Valiant Ecotec 837 - no hot water.

[heatservice]

The only valves on the Vaillant EcoTec combi that isolate the hot taps are: the main isolation valve on CW inlet & the filling loop valve which when in its open position isolates the cold feed to the PHE , when the filling loop valve is turned off again water then flows to taps via the PHE. Like most other combies its built in diverter valve switches the primary HW flow through the PHE (if a hot tap is ON) or around the heating system (if there is a demand for heating and all the hot taps are OFF) never both at the same time, I hope this clarifies it.

 

[fixitflav]

The only valves on the Vaillant EcoTec combi that isolate the hot taps are: the main isolation valve on CW inlet & the filling loop valve which when in its open position isolates the cold feed to the PHE , when the filling loop valve is turned off again water then flows to taps via the PHE. Like most other combies its built in diverter valve switches the primary HW flow through the PHE (if a hot tap is ON) or around the heating system (if there is a demand for heating and all the hot taps are OFF) never both at the same time, I hope this clarifies it.

So the filling loop valve is a 3-port valve, not on a tee as I'd assumed? It still doesn't explain the symptoms, unless it was left in the fill position, and the OP said the system hasn't been "messed with".

 

[heatservice]

I agree, that is why I suggested the CW inlet filter could be blocked, Ive seen it a few times before on the ecoTec, its basically a nylon washer with a fine mesh and if it gets blocked up there will be insufficient flow through the aqua sensor and the boiler wont fire up for HW. The aqua sensor is a spinning paddle which not only detects flow but also volumn of water (ltrs/min).

 

[fixitflav]

The only valves on the Vaillant EcoTec combi that isolate the hot taps are: the main isolation valve on CW inlet & the filling loop valve which when in its open position isolates the cold feed to the PHE , when the filling loop valve is turned off again water then flows to taps via the PHE. Like most other combies its built in diverter valve switches the primary HW flow through the PHE (if a hot tap is ON) or around the heating system (if there is a demand for heating and all the hot taps are OFF) never both at the same time, I hope this clarifies it.

So the filling loop valve is a 3-port valve, not on a tee as I'd assumed? I can see this would be useful, as it would prevent somebody opening a hot tap screwing up the fill operation. It still doesn't explain the symptoms, unless it was left in the fill position. OP said nobody had "messed with" the system.

 

[fixitflav]

So the filling loop valve is a 3-port valve, not on a tee as I'd assumed? I can see this would be useful, as it would prevent somebody opening a hot tap screwing up the fill operation. It still doesn't explain the symptoms, unless it was left in the fill position. OP said nobody had "messed with" the system.

Please ignore. I didn't think earlier one had gone, it was still saying Post Reply.

 

[cdbe]

Just to update - Sister finally got round to calling Vaillant tech support - she described the symptoms and they instantly said it was a collapsed dip tube in the storage tank.

I think it's about £15 and there's a nice youtube video guide so I can do it if she can't get hold of her engineer.

AND - big apologies - it's a 937 not an 837 - so I guess if you guys had been correctly informed by me at the start of the thread you would have all diagnosed this straight away!

 

[heatservice]

Thanks for the update, the 837 is much the same boiler but does not have the 15 ltr storage tank.