16-11-2016, 02:06 PM
Michael, the house was a council house, as you should have spotted from just a perfunctory skim of the news story.
As Sam says, the take-off from the top of the cylinder is taken up to the cold water tank, well above the water level. The cold water tank obviously has an overflow to the outside world, and by design this has to be in a conspicuous place so that it's noticed - this is for spotting a failed ballcock, as you say. But these don't always remain conspicuous. For example, in a house belonging to a relative, an extension means that water discharges from the overflow pipe and rolls across the new flat roof and into the gutters. You ain't gonna see that happening from the garden!
In this instance, some discharge from the overflow might well have occurred - like I said earlier - but as this happened at 2.30AM, it's highly likely that during the build-up to this, it simply wasn't spotted. It was late November, so dark at around 4PM, and the family had only just moved in - literally that very same day - so weren't familiar with the property and wouldn't have had a chance to work out all this sort of stuff. Indeed, beyond the likes of us, would a "normal" person make a point of locating overflow pipes on day 1 in a new house, whilst unpacking and trying to get their 2 kids bedded down in their new room? Indeed, the father was asleep but still dressed at 2.30AM when it happened, which suggests that they'd been so busy that they'd not had a chance to set up a bed in their own room yet.
I'm not sure the overflow pipe would have needed to have been dipped in the water in the tank, but could certainly see how that would greatly accelerate the process. With a faulty thermostat, the water in the DHW cylinder would have been bubbling away really quite violently, after all. And if the pipe runs were short, there would have been a reasonable amount of conduction via the water (I'm surprised at how warm my pipes are, even when they appear in the loft).
I can only presume that the previous tenants only ran the immersion heater for short periods of time.
There is one puzzling aspect:
It's not impossible, but it's really unusual for an "immersion tank" to be in the loft, assuming he meant "DHW cylinder". I'm assuming this is someone being unclear in their use of language, and that the cylinder was in the usual airing cupboard. Assuming that's the case, and the only thing in the attic was the cold water storage tank, then an inspection of that would have revealed nothing unless the immersion heater had been running for a decent amount of time when the inspection was carried out. Well, perhaps it might've revealed the overflow pipe being too close to (or in) the water? So that sounds like a poor excuse to me, sadly.
Regarding the question of negligence, inspecting an immersion heater sounds like a difficult task. How many hours would you have to hang around on site for? How would you ensure it's going on and off? One of those "clever" clamp meters that can estimate current in a cable (rather than a single core) might do the job, but those are rare, and the only one I've ever seen is no longer made. So you'd have to disconnect the heater and put an ammeter in series - or run it with the cover removed if there was access to the post-switch heater circuit. Or perhaps leave a logging thermometer? Really, I think this relies on a tenant reporting strange sounds or scalding water, but that's a whole other minefield!
From what I've read, some councils and housing associations decided to replace certain types of immersion heaters after this tragedy. Preventative maintenance.
Anyway, what happened happened, and it's happened on more than one occasion. Greater awareness of the risk can only be a good thing, and I'm sure the families concerned would wish that no-one else has to experience what they have. Ultimately, not all installations are perfect, and not all installations remain perfect (e.g. pipework can move when people throw things in their lofts). I remember taking great care in the design of my system to ensure that the pipework couldn't "slump" in future, but then I spent many weeks installing my new water tank - not a luxury available to the average contractor doing work for a local council who would have screwed the price right down.
As Sam says, the take-off from the top of the cylinder is taken up to the cold water tank, well above the water level. The cold water tank obviously has an overflow to the outside world, and by design this has to be in a conspicuous place so that it's noticed - this is for spotting a failed ballcock, as you say. But these don't always remain conspicuous. For example, in a house belonging to a relative, an extension means that water discharges from the overflow pipe and rolls across the new flat roof and into the gutters. You ain't gonna see that happening from the garden!
In this instance, some discharge from the overflow might well have occurred - like I said earlier - but as this happened at 2.30AM, it's highly likely that during the build-up to this, it simply wasn't spotted. It was late November, so dark at around 4PM, and the family had only just moved in - literally that very same day - so weren't familiar with the property and wouldn't have had a chance to work out all this sort of stuff. Indeed, beyond the likes of us, would a "normal" person make a point of locating overflow pipes on day 1 in a new house, whilst unpacking and trying to get their 2 kids bedded down in their new room? Indeed, the father was asleep but still dressed at 2.30AM when it happened, which suggests that they'd been so busy that they'd not had a chance to set up a bed in their own room yet.
I'm not sure the overflow pipe would have needed to have been dipped in the water in the tank, but could certainly see how that would greatly accelerate the process. With a faulty thermostat, the water in the DHW cylinder would have been bubbling away really quite violently, after all. And if the pipe runs were short, there would have been a reasonable amount of conduction via the water (I'm surprised at how warm my pipes are, even when they appear in the loft).
I can only presume that the previous tenants only ran the immersion heater for short periods of time.
There is one puzzling aspect:
Quote:John Williams, chief housing officer for Taunton Deane Borough Council, said that safety inspectors were not expected to examine attics of houses - where the immersion tank was - "because they don't have ladders".
It's not impossible, but it's really unusual for an "immersion tank" to be in the loft, assuming he meant "DHW cylinder". I'm assuming this is someone being unclear in their use of language, and that the cylinder was in the usual airing cupboard. Assuming that's the case, and the only thing in the attic was the cold water storage tank, then an inspection of that would have revealed nothing unless the immersion heater had been running for a decent amount of time when the inspection was carried out. Well, perhaps it might've revealed the overflow pipe being too close to (or in) the water? So that sounds like a poor excuse to me, sadly.
Regarding the question of negligence, inspecting an immersion heater sounds like a difficult task. How many hours would you have to hang around on site for? How would you ensure it's going on and off? One of those "clever" clamp meters that can estimate current in a cable (rather than a single core) might do the job, but those are rare, and the only one I've ever seen is no longer made. So you'd have to disconnect the heater and put an ammeter in series - or run it with the cover removed if there was access to the post-switch heater circuit. Or perhaps leave a logging thermometer? Really, I think this relies on a tenant reporting strange sounds or scalding water, but that's a whole other minefield!
From what I've read, some councils and housing associations decided to replace certain types of immersion heaters after this tragedy. Preventative maintenance.
Anyway, what happened happened, and it's happened on more than one occasion. Greater awareness of the risk can only be a good thing, and I'm sure the families concerned would wish that no-one else has to experience what they have. Ultimately, not all installations are perfect, and not all installations remain perfect (e.g. pipework can move when people throw things in their lofts). I remember taking great care in the design of my system to ensure that the pipework couldn't "slump" in future, but then I spent many weeks installing my new water tank - not a luxury available to the average contractor doing work for a local council who would have screwed the price right down.
