valiant ecotech pro 28 & drayton digistat 3

[scottsarajames]

Hi there.

New to the forum but I have the above valiant boiler. I have bought a new stat which is a drayton digistat 3 wired version.

I know the boiler has the connections 3 - 4 - 5 for an external 240v.

The stat has 3 connections common - load on - load off.

I am familiar with wiring diagrams and the like as I work in the air conditioning industry but I am not 100% sure which goes to which.

Connection 3 on the boiler has a 240v signal so that will be my common ????

Connection 4 is my load on ???????

Connection 5 is my load off ??????

Is this correct ????

Thanks in advance

 

[D_Hailsham]

You only use the common and ON (make on temperature drop) terminals. The OFF terminal (make on temperature rise) is really there when the controller is used for cooling systems.

So 3 to Common and 4 to ON.

 

[scottsarajames]

You only use the common and ON (make on temperature drop) terminals. The OFF terminal (make on temperature rise) is really there when the controller is used for cooling systems.

So 3 to Common and 4 to ON.

Tried that and it doesn't work.

The small flame signal comes on the controller but the boiler doesn't fire up.

Replaced the batteries in the controller as well just incase they were run down.

If I only need to use 2 connections on the boiler how come there are 3 ?

Thanks

 

[D_Hailsham]

Tried that and it doesn't work. The small flame signal comes on the controller but the boiler doesn't fire up. Replaced the batteries in the controller as well just in case they were run down.

The boiler requires a permanent 230v supply. Have you checked for voltage between L and N terminals on the boiler?

Disconnect the wires to stat from 3 and 4, then short terminals 3 and 4 together; the boiler should run continuously. If it doesn't there is a problem with the boiler. If the boiler runs, there is a problem with the thermostat or the wiring. You can find out which by a process of elimination.

If I only need to use 2 connections on the boiler how come there are 3 ?

Ask Vaillant, may be this board is used on something else or may be they are just using a stock connector with 12 terminals rather than having one with 11 terminals specially made.

 

[mickyg]

Hope you haven't done what you put in your OP cos that would blow the board. 5 is an optional neutral. You realistically only need 3 and 4

 

[scottsarajames]

Tried that and it doesn't work. The small flame signal comes on the controller but the boiler doesn't fire up. Replaced the batteries in the controller as well just in case they were run down.

The boiler requires a permanent 230v supply. Have you checked for voltage between L and N terminals on the boiler?

Disconnect the wires to stat from 3 and 4, then short terminals 3 and 4 together; the boiler should run continuously. If it doesn't there is a problem with the boiler. If the boiler runs, there is a problem with the thermostat or the wiring. You can find out which by a process of elimination.

If I only need to use 2 connections on the boiler how come there are 3 ?

Ask Vaillant, may be this board is used on something else or may be they are just using a stock connector with 12 terminals rather than having one with 11 terminals specially made.

Solved it.

Put a link between common and load on and the boiler fired up.

Need a new stat !!!!

 

[D_Hailsham]

Solved it.

Put a link between common and load on and the boiler fired up.

Need a new stat !!!!

Before you rush out to buy a new stat, reconnect the wires at the boiler, remove the stat and short the two wires together at the stat. This will check that there is no break in the cable from boiler to stat.

 

[scottsarajames]

Solved it.

Put a link between common and load on and the boiler fired up.

Need a new stat !!!!

Before you rush out to buy a new stat, reconnect the wires at the boiler, remove the stat and short the two wires together at the stat. This will check that there is no break in the cable from boiler to stat.

That's what I did.

I linked them at the stat so I could prove the cable worked.

 

[D_Hailsham]

That's what I did.

I linked them at the stat so I could prove the cable worked.

Cheat.