Vaillant ecotec plus 438 no heating or hot water

[noddy997]

Very good,
next test, select CH only on, ensure roomstat calling, does the boiler fire up?, if so, turn the roomstat down, does the boiler stop firing?

Yes it fires up and goes off when stat is down

 

[Johntheo5]

OK, turn both HW & CH OFF at the controller, the 3 port valve will/should remain in the (last port of call) CH only position, then switch in the HW only, ensure cylinderstat calling, does the boiler fireup and switch off when cylinderstat is turned down.

 

[noddy997]

OK, turn both HW & CH OFF at the controller, the 3 port valve will/should remain in the (last port of call) CH only position, then switch in the HW only, ensure cylinderstat calling, does the boiler fireup and switch off when cylinderstat is turned down.

Yes it does

 

[Johntheo5]

OK then, seems fine so far, (are we hoping for a failure!!)

Now call for both HW&CH with stats turned up, ensure boiler fires up, turn cylinderstat down, ensure boiler continues firing, then turn the cylinderstat back up, ensure boiler continues firing, then turn the roomstat down and ensures boiler continues firing, then turn it back up and ensure boiler continues firing, if so return to "normal"

If nothing strange shows up then as suggested above installing a indicating light semi permanently which may catch something.

 

[noddy997]

OK then, seems fine so far, (are we hoping for a failure!!)

Now call for both HW&CH with stats turned up, ensure boiler fires up, turn cylinderstat down, ensure boiler continues firing, then turn the cylinderstat back up, ensure boiler continues firing, then turn the roomstat down and ensures boiler continues firing, then turn it back up and ensure boiler continues firing, if so return to "normal"

If nothing strange shows up then as suggested above installing a indicating light semi permanently which may catch something.

But the light won't indicate where or what the fault is?

 

[Harry Bloomfield]

But the light won't indicate where or what the fault is?

No, but it will give you a very clear, unambiguous indication of demand/no demand for heat, thus confirming whether the intermittent problem is from your control system, or the boiler failing to respond to a call for heat.

 

[noddy997]

OK then, seems fine so far, (are we hoping for a failure!!)

Now call for both HW&CH with stats turned up, ensure boiler fires up, turn cylinderstat down, ensure boiler continues firing, then turn the cylinderstat back up, ensure boiler continues firing, then turn the roomstat down and ensures boiler continues firing, then turn it back up and ensure boiler continues firing, if so return to "normal"

If nothing strange shows up then as suggested above installing a indicating light semi permanently which may catch something.

when both heating and hot water are on and room stat is demanding heating and water cylinder stat is down the boiler switches off.

But It doesn't switch off when room stat is down and cylinder stat is demanding heat.

 

[Johntheo5]

when both heating and hot water are on and room stat is demanding heating and water cylinder stat is down the boiler switches off

This isn't correct operation, when both HW and CH are calling then the valve is/should be in mid position, when the cylinderstat is satisfied with the roomstat still calling then the valve should motor over to CH only position and the boiler should remain firing, have to think about this, maybe just repeat this part of the test for now

But It doesn't switch off when room stat is down and cylinder stat is demanding heat.

Correct operation.

 

[noddy997]

This isn't correct operation, when both HW and CH are calling then the valve is/should be in mid position, when the cylinderstat is satisfied with the roomstat still calling then the valve should motor over to CH only position and the boiler should remain firing, have to think about this, maybe just repeat this part of the test for now

Correct operation.

I have checked again and valve does move over and the central heating remains on.

 

[Johntheo5]

So no apparent problems just now??.

 

[noddy997]

So no apparent problems just now??.

Nope. But as there was the original s30 code when pressing i

 

[Johntheo5]

But that should disappear when the boiler is actually firing and a load of other status parameters appear if you scroll up/down, these are not fault codes.

 

[BlueLoo]

So what's actually happened here?
Has anything been done or what?

#confused

 

[noddy997]

But that should disappear when the boiler is actually firing and a load of other status parameters appear if you scroll up/down, these are not fault codes.

I meant from before. As the problem is intermittent and with that being the only code...

 

[Johntheo5]

What is the brown wire in terminal 3 connected to??.