Copyright 2014 Michael Bryant

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Baxi website
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First of all, thanks for visiting.

I'm Mike Bryant, also known as Mike the Boilerman. I specialise in maintaining and repairing older boilers, the type of well-made boilers made in the 1970s, 1980s and 1990s. These are often the boilers that other gas technicians are telling people must be replaced purely because they are more than ten years old. Madness in my personal opinion.

This feels instinctively wasteful to many people who would very much prefer to mend something which has broken whenever possible. It seems a wicked waste of resources to me too, to tear out a boiler with at least a decade of life still in it for want of a simple repair - never mind the cost of a repair usually being significantly less than that of a new boiler.

Anyway, to the Baxi Solo boiler...

The Baxi Solo was first introduced in around 1980 to 2002. The Solo came in four versions; the original natural draught Solo, the Solo WM series, the Solo II, the Solo III and the current Solo HE.

The original Solo was a natural convection boiler but there are so few around now there seems little point in writing much about them. I haven't seen one for  years.  Even so I'd expect any still surviving to have a fair chance of being repairable should I encounter another, so simple was the design. 

All the other Solo boilers are fan-flued, automatic ignition, non-condensing boilers and were very successful for Baxi with many thousands still in regular use today. 

The original Solo WM series:

The Solo WM series uses a cast iron heat exchanger looking very much like that found in the Baxi Bermuda back boiler (which fitted into a chimney breast and had a gas fire on the front), and is equally prone to cracking and leaking water all over the floor. Surprisingly this heat exchanger was still available recently, although may have been discontinued by now. 

The WM stands for 'wall mounted' and the flue is fan assisted. Fuel efficiency is stated as 68% by the government at Ignition is electronic, with a pilot light being lit by a spark delivered by the circuit board after the fan has started, then once the electronic flame detection is satisfied the the pilot has lit, gas is sent to the main burners. 

The WM is a bit of a horror to dismantle and service, with a large front panel with lots of screws and connections to remove to get inside, and a clumsily designed housing for the circuit board.

The most common failure is the fan. This is easily replaced if rather expensive. Occasionally I see a PCB failure where the boiler simply refuses to light. The air pressure switch fails sometimes too, but all of these parts are still freely available and easy to replace. The only terminal fault is a cracked heat exchanger for which this boiler is well known. This usually wrecks the rest of the boiler as the burner assembly and the electronics get soaked with water and repair costs approaching the price of a new boiler so is rather pointless.

The Solo II and Solo III

The original Solo WM was replaced by the phenomenally successful  Solo II. The Solo III is virtually identical in both appearance and inside, having just some minor changes to the fan design to improve the fuel efficiency. Both boilers use the same cast iron heat exchanger, a completely new design and format which seems to have overcome the cracking problem of the WM series. The big difference is in the fuel efficiency. The Solo II  is quoted as 68% and the Solo III, surprisingly for such a similar design, is whole 10% higher at 78%.

 Like the WM series, the flues are fan assisted and ignition and flame monitoring is electronic. The only difference internally I notice is in the venturis fitted to the fans for detection of fan operation. The inner case, heat exchanger, circuit board and many other components are identical in the II and the III.

Unlike the WM the most common failure is the control circuit board. So common in fact that I carry two or three in the van! Fans fail too but this is less common, and the gas control valve occasionally dies. All these parts are freely available and quick to install so anyone saying 'you can't get the parts for these guv, you'll have to have a new boiler' is fibbing, or can't be bothered to check...  

The Solo HE:

The Solo HE is a 'high efficiency' condensing version of the Solo and although it has a fuel efficiency of around 90% (depending on exact model) it has an unappealing habit of breaking down intermittently with electronics-related faults. I've also seen the odd one here and there dripping water from the bottom due to a cracked heat exchanger. 

The Solo HE isn't a 'proper' condensing boiler i.e. designed from the ground up as a condenser with, say a circular stainless steel heat exchanger with cylindrical burner in the centre like say, a Vaillant. It uses the old cast iron heat exchanger from the Solo II and II and improves the fuel efficiency by adding a strange second heat exchanger arrangement at the back which service engineers (like me) can't get at. Well we can, but it involves removing an aluminium casting that rots with the condensate, and the water seals leak when we put it back on (if it didn't fall to bits when we first removed it). So we boiler technicians have learned not to touch this bit. For this reason I don't really like the Solo HE.


So to finalise, I keep all commonly failing parts for the Solo II and Solo III in stock. I can generally offer a 'one visit fix' if you suffer a breakdown on a Solo II or Solo III. Contact me here for an idea of costs or if you'd like to book me to visit. 

For my main site, check out

Once again, thanks for visiting.

Mike Bryant, AKA Mike the Boilerman. 


First published 10th April 2014
Last updated 1st November 2014

Copyright 2014 Michael Bryant

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