Central heating systems

Matty2k52k5 · Feb 2, 2009

Does anyone know a good site for diagrams?
I've been trying to understand central heating for a while now but it all goes straight over my head.

Manufacturer provided diagrams seriously confuse me and i'm starting to get worried, i want to know exactly what i'm doing before i finish my apprenticeship.

Thanks in advance.

WarrenG · Feb 2, 2009

Hi Matty & Welcome!

There is a book that you can get which is good for wiring drawing connections:

Dave's Amazon Store - Domestic Central Heating Wiring Systems and Controls

However I don't think it will be too much dissimliar from the manufacturers instructions, as it contains connections to a wide range of systems?

Maybe some other members can offer some further information?

Warren

Guest123 · Feb 2, 2009

Hey mate.

I've had a lot of experience on central heating ranging from 2 bed bungalows to schools and hospitals etc.

Ground source heat pumps, underfloor, trace heating "y" plan "s" plan etc etc.

By and large the manufacturers instructions are pretty good and all you really need to remember is that all most systems are, is one way switches be it room stats, cylinder stats, zone valves, timers etc and once you know what they do connecting into your control box is easy.

If youy have a problem with a specific system let me know.

Cheers

lockhes · Feb 3, 2009

lennytheloon said:
Hey mate.

I've had a lot of experience on central heating ranging from 2 bed bungalows to schools and hospitals etc.

Ground source heat pumps, underfloor, trace heating "y" plan "s" plan etc etc.

By and large the manufacturers instructions are pretty good and all you really need to remember is that all most systems are, is one way switches be it room stats, cylinder stats, zone valves, timers etc and once you know what they do connecting into your control box is easy.

If youy have a problem with a specific system let me know.

Cheers

dont supose you could help me with a s plan system

we have just first fixed 1 and got told to put a 3 core to boiler 3 core to time clock and 3 core to thermostate all from the conection box does that sound right

Tiger · Feb 3, 2009

http://content.honeywell.com/uk/homes/Schemes/s1.jpg

hope this link works, not very good with computers

what about your room stat, cylinder stat

forget that cylinder stat will prob be in same place as junction box. dont forget room stat though.

Guest123 · Feb 3, 2009

Hey there.

The 3 core to the roomstat is right - live feed, switched live return "call", and neutral.

The 3 core to the boiler is right as some boilers need a permanent live feed for the pump overrun setting if the pump is within the boiler, switched live in from your zone valve for heating/hot water and neutral.

As for your the timeclock I would say you need 1 x 3core and 1 x T+E, permanent live feed, neutral, switched live out for the central heating and switched live out for the hot water. Also if there is a 3 port zone valve you will need a signal for hot water off.

In addition to these going back to your control box you should also have 2 x 2 port zone valves, 1 x cylinder stat, 1 x pump (if not in boiler) 1 x frost stat (depending on position of boiler).

If you need anymore help just ask, no problem.

Cheers.

Matty2k52k5 · Feb 4, 2009

Tiger said:
http://content.honeywell.com/uk/homes/Schemes/s1.jpg

hope this link works, not very good with computers

what about your room stat, cylinder stat

forget that cylinder stat will prob be in same place as junction box. dont forget room stat though.

Great diagram cheers.
I'm not doing too badly with combi boilers, they seem very easy compared to this type of boiler ... connecting up inside the 10 way box just confuses me completely. This should help me understand a bit more, thanks very much.

lockhes · Feb 4, 2009

lennytheloon said:
Hey there.

The 3 core to the roomstat is right - live feed, switched live return "call", and neutral.

The 3 core to the boiler is right as some boilers need a permanent live feed for the pump overrun setting if the pump is within the boiler, switched live in from your zone valve for heating/hot water and neutral.

As for your the timeclock I would say you need 1 x 3core and 1 x T+E, permanent live feed, neutral, switched live out for the central heating and switched live out for the hot water. Also if there is a 3 port zone valve you will need a signal for hot water off.

In addition to these going back to your control box you should also have 2 x 2 port zone valves, 1 x cylinder stat, 1 x pump (if not in boiler) 1 x frost stat (depending on position of boiler).

If you need anymore help just ask, no problem.

Cheers.

think we should be about right

we have it all wired up just waiting for plumber to set it all up

ta for your help

we got a plan today which was very easy to understand was our first time doing 1

rust1009 · Feb 4, 2009

Am i being daft in saying that you need 5 core to the boiler. Permanant live, neutral, earth, switched live (demand from cylinder stat or room stat) and pump live if its a pump overrun boiler. Most modern boilers are pump overrun because they have small low water content heat exchangers that require the pump to run and remove the heat from the boiler to avoid whats termed "kettling" that includes boilers that dont house theyre own pumps. You cant go wrong with following Honeywell's guide to the various 2 port, 3 port systems.

Guest123 · Feb 4, 2009

rust1009 said:
Am i being daft in saying that you need 5 core to the boiler. Permanant live, neutral, earth, switched live (demand from cylinder stat or room stat) and pump live if its a pump overrun boiler. Most modern boilers are pump overrun because they have small low water content heat exchangers that require the pump to run and remove the heat from the boiler to avoid whats termed "kettling" that includes boilers that dont house theyre own pumps. You cant go wrong with following Honeywell's guide to the various 2 port, 3 port systems.

Hey.

At most I would say 4core/3core+cpc. As far as I've seen there is no connection for an actual pump overrun signal. When the heating/water is satisfied and stops calling, the pump overrun is taken care of by the permanent live feed at the boiler should it need to. So permanent live, switched live, neutral and earth is sufficient.

rust1009 · Feb 4, 2009

When your pump is located in your airing cupboard the pump live is taken from the permanant live at your boiler (via the pump overrun stat or sometimes just a 2 minute overrun timer such as the worcester 24ri) and fed back to the wiring centre via your pump live (5 core) to supply your pump. This is the only way worcester will have their heat only boilers wired. Agreed though if the pump is housed in the boiler 4 core would be fine.

Guest123 · Feb 4, 2009

Good old worcester. The plumbers I know wont touch them. Vaillant mainly, for domestic installations.

rust1009 · Feb 4, 2009

Vaillant and worcester stand head and shoulders above every other manufacturer. Tough to choose between them. Do me a favour Lenny, i posted a question on another thread under inspection and testing you couldnt help me out with this one could you?

Cheers

WILLRUK · Feb 4, 2009

Don't know if this helps but Honeywell also offer a 1 day training course on heating controls for installers - including electricians. Cost is £35 for the day and they run them at venues around the country.

More info etc on their website. Click on the "SUPPORT SERVICES" tab then Training.

Probably a bit Honeywell centric but a good place to start.

Will