Wiring diagram help - plumber has given up !

[jtritton]

hi

hoping you can help with a wiring diagram, as my plumber has been unable to get the new system working and now i dont have any hot water

i have the following components

glow worm 60ff boiler

honeywell v4073a 3 port valve

honeywell st9400 7 day 2 channel programmer

cmt927 rf programmable room thermostat


(can you have 2 programmers on 1 system ? i was advised by the previous plumber to get these parts..)


many thanks
Jason

 

[gas4you]

Look on the Honeywell web site for a 'Y' plan wiring diagram.

 

[scatmanjohn]

 

[jtritton]

excellent, thank you

Do you know if you can have 2 programmers on one system ? seems a bit strange to me.

i would of thought they would get confused and i would just really need a wireless thermostat instead of a programmable one..

 

[misterdubya]

Why would you want 2 programmers?
1 Programmer 2 Channel is what you previously posted.

Mr. W.

 

[LearningSpark]

The programmable thermostat allows you to set different temperatures for various times throughout the day. The main controller will just tell the CH or HW to come on at a set time. Set main controller CH to constant then use programmable room stat to set temperatures.

 

[jtritton]

hi

the honeywell st9400 7 day 2 channel programmer is a programmer that does both heating and hot water BUT also the cmt927 rf programmable room thermostat is also a programmer that can control the heating.

I can only presume the cmt927 rf programmable room thermostat is for when you just have heating on a timer and the hot water is heated when used, which isnt the system i have.

i was recommended to get these parts, but this is why im getting confused. i dont see the need for the cmt927 rf programmable room thermostat, but its already cost me £100 and i cant send it back. therefore wondering if i can still use both programmers together on one system ?

cheers

 

[D_Hailsham]

i was recommended to get these parts, but this is why im getting confused. i dont see the need for the cmt927 rf programmable room thermostat, but its already cost me £100 and i cant send it back. therefore wondering if i can still use both programmers together on one system?

Whoever said you need both the ST9400 and the CM927 was talking nonsense. You needed the ST9100C, which is a single channel programmer, for controlling HW times (temperature controlled by the cylinder stat). As you cannot change the ST9400, you should just ignore the CH terminals.

This is the standard wiring for a Y-plan, using a 2 channel programmer and a traditional thermostat. You need to make the following changes:

(w/c = junction box aka wiring centre)

Remove the connection from ST9400 CH ON to w/c terminal 4

Ignore completely the connections for the T6360 Room stat

Connect CM927 L terminal to the w/c live terminal (normally terminal 1)

Connect CM927 N terminal to the w/c neutral terminal (normally terminal 2)

Connect CM927 B terminal to same w/c terminal as valve white (normally terminal 5)

Link CM927 L to CM927 A terminal.

(Edit 4/2 11: This diagram is now the correct one for a boiler with pump overrun.)

View media item 30148

 

[jtritton]

wow !! thank you. i can not believe how helpful this forum is

 

[Agile]

I would advise you to have the CH channel of the programmer wired and then leave it on 24 hrs.

The single channel is not usually any/much cheaper and not always stocked as many would just fit the two channel.

If the stat were to fail or as more usual the user gets the setting muddled then the programmer can be used.

As usual I wonder how any "plumber" who works on heating is unable to either wire a standard installation or knows someone who can.

Tony

 

[namsag]

Hark at Agile the man who didnt know boilers should be wired in heat resistant cable and used to use 2.5mm standard twin and earth cable.(see edit)
A little knowledge is a dangerous thing

edit
i will take it back what you did say was 2.5 heat resistant was too big for boiler termial strips and you choose to use thinner non heat resistant cable so it fitted

 

[Agile]

I do wish that you would not post abusive and untrue statements. Typical of someone who hides their identity! That does not help the OP or the forum.

Presumably you learnt that behaviour at British Gas.

 

[namsag]

Nothing abusive in that post at all and its perfectly true it was on the institute of plumbers site i think where you had to be told that .75mm heat resistant was the proper way to do it .

And i have told you in the past i just have an unusual surname Andy Namsag i think its what led me into this industry

No what i learnt at BG was to be a proper gasman with city and guilds not a retrained ariel repair man with a limited knowledge of the industry who comes on a DIY site and is condesending to joe public who are using the site for what it was intended

 

[Agile]

The question you refer to was NOT that I did not know that heat resisting cable has to be used. It related to the availability of smaller sizes of HR cable!

As I do few installations it was more relevant to my seeing so many installations made using incorrect cable types.

This has no relevance to this thread or the OP.

I consider it abusive for you to make untrue and derogatory statements!

But it probably just reflects badly on you.

 

[Agile]

And i have told you in the past i just have an unusual surname Andy Namsag i think its what led me into this industry

To make a statement like that only shows your non serious attitude to life!