Pulsacoil a-class no off-peak water heating

Hello,

Some time ago our aclass pulsacoil stopped heating up during off peak, I've checked and topped up the top tank which seemed to have resolved the issue, after some time it has stopped again but the tank is full, it gives the slow flashing led error. I haven't had enough funds to get some one to come and look at it so we were using boost function for hot water for quite some time now, today I had a look around under the lid again after reading some posts on the forum and found something like that.(photo below) Any advice on what might have caused the melting under the contractor and is there an easy fix by replacing any parts?
Please help :pray:

These two relays (C1 & C2) are what switch the two immersion heaters on and of via a signal from the system. Both immersion heaters are 3Kw which means they take a fair bit of current. If there are any loose or dirty connections they tend to generate heat and clearly both these relay bases have suffered the effects of excessive heat (the relays as well I expect). They both need replacing along with the relays, and all the terminals need checking to make sure they are clean and will therefore make a good connection. I would also suggest that the terminals in the heaters are checked as well to see that all is well at their ends. The relay push in contacts can sometimes deteriorate/loosen which leads to some heating which is probably the issue here. Ultimately my advice would be to get a suitably qualified person in to check everything out, either an electrician or heating engineer. I appreciate that this can be expensive but unless you are very confident in your abilities I would advise caution.

Aleks, you say funds are short, and I appreciate that, but my best advice would be to change it for a new thermal store. The A Class is many years old, now, and one day soon it's going to pop altogether...leaving you with no hot water, and maybe days or even weeks until you can get someone to replace it! If you have teenagers, try telling them that they won't have hot water for weeks! You'll be popular! Obviously I don't know where you are, but the cost (we charge) is £1,550 all inclusive (160 litre). I presume someone in your area would be roughly the same. I'm not being funny, but people expect their heating and hot water to go on forever, but change their car every few years.

mmartin wrote:These two relays (C1 & C2) are what switch the two immersion heaters on and of via a signal from the system.  Both immersion heaters are 3Kw which means they take a fair bit of current.  If there are any loose or dirty connections they tend to generate heat and clearly both these relay bases have suffered the effects of excessive heat (the relays as well I expect).  They both need replacing along with the relays, and all the terminals need checking to make sure they are clean and will therefore make a good connection.  I would also suggest that the terminals in the heaters are checked as well to see that all is well at their ends.  The relay push in contacts can sometimes deteriorate/loosen which leads to some heating which is probably the issue here.  Ultimately my advice would be to get a suitably qualified person in to check everything out, either an electrician or heating engineer.  I appreciate that this can be expensive but unless you are very confident in your abilities I would advise caution.

I agree with all Martin has said. I'd add that this is a really common problem with those plug-in relays and I always replace them with the type that has screw terminals for the wires. Also, these things are usually called "contactors" by electricians rather than relays. Asking for relays at an electrical trade counter usually results in blank looks and denials that they sell them.