Myson apollo on and off

[wilroda]

we have a myson apollo 80c boiler.

When the central heating comes on, it works fine for about 20 minutes and then starts to turn itself on and off at regular intervals of about a minute. The only way to stop this is to shut the heating off for a while and start again...

Any advice would be much appreciated.

 

[wilroda]

Having given it some thought and looking further on this great forum I am wondering if the problem is that the pump is failing.

Could this be the cause?

 

[ChrisR]

Possibly, or thermostat(s) . But bolers like yours have to turn on and off once the water's getting warm or they'd boil. What exactly makes you think it's faulty?

 

[wilroda]

Hi
Thanks for that.
The heating comes on as normal and warms the house but after about 20 minutes the boiler starts shutting down and firing up again for about a minute -or less - on and then off in a cycle. Turning the room thermostat (normally set at about 17 deg) down the boiler shuts down as i would expect - as the house cools -it starts up again - runs fine for a while and then starts the "cycling" again. Boiler on and off every minute or so.Very annoying!

 

[po0041]

Experiancing the exact same problem on my Apollo. Boiler ignites for approx. a minute before shutting down for a short while, then kicks in and repeats the cycle. Tried bleeding the rads and pump but no improvement.

Any help before getting the cheque book out would be much appreciated.

 

[JonB]

Agree with Chris, it is probably modulating correctly.
Does the heating return pipe under the boiler feel as hot as the outgoing pipe? Are the rads getting hot?

 

[po0041]

Both pipes above the boiler are equally hot. Rads upstairs are warm apart from one but all downstairs all are cold.

 

[Soggy_weetabix]

The high or low limit stat may be at fault here.

Which are you running it on? Alternate it and try operation then.

David

 

[ChrisR]

Lack of circulation then - tired pump, or sludge blockage - or both.
The OLD poster's problem was different in that it stayed on for 20 mins.

 

[joserulz73]

do you hear the boiler sparking?

 

[po0041]

Sparking? I hear it ignite.....and I suppose it does make a different sort of noise than usual...gets a little louder until it shuts off.

I'm running it on "high" I'll try alternating.

Thanks guys.