Heating

[Resu]

Hi all, question to the mentors (and/or fellow trainees!): I'm looking to learn a bit more about how heating systems (more boiler type) work. I can sit and wire a JB following a diagram no bother but struggle to understand some of the different systems. In most of our new builds it seems to be mostly underfloor heating so stats in each room all coming back to a wiring centre above the manifold (simple enough). Anyone know of any decent books or links online?

Thanks

 

[Marvo]

Heating covers a very wide spectrum, can you be more specific about what systems you want to learn more about?

 

[tazz]

We have a plumbers forum.....

 

[Marvo]

Good thinking and there's the green energy forum for ground source and air source heat pumps etc.

 

[telectrix]

and then there's geordiespark with his coal fire and tin bath in the scullery every friday night

 

[telectrix]

and then there's geordiespark with his coal fire and tin bath in the scullery every friday night

 

[Marvo]

Geordiespark's not as green as he is cabbage looking. Rumour has it he can solder as well as do electrical.

 

[Resu]

Sorry just your average domestic stuff, Boiler heats tank, programmer kicks in and stat decides when to call for heat, opens motorised valve but I get a bit confused when it comes to adding tank or pipe stats as depending on the situation ie back boiler or whatever they are or aren't used?

 

[Paul.M]

S-Plan heating diagram:-



Y-Plan:-

 

[Richard Burns]

This is a few diagrams I have drawn up that may be a bit too simple, but might help.
It is a basic diagram of the "programmer kicks in, stat decides when to call for heat, opens motorised valve, Boiler heats tank" approach and should be used in conjunction with the schematics above.
They are only intended to show the process and not the control centre wiring or layout.

I always felt that the system was so simple but never appeared simple, these are an attempt to simplify the process.
As they are ones I have drawn then if I have made any errors just let me know. (I am not a good artist!).

Adding a zone is merely adding another channel doing the same thing as the CH and HW.
I have also drawn a timer overrun that runs the pump on for a while after the stat is satisfied. Again at a very simple level.

 

[Resu]

Cheers Paul. I do have a copy of each of these already though.

Richard they may be simple but it does make a lot more sense seeing them drawn out like that!

Having thought about it again I have more questions! A tank stat only allows the heating valve to open when the tank is hot enough or does it kill the boiler/immersion when it gets to a set temp? Or can they be used to do either? And am I right in thinking pipe stats are used more in back boiler systems?

I know I should ask my journeyman but I feel these are things I should know already and don't want to be caught out! As I said I can follow the S and Y plans no bother. This is the only part of the domestic side of work we do that I am not happy with.

 

[Richard Burns]

Most thermostats used for heating controls have both a normally open and a normally closed contact but they may not be used in all cases (W plan and Y plan may well use the HW off signal).

Thermostats can also be used as high level controls (using a normally open contact) so that if the temperature exceeds a set point then the system operates to cool things down, often recirculating water without the boiler (which is where the pump overrun can be useful to prevent local heat build up)

A tank stat is normally connected so that at ambient temperature the contacts are closed (i.e. using the normally closed and common for connection) this is seen as a "call for heat" to the valve and the valve will open and energise the pump (if appropriate) and the boiler / immersion.
When the stat gets to the set temperature the contacts open and power to the valve (and therefore the boiler and pump) is cut off.

Pipe stats are often used in solid fuel systems to monitor the temperature of the water leaving the boiler, they will usually be operating to prevent an overheat of the water as well since the heating is not as regulated as with standard boilers (not sure about back boilers, sorry)

If you do not know something then it is generally better to ask than to try and fumble through and possibly make things worse.
If you do not feel you can ask someone at work this is a pity as you should be there to learn, no matter what level of experience you are at.

 

[Resu]

Cheers again. Richard. That's exactly what I was after. I know I can ask at work it's just me being stubborn lol.

 

[Jim-Bob]

This is my heating bible: http://www.timstephenson.me.uk/files/2012/01/sundial_complete.pdf

Has helped me understand heating systems a lot better! Keep all this with a zone valve data sheet together for the ultimate heating guidebook!


James