Radiators heat up when hot water is selected

[blade1212]

Hi, I have a Gloworm Ultimate 50FF boiler that likes to cause trouble at least once a year. This years' teaser is that when I select Hot Water, it doesn't heat the water, but instead heats the radiators. Also if I turn the thermostat that controls the radiators to minimum, the radiators still heat - it ignores this thermostat setting.

Any ideas why I can't get hot water ?

Many Thanks.

 

[namsag]

What motorised valves do you have and is it 2 two port valves or one 3 port valve

 

[blade1212]

It has 2 pipes going into it, some wiring to the pcb and a small gas pipe that outputs the pilot gas. If this is the correct device, then looks like 2 ports... is this also called a gas valve ?

fyi. This was replaced about a year ago for a different problem. The make is called Tandem.

EDIT - is the motorised valve likely be next to the hot water tank upstairs ? (ie not the gas valve mentioned above). It has a total of 3 pipes attached to it - so looks like 2 port - it also looks like a nightmare to replace due to the position of the damn thing.

DRAYTON 779H340-3OLO 28MM MID-POS VALVE - do you think it all needs replaced - i read somewhere there was an actuator that could be changed

 

[twgas]

get an engineer out, from your descriptions you obviously dont know anything about your boiler/system.

 

[blade1212]

yep, you got that part right. thanks for the input.

 

[rssteve]

also if its mid position i would say its a 3 port valve - 3 pipes to the same unit.

 

[weareleeds]

A possible cause is seized mechanically 3 port valve or an electrical fault on 3 port valve. To see if it is electrical turn off fused spur for a minute or so then turn it back on to see if it works (it may do it again though when you have htg only next time)