Turbomax plus 824e

[ChrisR]

It works, but when you turn a tap on the temperature drops right down to 28º before it starts to light. The HW Flow led comes on immediately.

So if the CH had been, on you get a warm bit, a long cold slug then it starts to heat up as normal.

Similar on CH. Fan comes on, pump runs, temp drops way down, then the boiler fires.

Old DV so I replaced it having first seen a HW problem and not the CH version - made no difference. Also tried new HW ntc - no difference.

Vaillant think it must be a pcb problem.

 

[ELZ4742]

might be completely irrellivant but have you tried it with the pre heat on?

 

[ChrisR]

Yes, that works, and helps the problem of the delay in the HW. The boiler still did the same but he effect was less noticeable at the tap.

The temperature displayed is I'm told derived from both the sensors on the hex (flow and return). I wish I'd tried swapping them, but from the feel of the water they were reading about right.