boiler problem

[samanthah]

hello we have just replaced our central heating pump in our central heating system we have bled the system several times to radiators seem ok and get hot but when the hot water is switched on the burner goes off after a minute or so , the pump keeps running . the boiler is an ideal mexico and the pump is a wilo 60

 

[gas4you]

Is this a fully pumped system or pumped rads and gravity primary?

 

[samanthah]

hi dave i think its a fully pumped system

 

[gas4you]

We need to be certain. How many pipes come off the boiler?

 

[samanthah]

dave its definatley a fully pumped system,we've just checked the diagram

 

[Agile]

Have you bled the pump ???

Arte you sure the feed is not blocked?

Tony

 

[samanthah]

hello tony , yes the pump has been bled and works fine with just the radiators its only when we want to have hot water does the burner stop after a minute or so . do you think it might be a faulty thermostat on the hot water cylinder

 

[sooey]

Did you open the motorized valve/valves manually when filling the system?
It sounds like you may have an airlock in the cylinder coil, you may have an airvent on the pipework by the cylinder.
Chrisr might come along later and show you a picture, he likes showing his pictures to strangers over the internet does Chris.

 

[samanthah]

thanks sooey, yes we did open the valves manually when refilling the system and we only get water out of the vent on the top of the coil

 

[Agile]

Can you select HW ONLY ??

If not then run both and turn off all the rads at one end. Run it like that for about 30 min then open rads one by one.

Tony

 

[samanthah]

hi tony yes we can run h.w only

 

[Agile]

hi tony yes we can run h.w only

try it anyway!

Then run both and turn off all the rads at one end closing one every minute. Run it like that for about 30 min then open rads one by one every minute.

Tony

 

[samanthah]

thanks tony, tried that but as soon as hot water switched on it runs for a minute or so then burner stops although pump is still running and motorised valves are open