Myson manifold wiring centres - Internal fuse blowing don't know why !

[wytco0]

I have a Daikin ASHP installed in 2011, it provides heating and hot water. The heating is via a wet underfloor system with 2 separate manifolds, each manifold is connected to a Myson Wiring centre which is linked to stats for each room.

Last year I noticed that one of the manifolds was not triggering the ASHP when the stats were calling for heat, the engineer came out and found that a blown fuse in one of the Myson Wiring centres, its a 300ma small glass fuse on the right hand side of the wiring centre. He checked things over and could not find a fault so he changed the fuse and it was fine for many months. However just recently the fuses in both wiring centres have blown on a couple of occasions.

There seems to be something that both wiring centres must be connected to that is causing this issue, initially I thought maybe one of the motorised heads on the manifold was drawing too much current but that would not affect the other manifold. Its only a small fuse so I don't think it can be controlling anything very powerful.

Has anyone had any experience of this sort of fault or any idea what's causing an abnormal load on the wiring centres?

TIA

 

[oilhead]

300ma glass fast blow fuses usually only monitor control circuits, so maybe one of the thermostats has become resistive.

 

[wytco0]

300ma glass fast blow fuses usually only monitor control circuits, so maybe one of the thermostats has become resistive.

OK thanks, is it easy to test if this is the case? I have 14 stats so I would prefer to test them myself !

 

[wytco0]

I just checked and the glass fuses are 200mA not 300. They are on the 240v side of the transformer in the wiring centre.