Honeywell Home Heating Support – UK & Ireland
Frequently asked questions
If your heating system is a boiler with radiators, there will usually be only one room thermostat to control the whole house. But you can have different temperatures in individual rooms by installing thermostatic radiator valves (TRVs) on individual radiators. If you don’t have TRVs, you should choose a temperature that is reasonable for the whole house. If you do have TRVs, you can choose a slightly higher setting to make sure that even the coldest room is comfortable, then prevent any overheating in other rooms by adjusting the TRVs.
Thermostatic Radiator Valves (TRVs) sense the air temperature around them and regulate the flow of water through the radiator which they are fitted to. They do not control the boiler.
They should be set at a level that gives you the room temperature you want. These settings may have to be different in each room, and you should set the TRVs to suit each room and then leave them to do their job.
Turning a TRV to a higher setting will not make the room heat up any faster. How quickly the room heats up depends on the boiler size and setting, and the radiator size. Turning a TRV to a lower setting will result in the room being controlled at a lower temperature, and saves energy.
TRVs need a free flow of air to sense the temperature so they must not be covered by curtains or blocked by furniture.
TRVs cannot turn off the boiler when the house is warm. To do that, you will need a room thermostat as well. The radiator in the room with the room with the room thermostat should not normally have a TRV, but if it does, keep the TRV on the maximum setting and adjust the room thermostat as explained with the instructions
A programmable room thermostat is both a programmer and a room thermostat. A programmer allows you to set ‘On’ and ‘Off’ time periods for your boiler to suit your own lifestyle.
A room thermostat works by sensing the air temperature, switching on the heating when the air temperature falls below the thermostat setting, and switching it off once this set temperature has been reached. So, a programmable room thermostat lets you choose what times you want the heating to be on, and what temperature it should reach while it is on. It will allow you to select different temperatures in your home at different times of the day (and days of the week) to meet your particular needs. Turning a programmable room thermostat to a higher setting will not make the room heat up any faster. How quickly the room heats up depends on the design of the heating system, for example, the size of boiler and radiators. Neither does the setting affect how quickly the room cools down. Turning a programmable room thermostat to a lower setting will result in the room being controlled at a lower temperature, and saves energy.
A heating system should only burn fuel when there is a demand for heat from the boiler, either for Heating or Hot Water. When this demand is satisfied, then the boiler should switch off again, it should not be able to fire until a new demand is created by the controls. This is called Boiler Interlock and represents the Minimum Standard required under Building Regulations for new and existing heating systems. Building Regulations apply whenever a boiler or cylinder is changed in a heating system. Both Heating and Hot Water should be controlled by both time and temperature (i.e, a programmer and thermostats). These should operate either motorised valves or the boiler (if it is a combi).Radiators should also be under the control of thermostatic radiator valves, except in the room where the room thermostat is fitted.
TPI (Time Proportional & Integral) control is an industry standard term for an On/Off control using an advanced energy saving control method that can be used by most heating systems in the UK. The controls simply switch current supplied to the boiler on or off at different times. Unlike a traditional thermostat, these rely on digital technology that matches the boiler firing to the load on the system. TACMA tests indicate that under steady state conditions as much as 10% energy savings can be made with TPI. This would be reduced by seasonal and operational losses. But in addition, because the control is so much more accurate, the set point can be reduced, without loss of comfort, introducing extra savings.
A thermostat operates using a fixed number of firing periods per hour (normally selected to suit the appliance and system). This can often mean a thermostat can fire the boiler even when the set temperature is reached.
A TPI room thermostat will have 100% demand when the system first calls for heat. When the room temperature approaches the set point, it then calculates how many minutes are required within each firing period to satisfy the set temperature. The TPI thermostat will then reduce the firing time in that cycle period in proportion with the demand. This means that as the room temperature approaches set point, the boiler is fired progressively less.
The biggest barrier to changing a heating system is the fact that what is installed already usually dictates what is achievable now. With wireless controls, this restriction is removed it is now easier to improve the efficiency of a heating system. They can be added to almost any system with the absolute minimum of fuss, mess and disruption.
Advantages of wireless controls:
• Can be fitted in places where no cables have been laid
• It is possible to divide a system into zones which are controlled to suit how you live
• Advanced control can improve control efficiency using data transmitted
• The demands from different zones can be synchronised so that they are satisfied simultaneously (instead of one at a time) making the boiler run more efficiently
The simplest upgrade to a heating system is to add a room thermostat where one is not fitted. This upgrade will have the biggest effect on a system, saving up to 30% of the heating bill (source British Gas).
