Under sink water heater, instant or stored?

[jimAuk]

Hi

We are planning a kitchen extension and due to distance from current hot water tank, rather than running loads of water off to get hot water, thought it might be best to fit an electric under sink unit that then utilises the tap as normal.

I have seen 2 types, ones that are instant water heaters, typicaly about 10Kw, and others that are about 3Kw which heats a small tank about10L of water up ready for use.

Some mention the need for expansion vessels others say if pipe run is long enough expansion can be in pipe.

Which type is best for domestic kitchen, normal hand washing etc. Dishwasher used for main washing.

Thanks

 

[tincup]

Hi

My choice would be stored as they are easy to install. And under 15L require no g3 ticket to fit.
For 10k water heater you'll need a 45A wire. This will need a dedicated position on the fuse board.



HTH

 

[jimAuk]

Thanks, that was my thought as well.

I have seen some nice 10L units for about £90.

Will still run hot water pipes to the sink locations, valves and caped off just in case electric unit failed, or change of mind.

Edit to add.

Think I will go with a 15L 3kw unit (ariston £120), as that will also allow me to cover another sink in a utility room we are also adding next to the kitchen.

 

[OwainDIYer]

An alternative would be to run a second pipe back to the HWC and install a circulating pump. Lag the pipes and you will always have HW ready at the tap.

Put the pump on a press-to-time switch, so in the kitchen press the switch and the pump runs for the next half hour or so.

 

[jimAuk]

Thanks that's a great suggestion, ideal if was doing a bit more disruptive work to the house. But the undersink option keeps all the mess and work to the new build section.