Help with Boiler issue

[M_r_jackson90]

I have a promax he plus combi boiler which has recently developed a fault where the heating and hot water stays on and even though the thermostat and timer are programmed to be off. This happened last week and turning off the boiler for a few hours rectified the problem however its happened again today and turning the boiler off hasn't solved it.

the boiler (heating/water) is on timer to come on morning and night. however it is still running when the timer program is not on. the radiators are red hot (when the timers off) and it is running even if no water is being used

any ideas

 

[muggles]

You have a sticking 3-port valve in your airing cupboard

 

[M_r_jackson90]

You have a sticking 3-port valve in your airing cupboard

how certain are you and how easy is this to repair, also what would be the estimated cost of repair

thanks in advance

 

[muggles]

Reasonably sure from the symptoms you describe. Cost to repair? £150-400 depending on a number of variables

 

[DaleRCL]

You have a sticking 3-port valve in your airing cupboard

On a combi?

 

[terryplumb]

Its not a combi Dale. System boiler ,op got that bit wrong