Hi, I have recently moved into a new place with a Grant Combi 90 MKII Boiler. Having done some decorating, one of the radiators has been off, and today I refitted the radiator.
On refitting the radiator, I allowed some extra water into the boiler system and then bleed the radiator. Before letting some water into the boiler the pressure was at zero (presumably because the radiator had been off).
Once bled, I brought the black pressure gauge up to the red line, by letting some more water into the system. The red line was on 1.5 bar (I now know manual says the system should be at 0.5 to 1 bar).
Once the cold pressure was stable at 1.5 bar, I fired the boiler up, by setting it to “timed” and turning the boiler on (with the timer set to provide power immediately).
The boiler seemed to fire up ok, however, the green neon light on the front of the boiler did not light (nor did the red light).
The boiler continued to heat, and hot water was felt from the taps (all good).
However, the system pressure rose to 2.5 bar and then continued on to 3bar. At which point I shut the boiler off! I now found that black water was dripping from around the expansion vessel. On pressing the valve at the bottom of the expansion vessel, it poured black water out.
So I am guessing that the over pressure has damaged the expansion vessel. Am I looking at just replacing the expansion vessel or has something else likely to have broken?
Also any ideas why the green neon light may not have lit?
Thanks
P
On refitting the radiator, I allowed some extra water into the boiler system and then bleed the radiator. Before letting some water into the boiler the pressure was at zero (presumably because the radiator had been off).
Once bled, I brought the black pressure gauge up to the red line, by letting some more water into the system. The red line was on 1.5 bar (I now know manual says the system should be at 0.5 to 1 bar).
Once the cold pressure was stable at 1.5 bar, I fired the boiler up, by setting it to “timed” and turning the boiler on (with the timer set to provide power immediately).
The boiler seemed to fire up ok, however, the green neon light on the front of the boiler did not light (nor did the red light).
The boiler continued to heat, and hot water was felt from the taps (all good).
However, the system pressure rose to 2.5 bar and then continued on to 3bar. At which point I shut the boiler off! I now found that black water was dripping from around the expansion vessel. On pressing the valve at the bottom of the expansion vessel, it poured black water out.
So I am guessing that the over pressure has damaged the expansion vessel. Am I looking at just replacing the expansion vessel or has something else likely to have broken?
Also any ideas why the green neon light may not have lit?
Thanks
P
