Worcester Heatslave 15/19 Problems - Please help.

[DigitalAura]

Hi folks,

I seriously hope someone can help me out here as I'm up in Shetland, disabled and housebound and my boiler is screwing around plus getting a plumber seems like an impossibility.

I think my problem is the water pump isn't running when I'm wanting heating as from cold the system runs for a bit, yet the radiators stay cold and then it switches off. The thermostat goes from clicking on to not clicking at all. I replaced the thermostat originally thinking that was the problem but I'm just going to use it as helpful diagnostic info as it made zero difference.

Now if I turn the hot water on it runs for longer and warms the radiators but I can only do this a couple of times before again the thermostat fails to react on the hot water side.

I figured out the heat exchanger is hitting around 85c which appears to be the limit for the central heating thermostat hence it reaching it's limit and switching off. I have to wait for the whole system to cool again before I can repeat the whole cycle.

Hot water on demand hasn't worked for a while (couple of years at least), it just hasn't been clicking on when i open a hot tap so I'm not sure whether to include that as diagnostic or not, I have a brand new diverter valve cartridge yet I don't know how to install it as I don't know how to drain the system or what hoses I would need to buy to do this. I don't know how to manual actuate the diverter valve.

Thermal image shows the point where the bulb for the heating thermostat enters and the heat exchanger temp.

Could this be a combination problem of a faulty relay on the control board not switching the pump on on the heating side and and perhaps a combination of a weak pump which isn't circulating water at a fast enough rate to keep the system cool?

Sorry for all the questions but I'm really at a bit of a loss and each time I open the machine causes me a great deal of pain.

I have the equipment to test and replace relays and the control board.

Thank you so much, just hoping I can find a solution to this as I'm losing sleep now trying to work this out and as you no doubt know, it's no fun in the cold especially with osteoarthritis and chronic fatigue. I'm prepared to do the work if someone is willing to guide me. I have a pretty good supply of tools, including electrical and electronic tools etc, just lacking knowledge and experience.

 

[oilhead]

To change your cartridge, isolate the flow and return valves, release the pressure in the boiler, and cover any vulnerable compents like the burner control box from any residual drips. The head twists off the body, and your new cartridge should have a spanner to unscrew the cartridge . Reolacement is the reverse.

 

[Harry Bloomfield]

Could this be a combination problem of a faulty relay on the control board not switching the pump on on the heating side and and perhaps a combination of a weak pump which isn't circulating water at a fast enough rate to keep the system cool?

Your first step, ought to be to see if power is getting to the pump, then checking if the pump is running, when it has power, but that boiler appears to be room sealed, and so it probably needs a GSE to open it up.

 

[oilhead]

This is an oil boiler. ^^^^^^^^

 

[Harry Bloomfield]

This is an oil boiler. ^^^^^^^^

Whoops, in which case no problem with a DIY investigation. As above, check the circulation pump.

 

[DigitalAura]

To change your cartridge, isolate the flow and return valves, release the pressure in the boiler, and cover any vulnerable compents like the burner control box from any residual drips. The head twists off the body, and your new cartridge should have a spanner to unscrew the cartridge . Reolacement is the reverse.

Never isolated flow and return valves, guessing my thermal imager could be of use here? and to release pressure, just bleed a radiator? I'm not going to be the fastest doing this as I have very little energy? I guess it's best to at least address a known problem and I can test the motor when I have it free.

 

[DigitalAura]

Whoops, in which case no problem with a DIY investigation. As above, check the circulation pump.

Is there an easy way to test this, or do I just check an on signal is being sent from the control board with a multimeter? I need to wait for the system to cool in order to run the CH side.

 

[Harry Bloomfield]

Is there an easy way to test this, or do I just check an on signal is being sent from the control board with a multimeter?

If you don't already know how to do this, then I would suggest it might be better to leave to someone who does know, rather than risk injury.

 

[denso13]

I think my problem is the water pump isn't running

Loosen the large centre screw on the pump and remove, then check the spindle is turning when heating is called for. It should be.

 

[DigitalAura]

If you don't already know how to do this, then I would suggest it might be better to leave to someone who does know, rather than risk injury.

I know electrical safety, electronics is or was my thing hence having all the test gear, thermal camera etc. Thanks for your concern though.

 

[DigitalAura]

Loosen the large centre screw on the pump and remove, then check the spindle is turning when heating is called for. It should be.

Thank you, I'll try this when the system has cooled sufficiently. Right now it's just a guess that it isn't running due to the radiators staying cold and the heat exchanger not cooling.

 

[Exedon]

Which model of Heatslave? there are several.
If you instalation manual follow the fault finding flow chart.
Or download correct manual.
3 port valve is a regular problem on Heatslave's.
Have you checked all the overheat stats?

 

[DigitalAura]

Which model of Heatslave? there are several.
If you instalation manual follow the fault finding flow chart.
Or download correct manual.
3 port valve is a regular problem on Heatslave's.
Have you checked all the overheat stats?

It's a 15/19. I'm going to swap out the cartridge in the valve as my first port of call, right now I'm waiting for the system to cool and building up energy to do this. Isolate the boiler from the radiators, drop the pressure, cover the delicate electronics on the burner and twist off the unit containing the motor. I have the service manual. The switch on the control box for the valve, a black thing hanging from the bottom is kind of floppy indicating the valve is stuck, at least that's what I think. I have plenty of time to read the service manual at least.

 

[Exedon]

15/19 is just the output
Worcester have made a number of variants over years some better than others.
Clear pictures of the front and internals of your boiler would be useful.

 

[Harry Bloomfield]

I know electrical safety, electronics is or was my thing hence having all the test gear, thermal camera etc. Thanks for your concern though.

Well then, it's fairly obvious - you apply the probes across the pumps terminals, to see if you get mains voltage at that point, then work back.

Removing the chrome bleed screw on the pump, to check for rotation, might be another way to ensure it is running.