Alde comfort issue.

[Rickent]

I have an Alde comfort boiler and for 5 years has been faultless,  this morning I put it on as normal and after about 15 minutes it sounded like the header tank boiled over and spat a load of water out.

Topped the header tank up and attempted to re light, but it will not fire up.

Any one had this issue ? Or have any ideas ? My first thought is a blockage somewhere in the circulation of the water , the flimsy little pump is working fine.

Edited April 10, 2020 by Rickent

[Tony Brooks]

Assuming a 2xxx model.

 

How long have you let it stand to cool down. I am almost sure there is a little "button" style bi-metallic overheat cut out fixed to the outside of the boiler. If it had boiled for any reason like low water (no circulation) then hopefully that would have tripped but it might take a while to reset itself.

 

Just looked in the 2928 manual and it does have an overheat protector but the illustration does not show the button style I thought it was and as I remember it. FWIW its number 18 on the illustrations at the back of the manual.

 

Unfortunately the Alde circuit diagram does not show the overheat protection as far as I can see so I don't know what it does, possibly it causes the flame failure to shut down.

Edited April 10, 2020 by Tony Brooks

[Rickent]

Hi Tony, yes omce it cooled down it has fired up ok and seems to be running ok at the moment, it didn't look to be low on water so must have been a blockage which seems to have cleared itself,  still concerning non the less.

[Tony Brooks]

4 minutes ago, Rickent said:

Hi Tony, yes omce it cooled down it has fired up ok and seems to be running ok at the moment, it didn't look to be low on water so must have been a blockage which seems to have cleared itself,  still concerning non the less.

So it looks like a simple overheat - I f the water level falls below the pump impeller it will not circulate and even before that point the circulation is likely to be impaired. ? I would diagnose lack of timely attention by the owner? so all you other 2xxx owners out there take note

Edited April 10, 2020 by Tony Brooks

[David Mack]

I've got a slow leak somewhere in my system which I can't find. So I always check and top up the reservoir before firing up the Alde.

[Rickent]

5 minutes ago, David Mack said:

I've got a slow leak somewhere in my system which I can't find. So I always check and top up the reservoir before firing up the Alde.

I will now put this into my routine for the foreseeable and see how it pans out.

[Rickent]

Plenty of water in header tank, just fired it up and it boiled up.

[Tony Brooks]

Check the motor is still driving the impeller. There is a rubber drive sleeve just below the motor  that can slip.

 

Unless there is a valve for rads or hot water or both that can also isolate the whole system form the boiler I find it difficult to believe the pipes & rads are blocked.

[bizzard]

20 minutes ago, Rickent said:

Plenty of water in header tank, just fired it up and it boiled up.

Is the little 12v pump motor working in the top header tank, you should be able to hear it whirring. I'd take it out and examine the inpellor too.

[Rickent]

2 minutes ago, bizzard said:

Is the little 12v pump motor working in the top header tank, you should be able to hear it whirring. I'd take it out and examine the inpellor too.

Yes, just had it out , runs perfectly, must be a restriction in the circulation of water.

[bizzard]

4 minutes ago, Rickent said:

Yes, just had it out , runs perfectly, must be a restriction in the circulation of water.

As Tony Brooks mentioned,    Switch the pump on whilst it's out, hold the impeller still by hand for a second or two to make sure the tube coupling is no slipping, Hold the impeller before switching on If the wires on the pump are separate make sure they are on the correct terminals, wrong way round and the pump will run in the reverse rotation.

Edited April 10, 2020 by bizzard

[MtB]

3 minutes ago, Rickent said:

Yes, just had it out , runs perfectly, must be a restriction in the circulation of water.

 

How did you check the impeller is securely fixed to the motor shaft?

 

 

It might only slip when hot, too. 

 

 

[Rickent]

10 minutes ago, Tony Brooks said:

Check the motor is still driving the impeller. There is a rubber drive sleeve just below the motor  that can slip.

 

Unless there is a valve for rads or hot water or both that can also isolate the whole system form the boiler I find it difficult to believe the pipes & rads are blocked.

It is running again now, whilst it is running and not overheating I will leave it as we need the hot water, when I have some hot water I will take the pump outvand check it's not slipping, but it sounds like it could be, I can see the rubber sleeve just below the motor and this is spinning.

