Vaillant echoplus 837, leaking diverter valve

Sounds like you need a new Thermo coupler.
Could be as simple as a dirty pilot and needs cleaning but I suspect a thermo coupler.

A stuck divert-er valve yes replace head, and know this will not cause leaks leaks,leaks are caused by o seals worn and getting old ..and olives on connections replace the above as needed some times a quick tighten with rench will do it leaks that is

yes it is your expansion vessel it sounds under charged to me?your expansion vessel needs to be recharged to 1 bar at least,but check manufacturers instructions it could state different.if the heating is fine and your getting hot water in intervals your diverta valve is moving and working?

We have just had our old system boiler replaced with a vaillant ecotec plus 837 and sounds like a similar working operation to ours. At first I was a little concerned,but I was told by our installer that he was told by vaillant that these very latest boilers size the system on start up for about 10 mins, then take temperature to target flow which you set boiler at. So even by setting target flow temperature very high you still get the initial sizing cycle, which ours was about 30-35c temp. These boilers seem to run biased for efficiency as after a while they modulate the boiler burner down and the radiators run more on the side of warm than really hot like the old type boilers. You also get better efficiency as at lower temperature the boiler condenses better. You will also find you get a more constant temperature in your home rather than over shoots. I was concerned at first, shame there was no info/explanation in user manual as people do need to know that this is normal operation. We are used to ours now, took a month and by the way these boilers can make a creaking noise but was told this normal expansion/ contraction but annoying when sited in bedroom cupboard. Best of luck!

water pressure keeps coming down

what do you mean from the radiator TEMPATUTE adjusting control ( thermosatic rad /valve) if so jurt replace valve

water must be set at 3lts a min ,check diaphragm valve move when hot tap is on, check microswitch ,best of luck

the problem is the diverter valve unit, source a corgi engineer to fit new one, cost for valve approx 80 quid +fitting

Kindly

Richie

diverter valve needs adjusting or replacing.

it sounds like the gland on the valve is leaking unusual in a valve so young but it does happen. is the valve electrical operated or water pressure. you should be able to get a complete diaphram kit with all seals etc .