boiler breakdown

[graham1030]

hi everyone,

this morning my housemate woke up and went for a shower as usual but when he turned the boiler on instead of firing up it starting making this awful banging noise which you could hear throughout the house and was vibrating the radiators. the boiler would make a noise like it was taking in water then it would bang about 5 times. at each bang the pressure gauge would fly up and down. even after turning the boiler completely off this still continued. also water was discharging quite rapidly from the discharge pipe. i even turned the stop valve off but the water still came out. i rang the landlord who is fixing it but im training to be a plumber so was just wondering what you think the problem might be as i haven't seen anything like this before.
thankyou

 

[zillaplumb]

could be a variety of things. I would check the circulation pump, pressure relief valve and expansion vessel at last instance, the banging sound was probably the PRV intermittently discharging causing a water hammer in its own sense.

 

[graham1030]

how do i stop the water because its flooding my garden? i have turned off the stopcock which has turned off the water to everything else but not the boiler

 

[zillaplumb]

should have asked is the boiler a combination boiler, or is it a tank fed open vent or sealed system type, with the combination boiler it is generally a sealed system so the prv will continue to discharge until the heating system is empty, as you have turned off the main stopcock the filling loop should not be in working order as you have cut water supply unless it is tank fed which i very much doubt. If it is an open vent type boiler you will need to get the the F&E tank which is usually in the loft and isolate the supply to it. hope this helps

 

[graham1030]

thankyou. it is a combination boiler. we have no tank feed. i turned the stopcock off and 2 hours later it was still discharging at which point i had to leave for work. hopefully my landlord will have sorted it otherwise its going to be a sleepless night. thanks for your help