4 minutes ago, Mike the Boilerman said:

 

How did you check the impeller is securely fixed to the motor shaft?

 

 

It might only slip when hot, too. 

 

 

Cheers Mike, will check that too.

[dmr]

I thought the Alde maintained its tank of water at the correct temperature by turning the burner on and off, if it didn't then it would run flat out all the time. Surely this mechanism should maintain the water temperature whether or not the water is circulating? so if the system is overheating and relying on its overheat sensor then the normal flame temperature control must be broken?????

 

...............Dave

[Tony Brooks]

1 minute ago, dmr said:

I thought the Alde maintained its tank of water at the correct temperature by turning the burner on and off, if it didn't then it would run flat out all the time. Surely this mechanism should maintain the water temperature whether or not the water is circulating? so if the system is overheating and relying on its overheat sensor then the normal flame temperature control must be broken?????

 

...............Dave

 

Yes, the room stat only controls the pump.

[bizzard]

There might be limescale or a foreign body in the recess where the impeler goes that's causing the impeller stick.

[Rickent]

1 minute ago, Tony Brooks said:

 

Yes, the room stat only controls the pump.

So there may be a bigger issue than just the pump.

[dmr]

8 minutes ago, Rickent said:

So there may be a bigger issue than just the pump.

I would say so. I only fire mine up once or twice to year to make sure it still works. I ignite the burner with the room thermostat switch off. After a while the burner shuts down....when I assume the water tank is up to temperature. I then turn the thermostat switch on and the pump starts up. A little while later the burner turns itself back on.

 

..............Dave

 

 

[MtB]

7 minutes ago, dmr said:

I would say so. I only fire mine up once or twice to year to make sure it still works. I ignite the burner with the room thermostat switch off. After a while the burner shuts down....when I assume the water tank is up to temperature. I then turn the thermostat switch on and the pump starts up. A little while later the burner turns itself back on.

 

..............Dave

 

 

 

This is a very good point and probably bang on. I'd add however, that the thermostat may possibly have been failing to turn OFF for years but the fault disguised by the pump running and dissipating the heat through the radiators. Until now perhaps, when the pump started intermittently failing to run. 

 

However, it is a bit unlikely that the primary control thermostat AND the overheat protection thermostat have both failed. My guess would be the gas valve failing to close completely and leaving the main burner 'ghosting' with a small flame when it ought to be completely OFF.

 

 

[Rickent]

10 minutes ago, dmr said:

I would say so. I only fire mine up once or twice to year to make sure it still works. I ignite the burner with the room thermostat switch off. After a while the burner shuts down....when I assume the water tank is up to temperature. I then turn the thermostat switch on and the pump starts up. A little while later the burner turns itself back on.

 

..............Dave

 

 

It must be an intermittent fault, it's running now and not overheating, seems to do it when fired up from cold.

When re started after overheating it seems to run ok.

[Rickent]

4 minutes ago, Mike the Boilerman said:

 

This is a very good point and probably bang on. I'd add however, that the thermostat may possibly have been failing to turn OFF for years but the fault disguised by the pump running and dissipating the heat through the radiators. Until now perhaps, when the pump started intermittently failing to run. 

 

However, it is a bit unlikely that the primary control thermostat AND the overheat protection thermostat have both failed. My guess would be the gas valve failing to close completely and leaving the main burner 'ghosting' with a small flame when it ought to be completely OFF.

 

 

The radiatior circuit is turned off, the boiler only heats the calorifier.

[MtB]

14 minutes ago, Rickent said:

The radiatior circuit is turned off, the boiler only heats the calorifier.

 

Ok, how do you decide when to turn the boiler OFF?

 

 

[Rickent]

9 minutes ago, Mike the Boilerman said:

 

Ok, how do you decide when to turn the boiler OFF?

 

 

Usually leave the boiler running for an hour, that heats up the water for washing up and a couple of showers.

[MtB]

Ok, and do you do the washing up and have those couple of showers while the boiler is on? Or later, some while later, after running it for that hour?

[Rickent]

4 minutes ago, Mike the Boilerman said:

Ok, and do you do the washing up and have those couple of showers while the boiler is on? Or later, some while later, after running it for that hour?

Usually turn the boiler off when the water is hot enough for a shower but not exclusively so, swmbo has just washed the dishes with the boiler running, is this significant?