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How to fix a common Pulsacoil fault yourself
The Pulsacoil Stainless ECO is second generation of Pulsacoils from Gledhill with a stainless steel internal tank, the first being called simply the “Pulsacoil Stainless”. All previous models had copper thermal store water containers inside which were prone to pinhole leaks. These leaks could not be repaired as there was no access to the inner copper tank through the riveted external steel case and urea formaldehyde foam. This meant that any pinholes inner container could only be repaired by replacing the whole appliance with new.
The Pulsacoil Stainless thermal stores address this problem by having a stainless steel inner tank instead of copper. Only time will tell if these have a longer life than the copper tanked versions but so far, it it looking good. I’ve yet to see a pin-holed Pulsacoil Stainless.
The “Stainless ECO” model appears to use the same outer case, inner case, internal stainless steel tank, heat exchanger and heater elements as the preceding model the “Pulsacoil Stainless”, but the pump, circuit board and water flow/temperature sensing are completely different. Instead of two heat sensors, a Grundfos pump and a large circuit board there is now a tiny circuit board controlling a low energy pump and a clever flow sensor with no moving parts. I have yet to figure out completely how this works in detail, with apparently no temperature sender, but it all works very well most of the time and tap water temperature being controlled at a nice stable level and the pump turned OFF as expected when hot water demand ceases.
This new “ECO” version is probably only very marginally more economical to run or ecologically sound than the previous version so I think adding the suffix “ECO” to the name is a bit misleading but that is just my opinion, and I expect Gledhill can probably produce reams of data to prove I’m wrong about all that!
Common faults and fixes:
1) Heater element failure
The heater elements are the same as most previous models of Pulsacoil and although they rarely actually break and stop heating, they leak. The thermostat pocket corrodes through and water escapes into the wiring connection box and sometimes into the thermostat itself, either blowing fuses or causing the overheat protection thermostat to trip.
2) Thermostat failure.
The thermostats in the heater elements fail, in several ways. They can lose their calibration and turn OFF at too low or too high a temperature, the y can be damaged by water ingress when the pocket holding them leaks, the integrated overheat protection built into them can randomly trip occasionally needing re-setting, or the overheat thermostat can trip correctly when the unit is overheating.
3) Scale contamination of the heat exchanger
The water flow from taps falls down towards zero and at the same time, what water flow there is, emerges cool. This happens when water scale gets deposited on the inside faces of the plates in the heart exchanger. The scale can be chemically removed but this is time consuming the chemicals are not cheap. The most economical fix is to fit a new heat exchanger.
4) Hot water runs cold when hot tap is running slowly
This is only a fault on the ECO version. Usually the user says the shower runs cold but all the other taps are fine. This is because some showers are actually quite economical with water and draw too low a flow rate to trigger the flow sensor and start the pump.
For information about repairing your Pulsacoil STAINLESS, call or text me on 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