Hi Everyone..Have an issue that is probably been discussed a few times. Have a Potterton Puma 80E Combi boiler that is at least 10 yrs old (I'm tenant in rented flat). For the past month, it has been "locking out" after hot water usage. Have to reset system by putting into standby. This now happens after each hot water usage (shower, washing up). We also have VERY hot water coming out of the tap at times, when the system has locked out (water is whitish and scaly). Had a guy round today, who after only listening to me describing the problem, said that HW exchange and/or diversion valve were clogged up. Recommended replacing boiler and power flushing radiator system. Said that the Potterton's were not very credible and that "repairing" after 10 years was throwing money down the drain. Comments or suggestions?? My landlady (South A. based) will have a fit and go into stall mode, unless I have some back up. [/u]