Non plumber here, just a householder so please go easy on me!
Our house was renovated several years ago and all plumbing replaced. It is a mixture of copper and hep20 - listed building so hep20 was better in some places to use existing holes in joists. The system was fully pressure tested after install.
We had a major flood caused by a pushfit connection which had come loose. An engineer investigated and came to the conclusion that it had not been properly pushed originally.
Several months on now I wonder whether there was a bit more to the issue.
The connection was on the secondary hot water return (we have a circulating system). Reading the hep20 manual this is generally not allowed but there is a carve out for domestic installs with intermittent timing on the pump. So ok so far because this is what we have.
At the time of the leak, our expansion vessel on the secondary hot water circuit had failed and was awaiting replacement. We have a booster pump which pumps our water and so at the time of the leak, when turning on a hot tap there was initially a pressure drop to almost nothing and then when the pump kicked in, normal service resumed a few seconds later.
Prior to the leak, I had noticed an occasional splutter of air at the highest tap in the house, only when opening the tap.
After the leak had been repaired and when the expansion vessel replaced this air issue went away.
I would be interested on the views of the experts on my alternative hypothesis about what has happened
1. Expansion vessel failure meant when a tap was turned on, there was an initial drop in pressure.
2. If a dishwasher or some other long running use of water was taking place and an outlet was turned on higher up the house, the demand for water would exceed what was available for a few seconds.
3. In this circumstance it would pull water from elsewhere in the pipe (validate please - this may be nonsense!!)
4. In this circumstance there was potential for a section of pushfit pipe to have no pressure in it at all (validate again please!)
5. Should this be possible, the pushfit pipe may lose its airtight integrity because pressure must be maintained in order to activate the grip (please validate!)
6. At this point, air could be introduced due to a vacuum in that section of pipe (please validate)
7. When the pump kicks in, demand is fulfilled and pressure is restored, including the section of pipe which experienced negative pressure.
8. This motion could lead to the pushfit connection gradually working itself loose over an extended period of time. (Please validate!)
9. Eventually the connection worked loose enough that even with pressure the pushfit could not maintain grip and the system leaked (please validate).
Looking to really try and understand the root cause here to prevent something like this happening again. I am not that convinced about the official diagnosis as had the pushfit connection not been fully pushed, in a pressurised water system it would have failed a pressure test or failed within the first few weeks of installation.
More generally, are pushfit connections airtight during complete loss of pressure? If not, does this not mean that when any pushfit based system is drained for maintenance there is potential for the pipe to shift slightly each time the system is repressurised? After many occurrences of this happening, there could be potential for a leak?
Remember, just a householder here so go easy on this unprofessional diagnosis - just think there is a bit more to it than as was diagnosed.
Thanks!
Our house was renovated several years ago and all plumbing replaced. It is a mixture of copper and hep20 - listed building so hep20 was better in some places to use existing holes in joists. The system was fully pressure tested after install.
We had a major flood caused by a pushfit connection which had come loose. An engineer investigated and came to the conclusion that it had not been properly pushed originally.
Several months on now I wonder whether there was a bit more to the issue.
The connection was on the secondary hot water return (we have a circulating system). Reading the hep20 manual this is generally not allowed but there is a carve out for domestic installs with intermittent timing on the pump. So ok so far because this is what we have.
At the time of the leak, our expansion vessel on the secondary hot water circuit had failed and was awaiting replacement. We have a booster pump which pumps our water and so at the time of the leak, when turning on a hot tap there was initially a pressure drop to almost nothing and then when the pump kicked in, normal service resumed a few seconds later.
Prior to the leak, I had noticed an occasional splutter of air at the highest tap in the house, only when opening the tap.
After the leak had been repaired and when the expansion vessel replaced this air issue went away.
I would be interested on the views of the experts on my alternative hypothesis about what has happened
1. Expansion vessel failure meant when a tap was turned on, there was an initial drop in pressure.
2. If a dishwasher or some other long running use of water was taking place and an outlet was turned on higher up the house, the demand for water would exceed what was available for a few seconds.
3. In this circumstance it would pull water from elsewhere in the pipe (validate please - this may be nonsense!!)
4. In this circumstance there was potential for a section of pushfit pipe to have no pressure in it at all (validate again please!)
5. Should this be possible, the pushfit pipe may lose its airtight integrity because pressure must be maintained in order to activate the grip (please validate!)
6. At this point, air could be introduced due to a vacuum in that section of pipe (please validate)
7. When the pump kicks in, demand is fulfilled and pressure is restored, including the section of pipe which experienced negative pressure.
8. This motion could lead to the pushfit connection gradually working itself loose over an extended period of time. (Please validate!)
9. Eventually the connection worked loose enough that even with pressure the pushfit could not maintain grip and the system leaked (please validate).
Looking to really try and understand the root cause here to prevent something like this happening again. I am not that convinced about the official diagnosis as had the pushfit connection not been fully pushed, in a pressurised water system it would have failed a pressure test or failed within the first few weeks of installation.
More generally, are pushfit connections airtight during complete loss of pressure? If not, does this not mean that when any pushfit based system is drained for maintenance there is potential for the pipe to shift slightly each time the system is repressurised? After many occurrences of this happening, there could be potential for a leak?
Remember, just a householder here so go easy on this unprofessional diagnosis - just think there is a bit more to it than as was diagnosed.
Thanks!
