Vaillant Turbomax 828E No Central Heating Demand!

[martynhr]

Hi,

My Vaillant Turbomax 828E will give me DHW without a problem but no CH. I have no fault codes stored. I have eliminated any external controls by looping connections 3 + 4 but still nothing. I have also tried removing the timeswitch. The status of the CH demand (i+-) (d08) is always zero and if i push 'i' i get 's30' code that means no ch demand from external controls.
However, I can get the CH to work by pushing both the + and - buttons together which I'm told puts it in some chimney sweep mode, although I have only let it run in this mode for a few minutes the radiators start to get hot so the pump must be working. This is the only time I can get the CH demand (d08) code to change.
I have also checked connections 3, 4 + 5 with a meter and I get 240v on connection 5 (meant to be neutral) and nothing on the rest.
Does this sound like main board failure?

If so whats the cost of a main board?

Cheers

Martyn

 

[chrishutt]

Is the polarity of the mains connection right? If you're getting 230V at neutral I suspect not.

 

[bobw1956]

Chris

Pin 5 is room stat which will have 230v 50Hz.
3x4 for programmer stat, which is linked normally

 

[martynhr]

I've checked the mains polarity and its correct.

According to the installation instructions connections 3 + 4 are for room stat with 5 used as a neutral for a 3 terminal room stat, and if there are no room stat/external controls then 3 + 4 are linked to simulate demand and it is controlled by either the timer or manually, (am I correct in assuming this?) but when I link connections 3 + 4 I still get no demand for CH even when the timer module is unplugged or set to on manually. Just thought it was a little strange to have 240v at neutral and nothing out of either terminal 3 or 4 where one of them should have 240v and the other to recieve back 240v to simulate demand.

Any ideas? I'm still thinking main PCB is the problem but a little reluctant to fork out £150 before I get some more feedback from someone who know a little more about it. Before this it had been working fine for about 3 years. (apart from a leaking air vent that I replaced after calling out a corgi registered engineer who told me it was the heat exchanger!)

I saw another post from 2005 where someone had the same problem but nothing was mentioned about whether it was fixed or not!!

Cheers for the suggestions for far.

 

[CorgiIOW]

This is purely based on my experience, Turbo Max, and of late, the Echo Max have a nasty habit of failing in either C/H mode or H/W mode.

Genrally, if you have absolute nothing, then 90% f the time, yes the boards dead.

In answer to you question, yes i would say the board is at fault, but then again im no electronics expert.

Also i have noticed, these tend to go around the 3-4 year mark, the same time the D/Valve starts playing its face up.

Dave

 

[martynhr]

Cheers Dave,

I might go ahead and order one, anyone know where the VUW number is located on the boiler so I can get the correct part?

 

[craig0031]

Cheers Dave,

I might go ahead and order one, anyone know where the VUW number is located on the boiler so I can get the correct part?

Any luck with this ???? i have the same problem now, noone seems to post back how they fixed it !

please message me or email [email protected]

thanks