undersink heater with a hot water vented cylinder

[CXR100]

any way i can combine these, customer want to put a undersink water heater so he can switch immersion off and only get instant how water in the kitchen sink (he has electric shower) anybody got any idea if this can be done without using 3 taps, i told him he might have to switch off some lever valves on/off under the sink and he was ok with it, im not to keen on the idea myself but if anybody has got any ideas id be gratefull as always

 

[jase158]

yeah, simples, the water heater comes off the cold mains, the unvented cylinder comes off the cold mains!! separate systems. cant see any issues, may be wrong

 

[jam1979]

we did a central heating job where there was a multipoint water heater under the sink and a forctic cylinder in the airing cupboard but no heating so we de comissioned heater and cylinder and put a combi in there was only 2 electric rads in the house that was all for the heating lol

 

[CXR100]

can see why i can put a check valve on the hot to the tap from the hw cylinder , then a lever valve, tee in above this to the hot from the water heater and put a lever valve here as well , so close the water heater valve on the outlet near the tap and open the lever valve above the check valve to get water from the cylinder, and close the lever valve above the check valve and open the one on the hot outlet of the water heater to get hot waer when cylinder is not heated up, what do you guys think???? im going to refuse to do it if anybody suggests it dangerous. the cwsc in the attic is galvenised so no chanse of melting if the lever valves get left open and the check valve fails . hot water would just pour out of the overflow wouldn't it???

 

[jase158]

oh I see, you want to use both for the kitchen sink, I wouldn't do it personally, because of the chance that they leave both open and cause problems later on. shouldn't be any problems, but I wouldn't do it personally. you would need pressure reducing valve on water heater set to same as unvented cylinder and as said before you would need non return valve before tee to tap and lever valves on each. you could put sure stop switch to make it easier for user to turn each one off.

 

[jase158]

could you fit one of these instead: InSinkErator 44318B GN1100BS Brushed Steel Instant Hot & Cold Water Tap (Tap Only)

 

[jam1979]

why does he want to use both on the kitchen tap

 

[stevetheplumber]

fit the under sink andf cap of the unvented supply

 

[lame plumber]

not really being sensible here, either one or the other to be efficient and safe, one will be full of nice stagnant water if its not being used wont it so not a healthy situation to have.

 

[stevetheplumber]

use a mixer with drinking water connection i think theres a second hand one around here somewhere