How can I fix my Baxi Bahama 100?

My daughter has a Baxi Bahama 100 and this has the problem that the central heating keeps firing up for a few minutes and then stops for a short time before starting up again. The pump keeps running. The pressure is correct. The hot water is also correct. Suggestions please.

121132
November 2019

For anyone else looking for problems with the Bahama switching itself off, I thought I would add my experience in the hope it can help someone. My boiler was remaining on for only short periods of time before switching itself off again in central heating mode and then refusing to restart until the mains was switched off for a few seconds. The vast majority of the time, the flame out light was not showing. This led to a lot of googling and experimentation to find out what the problem was. The problem turned out to be corrosion on the flow switch connector for the central heating which meant even though the flow switch was working, the resistance to the PCB wasn't changing! To check these switches out for yourself, get your manual and locate the switches (check both). Switch off the boiler at the mains and then disconnect the hot water flow switch connector. Put a multimeter into the switch side connector, set to measure resistance and then turn on hot tap. You might be able to hear a small click from the switch and the resistance should drop to zero. If it doesn't, replace this flow switch (you only need to turn off the mains water for this). Reconnect the wires on the first switch and then disconnect the connector on the central heating flow switch. With the multimeter plugged into the second switch, switch on the mains and start the central heating. Again, the resistance should drop to zero. The central heating will only fire for a short while like this because the PCB will not be detecting a flow. If the resistance stays at 1, then replace this flow switch (you will need to drain the boiler for this). If both switches are OK, then make sure that the pins in the connector blocks are not corroded - this was my problem and it took a while to figure it out. If this isn't your problem, after reconnecting everything, but while you still have the front of the boiler open, make sure that you can hear the divertor valve switching between hot water and central heating by having the boiler in central heating mode, resetting the mains power if needed to get it going and then switching on a hot water tap to make sure that it switches OK. You should be able to see the front of the divertor valve motor move slightly as it exerts force on the valve. If not and you get no hot water at all, then as Brian suggested, you can have this replaced. If the flame out light is going on regularly, you can try replacing the flame sensing electrode in the flame box, this part should be less than £10. If everything else checks out, you can try replacing the PCB located inside the drop down front panel. These are available for less than £40 on ebay and if it doesn't fix your problem, you can always sell it on! Finally, it does say on the boiler inside cover (on mine at least), that the boiler is very sensitive to air in the system, so it is worth making sure that it is completely bled of air. I am not entirely sure how to do this as it has an automatic air vent, so you may need to get a plumber to help. One other thing that could fail that I never even got round to locating is the thermistor which is the water temperature sensor.
Hope this helps someone!
Matt.

Matt
March 2010

most faults on the bahama are related to the divertor valve cartridge.
these cost around £20 and come with the tool to remove the old one.
sludge forms around the inside of this device and usually results in intermittant failure when moving from one position to the next.
pcbs are often purchased but this is not normally the answer.
flow switches are commen - flush your system regulary with a cleanser and add a inhibitor.

mike
September 2009

I have a similar problem, do I need to drain the boiler to replace the flow switches?

Many thanks

wayne
November 2007

We have replaced pretty much all the main parts for this boiler in the last 5 years or so. The most recent problem has been the boiler doing the same as this and also cutting out before the central heating is up to temperature. However, when i bypassed the CH flow switch it fixed it so another flow switch is needed again!

Manic
November 2005

I have replaced both flow switches and the return spring and the boiler now works perfectly. Thanks for the help.

Brian
July 2005

i would replace flow switches again as mine does the same problem every 6 months and just give the spring on heating side a pull when putting flow switch back in

an unluckly baxi bahama owner
July 2005

The result is exactly the same.

Brian
July 2005

what does it do in hw/ch mode is this the same problem

an unlucky baxi bahama owner
July 2005