Unvented system ...No hot water...

[RayPlumb]

I have a unvented system with a combi boiler. Reciently there is no hot water. The central heating works ok. Switched on emmersion heater for hot water.
Any suggestions what to check first..??

 

[heinz57]

Check the motorised valve feeding the cylinder (the metal square box) is it jammed?, is there a power supply problem? if you select hot water it should take about 20 odd seconds to open and about half that to close. If the motor has gone you can buy a new one for about £20 and there easy to fit. Just remember to isolate the electric supply first. Also check your thermostats, sounds like the low level one is ok but you have
a second one higher up the tank and poss on boiler as well, keep us posted and dont neglect this as unvented systems can under certain circumstances be dangerous. Good luck!

 

[Jimbob]

as said, sounds like the overheat stat has tripped, this would need to be manually reset. Really need an engineer to service it because it would have tripped for a reason

 

[RayPlumb]

Checked Motorised valve/ Diverter valve and seemed ok. Tried calling for only hot water again and it worked for about a minute or two, then boiler switched off. Tried it again a few min later with it only calling for central heating and again it worked for about a minute then boiler shut down.
I am guessing it is the boiler faulty and safty switch kicking in.
What do you think .....???

 

[Puddle]

What make/Model of boiler do you have,check pump operation

 

[RayPlumb]

The plumbing problem is a client and didn't take down the make of oil fired boiler. I am not Gas or OFTEC reg so gave the cleint the number of the installer to have a look. Will let you know what they say.
Thanks again

Felt the pump and seemed to be working...