HEATING PROBLEM my hotwater works but not the central heating what is probable fault? it does not have a diverter vaLVE WITH THIS MODEL ARISTON MULTICOMBI 23 MFFI 2

Boiler set to central heating only?
Needs pressurizing?
Seized diverter valve?

Low water pressure or low boiler pressure is one of the most common faults Ariston boilers experience (as is common in many other brands too). In the event that your Ariston boiler's pressure does drop too low, the boiler will stop working or "lockout" and display the 108 fault code on the interface.
Jul 7, 2023

Ariston Boiler Problems (Error Codes) & Fixes - Heatable

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Combi-boiler-turn hot water tap on/off and the heating stops for ...

singletrackworld.com/.../combi-boiler-turn-hot-water-tap-onoff-and-the-...

Combi-boiler-turn hot water tap on/off and the heating stops for 20secs ... hot watertakes priority over central heating so when you run the hot tap, heating is ... Yeah onmy worcester combi there is a diverter valve - it feeds either the heating or ...

My central heating works but I have no hot water - 24'7 ...

https://www.247homerescue.co.uk/my-central-heating-works-but-i-have-...

Diverter valves switch heat between the hot water and the central heating. When youturn your hot tap on, the diverter valve temporarily shuts off the water supply ...

Does your boiler keep switching itself off? Here's why ...

www.dhs-uk.com/does-your-boiler-keep-switching-itself-off-heres-why/

Jul 7, 2015 - ... Bathroom Suites, - Showers, - Wet Rooms, - Taps and Accessories, Information and ... Low water pressure can cause your boiler to turn itself off. ... boiler is not turning off, you aren't getting the amount of hot water you require. ... If there is air in your central heating system, then your boiler may shut down.

it could also be the heat exchange

diverter valve fault most likely. when you call for central heating do you get 3 swiggley lines coming off radiator symbol in the boiler display if you do and not getting central heating then definitely diverter fault

Sounds like the by-pass valve diaphragm. This valve detects that hot water is being drawn off at the tap and then diverts the mains input water across the heat exchanger. Very often it's the diaphragm inside the valve which is punctured or split.This can be replaced [depending on model] if you take apart the valve
. Remove the front panel and lower the control panel.The valve is at the bottom left of the boiler
Suggest turning off the service taps to the two heating pipes and the cold mains inlet pipes before tackling the valve

Check the heat exchanger. Often they and gummed up.& you will have to try & flush it out or replace. If this model has the cylindrical type, they are pigs to do.
If this machine is 10 yrs old or more, you might find it better in the long run to have a new boiler
Just a thought, but I assume that the valves on the 3/4 " central heating pipes are turned on
Parts to look forward to later - fan £80 - pump £65 - heat exchanger £110 - diverter valve £65 - pressure relief valve £45

d2 is the code symbol for delay after central heating. and is not a fault code.. however if this is coming on then stopping the operation of the boiler then it usually points to a sticking diverter valve.

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

Kindly

Richie

having found a circuit diagram, realised that the divertor valve was electrically operated.i unplugged this then unclipped the motor from the valve body,the diverter valve is spring loaded and once i'd removed the motor the spring raised the valve to divert water through the dhw heat exchanger,giving us hot water but no heating, if i refit the motor the problem comes back heating no dhw.ordered new motorised valve assembly £30 next day order .
this was a simple fix without having to drain the system down.

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 .