change or you do not have weekends off.

Focus on: How smart controls work

Smart controls are all programmable thermostats that are connected to the internet and operable via a smart phone app. They all use some form of advanced heating control (i.e. weather compensation, load compensation and/or automation/optimisation features). Many are now compatible with Alexa, Apple, IFTTT and other smart home devices. This can provide additional functionality, for example you can turn your heating on and off via the voice activated smart home device or active geofencing sensors (the heating will come on as you near home via a GPS signal from your phone). NB some smart controls such as Nest and Tado come with geofencing as part of the device.

Focus on: how advance heating controls work

Advance heating controls ensure the boiler is on for the shortest possible time to meet the room temperature. They all operate slightly different but the net result is to reduce the heat output of the boiler before it can overshoot the required temperature. Advance controls also increase the amount of time the boiler spends in ‘condensing mode’ which is when it is at its most efficient. For purposes of Boiler Plus advanced controls are: Weather compensation, load compensation and automation/optimisation settings.

Weather compensation estimates the heat demand for the property based on the difference between a measured external temperature and the desired internal room temperature. Depending on whether you have an old on/off boiler or modern modulating boiler (see See On\Off & Modulating Boilers section below) the thermostat either adjusts the boiler’s output, or reduces the amount of time it is on, to close the gap between the two temperatures as weather conditions change. This ‘advance warning’ allows the boiler to make small adjustments to the boilers output or periods of operation in order to meet the heat demand as efficiently as possible.

Load compensation works in the same way as weather compensation, but instead uses the difference between the internal room temperature and the desired room temperature to control the boiler’s output to close the gap. Load compensation can either be manually set for on/off boilers or it can adjust itself automatically known as ‘modulating’. NB the boiler and control must speak the same language in order to adjust the boiler’s output in this way –see also our Guide to Advanced Heating Controls.

Smart controls with automation and optimisation functions (NB this is not necessarily an internet control) automate the time and temperature settings based on occupancy detection, geolocation and/or stored data from user patterns over time. Smart controls work on a learned schedule of use and how quickly your home loses or gains heat. Over time the control will know how early the boiler will need to come on to meet the set temperature operating in its most efficient condensing mode.

Focus on: On/off boilers and modulating boilers

Before you start to think about which heating control to buy, especially if you are considering an ‘advanced heating control’, you need to know whether you have an ‘on/off boiler’ or a ‘modulating boiler’. NB if you are buying a new boiler it will be modulating and you just need to make sure your chosen thermostat it is compatible – see our Guide to Opentherm compatible products.

On/Off boilers

These tend to be older boilers. An on/off boiler will always fire at same rate, for example an 18kW boiler will always work at 18kW. The efficiencies of on/off boilers can be improved by using a TPI control or control with optimisation features. These learn the actual output required to meet the desired room temperature and proportionally reduces the period of time the boiler on.

Modulating boilers

All modern boilers are ‘modulating’. This means that they can adjust their output up and down. For example, an 18kW rated boiler can adjust its output to fire between 3kW and 18kW. Modulating boilers are far more efficient, however to achieve their maximum efficiency they must 1) work with a compatible ‘modulating’ heating control and 2) spend as much time as possible in ‘condensing’ mode which can be achieved with the right heating control. (See also our Focus on Advanced Heating Controls).

Focus on: How is it wireless?

A wireless thermostat kit consists of a ‘receiver’ and thermostat control. The two units communicate via radio frequency (NB this is the same for smart/internet controls). The receiver will be wired into the boiler and will receive a signal from the thermostat control for the boiler to come on and then switch off once the set room temperature has been reached. A wireless programmable room thermostat operates in the same way, but will control the times the boiler comes on and off as set by the user.

Jo Alsop

Heating Hero

The Heating Hub

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