Vaillant ecotec heating on when switched off.

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I have a Vaillant ecotec plus which has been playing up. Sometimes when the heating is switched off I come down in the morning or even come home during the day to find the radiators are hot but the heating is switched off. I know about the warm start option and if I switch it off the problem stops. In winter this makes the water run warm but not hot. At times the only way to stop the boiler heating is to switch the warm start off. Is a valve faulty somewhere allowing the heating to come on when the warm start kicks in? This is driving me mad not to mention all the gas I am using. It seems to be worse when the heating is switched off and not on auto. Oh for the days of a nice simple non condensing boiler!
 
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Got nothing to do with condense!

How long has this been going in for? Have u mentioned it to your service engineer?

Probably the most common fault on ecotec. Diverter valve but it could be much more than that.
Needs testing by someone who knows what they are doing.
 
Not a DIY job then Phill? I thought it must be a valve of some sort. The boiler is due a service so I will mention it to my engineer. A little relieved to know it is a common fault.
 
Whilst it is good to do a service at the same time, it is rather more involved that a service and needs a part.

In the meantime you can save most of your woes ( and gas ) by just turning off the warm start.

Tony
 
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Yes Tony I have seen how much the valve is £122! If I turn off the warm start the hot water doesn't seem to get hot enough. Will I have to turn the temp up?
 
You can try turning up the hot water temperature or turning off some larger rads.

But the correct solution is to repair the boiler!

Tony
 
Do you have to top the pressure up?
Diverter valve could be leaking.

It's an easy job to do if I know how to do it. But on this model the front cover forms part of the combustion chamber and as such shouldn't be opened by those not registered/competent or without the equipment to test it afterwards.

I wasn't suggesting it would be done as part of a service, I just got the impression from your post it had been going in for some time.
I'd have no issue with going to do a service and replacing the Diverter valve at the same time at the customers request. It would save them a call out/diagnostics visit, but without that visit I couldn't guarantee the Diverter valve would solve the problem.
 
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The last one that I repaired had been leaking and it damaged the PCB which also needed to be replaced.
 
Do you have to top the pressure up?
Diverter valve could be leaking.

It's an easy job to do if I know how to do it. But on this model the front cover forms part of the combustion chamber and as such shouldn't be opened by those not registered/competent or without the equipment to test it afterwards.

I wasn't suggesting it would be done as part of a service, I just got the impression from your post it had been going in for some time.
I'd have no issue with going to do a service and replacing the Diverter valve at the same time at the customers request. It would save them a call out/diagnostics visit, but without that visit I couldn't guarantee the Diverter valve would solve the problem.

Yes Phil it has been going on for some time on and off. I will be phoning my engineer tomorrow. I had lots of trouble with this boiler when it was first fitted, especially with the heat exchanger. I suspect that the guy who did it when the kitchen extension was built didn't flush it first. I have been told that fitting an external something or other will cure the heat exchanger problems.
 
Yes Phil it has been going on for some time on and off. I will be phoning my engineer tomorrow. I had lots of trouble with this boiler when it was first fitted, especially with the heat exchanger. I suspect that the guy who did it when the kitchen extension was built didn't flush it first. I have been told that fitting an external something or other will cure the heat exchanger problems.

A filter will help but best to get the system cleaned really.
A dirty system is the Likley cause of your current problem.
 
There is a moving pin in the part which has become faulty.

Dirt in the system wears away the rubber seal and it leaks.

Dirt also becomes deposited on the shaft and this becomes stiff to move in the rubber seal and so the part does not fully move to the correct position.
 
There is a moving pin in the part which has become faulty.

Dirt in the system wears away the rubber seal and it leaks.

Dirt also becomes deposited on the shaft and this becomes stiff to move in the rubber seal and so the part does not fully move to the correct position.

So a flush would be in order? Oh! well, considering the time the system was enlarged for the extension it hasn't cost me too much. Just a couple of small parts I managed myself. I am going to take off the cover and see what is involved in changing the valve. I do know my limits and if it looks at all unsafe to do it I won't. Are there any "how to's" on the forum?
 
Just been looking on Ebay at diverter valves and as my boiler is pre 2012 it looks like I can get one for about £50. (ECO Tech plus) This is the brass type which according to one youtube video can't be repaired. Valve part number 178978
 

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