Electric Undersink Water Heaters

[MichaelwGroves]

I have a property divided into several bedsits. Currenty hot water to the basin and sink is from over sink water heaters.
These are now old and look unsightly. I would like to replace with undersink water heaters.
My concern is from what I have seen you need to buy vented taps for these. Due to thier nature on water heat up they drip. My concern is my tenants will think the tap is leaking and over tighten and then break the vented taps which are expensive.
Surly someone has designed an undersink water heater that vents into the waste pipe or expansion vesel so that you can use standard cheaper taps. But I can't find anything, maybe I'm putting the wrong seach into Google. Can anyone recommend an undersink water heater, or let me know what I should be searching for?

Thanks
Michael

 

[lame plumber]

europrisma under sink heaters, own little expn vessel and prv , use with hepvo trap and tundish.

 

[MichaelwGroves]

Thanks for suggestion, I'm looking on Plumbnation, 2kW Heater £89. I assume i then need to buy Ariston Water Heater Kit A - 2 litre expansion vesel @ £32, plus HepVO ?
I assume the expansion vessel and tundish go on the hot water side, or is there a tap into the vessel.
Also, is this a standard for any undercounter water heater to remove need for vented tap?

Thanks

 

[lame plumber]

have a look on the company web site for full instructions for each model, no vented tap needed if set up iaw mfi

 

[lbp plg & htg]

Vented = drip
Unvented = dearer and accessories ie vessel, erv,etc.

 

[MichaelwGroves]

Looked at manuel online for setup, then phoned Ariston technical. Even though manuel suggested vessel not required if tap over 2.8M away, technical said always put vessel. Also he suggested in 99% of all installations mains water will be over 3.5bar so also require restrictor. What are your thoughts?

I assume the Ariston setup is standard, is this the best brand, are there any more recommendations?

 

[lbp plg & htg]

Definite for the prv as you never know if the pressure will rise. As for the vessel then if you have the amount of pipe required to take up the expansion then not a problem.

Not the best brand imo (washing machines yeah), i always go for Heatrae Sadia products personally.