Home » Heating

Category Archives: Heating


Central Heating Radiator Types [type 11, type 21, type 22]

Radiators are available in three main types, detailed as follows:

Type 11 Single panel, single convector. The first digit indicates 1 panel, second digit 1 convector [ridged metal fins on back of radiator]

Type 11 Radiator

Type 11 Radiator

Type 21 Double panel, single convector. The first digit indicates 2 panels, second digit 1 convector [ridged metal fins in middle of radiator, between panels]

Type 21 Radiator

Type 21 Radiator

Type 22 Double panel, double convector. The first digit indicates 2 panels, second digit 2 convectors [ridged metal fins in middle of radiator, between panels]

Type 22 Radiator

Type 22 Radiator

Always check the manufacturers heat output data for each radiator you want to install.

It is also important to compare different radiator styles for heat output. A heated towel rail, as shown below, may look quite big – but often not too good for heating a bathroom.

Chrome Heated Towel Rail Radiator

Chrome Heated Towel Rail Radiator

Sadly heated towel rails are not sufficient to heat a bathroom. It is always worth going for a larger size towel rail, if you intend it to also heat the bathroom. Manufacturers data will confirm the design heat output. Add 25% capacity required if you are hanging towels on it. As radiators can not warm towels and heat rooms very efficiently at the same time.

Please leave a reply or email me at aim.home@gmx.com if you want any help with this post.

I have put a post together giving details of how to choose the right size of radiator for heating a room. The link https://aimhome.wordpress.com/2012/12/30/central-heating-radiator-sizing/

will take you there.

AIM – improving your world without costing the earth


Central Heating: Smart Controls to Save Money

A fully manual central heating can be very inefficient and costly to run. There are a number of measures you can take to improve efficiency and save money.

1 Time Control Clock

Many modern boilers are fitted with an integrated time control clock. Many boilers, especially those more than 5 years old do not have any built in time control.

An independent time control clock is fitted between the fused isolator switch and the electrical connection to the boiler. There are two types of control clock:

Mechanical timer clock.

The Danfoss 103 as shown below was once very popular, and still available if anyone wants one.

Danfoss 103 Mechanical Timer

Danfoss 103 Mechanical Timer

Digital RF* room thermostat.

Digital equipment is now becoming much more affordable. Prices have fallen by 50% in the last couple of years. It is now possible to buy wireless RF thermostats for under £50.00

Danfoss RF Room Thermostat

Danfoss RF Room Thermostat

* RF stands for Radio Frequency [typically 433MHz, with a working range up to 100 meters]

The items above can be combined into a fully digital timer/control/thermostat arrangement [RF programmable room thermostat] as shown below.

Danfoss Prgrammable RF Room Thermostat

Danfoss Programmable RF Room Thermostat

There are three options for the programmable functions. A RF thermostat will only be ONE of the following:

24 hour – one set of time settings will be available for all days of the week. This offers least flexibility of function/lowest cost reduction [if you like a lie in on some days, the heating will come on at the same time regardless]

5/2 day – this offers one set of times for Monday – Friday and the option of different times for Saturday – Sunday. Better than the 24 hour option, but no good if you want to alter different days.

7 day – the best option by far. The 7 day option offers the facility to set different times for each of the 7 days of the week. Fully flexible and gives the option to control heating times around your lifestyle.

The same RF technology is now available for hot water cylinders as shown below.

Danfoss RF Cylinder Thermostat

Danfoss RF Cylinder Thermostat

The standard mechanical thermostat is shown for completeness

Danfoss Mechanical Cylinder Thermostat

Danfoss Mechanical Cylinder Thermostat

The disadvantage of the mechanical setup is that it needs to be hard wired to the boiler controls. The saving in time and materials is much better if a. more expensive,  RF wireless cylinder thermostat is installed due to savings on labour charges.

The most radical and energy saving change to heating controls in recent years are the eTRV [Thermostatic Radiator Valve] and programmable TRV. These two devices offer full automation of each radiator. Before these valves were available it was a major task involving both plumbing and electrical works. at considerable cost, to create separate heating zones.

