07947 315860

01884 260122    

office@muglestons.co.uk

Offering a full range of high-quality Plumbing & Heating Services, based in Faringdon, Oxfordshire

Home Design and Installation Maintenance Breakdowns
Gas Boiler Maintenance Oil Boiler Maintenance Unvented Cylinders

The Range Powermax boiler series.  

These boilers are treated as a special case because they have often suffered many years of neglect (in fact, I’m yet to come across one that has been looked after properly).  This is partly down to the fact that a large percentage of boiler engineers are uncomfortable working on these unique and quirky beasts, so they do their best to avoid them.  As a result, they almost invariably require a considerable amount of work and a number of parts to get them back up to fully serviceable condition and ensure that they are safe and efficient in use.  Servicing is therefore carried out on a case-by-case basis, with the minimum charge being £70.00+vat and the maximum that I’ve had to charge so far being half a day’s labour plus around £200+vat in parts.  


Range Powermax – a unique boiler requiring unique care.

The Range Powermax series, of which the 155 and 155x were most popular, was a unique concept of boiler and hot water cylinder in one appliance, developed in the late 1980s and manufacturered up to 1996.  It was designed to minimise the amount of space taken up whilst maximising the potential hot water flow rate, and this it did very well.

Unfortunately, it does suffer from some inherent design issues which make it rather a tricky beast to look after.  It was, unintentionally, the first condensing boiler ever made.  I say unintentionally because it was never designed to condense, but the burner design and flue arrangement mean that it often does, and boiler condensate is quite acidic.  This is a problem, because whilst it makes it quite efficient for its age, it also suffers quite badly from internal corrosion.  Specifically, the eight turbulator tubes in the downward-firing burner rot away at the top, then drop down into the sump, which itself becomes difficult to remove and clean if not done regularly.  The flue also has a habit of rotting away, and if this has happened it can (and indeed has) lead to a carbon monoxide poisoning incident.  The gas valve is also a tricky one to set up, and getting it wrong will result in householders being disturbed by a ghostly howl whenever the boiler fires up.

 A full Powermax service therefore requires:-

 Inspection of the entire flue length to ensure that it is complete and free from defects  Where the flue runs through a ceiling, this will require the installation of inspection hatches at sufficiently regular intervals to be able to inspect the flue in its entirety.  Approx £35 each hatch.  If the flue is discovered to be damaged, it cannot be replaced and the boiler is condemned as Immediately Dangerous due to the very real risk of CO poisoning and death.  Assuming the flue is found to be satisfactory, then the service continues….

 Removal of the fan and burner, and replacement of the single-use gasket that seals the burner to the boiler.  Approx £15 for a gasket

 Inspection of the combustion chamber, blast pipes and turbulators to check for condition and, in the case of the blast tubes, signs of corrosion

 Removal and replacement of any turbulators which are corroded and in danger of falling into the sump.  Turbulators are £17.50 each, maximum of 8 to be replaced

 Removal of the sump (often via hammer and chisel, and on some models requiring removal of the pump which sits in the way) and drawing out of any turbulators which have already fallen into the sump

 Replacement of the sump seal (£15), which has been damaged during the removal of the sump (this is unavoidable unless it’s been removed every year and properly greased)

 Cleaning of the sump and blast tubes

 Reassembly of the boiler, checking and setting the gas valve, then checking for satisfactory combustion

As mentioned on my main gas boiler servicing page, this whole process on a really badly neglected Powermax can take half a day, but on completion you will have a reasonably efficient boiler which should continue to give good service for a few more years.  The only real risks once the full refurbishment service has been completed, assuming an annual servicing schedule is maintained, are rotting flues and rotting blast tubes.  There isn’t much that can be done about either of these sadly, and once either happens the boiler is immediately deemed to be unsalvageable.


Fortnuately, however, I can offer an ideal solution to a broken Powermax in the form of the Intergas Combi Superflow, which will deliver even more efficiency in a smaller package with equally good hot water flow rates.

If you’d like more information on either the servicing or replacement of your Powermax, please do not hesitate to contact me