T junction after filling loop?

[rhysjc]

Hi all,

Flummoxed on this one. I've had to change a rad valve the other day, and topped the system pressure up this morning. This afternoon I noticed the pressure was about 3 bar and the PRV had been discharging outside. The filling loop had been left connected, the valve on the mains side was left open (head had stripped, assume previous occupier couldn't be bothered to sort it) and so can only assume the non return valve isn't 100%. Anyway, I managed to turn the mains valve with some pliers, disconnect the loop and put the cap on, so problem solved (for now).

However, I noticed that between the end of the filling loop and the boiler, there's a T junction. The pipe goes up the wall beside the boiler, through it, out in to the kitchen, along the wall there and up in to the ceiling. Any ideas at all what this might be for?!

 

[terryplumb]

It goes to / from the central heating radiators

 

[rhysjc]

@terryplumb there’s another pipe coming out on the left which has a radiator symbol on it, I assumed that’s what that was?

 

[terryplumb]

Your boiler has one pipe that takes the water it heats to the rads ,and another that returns the water to the boiler from the rads for re heating ,they are called flow and return pipes.

 

[rhysjc]

Thanks. I’m familiar with both of those but online I’d not managed to find a picture of a boiler with the same setup.