Off Peak Immersion Failure?

Hello,

I have a Pulsacoil III unit installed in my flat. For a while now I have been unable to get hot water unless I use the on peak booster function.
Having found this useful forum I have removed the cap from the off peak (lower) immersion and found there is a lot of limescale it in and water dripping from it!! I guess this unit needs to be replaced!
I think the part I need is an XB078 and have found a number of stockists on the internet. (mytub.co.uk are the cheapest I have found for this part, £62.72 incl VAT) Can you confirm this is the correct part?
Are there any other parts that I will need to do this? Do I just drain the tank, replace the faulty immersion and refill the tank? Do you recommend a scale inhibtor additive, if so which one and in what quantity? I have a 160L tank.
Today the overheat light on the front panel has gone out. Hot water still seems to be functioning as it has been. Is replacement of the immersion likely to remedy this aswell?
Any advice you can offer would be great.
Cheers

You are right on both counts, First you must use a good strong immersion heater spanner, I use the box type, not the type with the handle because they slip or buckle, if in doubt hire, it don't waste your money on the rubbish in B&Q. The tank is stronger full, so before draining remove the cable and crack the joint by 1st tightening, then back up, 1/2 a turn is enough, now drain it. It will take a good while to drain off the water as the drain point is very small, you can also use the draincock by the pump with 2 hoses. When dry replace the washer in the MT cock (drain point), or better still replace it with a good quality 1/2" valve and hose union. Clean the flange and use the washer plus 18 turns of ptfe tape on the tread. Yes use 2 litres of any corrosion inhibitor. The price you have seems high, try ringing gledhill themselves for spares.

That's just what I needed. Thanks ST.

Will try Gledhill for parts direct. Their website says they only deal with trade though.

Just to clarify, the flange washer and ptfe tape I refer to is with reguard to the immersion heater not the drain point. Good luck.

You can find parts for the Pulsacoil 3 via this link: Gledhill Pulsacoil 3 Spares