Home » Posts tagged 'central heating'

Tag Archives: central 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: 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.

%d bloggers like this: