valves

[hammers4spanner]

come across this today , a 3 port valve then followed by a 2 port what would be the logic of the two port ?? Also from my understanding after recent convo with honeywell you cant fit 3 ports on unvented these days , this system obviously had no signature on the cylinder and is a couple year old ., but main question why the 2 port??

 

[Mike Jackson]

Because it's an unvented cylinder and you need the two port to comply with G3. Seems a bit pointless sticking in a Y plan on an unvented but some people like to.

 

[Howsie]

One of the three safety devices. It's a must.

 

[SimonG]

It's easier to go S plan on an unvented as you have to fit the 2 port. In essence it's been done right, you can go y plan and fit the 2 port as well, but not how i would have done it.

 

[AWheating]

probably find the installer had ordered a y plan pack either because its cheaper or by mistake and could not be bothered to swap due to time.

 

[Roger Welton]

Or possibly was a Y plan then swapped over to a unvented, and just added the 2 port to comply with regs rather than convert to S plan

 

[Stuthewarrior]

Three way valve doing the heating and hot water, honeywell valve to shut of hot water to the tank if the temp stat fails.

 

[neily01]

if the uv cyl over heats it brakes the feed to two port valve which will spring shut if not under power killing the cyl htg feeds. just a safety device.