Hello, I’m looking for advice regarding a very loud water hammer issue in my home, which so far no one has been able to explain.
I’ve lived in a 3-bedroom mid-terraced house for the past 15 years. Shortly after moving in, I had a combi boiler installed in the loft and removed the old water tank from the bedroom. The property is mains-fed: the water supply enters from the street at the back of the house, rises in the corner of the kitchen, and runs up the wall to supply the washing machine, dishwasher, and kitchen sink. From there, it runs along the ceiling to feed the toilet, bathroom sink, and bath, before continuing across to the opposite side of the house and up the bedroom wall into the loft, where it supplies the shower and boiler.
The hot water follows a similar route from the boiler, supplying the shower, bath, bathroom sink, and kitchen sink.
A few years ago, while decorating in the bedroom, I found two 22mm hot water pipes connected at both ends, running between the bedroom and bathroom. Assuming this might be why the bath was taking a long time to heat up, I removed one of the pipes. Since then, I’ve had a loud water hammer noise whenever water is used—particularly when turning taps on, rather than off.
I’ve since tried a number of fixes, but none have resolved the issue. So far, I have:
Replaced all pipework (ensuring pipes are deburred for maximum flow)
Installed full-flow isolator valves
Ensured all pipework is laid with a gradient to avoid trapped air
Clipped and secured pipes every 50cm to prevent movement
Replaced the toilet fill valve
Replaced all taps (kitchen sink, bathroom sink, and bath)
Ensured pipes are not in contact with joists, skirting boards, etc.
Insulated all pipework with foam wrap
Installed a check valve and a pressure-reducing valve
Installed multiple water hammer arrestors
Replaced the stopcock
I’ve been told the mains pressure is around 4 bar, and I’ve reduced it to 2 bar using a pressure-reducing valve. However, the banging persists even at the lower pressure.
I do have a couple of theories, though I’m not sure if they’re valid:
Could differences in water density or flow behaviour between horizontal and vertical pipe runs be a factor?
Could there be an airlock in the boiler, given that it sits at the highest point in the system?
Before I spend any more money trying to resolve this, I’d really appreciate any suggestions. Has anyone experienced something similar, and if so, how did you fix it?
These pipes are driving me mad—any help would be greatly appreciated.
Thank you in advance!
I’ve lived in a 3-bedroom mid-terraced house for the past 15 years. Shortly after moving in, I had a combi boiler installed in the loft and removed the old water tank from the bedroom. The property is mains-fed: the water supply enters from the street at the back of the house, rises in the corner of the kitchen, and runs up the wall to supply the washing machine, dishwasher, and kitchen sink. From there, it runs along the ceiling to feed the toilet, bathroom sink, and bath, before continuing across to the opposite side of the house and up the bedroom wall into the loft, where it supplies the shower and boiler.
The hot water follows a similar route from the boiler, supplying the shower, bath, bathroom sink, and kitchen sink.
A few years ago, while decorating in the bedroom, I found two 22mm hot water pipes connected at both ends, running between the bedroom and bathroom. Assuming this might be why the bath was taking a long time to heat up, I removed one of the pipes. Since then, I’ve had a loud water hammer noise whenever water is used—particularly when turning taps on, rather than off.
I’ve since tried a number of fixes, but none have resolved the issue. So far, I have:
Replaced all pipework (ensuring pipes are deburred for maximum flow)
Installed full-flow isolator valves
Ensured all pipework is laid with a gradient to avoid trapped air
Clipped and secured pipes every 50cm to prevent movement
Replaced the toilet fill valve
Replaced all taps (kitchen sink, bathroom sink, and bath)
Ensured pipes are not in contact with joists, skirting boards, etc.
Insulated all pipework with foam wrap
Installed a check valve and a pressure-reducing valve
Installed multiple water hammer arrestors
Replaced the stopcock
I’ve been told the mains pressure is around 4 bar, and I’ve reduced it to 2 bar using a pressure-reducing valve. However, the banging persists even at the lower pressure.
I do have a couple of theories, though I’m not sure if they’re valid:
Could differences in water density or flow behaviour between horizontal and vertical pipe runs be a factor?
Could there be an airlock in the boiler, given that it sits at the highest point in the system?
Before I spend any more money trying to resolve this, I’d really appreciate any suggestions. Has anyone experienced something similar, and if so, how did you fix it?
These pipes are driving me mad—any help would be greatly appreciated.
Thank you in advance!
