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How to fix a common Pulsacoil fault yourself
The Pulsacoil BP and Pulsacoil PCR identical inside as far as I can tell. The only difference I can see is the PCR has a white outer case, while the Pulsacoil BP is grey. Neither model was produced for very long and I rarely encounter either.
These two thermal store models revert to the format of the Pulsacoil original, having a coil of tube inside immersed in the thermal store water, so there is no pump and no electronics, these are entirely passive mechanical appliances. There is a blender valve on the outlet to moderate the hot water to a safe temperature to prevent scalding. The internal coil heat exchanger is however horribly prone to blocking with accumulated water scale so with future models, Gledhill reverted to the more complex format with pump, circuit board, external heat exchanger etc which is more resistant to scaling and more easily fixed if/when scaling occurs.
Pulsacoil BP and Pulsacoil PCR faults:
1) Depleted water in the thermal store.
PulsaCoil BPs have a top-up cistern attached to the top. This may or may not have a float valve connected to the mains water supply to fill it. (When there is NO mains connection, there is usually provision for manual filling by the user by means of a tap on the wall nearby.) Water is continually lost from the thermal store through evaporation and/or leaks, and when there is no float valve to top it up, the user needs to do it manually from time to time. Low water level in the cistern at the top will eventually prevent a PulsaCoil BP from working properly because once the top-up tank is depleted, the water level inside the store begins to fall too. Once the heat exchanger coil is no longer fully immersed in the thermal store water, hot water performance will be affected. The answer is to check the water level in the top-up cistern and top it up to the waterline embossed into the wall of the cistern.
2) Immersion heater element failure.
The unit fails to heat up. Easily diagnosed by measuring the resistance of the heater element. A good element will measure 18 Ohms approximately.
3) Immersion heater leaking.
The 'Skel' brand immersion heaters (fitted as original equipment) seem to suffer from leaks in the thermostat sensor pocket as they grow old. On many occasions I've seen water emerging from the copper tube in which the thermostat sensor is housed. This is clearly dangerous as it introduces water into the electrical connection box on the heater element head, and it often results in thermostat failure. The only repair is to replace the whole immersion heater and thermostat.
4) Thermostatic blender valve failure.
The thermostatic blender valve is susceptible to contamination by water scale in hard water areas. There is a component inside which breaks and the blender valve delivers just luke-warm water to the taps. A new blender valve cures the problem.
5) Water scale-contaminated internal heat exchanger coil.
The plate heat exchanger is prone in some areas to water scaling. This presents as maximum water temperature becoming progressively lower, and in the final stages of scaling, the flow rate from the taps reducing too. The fix is to either fit a new plate heat exchanger, or to descale the existing heat exchanger using conventional descaling techniques.
6) External Economy Seven time clock failure.
PulsaCoils are usually connected to an Economy Seven tariff electricity supply. When there is no separate off-peak power supply to the unit an Economy Seven timer will have been fitted. These seem to fail after a few years and no longer deliver power to the immersion heaters, even when the indictor lights on the timer say power is being delivered!. Although it's a straightforward matter to replace these timers, finding an electrical merchant who keeps them in stock is difficult. I keep them in stock myself as a result.
If you'd like me to come and fix your PulsaCoil BP or PCR, contact me by calling or texting my mobile, 07866 766364.
Mike the Boilerman - Independent Gledhill Pulsacoil repair specialist, covering everywhere within driving distance of Hungerford, Berkshire
Call or text me on: 07866 766364
Copyright Michael Bryant 2020
Site first published 2nd January 2007
Last updated 30th April 2021
Gas Safe Register 197499, CIPHE registration number 56207