Inlet expansion water heaters

[Readingplumber]

Hi on inlet water heaters 15 litres and less- you can have the expansion on the cold mains pipe rather than have an expansion vessel if you can reach recommended length mains pipes. -

My question is saying you have an non return valve 1.5 metres away - as permitted by some manufacturers how does the expansion in the 1.5 metres of pipe happen as it is already full of water and cant push its way back into the mains as there is a non return valve there?

Thanks Again

 

[Puddle]

Well the expansion will be converted into extra pressure,I do not have the figures but persume manufactorers have worked out any pressure increase by heating unit will not be detrimental to water supply pipework,as long as a certain length of pipework avalible to take pressure increase caused by expansion
Some systems have special pressure activated taps that open if pressure becomes to great

 

[Bernie2]

Agree with Puddle.

We are often told water is incompressible that isn't strictly true it will compress a certain amount. So that is probably the basis of it.

Also many inlet heaters expand through the spout or special taps as Puddle says.