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0118 942 4981

0770 231 6157



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Scalgon Descaling



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Underfloor Heating (wet)

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Got a problem with your Gledhill PulsaCoil?


How do you know if your Gledhill PulsaCoil BP is scaled up?

The hot water at your tap will be cooler than it was. Indeed, it can be almost cold. If the build-up of limescale is severe then you may find your water flow reduced too. However, you can’t be sure what the problem is because the store might not be heating up properly. So check the obvious first - that the store of water is actually heating up.


How can you do this?

Remove the front cover of your PulsaCoil BP and look at the picture.


Feel the pipes, are any of them hot?

If yes then at least the store is heating up. If you have turned the boost immersion heater on then this check isn’t valid. Turn the boost off and wait 24 hours - then see if this pipe is hot.


So you’ve done that and the pipe isn’t hot.

Then the most likely problem is the lower immersion heater. Call us and we’ll replace it.


Or...the pipe IS hot (and you haven’t activated the boost) but you still haven’t got hot water.

Then it’s either going to be the thermostatic mixer valve (in which case call us and we’ll replace it) or the internal heat exchanger has scaled-up. Call us and we’ll descale it for you.


PulsaCoil A-Class not giving hot water?

The A-Class has electronics which control its function. Unlike an ordinary immersion-heater based water heater, the A-Class controls its heat by use of sensors rather than thermostats. These sensors tell the printed circuit board (PCB) that they are happy, or not. But it gets far more complicated than that. There are also relays controlling the switching of the off peak and the boost. There’s also a pump that has its speed control governed by the PCB, and electrical relays too! There’s also a plate heat exchanger which suffers from limescale. Call us if you think yours has scaled up, and we’ll replace it for you. A-Class acting odd? Hot water sometimes but not others? Highly likely to be one of the two sensors (GT198) - and best to replace both the cold and hot ones. A word of caution if you have decided to do this yourself! We know that there are companies selling this part that will supply the part only - without the nuts & olives. This is because GT198 is used as a sensor elsewhere as a dry sensor. Make sure you order the nuts & olives as well as GT198. Fitting the new ones (which you would think would be easy) can cause water leaks. The new sensors can be a tight fit, and it’s very important that you have crushed the olives onto the sensor body. To do so requires tightening the nut considerably (more than you usually would with such a small nut) and a sealant. Hold the octagonal brazed nut as you tighten with another spanner. Some of them have to be ridiculously tight to ensure they don’t leak, and you sometimes feel they are going to break apart! More often than not, A-Classes are fitted in upstairs flats, so if these leak then you won’t know about it until the flat below you complains about their ceiling! Engineers like me already have the sensor housing kicking about in our toolboxes, so we crush the olives on before we fit them, but that won’t be obvious to a diyer. Maybe best to call someone who is used to working on A-Classes.


PulsaCoil III or 2000

This appliance is relatively simple, but it still has relays, a PCB, control sensors and that plated heat exchanger. So some of the faults that apply to the A-Class also apply here. There’s also a little red LED on the PCB. This can indicate the nature of a fault...but not always! If your PulsaCoil has a fault then tell us (by email please) how that red light is flashing and we MAY be able to tell you the problem.


The Plated Heat Exchanger

Many Gledhill appliances use this heat exchanger, the GT017 - and it really gets scaled up! We don’t usually recommend descaling it as it is usually quicker to simply replace it with a brand new one. The cost is £168.00 including vat, but plus delivery/fitting. However, we have reconditioned GT017 HEs for £84.00 plus delivery/fitting (not currently in stock).


BoilerMate (like a PulsaCoil, but not)

See the brass valve with the white cap on top at the top left of the picture? That’s the thermostatic mixer valve (or blending valve). It is connected to the internal coil heat exchanger. The coil inside BoilerMates and similar appliances gets completely blocked with limescale. This can mean cooler water and/or reduced flow. We can easily descale it for you - just call us.


The Gledhill PulsaCoil is perhaps one of the ‘better’ thermal store hot water heaters. ‘Better’ because it works ‘vented’ rather than ‘unvented’. It provides enough hot water on overnight tariff for the needs of two people - if showers rather than baths are taken. However, it does have electronics, especially the A-Class, which can be troublesome. In hard water areas the heat exchanger is particularly prone to limescale too. By far the best is the PulsaCoil BP. But before you email or call us just check one thing (which can cause a ‘fault’ that isn’t really there)...check that there is sufficient water in the ‘feed and expansion’ tank!


We are used by many housing associations and national property development companies to attend to descaling of Gledhill Torrents, PulsaCoils and BoilerMates. PLEASE NOTE we do NOT attend to these or other Gledhill appliances for general faults.