Ariston dielectric spacers

[mikeyd]

Not sure if this is plumbing or electrical.
I swapped out a heatrae sadia multipoint II for an Ariston. I'm not a plumber and had to get my old camping gaz blowtorch out. The pipes kind of lined up but I had a leak from the top of the plastic dielectric 1/2" male to female that you have to fit. I basically overtightened it on the H/W side as it wasn't lined up perfectly and stripped the threads. As said I'm not a plumber. I've ordered replacements and will sort out the pipes so not a problem fixing it but does anyone know what the point of the dielectric spacer is? The hot and cold pipes are bonded electrically to the MET, and obviously, the heater has a CPC/earth connection so I don't get the point of it.

 

[oldbuffer]

1. Not sure what you mean by dielectric spacer.
2. If you mean the plastic component to the extreme right of your photograph, this is a tun dish.
3. Its purpose is to let you see if any water that is being sent to the drain.

 

[bernardgreen]

Not sure what you mean by dielectric spacer.

Seems to be an insert of electrically non conducting material, probably fitted with the intention of electrically isolating the external pipework from the internal pipe work of the cylinder.

Why the need to electrically isolate is a another question. Is all pipe work to the cylinder fitted with these ?

 

[muggles]

Depending on your point of view, they're either there to prevent electrolytic corrosion of the body of the water heater, or they're a great warranty get-out for Ariston as a lot of people will chuck them in the bin

 

[muggles]

1. Not sure what you mean by dielectric spacer.

The little nylon fittings that go on the inlet and outlet of the water heater

 

[Nige F]

Something to do with it's factory in Wales ? Dai electric ?

 

[bernardgreen]

they're either there to prevent electrolytic corrosion of the body of the water heater,

Interesting, do all pipes connected to the body of the water heater require this isolation ? Does the inside of the cylinder have to be totally isolated electrically from all external pipe work ? I assume it has an immersion type electric heater. Does the Earth of the immersion heater supply have to be isolated from the internals of the cylinder ?

It might be that the isolation is considered necessary in case the heater develops an electrical fault that put Live voltages onto the cylinder and as a result un-isolated external pipes would become Live.

 

[bernardgreen]

Something to do with it's factory in Wales ?

Probably why they leek

 

[mikeyd]

Interesting, do all pipes connected to the body of the water heater require this isolation ? Does the inside of the cylinder have to be totally isolated electrically from all external pipe work ? I assume it has an immersion type electric heater. Does the Earth of the immersion heater supply have to be isolated from the internals of the cylinder ?

Yes, both pipes are supposed to be fitted with them. No, electrically it is all standard and has to have a CPC. It's just a small under cupboard hot water supply.

It might be that the isolation is considered necessary in case the heater develops an electrical fault that put Live voltages onto the cylinder and as a result un-isolated external pipes would become Live.

No. I think I shouldn't have mentioned electricity at all. I was just wanting to know how putting a plastic spacer in helps reduce corrosion when all parts are connected anyway, either through wires or even water.

I did a bit more searching today and I think muggles might be onto something.

Depending on your point of view, they're either there to prevent electrolytic corrosion of the body of the water heater, or they're a great warranty get-out for Ariston as a lot of people will chuck them in the bin

I can only assume from what I've read that the pipes in the heater are some sort of cast iron, and connecting copper straight to it causes it to corrode. I'll fit the replacements anyways.

Thanks all.

 

[Nige F]

I did a bit more searching today and I think muggles might be onto something.


I can only assume from what I've read that the pipes in the heater are some sort of cast iron, and connecting copper straight to it causes it to corrode. I'll fit the replacements anyways.

.

Maybe not cast iron - maybe zinc coated or galvanized , those would react with copper if touching.

 

[mikeyd]

1. Not sure what you mean by dielectric spacer.
2. If you mean the plastic component to the extreme right of your photograph, this is a tun dish.
3. Its purpose is to let you see if any water that is being sent to the drain.

I was on about the white bits on the inlet and outlet to the heater.
The tundish is old, and not plastic. Was previously connected to the old heaters vent pipe.
It was a surprise for me, (not a plumber) but this new one must vent back out the cold supply as they supply a relief valve (bit with the red dot in it) to plumb in before the tundish (And obviously there is a non-return valve and a 3 bar reducer valve already in place from the old setup)
I'll attach a pic of the old one, which I think was not repairable:

 

[Madrab]

Agree .... It's to avoid sacrificial corrosion. You can get an electrolytic reaction between the dissimilar metals in the pipework (as copper must be used) and internal to the heater therefore the plastic (dielectric)connections create an insulated barrier between the 2.