Immersion heater tripping!

[Shortcake]

I have fitted a new tank and immersion heater in the loft - all seemed ok and was put in to replace old ones which kept tripping out. BUT this has now tripped and I have to get back into loft to reset it! It is such a simple system so I can't understand what is going wrong. Is it tripping because it is overheating or could it be an electrical fault elsewhere in the system? Any advice gratefully received.

 

[secret squirrel]

Sounds like an electrical fault, if two have started tripping!

 

[easyt]

By Tank I assume you mean hot water storage cylinder and not a cistern. Is the cistern far enough above the cylinder to have adequate head to feed it ??

 

[Shortcake]

Thanks for your respoonse. I was thinking that it must be the thermal trip going because I haven't had any fuses blow etc - its always the trip on top of the immersion heater itself. But do you think it could be an electrical fault somewhere else in the system - i.e at the timer switch?

 

[easyt]

How far above the cylinder is the storage cistern that supplies it. What diameter pipe supplies the cylinder. If you run the hot tap in the bath does it, in effect flow, out of the cylinder faster than it can get in because of lack of head and/or pipe sizes resulting in the element being insufficiently covered and thereby overheating. I am sure that if you supply more details one of the chaps on here will be able to advise more.

Edit: Is your mains supply tap open fully enough. Have you checked if the bath taps beat the cistern fill??

 

[Shortcake]

Thanks - I do mean hot water storage cylinder. The header is definitely sufficient. The micro-circuit breaker and the fuse spur are not blowing - just the thermal trip on the immersion heater.

its a 22mm feed to the bottom of the cylinder and there is a 22mm feed off the top of the tank. My understanding is that the cylinder can never run empty with that set up - I may be wrong!!!!!!!

the cistern is 3ft above the cylinder.

 

[easyt]

Might be worthwhile doing a test and see if the take off exceeds the fill up. Run bath tap hot and check in storage cistern to see how well it maintains. Does it maintain too well (ie is there a blockage in the flow to the cylinder? Is there a valve between cistern and tank and is this fully open? Is mains tap fully open? Is there any danger there may be a partial blockage in the supply to the tank due to insulation having dropped in tank and been sucked in so reducing flow from cistern to cylinder ??

If the previous immersion was also tripping and there is no problem at main fusebox I would suspect overheat due to shortage of water. I am not an expert but those would be my thoughts

Easy T.

 

[Bernie2]

Hmm!

Obviously an immersion heater thermal trip, trips because something is over heating.

The question is "Why is it overheating?"

Most of the responses are trying to find out, if for some reason the immersion heater elements are exposed to air inside the cylinder.

In short is water being pulled out too fast and causing an air gap in the top of the cylinder, which exposes the immersion heater elements to air and causes them to overheat?

Its a bit hard to say if it could be external influences.


Its possible of course, the supply cable could be too small or the Kw of the immersion heater has been increased and its drawing to much power making it overheat. You could have earth leakage problems, but that would have probably tripped your RCD or ELCB by now. That is of course if you have one fitted. I would get the system checked out if your unsure, because unrestricted earth leakage is highly dangerous especially if you have no ELCB or RCD.

 

[ecowarm]

Has it got a solid fuel boiler connected to it?

 

[Shortcake]

Thank you SO much everyone - I think there is a problem when lots of sources are used at the same time and the cylinder is not filling quickly enough - so will be looking into that. MANY MANY THANKS FOR ALL HELP.