Fabdec Thermacoil:

Although the Fabdec Thermacoil is not a Gledhill appliance, I’m mentioning it on this website because it is still a thermal store of the same type, and I’m now getting a trickle of calls to repair them since the suppliers appear to have ceased trading. There is also an appliance with the same name (Thermacoil) by a company called NextGen. I’ve yet to write a page on this but it is similar to the Fabdec in operation, although very different in appearance.

Anyway, both Thermacoils are low-cost thermal stores. The Fabdec has no outer case to protect the pipework and expansion vessel. It also has an internal heat exchanger comprising just a coil of pipe suspended inside the store water (in the same style as the Pulsacoil BP and Pulsacoil Original) thus saving the cost of a pump, control electronics and plate heat exchanger. For water temperature control it has a thermostatic blender valve instead of the electronic control of the later Pulsacoils. The Thermacoil made by Nextgen shares many of the features of this Fabdec version, but came in a very stylish and futuristic-looking rectangular matt black casing rather than round as in the photo here. Also long discontinued, I am unsure if both were by the same manufacturer. I’ve written more about the Nextgen Thermacoil on my other website, here. (Link opens in new tab.)

Common faults and fixes:

1) Heater element failure

As with all electric thermal stores, the heater elements fail with age rather than water scale contamination, as the water in the thermal store never changes. So unlike with a conventional hot water cylinder, the heaters are not heating a continually refreshed supply of hard water.

2) Thermostat failure:

The thermostats in heater elements fail from time to time and need replacing.

3) Scale contamination inside the heat exchanger:

The water temperature from a hot tap is nice and hot initially but rapidly falls to just ‘warm’. This is a classic symptom of water scale in the heat exchanger in a thermal store, and chemical descaling is the fix when the heat exchanger is an internal tube as with the Thermacoil. Often, the blender valve will be damaged by water scale at the same time and need replacing. 

4) Blocked filters on the blender valve:

When a magnetic or electronic water conditioner has been fitted by the appliance installer, water scale precipitates as particles like sand rather than sticking as scale to hot surfaces inside the heat exchanger. This sand-like material instead accumulates in the hot inlet filter to the blender valve and eventually completely blocks it. It can often be cleared out but sometimes this damages the blender which then needs replacing too.

5) Pipes popping off.

This is not strictly a Fabdec appliance fault to be fair, but these Thermacoils have very hard stainless steel inlet and outlet pipe stubs, and installers are very fond of connecting to these using modern push-fit plastic pipe fittings. Most push-fit fittings use serrated grip rings designed to dig into copper tube to hold the fitting securely onto the pipe, and these grip rings do not dig into and grip hard stainless steel. Consequently push-fit fittings should not be used to connect to a Fabdec Thermacoil as there is a risk the pipes will just pop off at a random time in the future causing a major leak. 

If you need a repair to your Fabdec Thermacoil, call or text me on my mobile 07866 766364.