What has gone wrong with my unvented system?

[dpm_dpmartin]

Ah, the answer is "no" then. Should I? Could I?

 

[dpm_dpmartin]

Is there something that shows me the pressure of the cylinder? Nothing is jumping out at me...

 

[dpm_dpmartin]

Just found this underneath the expansion vessel - that's looking good, right?

Images located at a URL are not working again - anyone know why?

http://www.hmusiccentre.org.uk/forumimages/boiler-03.jpg

 

[John D v2.0]

Looks about right, what does it go up to when the tundish is running?

 

[dpm_dpmartin]

I could certainly check that... I definitely need a shower!

 

[John D v2.0]

Also, does it stop running when you turn on a hot tap?

 

[dpm_dpmartin]

It will slow down, yes; and it will stop if I turn off the immersion heater(s) and after having run some hot water off.

 

[John D v2.0]

My money is that the pressure needle will go up to 4 then it will start running. Probably lost some charge from the expansion vessel so you've only got limited expansion capacity left. Ree charging is a simple job for a pro, and is more likely than a faulty vessel.

How hot is the hot water after its been running? Hot then it usually is off the heating? Scalding hot? Or just very hot washing up water hot?

 

[dpm_dpmartin]

When it was gushing down the tundish at quite a flow it was very, very hot. I would say scalding hot, yes.

If I put my finger in the tundish space when it's just starting to dribble, then it's merely very-warm! I don't even know what I'm describing there - do I? But you get the idea, it's a lot hotter when there's a lot more of it, which makes sense. I've obviously been turning the immersions off when it starts to release water now... there's no point watching it allow loads of hot water to exit the house (I want it!).

 

[Lower]

Have you tried manually operating the motorised valve that controls the hot water flow from the boiler through heating coil in your hot water cylinder?

If you hook the lever on the valve into the overide position you would be getting hot water whenever the heating was on and wouldn't have to use the immersion heaters.

 

[dpm_dpmartin]

Now that is a new one on me... there's 3 motorised valves that I can see... I'm gonna guess that you mean one that goes to the big cylinder where there's a label marked "Primary Flow"?

 

[John D v2.0]

It sounds like around 60c to me? So maybe no fault on the thermostat. Maybe the normal heating never heats it that hot so you didn't notice the expansion vessel loss.

 

[John D v2.0]

Now that is a new one on me... there's 3 motorised valves that I can see... I'm gonna guess that you mean one that goes to the big cylinder where there's a label marked "Primary Flow"?

Yes primary flow into the cylinder is the one.
Bear in mind the cylinder thermostat won't cut it off so you'll need to keep an eye on it.
What's the cylinder thermostat set to?

 

[St0rmer66]

Manually opening the zone valve is effectively bypassing a safety device and potentially dangerous. This is why unqualified people shouldn't be giving out advice to unsuspecting people.

 

[Wildcat1961]

My money is that the pressure needle will go up to 4 then it will start running. Probably lost some charge from the expansion vessel so you've only got limited expansion capacity left. Ree charging is a simple job for a pro, and is more likely than a faulty vessel.

How hot is the hot water after its been running? Hot then it usually is off the heating? Scalding hot? Or just very hot washing up water hot?

Do you hold the relevant G3 qualification John?