Lukewarm 'hot' water - secondary heat exchanger already changed

[Neil Sutherland]

Hi, I'm looking for help with a persistent problem. I have a Vaillant TurboMax Plus 837E combination boiler which appears to be in fine working order. However, it provides only lukewarm water to the taps and shower. To date three engineers have looked at it but failed to resolve the problem. The diverter valve appears to be working normally, closing the supply to the radiators when a tap is turned on. The boiler temperature remains stable at 60 degrees or higher. I have had the secondary heat exchanger replaced and there seemed to be an improvement immediately afterwards; but it proved short-lived. As things stand, we are able to get hot water to the en suite shower but only by opening a hot tap in the main bathroom. The tap then runs cold, but the shower is warm! It works, but is very wasteful of water. You'll understand that I'm reluctant to call yet another engineer without having some idea what is going on, so if you have any ideas for things to check I'll be most grateful. Thank you.

 

[Neil Sutherland]

Success - at least partially. When I stripped down the Grohe shower valves I found that one was missing the non-return valves in the elbows. I've fitted new valves and, while I was at it, fitted flow restrictors on the cold side. I now have hot water at the taps and even the showers are tolerably warm. I suspect there may yet be more to find, but I'm feeling a lot happier - as is the rest of the family! Thanks to everyone who's chipped in to this thread.