I’m Mike Bryant, also known as Mike the Boilerman and I specialise in repairing old or unusual boilers. Pulsacoils are a good example, I fix a lot of Pulsacoils and keep a full stock of spares in the van. Much of my work is in Berkshire, north Hampshire, Oxfordshire, Surrey and west London but I’m happy to travel to anywhere within driving distance of my home/office in Marlborough, Wiltshire. The further you are the higher the travelling costs will be, but I'm happy to do the travelling.
Gledhill Pulsacoil water heaters are 'thermal stores', which work in a significantly different way from ordinary hot water cylinders and water heaters. The Pulsacoil is different enough to to mystify many heating engineers when it comes to fixing them, it seems. Pulsacoils are not particularly difficult to understand but the later versions can look intimidating with the cover removed and without background knowledge, many heating engineers understandably struggle to diagnose and repair them.
A thermal store is a tank filled with very hot water at very low pressure, which is not the hot water that comes from your hot taps. The water is used to store heat energy only, hence the term ‘thermal store’. This very hot, low pressure stored hot water is then used as the heat source to heat high pressure cold mains water in ‘real time’ on its way to the hot taps, showers etc, in much the same way as a gas combi boiler using a heat exchanger. The point of this is to take advantage of the high water pressure in the street mains water supply, to deliver high pressure HOT water to the shower in particular, without the use of pumps. Showers fed from tanks don’t really work very well (or at all) and the alternative is a “mains pressure unvented hot water cylinder”. The mains pressure cylinder is generally known amongst plumbers as a “Megaflo”, which is the trade name of the market leader in these devices. A “Megaflo” is a tank of hot water at high pressure and contains a lot of energy, and if things go wrong can be a serious safety risk so installation is governed by law to those qualified to fit them, similarly to gas. The most onerous aspect to fitting one is a requirement for a metal safety discharge pipe capable of carrying away steam to outside under fault conditions. Architects often specify thermal stores when installation of this safety discharge pipework is not practical, e.g. when the airing cupboard is in the centre of an apartment and not near an outside wall. This is why so many modern town centre apartments have Pulsacoils installed - in a nutshell to make the showers work!
There have now been quite a few versions of Pulsacoil made by Gledhill over the years and there are pages here describing each in a bit more detail along with what goes wrong with them and the possible solutions. If these don't help, I'm happy to give advice to anyone wanting it via my Gledhill Repairs discussion forum (it's here) or by text, WhatsApp or email. Gledhill themselves also offer telephone technical support during normal office hours but it's expensive - 60p per minute last time I checked. Their technical helpline number is 0906 611 0005.
If you’d like to talk to me about a repair, call or text my mobile 07866 766364.
Copyright Michael Bryant 2020
Site first published 2nd January 2007
Last updated 21st March 2020
Gas Safe Register 197499, CIPHE registration number 56207