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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Boiler Wiring https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1252151081 Message started by wozzy on Sep 5^th, 2009, 12:44pm

Title: Boiler Wiring
Post by wozzy on Sep 5^th, 2009, 12:44pm

been handed a wiring diagram for a large heating system, the diagram includes a part labelled SPDT (and has a electrical symbol type drawing of a couple of components) . In the print at the bottom is states this part is not included.

What is this part? Anyone installed one? I take it im going to have to make it myself?

Cheers lads

Title: Re: Boiler Wiring
Post by sparky415 on Sep 5^th, 2009, 2:11pm

The only thing I could find was

ON-ON
Single Pole, Double Throw = SPDT
This switch can be on in both positions, switching on a separate device in each case. It is often called a changeover switch. For example, a SPDT switch can be used to switch on a red lamp in one position and a green lamp in the other position.

So a two way switch to you and me
But then again someone clever will tell us what it really means :)

Title: Re: Boiler Wiring
Post by Lectrician on Sep 5^th, 2009, 4:01pm

Sounds like a relay.

Why not post the diagram?

Title: Re: Boiler Wiring
Post by CWatters on Sep 5^th, 2009, 6:51pm

If it is a relay.. Maplin sell them. I needed one on my heating system. You can get plug in relays and matching sockets that are DIN rail mounted. The rail and a suitable small box to put it are harder to find and cost more than the relay itself. You will need to know the contact rating (in Amps) and the coil voltage (12V DC or 230V AC typically).

Examples:
http://www.maplin.co.uk/Module.aspx?ModuleNo=2567&C=SO&U=strat15

http://images.maplin.co.uk/300/jg54j_jg53h.jpg

http://www.rapidonline.com/Cables-Connectors/Control-Gear-Din-Terminal/DIN-Rails-Mount-Boxes/DIN-Rails/64094/kw/din+rail

http://www.rapidonline.com/Tools-Fasteners-Production-Equipment/Cases/DIN-Mount/DIN-Rail-mounting-module-boxes/62579/kw/din+rail

Main problem with finding suitable small boxes is the height. Internal height needs to be enough to take the rail, socket and relay.

Title: Re: Boiler Wiring
Post by Lectrician on Sep 5^th, 2009, 7:10pm

Most wholesalers keep the relays, bases and enclosures.

Edmundsons and likely many others keep a budget brand called IMO - They manufacturer the relay, base and enclosures with dinrail.

http://www.imopc.com/products/6/enclosures.html

Title: Re: Boiler Wiring
Post by wozzy on Sep 6^th, 2009, 9:46am

Hope this works.

I cant scan the diagram as my scanner has gone mad and needs sorting out, it was sent to me in a email but the attachment didnt work properly so i only have a hard copy, i used powerpoint to draw this as best i could.

I was hoping this item would allow the boilers the work independently as the plumber wanted but as both boilers are fired from terminal 11 i cant see how this will happen.

I shall carry on trying the get the full diagram up here soon as i have got to wire this tuesday and the plumber is a bit in the dark with this as am i!

cheers lads

[gallery]wozzy/1252226436.jpg[/gallery]

Title: Re: Boiler Wiring
Post by wozzy on Sep 6^th, 2009, 9:50am

oppppps forgot to put the numbers on!

Cm - fires boilers up
NC- ORANGE FROM hot water zone valve
NO- PERM LIVE
N- neutral
L- BOTH oranges form both zone vales

Both boilers are meant to fire for heating, one boiler is meant to fire for hot***er, besides this part and the fact theres two shunt pumps both truned on from Cm, i cant see how these boilers will work independently as it looks like a standard S plan with two heating zones????

more i look more i dont understand

Title: Re: Boiler Wiring
Post by sparky415 on Sep 6^th, 2009, 10:01am

I have just found a great little site with car relay demos
:)
you want the second one down

http://www.bcae1.com/relays.htm#demo

Title: Re: Boiler Wiring
Post by wozzy on Sep 6^th, 2009, 1:06pm

cheers so i all i have to get is a SPDT relay and a enclosure?

I cant see how this system is going to work as the plumber wants at all.

Title: Re: Boiler Wiring
Post by Lectrician on Sep 6^th, 2009, 5:51pm

Most relats are DPDT, the extra pole will just not be used.

Title: Re: Boiler Wiring
Post by wozzy on Sep 8^th, 2009, 8:08pm

to start thankyou very much guys for all the help didnt fire up the system today due to quite a bit of extra work needed and plumber wasnt ready but did wire a fair bit of the panel including the relay, which thanks to your advice i understood even though it wasnt the correct one as Lec pointed out.

To save starting a new thread i though i would add to this one.

My concern now revolves around loading of the system. The supply is from a D16 breaker, then it went into the panel and through B6 breakers. I have had to remove these breakers to allow for a more traditional system plan. My problem is these boilers are large and there are four small pumps and one large pump. Some items such as wireless stats require the supply to be fused to 3amp.

I think i will struggle running this lot on three amps, i take it my only option is put the supply for the stats through 3amp din rail mounted fuseholders?

Title: Re: Boiler Wiring
Post by Lectrician on Sep 8^th, 2009, 8:21pm

I would not worry too much about fusing 6amp down to 3.

Why a D type breaker? Seems extreme? Especially if this then feeds an array of B's.

What size pumps are they? They cant be too beefy surely? What size pipework is it? They are typically around 30/40 watt for the smaller ones, 100watt upwards for a 'decent size'. I have seen some 300w ones, but that was the largest, and that was for a huge school.

Title: Re: Boiler Wiring
Post by wozzy on Sep 8^th, 2009, 8:37pm

i though type D was a bit extreme. It may be because the old pump was a huge belt driven thing.

i have removed the B6s so was going to change the D16 to a C6 at the disboard.

The pipe work is 38mm i think with some sections of large welded steel where it would have been impractical due to the number of tee's. The pump is a grundfos 4180 i have seen a data sheet for it but gave no indiction of loading just pumping stats and so on. :-?

dont want this to cause problems when firing up, most of the time 3 pumps will start up simultaneously.

I will take some pics of this lot once done and post them if anyone is interested?