The eTRV is shown below

eTRV [Thermostatic Radiator Valve]

eTRV [Thermostatic Radiator Valve]

The eTRV is controlled by a remote device similar to a television remote control.

eTRV Remote Control Handset

eTRV Remote Control Handset

The eTRV actuator head can be fitted to many existing standard Thermostatic Radiator Valves. This makes retro-fitting a simple and cheap solution.

Check the link below for the eTRV compatibility guide


Programmable TRV.

The programmable TRV differs from the eTRV in that the time control function is fitted, individually, to each TRV actuator head. The picture below shows a programmable TRV.

Programmable TRV

Programmable TRV

These units again can be retro-fitted to many existing TRVs quickly and at little cost.

The great thing about eTRVs and programmable TRVs is that you can independently switch radiators on and off, regardless of the control settings of the boiler. An example of what can be done is as follows:

Boiler starts at 06:00 and is on until 23:00.

The upstairs TRVs are set to come on at 06:30 and go off at 08:30.

The downstairs radiators are set to come on at 07:00 and go off at 22:00

The upstairs radiators are set to come on at 21:30 and go off at 22:30

From the time settings above the boiler is in operation for 16 hours a day. However 50% of the radiators are only on for 3 hours. The heat demand from the boiler is therfore 100% for 3 hours and 50% for 13 hours.

Typical savings for a boiler consuming 60p worth of gas per hour are 3 x 60p = £1.80 and 13 x 30p = £3.90 total spend = £5.70

If standard radiator valves are installed, without intelligent controls, the same boiler demand would be 16 x 60p = £9.60 almost £4.00 more spent per day, over £27.00 per week, OVER £1400.00 PER YEAR.

With Programmable TRVs and eTRVs costing upto £15 to£40 per unit, they are not cheap. However the cost for a typical property with 3 bedrooms and with 12 radiators would be between £180.00 and £480.00. Still could be £900.00 better off in year one.

Please e-mail me or call me on 07901380746 if you need any further help or advice with heating controls.

Remember once money is spent on wasted energy, you can’t get a refund

Central Heating: S Plan and Y Plan wiring arrangements

There is often great confusion regarding the wiring of central heating systems.

The two most common are known as S Plan and Y Plan. The basic differences are the Y Plan has one three port valve supplying heating and/or hot water. The three port valve can look like a Y shape when looking at the schematic layout of pipework, as shown below.

Y-Plan-Water S-Plan-Water-300x208

The S Plan has two SEPARATE motorised valves, one for heating and one for hot water. These two valves can be independently controlled and switched. It is also possible to add further zones by adding additional thermostats and motorised valves to each circuit.

The wiring of both systems is reasonably uncomplicated if the following diagrams are followed. I have put these together with reference to most popular manufacturers instructions. Trying to mix and match different manufacturers equipment and instructions can be very confusing, and time consuming. The following diagrams are based on a standard 10 way wiring centre. I have included CPC details for all conductors for completeness.

The S Plan diagram is shown below.

S Plan Wiring Centre

The plan above includes provision for a second circulating pump. This may be the case in a larger property where pumped hot water is needed to avoid drawing off too much cold water on long pipe runs from the boiler.

The Y Plan system is less complicated as there is only one three port valve needed.

Y Plan Wiring Centre

The cost savings from installation of thermostatic and timer controls must not be under estimated. I have had Customers who have saved £20.00 PER WEEK in times of peak demand. It should cost between £125.00 and £350.00 to upgrade the heating and hot water control systems. Money well spent, and should be recovered within 12 months due to reduced gas consumption.

Please contact me if you need any further advice or have ideas to improve this article.

I have PDFs for the two wiring centre diagrams. E-mail me at aim.home@gmx.com if you would like copies.

I’ve also included a link to the Honeywell download page. The wiring guide PDF shows details of all available heating/hot water system configurations.



AIM – improving your world without costing the earth.

Central Heating Radiator Sizing

Radiators are often not correctly sized for the room size or intended use. It is important to correctly size radiators for the size of room to be heated and environmental conditions. Rooms with large windows, north facing [in northern hemisphere] and south facing [in southern hemisphere] take more energy to maintain at a comfortable temperature. Radiator sizing also needs to take account of ceiling height. As heat rises a larger radiator size is needed for higher ceilings.

Always check manufacturers data for heat output, stated in BTU/Watt values. Note bathroom towel rail type radiators are generally not suitable to heat a bathroom. Be sure to calculate room heating requirements when choosing a towel radiator.

Chrome towel radiator. Check heat output Watt/BTU if you want this radiator to also heat your bathroom.

The table below details the correct values for different types of rooms and locations. The values are based on 1m³. You can multiply the table values by the volume of your room [length x width x height] to see what you need. Manufacturers and Retailers can give details of Watts/BTU values for each radiator size and type.

Per m³ lounge, sitting room, study, games room, dressing room, dining room bedrooms, bathrooms and shower rooms common areas, halls, landings and kitchens
Approximate heat loss value Approximate heat loss value Approximate heat loss value
Room type Watts BTU Watts BTU Watts BTU
standard room, where non of the factors below apply 51 174 41 140 31 106
north facing room 59 200 47 161 36 122
very large windows or french windows 61 209 49 168 37 127
double glazed 46 157 37 126 28 95
very large double glazed or french windows 56 191 45 154 34 116
north facing with double glazing 54 183 43 147 33 111
north facing* with large windows or french windows 69 235 55 189 42 143
north facing room with very large double glazed windows or french windows 64 218 51 175 39 132

* North facing in northern hemisphere and south facing in southern hemisphere. This is because the exterior structure of the building is in permanent shade. This could also apply to buildings in close proximity to each other. It may also be the case that exterior walls are in permanent shade.

When adding a new radiator to an existing system it is important to check the radiator sizes of all existing radiators. The heat output capacity of your boiler needs to be checked to confirm the additional radiator[s] will work efficiently.

Central Heating Radiator Types [Type 11 Type 21 Type 22]

Radiators are available in three main types, detailed as follows:

Type 11 Single panel, single convector. The first digit indicates 1 panel, second digit 1 convector [ridged metal fins on back of radiator]

Type 11 radiator, single panel single convector

Type 21 Double panel, single convector. The first digit indicates 2 panels, second digit 1 convector [ridged metal fins in middle of radiator, between panels]

Type 22 Double panel, double convector. The first digit indicates 2 panels, second digit 2 convectors [ridged metal fins in middle of radiator, between panels]

Always check the manufacturers heat uotput data for each radiator you want to install.

Please contact me if you need any further help with choosing radiators for your property.

Is Your Gas Boiler Costing Too Much to Run?

Is Your Gas Boiler Costing Too Much to Run?

This post is put together to help you identify if your central heating/hot water gas boiler is consuming too much gas. You do not need any specific skills other than being able to record gas meter values and work with the values shown on your gas bill.

All work on gas appliances must be undertaken by a competent person registered with Gas Safe. The following link will help you confirm the competency of anyone undertaking gas appliance work at your property.


Get to Know Your Gas Meter

Measurement is management. The biggest part of energy efficiency is knowing how much energy is being used. Your gas meter may be either imperial or metric. A metric meter has m3 next to the number counter.

A metric meter displays gas consumed in m³. The following shows the changes in reading for consumption of 1.5 m³.



If your gas meter is imperial [not showing m3 next to the number counter; the following factor can convert cubic feet cubic meters.

100 ft³ = 2.831684659 2 m³

The following link gives details for all heating and hot water boilers


Detailed below are the published values for two Alpha boilers.

Boiler Heat input Heat output Gas Flow
Alpha CB24 12.1 to 28.4 kW 9.3 to 23.3 kW 1.16 to 2.71 m³/h
Alpha CB28 14.3 to 34.0 kW 11.2 to 28.0 kW 1.37 to 3.25 m³/h

This section contains the calculations to convert the published values into cash terms.

