What controls for Vaillant Ecotec Plus 937 2 heating zones?

[Stapenhill]

Help please?

We have installed a Vaillant 937 in 4 bed detached 1930's house we are rennovating with 1 bathroom & 1 en-suite, seperate pipe work installed for upstairs and downstairs heating zones.

We want to be able to control the heating for up and down independantly, and have fitted 2 x two port Honeywell valves, a Vaillant VR65 control centre, 140 Timeswitch boiler mounted, VRT50 for downstairs and Honeywell 230v Thermostat upstairs (cyclinder stat?)

We have a permanent F78 fault displayed on the boiler and malfunction displayed on the VRT50, the boiler will not adhere to the programme set and continually cycles at night when it should be off, there also seems to be problems with amount of hot water produced, once internal tank is empty starts to run cold. Given that we are unable to control it, we are having to switch it on and off or have it on continually.

We are not sure if all the controls we have are correct for what we are trying to achieve, and would be very grateful if anyone could provide some advice on what to change to resolve the problems as our plumber wasn't any help.

Many thanks!
Helen

 

[David937]

Your whole control system is not compatible.

There should be no cylinder stat, where is the cylinder stat installed?

The system should be wired as an S plan with no Vaillant controls (in your case the VRT50, VR65 and Timeswitch 140).

I would recommend you get rid of all Vaillant controls and fit:

A programmable room thermostat for each zone. The Honeywell CM927 is a good product.

 

[gas4you]

You're certainly learning quick David, but you may need to slow down a bit

The first and foremost problem you have is that the VRT50 is NOT compatible with any other control that uses ebus, which in your case most do.

As said you need to 'throw away' the other Vaillant controls and wire/fit a standard 'Y' or 'S' plan

 

[David937]

BTW I think the mods have stopped me posting new topics, I have posted something three times and it disappears after a few hours

 

[gas4you]

If that is the case then they are totally wrong.

You, at your tender age, but with accurate research, give much more genuine advice than BigBurner.

Note to mods, Big Burner needs banning as you did previously when he was posting as Dr Drivel, not this David937.

His experience may be lacking, but his advice so far has been accurate.

Mods should start to question themselves

 

[Stapenhill]

Thanks for your replies, however need some clarification: do we need to get rid of all the Vaillant controls and replace with 2 x Honeywell CM927 or what about Siemens REV23's mentioned on other posts?

Do the thermostats need to be wired direct to boiler somewhere? (Ebus?) and how do they work in connection to the 2 x 2 port valves to control the 2 zones?

What is a Y or S plan?

We appreciate any advise you can give as we are in the dark as to what to do next and can't afford to spend more money for it still not too work correctly.

Many thanks!
Helen

 

[gas4you]

The Honeywell 927 are very good products.

Personally if I had a choice I would go with the new Siemens REV24, but many people seem to find Siemens controls difficult to understand, although the newer ones have been simplified.

A 'Y' plan has a 3 port mid position valve fitted to it, whilst an 'S' plan uses 2 x 2 port zone valves.

These are all wired (including any stats etc) back to a central wiring centre, from this a switched live is taken back to terminal 4 on the 937 to tell it when there is a demnd for heating somewhere.

 

[David937]

If that is the case then they are totally wrong.

You, at your tender age, but with accurate research, give much more genuine advice than BigBurner.

Note to mods, Big Burner needs banning as you did previously when he was posting as Dr Drivel, not this David937.

His experience may be lacking, but his advice so far has been accurate.

Mods should start to question themselves

Did you see my post called: Poor hot water with Biasi combi boiler?

 

[gas4you]

Mod 11; Who are you implying is being abusive in this post?

From where I am I have seen no abuse whatsoever