Vaillant Hot Water Mode

[Simon_NoWH]

I have just bought a house with a Vaillant ecoTec 637. The previous owner had some terrible Honeywell system installed but took all the controllers. So I can’t control the system, and in particular I can’t get the hot water on, no matter what I do. I had previously used a tado system, so I have connected this to the eBus as instructed, but still no HW, even if I can now control central heating.

Oddly the boiler doesn’t display the target hot water temp… it seems to be in a central heating only mode. What do I do? I have been through the installer mode for the boiler but I can’t find a setting. Some of the old wiring for the Honeywell evohome is still connected though I have disconnected the thermostat/bridge BDR91… HELP!!
I have all i need for tado, which should work, but doesn’t.

 

[Deleted member 267285]

You need a programmer for the hot water, a cylinder thermostat and a zone valve to activate the boiler. Do you have these?

 

[Simon_NoWH]

I don’t know. How do I tell?
I imagine the whole thing was working fine before the old owners moved out?
The boiler was controlled by a Honeywell evohome system. This was wired to a thermostat BDR91A1000 and a Potterton EP2 controller was attached, but the potterton didn’t seem to control anything - the boiler was on all the time irrespective of settings on the boiler. These are wired to a couple of relay controlled valves via a wiring loom.

 

[Deleted member 267285]

So your Potterton EP2 is the programmer. Where the hot water cylinder is situated, there should be a small thermostat strapped in place with a wire - a bit like a net curtain wire. Wiring loom? Relays? The relays may bring your hot water on. Also if you’re in need, you may have an immersion heater. A couple of photos at this point might be best.

Cylinder cupboard showing: cylinder, any valves and wiring.

 

[Simon_NoWH]

I enclose some pictures below:

 

[Simon_NoWH]

The potterton unit is no longer attached. This has been replaced by a tado extension attached to the + and - terminals of the eBus as instructed by tado.

 

[Simon_NoWH]