tepcon cylinder stat with cut out

[egginyourface]

Im an electrician and ive been asked to fit a tepcon cylinder stat.

The thing i dont understand is that there were 2 cables going to the old stat.

Can i just use one of the flexs go through common on the cut out, then from number 2 loop to the common on the stat and out of 1 to the load??

Why is there 2 cables. I would have just copied the exisiting one but the plumber just cut the cables of the old stat and i cant see how it was connected.

This is what the new stat looks like

 

[egginyourface]

Tepcon TPSRM1-1000 Dual Thermostat: Heating Controls Online

 

[BLOD]

what unvented cyclinder is it ?

 

[egginyourface]

tepcon tpsrm1 1000 dual thermostat

 

[egginyourface]

i dont understand why there would be 2 cables going to it. When i go there tomorrow Im goin to open the connection unit and see where they connect.

Any pointers would be appreciated

 

[egginyourface]

Ive forgotten which cylinder it is. Its either ariston or potterton

 

[BLOD]

A Zone valve could be wired through it

 

[egginyourface]

Its a s plan heating system. The Cylinder stat has 2 commons and 2x 1 and 2 connections. The diagram shows L connects to no2 then loops to the actual stat into common.
No1 on the stat shows it connects to A? unsure where this is. The stat shows 1 and to connect to U

 

[egginyourface]

Cant i just go through the cut out through common then to the stat as the cut out will operate and cut supply to boiler if it operates

 

[BLOD]

for s plan hw on from programmer, through high limit stat, then through cyl stat then to 2 port sounds right to me - but don't take my word for it check the diagram for that particular unvented.

 

[egginyourface]

Thanks going to ask the plumber if he has the manual for the particular cylinder

 

[tamz]

Are there 2 immersions on it?

 

[M.Joshi]

This link may explain the function of both SPDT switches a bit better:

Danfoss Randall ITD Dual Cylinder Thermostat: Heating Controls Online

Although not exactly the same stat, it explains what both switches do.

On modern thermostats, you usually wire the safety cut-out in series with the normal cut-off. Although, the safety cut-out could also be used to close a valve or switch off the boiler.

I believe the one you have purchased is for Ariston cylinders.

Look at pages 21-23 of this manual for a guide on how to wire up the two switches in series:

http://www.ariston.co.uk/uploads/doc4e83348036fb1.pdf