This was a repair I did on a Vaillant ECOTEC Plus 937 this week in Sheffield S8. I was called to fix an issue where the hot water pressure and flow coming out of the hot tap would suddenly drop down to a trickle shortly after opening the tap.
With this particular problem the boiler does not know there is an issue hence it will not display any fault codes.
This is a relatively common issue on the 937 which affects the hot water flow but not the temperature of the water coming out of the faucet. There is a plastic tube about a foot or so in length which sits inside the hot water storage tank which are situated behind the boiler. Most refer to this as a “Dip tube”.
Bottom of vaillant 937 dip tube visible from underneath
The dip tube connects to the domestic hot water outlet pipe and is designed to draw the hot water from the upper part of the storage tank. The dip tube being made from plastic is clearly a poor design decision as the plastic goes brittle over time. The tanks are designed to store the hot water at 80 degrees centigrade, which eventually causes the plastic to become soft mostly around the top end of it.
Vaillant ECOTEC plus 937 plastic dip tube failure
The force of the water being drawn through eventually causes the plastic dip tube to squash restricting the flow. The upgraded tube is now made of stainless steel which shouldn’t cause any issues.
Vaillant ECOTEC Plus 937 plastic dip tube next to stainless tube
I was able to repair the hot water issue on this boiler with one visit as I carry the dip tube as stock item for repairs such as this. The replacement of this tube is not something I do every day but I like to stock the part as it enables me to provide a better service being able to fix this problem in one visit.
Areas where I can repair your Vaillant ecotec plus 937 combi boiler
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.
Rotherham:
I cover the whole area of Rotherham including central Rotherham, Brinsworth, Catcliffe, Canklow, Masbrough, Treeton, Whiston, Greasbrough, Kimberworth, Thorpe Hesley, Rawmarsh, Wentworth, Bolton-on-Dearne, Goldthorpe, Thurnscoe, Wath-on-Dearne, Mexborough, Swinton, Kilnhurst, Hooton Roberts, Ravenfield, Thrybergh, Bramley, Hellaby, Maltby, Thurcroft, Wickersley and Braithwell.
Barnsley:
I cover most of Barnsley including central Barnsley, Birdwell, Stairfoot, Worsborough, Kendray, Ardsley, Athersley, Monk Bretton, Lundwood, Royston, Brierley, Cudworth, Cortonwood, Great Houghton, Shafton, South Hiendley, Brampton, Darfield, Wombwell, Hemingfield, Elsecar, Hoyland, Jump, Barugh Green, Cawthorne, Darton, Dodworth, Gawber, Mapplewell, Pogmoor, Staincross, Wilthorpe, Worsbrough, Thurnscoe and Tankersley.
Doncaster:
I cover a small part of Doncaster including central Adwick, Conisborough, Edlington, Warmsworth and Mexborough.