Calorific value (CV) is a measurement of the amount of energy contained in gas. CV is usually quoted in mega joules per cubic metre (MJ/m³). Gas has a CV of between 37.5 MJ/m3 and 43.0 MJ/m3.

One cubic meter (1 m³) of gas is equivalent to 11.06kWh.

From the above table it can be estimated the CB24 boiler will consume between 12.83 kW to 29.97 kW

If we base the calculation on a gas price of 5 pence per kWh the CB24 boiler will cost as follows:

Published consumption value x 11.06 x cost of gas (per 1m³)

For the CB24 the calculation is

The minimum gas flow rate calculation is 1.16 x 11.06 x 0.05 = £0.64

The maximum gas flow rate calculation is 2.71 x 11.06 x 0.05 = £1.50

You can use the above calculation, adjusted to the published values contained in your boiler manual. To identify how much your boiler costs to run.

Step 2 Compare Gas Bill to Calculated Data

You can check your gas bill total against the calculated data in the following ways:

Central Heating/Hot Water Timer Control Fitted

  1. Check details for your heating/hot water timer and note total daily hours of operation
  2. Multiply daily values by the time period on your bill.

Central Heating/Hot Water Timer Control NOT Fitted

  1. Divide bill total (minus any standing charges) by the number of days in the time period of the bill.
  2. Divide the daily total by the approximate number of hours of operation per day.

It would be more energy efficient to fit time/temperature control equipment. If not you could note approximate times of operation to compare published consumption data against the cost of your gas bill.

There are many variable conditions that affect boiler performance. A summary is listed below:

  1. System type [Combi, sealed system, open vented]
  2. Size of boiler & central heating system
  3. Age of boiler & central heating system
  4. Ambient temperature
  5. Thermal efficiency of the space being heated. A cold drafty house will cost much more to heat.
  6. Time of operation per day [timed, continuous or manual operation]
  7. Type of central heating controls, if fitted.

Please contact me if you have any experiences of checking your gas bills and if your bill is correct against manufacturers published data.

I would also appreciate if you have any ideas for energy efficiency, or questions to ask. Please let me know.

Save Gas by Boiler Optimising and Servicing

We will match your boiler output to the size of your home. Many boilers use more gas to heat your home than is actually needed. Following boiler manufacturers guidance, we will match boiler output to your house size. Making your boiler cleaner, greener and saving you money!

Our boiler servicing will involve fully inspecting your boiler both inside and out. Some National Companies do the minimum to meet legal requirements. We are thorough, complete and check every part to ensure your peace of mind and safety. Our boiler servicing can take up to two hours to complete. We guarantee a first class service, our reputation depend on it.

SEDBUK was developed under the Government’s Energy Efficiency Best Practice Programme with the co-operation of boiler manufacturers, and provides a basis for fair comparison of the energy performance of different boilers. The following link gives details of boiler efficiency.


There is also a cost calculator so you can check how much future gas prices will cost you.

We will balance your boiler output to supply heating to all radiators in the most efficient way. With the correct chemical inhibitor treatment, correct pump speed and radiator valve settings it is easily possible to improve boiler efficiency by up to 20%.

Central Heating system improvements and Control Upgrade

The addition of a filter within the central heating circuit can improve boiler efficiency by up to 6% [£60.00 per year for a three bedroom house]. This can also extend the lifespan of the boiler, pump and radiators by five or more years. This could save you an additional £500.00 based on the replacement cost of a new gas boiler, pump or radiators.

Your home will get warmer quicker and the temperature levels will be better matched to the needs of your home. You will be more comfortable and saving money!

A £150.00 spend could save you £800.00 over five years. A much better rate of return than any Bank or Building Society could offer.

We offer a range of radiator valve options that let you control each radiator by timer control. This can save up to 20% of boiler operation, without heat level reductions in the rooms in use during day and night. A £300.00 spend could save you £200.00 per year; making you £700.00 better off after 5 years.

Contact us for further details.

AIM – making your home warm and safe, without costing the earth

%d bloggers like this: