This was a repair I did this week on Wednesday, on a Vaillant ecotec Plus 937, in Norton, Sheffield, S11, South Yorkshire. The issue was with the hot water not working properly.
I can typically repair hot water issues with the 937 within one visit. I carry plenty of spares these models including the expensive actoSTOR pump that you will read about.
With this particular boiler the central heating was still working ok, but the hot water would run hot for a couple of minutes and then run cold. The boiler was not showing any fault codes. This is often the case with a 937 at some point.
One of the most common faults with the 937 is when the actoSTOR pump fails. This is a secondary pump which is partly responsible for delivering hot water. When these pumps fail the boiler will eventually show up the F81-F91 fault codes. Usually these pump either work or they don’t. When they fail it means you have no water either.
These two faults codes are usually indicative of a pump failure but there are other issues that can these faults. This is why it is important for someone to check the appliance over properly before fitting expensive parts that may not be needed.
Vaillant 937 failed actoSTOR pump next to new pump
An issue with the primary PRINTED CIRCUIT BOARD or the second PCB that controls the pump could also potentially result in the F81-F91 fault. There are others components that can potentially contribute to these problems, which makes repairs on the 937 a bit more difficult than the standard ecotec Plus boilers.
If you consider that the primary pcb retails for around £200, the actoSTOR pump is well over £200, the plate heat exchanger is at around £170 or so and the second pcb is around £60. All these parts cannot be returned to a supplier once they are fitted. Once you start guessing and fitting parts it could end up being a rather expensive repair.
The fault with this particular boiler was slightly less common as the actoSTOR pump was still working intermittently, cycling on and off. On the 937 the hot water storage tanks are designed to be heated up within a set period of time. When the tanks don’t heat within this time period the boiler shows the F81-F91 faults. However when the pump is still working intermittently it may still charge the tanks within the set time hence no faults codes will show.
However when you run the tap the pump doesn’t run long enough to provide consistently hot water, so once the tanks are emptied the water runs cold.
On this boiler it was just the actoSTOR pump that needed to be replaced. This fault with no fault codes can make the 937 much more difficult to repair for individuals who have less experience with them. This pump seemed to have suffered from the effects of limescale, I haven’t seen one like this in Sheffield before to be honest.
Vaillant 937 actoSTOR pump impeller
I repair a lot of these boilers and carry most of the parts mentioned above aside from the least common parts that are rarely needed. As such when I repair these boilers it is for a fixed price and I guarantee that I will only need to replace the components that are faulty.
I also carry the actoSTOR pump as a stock item. Nobody carries this part not even suppliers, it usually has to be ordered in. You will not find anyone else independent with more experience who carries parts like this.
Areas in Sheffield where I can repair your Vaillant ecotec Plus 937
I am located in Elsecar, Barnsley, South Yorkshire. I cover a large part of South Yorkshire including most of Sheffield, Rotherham and Barnsley. I also cover a small part of Doncaster.
Sheffield:
I cover most of Sheffield including central Sheffield, Chapeltown, Ecclesfield, Grenoside, High Green, Oughtibridge, Thurgoland, Wortley, Aston, Aughton, Swallownest, Todwick, Hillsborough and Stannington.