Changing lower heating element.

I'm pretty sure that the main off-peak lower heating element has gone in my Pulsacoil 2000. I checked the resistance over the element and it is open circuit (although strangely it does seem to heat slightly overnight). I also checked that 240V is getting there and it is. The resistance of my booster heating element is 18 ohms which I think is OK, this heater seems to work fine.

I was wondering how hard it was to change this myself? I can buy a replacement for around 50 quid I think and this must be a cheaper option than getting someone out to do it for me. Do I simply just drain the unit and switch them over? Any tips would be greatly appreciated.

Also, in the meantime is it feasible to switch the wiring over inside so that the top booster heater can be connected to my timer so I heat with this heater using my Economy 7 electricity? This will save me some more cash.

Hi mikcarr,

I agree with your diagnosis. If you are getting 18ohms on the top heater then your testing method is proven good so you can rely on the 'open circuit' result for the lower element. I've noticed too that a failed element can still warm the water to a degree and my theory is that this happens on failed elements where the outer sheath has split and water has saturated the ceramic powder insulation inside allowing current to flow from live to earth before the break in element continuity. The ELCB should stop this happening but maybe your system does not have one or it has failed.

Yes the element is as easy to change as you think. Very time consuming so you'll save a lot of labour charges!

Yes you can wire up your E7 timer output to the 'on peak' heater terminals too and it will do as you suggest. In fact why bother changing the bottom heater at all? Just wire in the E7 timer to the upper heater and use that until it fails too at some indeterminate time in the (hopefully distant) future.

Cheers, Mike

Thanks Mike for the quick reply, great to have clarification from an expert that I'm thinking along the right lines.

I've set it up with the E7 timer connected to the working heater and now things seem to be fine, fingers crossed it'll keep going for a while...

Just another quick question. When I do get around to changing the heating element do I need to add anything to the water when I refill the system? Any inhibitor or anything?