Myson Kickspace plinth heater fuse keeps blowing whenever it comes up to temperature

[opps]

I thought I'd sent the following reply earlier but it was still sitting here:

If the unit is wired according to that diagram I see nothing that can give the symptoms you describe other than component failure and the only component I can envisage doing that is the thermostat. I imagine it may be shorting to the metal case when it operates. It's a bit tricky from the photo but are you able to verify it is all correct?

Seeing the way the thermostat is mounted on the heat exchanger it could have easily been overheated during manufacture.

The way the system works in heating mode is is different to how many expect; when the heat exchanger reaches temperature the thermostat kicks in and runs the fan to circulate warm air.

The next test to do is run the heating up to temperature with the switch set to summer so the fan runs and see what happens when it reahces temperature NO DON'T...Just noticed it's wired wrong and thank you for the annotation! I'll have another look and get back


Thank you again for your Brilliant annotation and Adam (now that I've checked more of the thread). What has happenned is the connectors on the supply cable are on the wrong terminals, the whole of Supply Blue + Stat Blue (b) needs to be exchanged with Supply Brown (d)

View attachment 315834

Wired incorrectly by the manufacturer?

 

[SUNRAY]

Wired incorrectly by the manufacturer?

Looks that way.

Spot the difference:
-----------------------------As designed------------------------------------------------------------------ As supplied-----------------------------------

 

[JohnW2]

If products require internal fusing then the manufacturer will fit a fuse; if they have not then one is not required.

That clearly is how one would hope it would be, but it doesn't seem to be how a good few manufacturers think - since, as you know, they not infrequently 'require' an external fuse much smaller in rating than would be required to protect any credible cable - which presumably implies that they believe that such a fuse is 'required'.

Kind Regards, John

 

[SUNRAY]

Looking at the way this is currently wired it can only do anything in summer mode

 

[SUNRAY]

That clearly is how one would hope it would be, but it doesn't seem to be how a good few manufacturers think - since, as you know, they not infrequently 'require' an external fuse much smaller in rating than would be required to protect any credible cable - which presumably implies that they believe that such a fuse is 'required'.

Kind Regards, John

This item comes without a plug and is classed as a component, as such it falls without the requirement to be fully internally protected, just like a time switch/programmer, thermostat or motorised valve for central heating etc. etc.

 

[JohnW2]

This item comes without a plug and is classed as a component, as such it falls without the requirement to be fully internally protected, just like a time switch/programmer, thermostat or motorised valve for central heating etc. etc.

Fair enough, but that's because they are not considered to require any 'protection', beyond that provided by whatever circuit they are connected to.

I was talking about those situations in which MIs 'require' something (e.g. an extractor fan) to have (necessarily 'external') protection beyond that need to protect the circuit/wiring. If they state that 'requirement' presumable they believe that such a level of protection is 'required' (by their product) even though they don't provide that protection internally?

Kind Regards, John

 

[EFLImpudence]

That clearly is how one would hope it would be, but it doesn't seem to be how a good few manufacturers think - since, as you know, they not infrequently 'require' an external fuse much smaller in rating than would be required to protect any credible cable - which presumably implies that they believe that such a fuse is 'required'.

Equally they also, for the UK, state that an isolator is required.

This is obviously unrelated to the construction of the item so perhaps no more valid than their demand for a fuse.

Perhaps they just think like you that as the UK has such things, they may as well be fitted or are actually required.

 

[JohnW2]

Equally they also, for the UK, state that an isolator is required.

They do, and that one really does seem to be sheer nonsense, since there is no way in which their product can 'rwequire' (e.g.'need for protection of itself') an isolator!

This is obviously unrelated to the construction of the item so perhaps no more valid than their demand for a fuse.

As implied above, in the case of the fuse one can at least see why that might think it could 'of value' to their product - but that'snot true of an isolator

Perhaps they just think like you that as the UK has such things, they may as well be fitted or are actually required.

I'm not sure what you think "I think", but I don't think I have ever installed an FCU or an isolator for an extractor fan in my life. (although I suppose I'd probably have to install an FCU if I was going to run one from a sockets circuit - but I don't think I've ever done that).

Kind Regards, John

 

[SUNRAY]

Are you aware this product doesn't always contain an on off switch as it's expected to be installed as a component in a system?

Usually remote on/off switch and often thermostat or included in the heating system.

Used to be popular in hotel rooms where aircon is now the thing.

 

[michael123123]

UPDATE: just got home and switched the wiring.

All working perfectly now

Thanks for the help everyone.

I'll send a quick email to Myson just to let them know!

 

[SUNRAY]

Thanks for the feedback and well done. Your inspection and accurate annotation was invaluable to the solution.

 

[JohnW2]

Are you aware this product doesn't always contain an on off switch as it's expected to be installed as a component in a system? .... Usually remote on/off switch and often thermostat or included in the heating system. ... Used to be popular in hotel rooms where aircon is now the thing.

If you are referring to my most recent post, I was (since EFLI had raised the issue) talking about 'isolators' for extractor fans, nothing to do with "this product".

If an electrical product does not have an 'on/off switch' (e.g. an immersion heater, and a good few other things, particularly heating ones), then there obviously has to be some external functional switching (not necessarily an 'isolator') - but that's simply common sense.

Kind Regards, John

 

[SUNRAY]

If you are referring to my most recent post, I was (since EFLI had raised the issue) talking about 'isolators' for extractor fans, nothing to do with "this product".

If an electrical product does not have an 'on/off switch' (e.g. an immersion heater, and a good few other things, particularly heating ones), then there obviously has to be some external functional switching (not necessarily an 'isolator') - but that's simply common sense.

Kind Regards, John

It was more a general post to several posts heading along the same lines.

 

[JohnW2]

It was more a general post to several posts heading along the same lines.

Fair enough but, also as a 'general' point, and as I said, if an item (any item) of electrical equipment has no 'on/off switch', then it's pretty obvious that one has to provide some external means of switching it on/off !

However, I suppose I should add (since pedants have been known to lurk ) that strictly speaking, to do that the external thing one needs is a 'functional switch', not necessarily something which qualifies an 'an isolator'.

Kind Regards, John

 

[SUNRAY]

Fair enough but, also as a 'general' point, and as I said, if an item (any item) of electrical equipment has no 'on/off switch', then it's pretty obvious that one has to provide some external means of switching it on/off !

However, I suppose I should add (since pedants have been known to lurk ) that strictly speaking, to do that the external thing one needs is a 'functional switch', not necessarily something which qualifies an 'an isolator'.

Kind Regards, John

Yes but for maintenance purposes one should isolate all poles somewhere in the system and incorporating both functions into the same device has advantages.