GLEDHILL Pulsacoil explained

Understanding a Gledhill Pulsacoil and your options for replacement

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How does a PULSACOIL work?

The purpose of section is to explain what a Gledhill Pulsacoil is and to explain in general terms how it works. It is not a definitive statement and you are advised to research whether a Pulsacoil will be suited to your needs. We hope this section will help you to understand the process that goes on behind the front panel to give you mains pressure hot water.

If you already own or have inherited such a unit you can obtain spare parts here in the event you have a malfunction. Simply give us a call.

Gledhill PULSACOIL

The name 'PULSACOIL' is simply a name invented by the manufacturer Gledhill. It is not entirely clear where the name originated as there doesn't seem to be anything pulsing within the unit and in many models there isn't even a coil. One thing is for sure though, when you open the cupboard and discover a unit with such a grand name you can be excused for feeling intimidated by it. In fact this can be the problem when it comes to getting one fixed or replaced - very few people fully understand quite how this product works! As such, you are likely to fall prey to the unscrupulous who will often blind you with 'science' and overcharge because they can tell you anything they wish. After all, if you don't understand it on what grounds will you object?

What is a PULSACOIL and how does it work?

Pulsacoil is a thermal store. To be more precise, a Pulsacoil is a DIRECT thermal store. A thermal store (as the name suggests) is a device that stores heat. It generates thermal energy with electrical immersion heaters and stores it in an internal store of water. The store of water is open vented. This is to say it is under no pressure - at atmospheric pressure (rather like a bucket of water). This is a key feature of a thermal store. Being at atmospheric pressure it is entirely safe (unlike unvented devices that can explode if they malfunction and go 'over temperature or pressure'). The clever yet simple thing with a thermal store is the way it creates high performance hot water for your domestic use whilst remaining open vented. It does this by employing the process of heat exchange. The heat exchanger enables stored heat (in the thermal store) to be imparted to mains pressure cold water as it passes through the unit. This simple process enables a vented store of hot water to make mains pressure hot water.

Replacing a Pulsacoil

Simple? This rather depends on what you are replacing. Although Pulsacoil remains simple in principle the way the unit does its job has changed over the years. This affects installation requirements if you are replacing an older unit.

The origins of Pulsacoil

Pulsacoil used to be made by the Water Storage division of Gledhill. A few years ago this division went into liquidation. Although Gledhill continue to make Pulsacoil they do so now through their Building Products division. For this reason and to denote the rise of the new unit each were allocated a 'BP' suffix. While retaining a similar look and name the product had changed internally. The Pulsacoil BP utilised an immersed heat exchanger coil (whereas earlier models had used a plate heat exchanger with micro processor controls for everything). The BP model required an external switching device for the immersion heaters.

The early model Pulsacoil (picture above right) used to use plate heat exchanger technology to create mains pressure hot water. This required a pump to circulate hot water from the store through the exchanger. Water temperature was regulated by modulating the pump speed according to feedback from temperature sensors. This function and others of switching and timing utilised a micro processor circuit board that can be seen near the top. The immersed heat exchanger of the BP model simply relied on a thermostatic blending valve to regulate output water temperature arguably a simpler method.

The PULSACOIL BP

The Pulsacoil BP utilises an immersed heat exchanger (unlike the plate heat exchanger on the earlier type that was situated within the cabinet but outside the store). This is to say the heat exchanger is immersed within the hot water in the thermal storage compartment.

How Pulsacoil BP works

Mains pressure cold water is passed through the immersed heat exchanger, is rapidly heated and exits as hot mains pressure water. Temperature control is achieved using a thermostatic mixing valve (TMV) on the outlet that limits the maximum temperature water can emerge (usually set to approx 55^oC).

PULSACOIL STAINLESS (Circa 2014)

Early 2014 Pulsacoil changed yet again. Notably, where copper had been preferred as the construction material for the store now stainless steel would be used for the first time.

It could be argued that stainless is a little more resistant to corrosion and therefore the machine would be better suited to hard water areas. However, in reality the bulk of water in a thermal storage device theoretically doesn't go anywhere, the store is filled and that's that apart from a small amount of evaporation. So once the water from the initial fill has done its deed there is relatively little more going on. So, why stainless? Those who are a little cynical have attributed the change entirely to cost of material. Stainless is cheaper now than copper. There may be a slight advantage to the resilient nature of stainless but not the primary reason for the change.

The PULSACOIL STAINLESS could be described as a hybrid of all the earlier models - with the only exception being that of build material.

The PCS has re-introduced the use of a plate heat exchanger and associated control, although the switching of the immersion heaters is still a matter for an external device which is not part of the package you buy. Depending on which model you may be replacing you may or may not have the necessary off-peak controller already.

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Conclusions about Pulsacoil

A safe vented unit producing mains pressure hot water must be considered a good thing. Pulsacoil is presented in a smart little cabinet (looking a bit like a filing cabinet) which is pleasant in appearance. No requirement for a high pressure vent pipe to atmosphere makes them simpler to install and less obtrusive. However, since it's conception it has been substantially modified throughout it's various guises.

Pulsacoil is just a thermal store in a steel cabinet. The cabinet only performs an aesthetic function and the internals only do what all other direct thermal stores do (vented, 2 heaters, cold in, hot out).

Installation/retrofit of a Pulsacoil:

Pulsacoil is a product that has become a victim of its name. After all, what does it mean? The truth is that the Pulsacoil is a very simple machine. It is an open vented store of water (a bit like a bucket) heated by two electrical immersion heaters (exactly the same as an Economy 7 cylinder). So... why should you pay more to have a Pulsacoil fitted than a copper E7 cylinder? Yet, some plumbers would have you believe otherwise!

In short, Pulsacoil is delightfully easy to install. There are no special qualifications (G3) required for installation as the unit is open vented. The unit does not require annual servicing. Mains pressure hot water is achieved by a heat exchange process, which in reality is no issue as the machine is set up to work once the simple installation instructions have been followed.

PULSACOIL Value for money

Pulsacoil is offered by us at a very attractive price. So good in fact that there is nothing else on the market at present that can compete.

Alternatives to Pulsacoil

Pulsacoil is a thermal store. It gathers electrical/thermal energy and converts this to mains pressure hot water whilst remaining open vented itself. It is best suited to small properties such a apartments and flats. For bigger heavier applications you might consider Boilermate and Torrent Greenheat thermal stores.