On Sat, 9 Mar 2019 15:19:02 +0000, John Rumm
wrote:

On 09/03/2019 13:39, AnthonyL wrote:
On Fri, 8 Mar 2019 16:22:03 +0000, newshound
wrote:

On 08/03/2019 12:24, AnthonyL wrote:
I've been trying to understand what happens with the hot water when my
wife screams that it has gone cold in the shower so I watched it the
other day.

Turn shower on, burner comes on, led lights (Baxi 105HE) start to
light up to a maximum. Everything fine for a few minutes then the
burner turns off, leds go back, and wife screams. Burner comes back
on - repeat and rinse.

Shouldn't the burner flame just adjust to maintain the temperature
rather than cut-out? Obvious behaviour of the CH but not for DHW.

Otherwise is this indicative of a thermistor problem with hysterisis
or similar? Is it easy to replace?




I had that sort of problem from new with both a Vaillant and a Halstead,
admittedly in an older and rambling house with longish pipe runs. Given
up and gone to a proper system boiler.


I thought the Vaillant was a proper system boiler?

Vaillant make Heating only boilers (vented and unvented), System
boilers, and Combi boilers. Typically the 400, 600, and 800 series
respectively. So a HE 624 is a 24kW System boiler and a 838 a 38 kW Combi.



Goes to show what I know about boilers. Too many years with coal
fired heating.

I'm guessing our bungalow used to have a system boiler in the loft
with supplementary immersion heating. In fact that's pretty well what
I had in my previous coal fired property and to be honest that worked
well as the immersion heater wouldn't need to do anything when there
was a fire and kept a stock of hot water using E7 when heating was
needed.

--
AnthonyL