Honeywell have developed robust wireless protocols that ensure any signals transmitted are received correctly and acted upon. Our products operate in the 868MHz band, transmissions are restricted to intermittent signals with a utilization of less than 1%. This means that not only are the signals clear and strong, but there is little chance of them being affected by other signals.
A radiator thermostat is a modulating control that allows proportionally more flow for a greater demand, and less flow for smaller demand, thus controlling the amount of heat available to be emitted by the radiator. When the air temperature has risen to be the same as the set point temperature, the radiator thermostat will not be fully closed; it will still be partially open. This is so that the air temperature can be maintained by the flow through the radiator thermostat. If the valve were to close fully, the temperature would fall as the radiator would start to cool down.
Room thermostats need a free flow of air to sense the temperature, so they must not be covered by curtains or blocked by furniture. Nearby electric fires, televisions, wall or table lamps may prevent the thermostat from working.
A thermostat simply switches the heating system on and off as necessary. It works by sensing the air temperature, switching on the heating when the air temperature falls below the thermostat setting, and switching it off once this set temperature has been reached. Turning a room thermostat to a higher setting will not make the room heat up any faster. How quickly the room heats up depends on the design of the heating system, for example, the size of boiler and radiators. Neither does the setting affect how quickly the room cools down. Turning a room thermostat to a lower setting will result in the room being controlled at a lower temperature, and saves energy. The heating system will not work if a time switch or programmer has switched it off.
The way to set and use your room thermostat is to find the lowest temperature setting that you are comfortable with, and then leave it alone to do its job. The best way to do this is to set the room thermostat to a low temperature – say 18ºC – and then turn it up by one degree each day until you are comfortable with the temperature. You won’t have to adjust the thermostat further. Any adjustment above this setting will waste energy and cost you more money.
The way to set and use your programmable room thermostat is to find the lowest temperature settings that you are comfortable with at the different times you have chosen, and then leave it alone to do its job. The best way to do this is to set low temperatures first, say 18°C, and then turn them up by one degree each day until you are comfortable with the temperatures. You won’t have to adjust the thermostat further. Any adjustments above these settings will waste energy and cost you more money.
If your heating system is a boiler with radiators, there will usually be only one programmable room thermostat to control the whole house. But you can have different temperatures in individual rooms by installing thermostatic radiator valves (TRVs) on individual radiators. If you don’t have TRVs, you should choose a temperature that is reasonable for the whole house. If you do have TRVs, you can choose a slightly higher setting to make sure that even the coldest room is comfortable, then prevent any overheating in other rooms by adjusting the Thermostatic Radiator Valvues.
Only heat those areas where it is necessary. Zone off other areas and provide background (or setback) heating to prevent damp.
Adjust your heating so that it does not overheat your home before you get up in the morning. This means that you need to check to see what the weather is likely to do each night and adjust the start time for the next day, or you can just fit a programmable room thermostat with Optimum Start. This learns the heat up characteristics of your home and adjusts the start time each day to suit the conditions.
Make heat more efficiently
Modern condensing boilers need modern controls to help them to operate at higher efficiency. Advanced controls which use Time Proportional and Integral (TPI) control technology will help to keep the flow temperature returning to the boiler below the dew point (55°C) which means that the boiler can operate in its condensing mode more frequently. This is how the boiler becomes more efficient. How can this be done? By adding controls.
Make sure that each part of the heating system is controlled by time and temperature. For systems with stored Hot Water make sure you have a programmer fitted and a room thermostat and cylinder thermostat. These will operate motorised zone valves to control the heat from the boiler and switch it off when no further heat is required. For Combi-boiler systems make sure you have a time and temperature control for the Heating. The Hot Water is controlled when you turn on a tap.If you have no room thermostat fitted it is easy to install one now, without chasing cables into walls. A wireless room thermostat can be sited for optimum performance without requiring any electrical connection. A receiver box needs to be connected to the other controls, this is best done by a heating professional.
The basic control principle of timer and room thermostat was developed over forty years ago. Despite changes in manufacturing methods this has not changed. Nowadays, there are far better controls available such as programmable room thermostats -These combine time and temperature control in one product. They also allow for control to different temperatures at different times of day. Honeywell Home thermostats THR870 and THR872 use the advanced control functions of TPI control as well as temperature overrides for better performance.
Most UK heating systems waste energy by firing unnecessarily early for most of the year. Homeowners set the times based on when they wake up, but then make a guess about when the boiler should fire. So if you want to be warm at 7.30am, you may set your timer to come on 6am. Yet the time taken for your home to warm up varies considerably throughout the heating season. Optimisation allows for energy savings, by varying the start up time of the boiler, depending on the weather. It then learns how the house reacts, so that the calculation can be more accurate the next day.
How to guides
No How to guides found