Worcester Heatslave Highflow

[brokenboiler]

Got a problem with our boiler, a Worcester Heatslave Highflow where it happily pumps out hot water, but no central heating...
...its been switched onto hot water only until now, and i'm thinking a valve might have got stuck in the last 9 months over summer...?

...anyone know a quick fix, or what the problem might be??

 

[esra_ptrap]

If you have not been using the central heating much it's likely to be a siezed diverter valve or knackered actuator or both.

If you take off the front panel of the boiler (pull out at the bottom then lift off) the diverter valve is the big brass coloured thing immediately below the thermostats on the control panel with three 22mm pipes going into it at the 12, 3 and 6 o'clock positions ... the actuator is fitted at the 9 o'clock position.

To test if the valve is operating switch the boiler on and select just hot water with the HW thermostat selected to minimum I (the main burner should light and heat the water until the correct temperature has been reached ... Once this happens the main burner should go out).

At this point carefully feel the temperature of the pipe at the 12 o'clock position on the diverter valve which should be relatively cool compared to the other 2 pipes ... Turn on the central heating with the CH thermostat to max (fully clockwise) and watch the indicator on the diverter valve actuator to see if it motors to the CH position. If it does feel the temperature of the pipe at the 12 o'clock position again and see if gets hotter (more like the other 2). Chances are it won't as the valve is probably jammed.

Bad news is that it is quite a major job to change the diverter valve on the Highflow for a DIY'er ... System draindown (unless you're lucky and all the boiler feed pipes have isolation valves ... Most don't), quite a bit of dismantling to change the valve and re-pressurisation, bleeding etc etc.

Good luck

 

[brokenboiler]

Have had a look at the boiler again...

The hot water is super hot, even with the switches off. In fact, the burners are lighting, even with the switches off...

All three pipes at the diverter are hot too... although that could easily be just conduction... would have to switch it all off and let it cool down to see for sure...

The actuator thingum has no indicator... just a flappy switch type thing on the bottom that is either on or off... v vague, i know

Thanks for the tips... think we'll need some expect eyes on site..

 

[esra_ptrap]

Despite the name "boilers" they never actually boil any water and there are many devices to prevent this fault condition.

If the main burner lights with both stats turned off and the gas supply (including the pilot) isn't cut off by the overheat stat the boiler is potentially dangerous as all of the safety mechanisms to prevent it from boiling aren't working.

The only final safeguard you have is the PRV and if this is seized also your normally safe boiler is now a pressure cooker with no relief valve

Get a pro in straight away and don't use the boiler in the interim.