Combi boiler

[ed-ectrician]

I'm a bit of a novice when it comes to boilers. I need to wire up a combi so no s or y plan to worry about. It has a faulty external control/programmer. Is it as simple to wire as 3a fused spur to control to boiler flex? Can i use any controller? Which one should i ask for?! Are they easy to wire up? L-n-e in and out? Easy as that?!

Thank you VERY much

Ed

 

[Swicade]

On a Combi boiler you only need to control the central heating as Hot water is on demand.

A single channel programmer achieves this and is usualy connected across 2 terminals in the boiler totaly seperate from the mains in. So you have a mains 3 core supply from a 3A switch fused spur (as i was informed gas safe regs require double pole switching) and a seperate flex to the programmer fed from the boiler (not the sfs).

Quite often around here people use those remote programmable room stats as the programmer.....reciever unit is mounted close to the boiler and wired up and programmable roomstat (which is battery powered) can be anywhere in the house.

 

[ed-ectrician]

Thanks. Any other help from anyone else?

 

[Mark_Burgess]

Thanks. Any other help from anyone else?

Yep, I echo Swicade's post.

 

[ruston]

Same really , I use Grasslin or Honeywell programmers though , if that helps . Piece of cake to do. Geordiespark will tell you all you want to know about boilers for a couple of bottles of brown lol.

 

[Guitarist]

Definitely worth getting the remote style programmer/stat, as Swicade says. Costs a bit more to buy, but great flexibility and a doddle to install the base. Just make sure you get the correct unit for your boiler.

 

[SKY]

Love the honeywell CMT 927 - not the cheapest but very reliable and gives a nice constant temp in the house but ramping down the boiler when nearing temp but not stopping it.

 

[Geordie Spark]

Same really , I use Grasslin or Honeywell programmers though , if that helps . Piece of cake to do. Geordiespark will tell you all you want to know about boilers for a couple of bottles of brown lol.

Aye ..... Aahhv messed aboot wi' a few dodgy boilers in me time, but aahhv gorra Tidy one noo.

 

[sedgy34]

I have fitted lots hard wired and wireless
when the lecky goes off with wireless some people don't know how to sync them back up can be a pain with revisits

 

[mountainman]

Remember to use heat resistant cable inside the boiler.

 

[ed-ectrician]

According to pg8 of this i need a l n and e from dp spur, to controller then l and n to boiler then 2 switched lives from boiler to controller. Where does 3 core come in? Are u saying use all four conductors in threecore cable (sleeved as lives) and run 3 core from boiler to controller then?

Wouldnt that 3(4) core have to be butyl cable or similar?

Bleaurgh

http://www.plumbnation.co.uk/site/h.../honeywell-cmt927-technical-specification.pdf

 

[ed-ectrician]

Forgot my earth. Think i've got it though.

 

[sedgy34]

Wtf
from spur to programmer LNE from programmer to boiler 5 core flex heat resistant from programmer also 3core &earth to statt (simples)

 

[ed-ectrician]

Thanks. But Stat's wireless so not the 3 core to stat?! Sorry to be a dimlo

 

[mountainman]

I think that you would be wise to employ a spark or, heaven forbid, a heating engineer. Imho

 

[ed-ectrician]

I am a spark, done lots of everything domestic but never did boilers. 2330 is the PRINCIPLES of electrotechnology unfortunately they dont tell you how to do absolutely everything that's what experience and this forum is for! The bloke asking me to do the job is a heating engineer he hasnt got a either! Ta!

 

[mountainman]

Sorry if i insulted you but your comment about a wireless stat not having a cable tickled me, does it not have a receiver that is wired?

And a heating engineer who doesnt know how to wire a combi or follow the MI's would worry me considerably.
I hope that he is GSR.

 

[Merl]

Swicade has it covered in a nutshell!

3 core flex to boiler from 3A SFCU. 5 core flex from boiler to wireless room stat receiver unit as per wiring diagram 'b' page 7 of the link you posted.

Hope it helps!

 

[Swicade]

I wire them exactly as Merl says....the 5 core flex from boiler to room stat receiver gives you live,neutral,earth supply to receiver AND live/switch return from control terminals on the boiler to contacts on the receiver.

 

[ed-ectrician]

Yep got it now!! Sorry it took me a while! Not insulted just explaining where i'm coming from. Final question, if i dont get this honeywell one are principles the same for most similar ones the only difference being more or less switched lives.

 

[Geordie Spark]

Yep got it now!! Sorry it took me a while! Not insulted just explaining where i'm coming from. Final question, if i dont get this honeywell one are principles the same for most similar ones the only difference being more or less switched lives.

All wired stats are pretty much the same as each other, the only difference being some need a neutral running to them so they are known as 3 wire stats (live, switched live, neutral and of course the CPC) while others only need live and switched live & CPC. These are known as 2 wire stats.

Wireless stats are all pretty much the same as each other too - as far as installing them is concerned anyway.

Whichever method you choose - wired or wireless - you have a choice between a simple thermostat or a programmable one. The simple one is used in conjunction with a time switch of some sort which can either be built into the boiler, or a stand alone fixed to the wall next to the boiler.

The programmable thermostat incorporates its own timer and these can switch the boiler on & off at different times of the day and can also select different temperatures for different times of the day, and a completely different set of switching times and temperatures for weekends.

 

[mountainman]

Yes they are all very similar, just read the 'stat wiring diagram in conjunction with the boiler wiring destuctions and all will be good.

 

[ed-ectrician]

Customer doesnt want to pay over hundred quid for the honeywell 927, no wireless needed. Any recommendations for a simpler cheaper stat? Thanks

 

[ruston]

Customer doesnt want to pay over hundred quid for the honeywell 927, no wireless needed. Any recommendations for a simpler cheaper stat? Thanks[/QUOTE

Be more than that if you have to hack a cable in to do it the hard wired way.

 

[Geordie Spark]

Dear God ....... I give up !!!! :hanged: