We have a Valliant EcoTec Pro 28 (combi boiler) that supplies the hot water to a small two bed flat.
Following a water cutoff from Thames Water last week, we are now having problems with continuous hot water provision, particularly to the shower. Although turning on the hot water tap for the shower initially triggers the boiler as per usual, after about 3-4 minutes of constant provision the boiler will switch off, almost as though it does not recognise that it still needs to provide hot water, leaving the shower freezing cold unless another hot water tap is then fully turned so as to re-trigger the boiler.
We're unsure whether this is a problem with the boiler itself or simply a flow problem whereby there is insufficient hot water draw from the taps to trigger the boiler.
Help would be much appreciated, whether from a boiler engineer or plumber
Are you a tradesperson and able to answer this question?
Hi Yalda. It sounds as if your problem is directly related to the water being cut off in which case it is almost certainly going to be muck in the diverter valve or filter.
When the water is cut off for maintenance & subsequently turned back on it is very common for water borne debris & colouration to occur until the pipes have purged themselves. If any of the local infrastructure is still the old iron type & you noticed water colouration when the supply was restored then the latter explanation will be responsible.
You may have an inline filter somewhere between the main stopcock & the diverter on the boiler. These will be the ones to check first. If not then there may be a gauze filter inside the fitting on the diverter valve connection,, if not the diverter may need stripping & cleaning. A service kit for this should be available which will have all the seals & a diaphragm. It is desirable get the kit before doing such a job as you don't want to re-assemble with old worn seals. Otherwise fit a new diverter but do check if there are any filters first as a simple clean out may be all that is required.
Other things worth noting are; Is the flow rate or pressure on the hot side less than it was before ? If the answer is no then the DV diaphragm may have become damaged, in which case you are looking at a strip down.
I hope this helps & has clarified the issue for you. Martin.
