Whats this pipe for ?

[steve 006]

Hi folks
I want to fit a 3 port Motorised valve to my boiler, I only have 1 two way on the heating side so hot water is wild and probably taking valuable heat from the heating side as it is always open.

One question I have a Glow worm space saver 75 about 25/30 yrs old. I can see the gas pipe in, and the 28mm flow which splits to CH/HW expansion and and the return which join up again from Hw/Ch pass through the pump and back into the return of the boiler , but at the top of the boiler going into the back there is another 15mm copper tube that goes into boiler, any ideas what this will be?

Thanks
Steve

 

[oldplumber]

Would you not be better off using the boiler scrappage scheme, looking at the cost savings of a new HE combi or vented boiler if you have to keep your 25 yr old cylinder, that will start leaking soon and employ a plumber that knows what hes doing. A little knowledge can be awfully dangerous in this situation.

 

[wnjswozo]

cold feed,but would agree with oldplumber,the boiler youve got is very old