C
CraigT
Hi,
I've got a Worcester Bosch 20/25 Heatslave which is about 11 years old (yes, I know it's old, but despite numerous problems over the years I've managed to repair them all myself fairly cheaply!).
Anyway, a year after I bought the boiler our electrics in the house kept tripping out & at the same time I noticed a bit of a puddle under the boiler. It turned out that the flow switch had been leaking & the water had run through the outer sheath of the leads on the back of the switch & dripped directly onto the boiler electrical board (Great design WB!). Luckily we'd only recently updated the house electrics & it was causing the RCD to trip, else we could have ended up with a 'live' boiler. The flow switch was replaced under warranty & at the time the engineer said that this was a fairly common fault.
Not wanting the same thing to happen again I slightly shortened the outer sheath (to just outside the electrical box) so that if the new one leaked it wouldn't channel water onto the electrics. Clever I thought!
So, jump forwards another few years & the electrics started tripping again. The first thing I checked this time was the flow switch & 'funny old thing' it was leaking again - although this time the water wasn’t just channelling along the outer sheath, it was also managing to get through the insulation around the main conductors (I measured the flow rate to be about 15ml over about 8 hrs!). Even worse, the water that had come out of the conductors had pooled within the electrical box & then managed to seep all the way down the cable running out of the bottom of the box & into the burner electrics!!!
Faced with a £50 - £60 replacement flow switch (that I knew would eventually leak again…) I did some searching on the web & came up with a ‘magnetic flow sensor’ from Farnell (order code 2294172) that has no external moving parts & therefore has no chance of leaking FS-90/1 - MEASUREMENT SPECIALTIES - SENSOR, LIQUID FLOW, 3L/MIN, COPPER | Farnell United Kingdom. Basically there’s a moving magnet inside which triggers an external reed switch at the set flow rate. The flow rate on this switch is 3 l/min, which is apparently the same as the original switch (I did originally try a similar alternative from Ebay, but the switch triggered at 0.5 l/min & it was too sensitive). The switch was simple to insert inline instead of the original switch. It’s more compact, cheaper at only £12.52, & more importantly it can’t leak… The only other thing that I had to do was solder the original plug onto the end of the contacts & cover the join with heat-shrink.
I thought I’d share my findings with you. It was a cheap & simple replacement & the boiler is working absolutely fine with it!
Cheers,
Craig
I've got a Worcester Bosch 20/25 Heatslave which is about 11 years old (yes, I know it's old, but despite numerous problems over the years I've managed to repair them all myself fairly cheaply!).
Anyway, a year after I bought the boiler our electrics in the house kept tripping out & at the same time I noticed a bit of a puddle under the boiler. It turned out that the flow switch had been leaking & the water had run through the outer sheath of the leads on the back of the switch & dripped directly onto the boiler electrical board (Great design WB!). Luckily we'd only recently updated the house electrics & it was causing the RCD to trip, else we could have ended up with a 'live' boiler. The flow switch was replaced under warranty & at the time the engineer said that this was a fairly common fault.
Not wanting the same thing to happen again I slightly shortened the outer sheath (to just outside the electrical box) so that if the new one leaked it wouldn't channel water onto the electrics. Clever I thought!
So, jump forwards another few years & the electrics started tripping again. The first thing I checked this time was the flow switch & 'funny old thing' it was leaking again - although this time the water wasn’t just channelling along the outer sheath, it was also managing to get through the insulation around the main conductors (I measured the flow rate to be about 15ml over about 8 hrs!). Even worse, the water that had come out of the conductors had pooled within the electrical box & then managed to seep all the way down the cable running out of the bottom of the box & into the burner electrics!!!
Faced with a £50 - £60 replacement flow switch (that I knew would eventually leak again…) I did some searching on the web & came up with a ‘magnetic flow sensor’ from Farnell (order code 2294172) that has no external moving parts & therefore has no chance of leaking FS-90/1 - MEASUREMENT SPECIALTIES - SENSOR, LIQUID FLOW, 3L/MIN, COPPER | Farnell United Kingdom. Basically there’s a moving magnet inside which triggers an external reed switch at the set flow rate. The flow rate on this switch is 3 l/min, which is apparently the same as the original switch (I did originally try a similar alternative from Ebay, but the switch triggered at 0.5 l/min & it was too sensitive). The switch was simple to insert inline instead of the original switch. It’s more compact, cheaper at only £12.52, & more importantly it can’t leak… The only other thing that I had to do was solder the original plug onto the end of the contacts & cover the join with heat-shrink.
I thought I’d share my findings with you. It was a cheap & simple replacement & the boiler is working absolutely fine with it!
Cheers,
Craig
