electrical isolation of undersink water heater

[nedwards9820]

I have taken delivery of an undersink water heater. It is fitted with an RCD on the electrical supply cable which terminates with a euro-plug. I am planning to cut the plug off and hardwire it to a switched fused spur. There is a curious electrical isolation connection that is supposed to be fitted to the hot water outlet. The installation video shows metal-braided water hoses being fitted to the cold and hot water connections. What is the isolator supposed to be doing?

Do you think it is preventing electro-galvanaic processes within the heater? Maybe for properties that have copper water pipes?

As the heater contains a stainless steel heating tank with metallic pipe connections, I can't see that the electrical isolation device on just one side will actually actually achieve any electrical isolation.

Is this a misplaced attempt at double isolation? Maybe the water connections are supposed to be made with non-metalic hoses? Stills from the installation video ( assembly vedio.mp4 - https://we.tl/t-MTnshSodkE ) are attached.

The manual says to ensure you have a professional electrician wire the heater to a 110V supply.

 

[westward10]

Where have you obtained something like that?
Are you in the UK because if so I would be getting a water heater from a reputable source, certainly not from where that came from.
Is it actually suitable for UK voltage?

 

[davesparks]

A number of water heaters, such as those little ariston ones you see everywhere, are supplied with 'dielectric junctions' which are just plastic threaded fittings to isolate installation pipework from the heater tank and element.

The reason for this is to prevent galvanic corrosion through the interaction of dissimilar metals, if you don't fit them you can expect the water heater to rot out and leak relatively quickly.

 

[MJPD29]

The Chinese writing sends alarm bells ringing. Return it and buy one from somewhere local, they aren’t that expensive or hard to find.

 

[James]

as @westward10 has said above.
Before connecting that thing to any power, you need to be certain that it is suitable for use in the uk.
we have many standards for electrical devices, more for water heaters because of the risks involved such as electric shock and even explosion if some faults happen.
if it is not CE approved, then I would not be fitting it in my house or any customers premises.

in all honesty, the only place i would install that thing would be at the the local recycling center (towards the back of the skip so nobody can fetch it back out)

 

[Moley]

The manual says to ensure you have a professional electrician wire the heater to a 110V supply.

The OP says he's going to cut off the plug and wire it to a fused spur. Well, if it's 110v then you certainly don't want to do that.
OP, chuck it in a skip, take a trip to Screwfix and buy one of these Ariston Link Don't forget you'll probably need to fit an expansion vessel too.

 

[nedwards9820]

as @westward10 has said above.
Before connecting that thing to any power, you need to be certain that it is suitable for use in the uk.
we have many standards for electrical devices, more for water heaters because of the risks involved such as electric shock and even explosion if some faults happen.
if it is not CE approved, then I would not be fitting it in my house or any customers premises.

in all honesty, the only place i would install that thing would be at the the local recycling center (towards the back of the skip so nobody can fetch it back out)

The RCD is CE rated and 230V. Is there any way to check it really is CE rated?

 

[Moley]

I'm sure what James meant is - is the water heater CE approved and suitable for UK use. Can you take a picture of the rating plate on the water heater. If, as you said above, 'ensure you have a professional electrician wire the heater to a 110V supply' then it's not suitable for UK 240V

 

[nedwards9820]

A number of water heaters, such as those little ariston ones you see everywhere, are supplied with 'dielectric junctions' which are just plastic threaded fittings to isolate installation pipework from the heater tank and element.

The reason for this is to prevent galvanic corrosion through the interaction of dissimilar metals, if you don't fit them you can expect the water heater to rot out and leak relatively quickly.

The heater comes with a (single) non-metallic hose. This on the cold side plus the plastic fitting on the hot side would prevent galvanic corrosion. It's a pity a) the manual doesn't state that this is what the plastic isolator/junction is for and b) the non-metallic hose provided should be used if it is installed with copper water pipes and c) the installation videos shows metallic hoses (but to a plastic water pipe). And as I'm connecting to an installation with plastic water pipes neither is necessary as galvanaic corrosion won't occur, I guess.

 

[westward10]

It has been asked a few times, is it suitable for UK mains voltage.

 

[nedwards9820]

I'm sure what James meant is - is the water heater CE approved and suitable for UK use. Can you take a picture of the rating plate on the water heater. If, as you said above, 'ensure you have a professional electrician wire the heater to a 110V supply' then it's not suitable for UK 240V

There is no CE label on the body of the heater but there is on the integrated RCD. The plate on the heater hasn't been filled in -- which is pretty poor in itself. The energy rating sticker has a GB label.

 

[westward10]

I'd be sending that straight back from where it came from and purchase a heater from a reputable source. If I was at work and someone asked me to connect that up I would refuse to. The chances of that being non compliant and dangerous are pretty high.

 

[nedwards9820]

Thanks to everyone for their views on this. I'm sending the heater back with this note: "The heater itstelf has no CE rating plate on it so it shoud not be sold in the UK. The information plate that is on it has not been completed to identify basic essential electrical safety information such as the voltage. I will be returning the unit. Please send me a postage-paid label."

 

[DPG]

Thanks to everyone for their views on this. I'm sending the heater back with this note: "The heater itstelf has no CE rating plate on it so it shoud not be sold in the UK. The information plate that is on it has not been completed to identify basic essential electrical safety information such as the voltage. I will be returning the unit. Please send me a postage-paid label."

Definitely the best course of action. Let us know what they say.

 

[MJPD29]

Thanks to everyone for their views on this. I'm sending the heater back with this note: "The heater itstelf has no CE rating plate on it so it shoud not be sold in the UK. The information plate that is on it has not been completed to identify basic essential electrical safety information such as the voltage. I will be returning the unit. Please send me a postage-paid label."

Wise decision