Vaillant EcoTec; heating but no hot water

[douglasheld]

Happy new year!

I'd returned yesterday to a flat that's been more or less vacant since August. The pressure on the Vaillant Ecotec was low, so I used a screwdriver to refill back to 1.5 bar.

The heating works now, but hot water does not come reliably from the taps. If I turn on the tap, the flame comes on and the water runs warm for a moment, then cold.

As for the radiators, I have one that never worked, two are running nice and warm, and one that used to work is now cold. I don't have the feeling that's related but thought I'd mention it.

I have drained and refilled the boiler, cycled the power, and have experimented with the various heating modes and settings as well as making and undoing random small adjustments to the water valves on the heater's underside. All to no effect.

Any thoughts?

 

[douglasheld]

"i" button shows S.7 a moment ago, now S.8, S.2, S.3, S.4 as the flame is relit. This without the water running.

I have no thermostat installed.

Both temperature rheostats are set to the "2 o'clock" position; LCD display reads 47 degrees.

 

[bobw1956]

]"i" button shows S.7 a moment ago, now S.8, S.2, S.3, S.4 as the flame is relit. This without the water running.


S7 = Pump over run
S8 = Anti cycle mode

S2 - S4 = Ignition sequence heating mode.

So the heating side is working correctly.

Now open the hot tap press the "i" button and tell us what the "S" code is showing,

 

[Agile]

It could well be the diverter valve sticking.

The rad that stopped working may well have become sludged up and that needs the system water to be treated or power flushed.

Tony

 

[douglasheld]

]
So the heating side is working correctly.

Now open the hot tap press the "i" button and tell us what the "S" code is showing,

Green light flashes; the status cycles between S.10, S.13, S.14 over and over. I can hear the flame relighting with each sequence.

 

[Agile]

But where is the heat going?

Into the hot water or into the rads?

It sounds as if there is a failure to sustain the flame but you say the heating works normally ??? so that would be unusual !

I must conclude that you really have a blocked plate heat exchanger. But to confirm this you would need to measure the temperature differential across this rapidly, ideally with a dual probe thermometer!

You may need to call a good boiler engineer!

Tony

 

[douglasheld]

Hmm, also see this: //www.diynot.com/forums/viewtopic.php?t=100909

Perhaps in the morning when it's light I'll go check the flue for mice/pigeons or whatever.

 

[bobw1956]

Green light flashes; the status cycles between S.10, S.13, S.14 over and over. I can hear the flame relighting with each sequence.[/quote]

I agree with Agile it looks like the p/heatex is blocked