Boiler not starting

[athlonoc]

Hi,

I have a Potterton Suprima 40 boiler with EP2002 programmer. I seem to have a problem with the boiler taking ages to fire up. It seems to take on average an hour to start when the programmer fires it up for the central heating. I have no issues with the hot water.
I thought it was the room thermostat at fault but I have just replaced it with a brand new one and I still have the same problem.

Could the 3 port myson valve have anything to do with it. For about a year now it makes a hideous buzzing sound which it never use to do, only when the timer kicks in to start everything up in the morning. It doesn't make a noise later on.

So in summary

1) Heating takes about an hour to start up. Once started no problems, room stat switches off with change in temps etc.

2) Is my Myson 3 port power extra valve either faulty by it's own noise and or is this the possible cause of the boiler not starting .


Lastly just out of curiosity. How long should a boiler take to fire up when the timer switches it on to start the central heating.

Many thanks

Lee

 

[Newboy]

The three port diverter may be stuck and failing to tell the pump to start and hence the boiler to fire.

When you demand heating only does your pump run immediately (assuming the room stat is set above room temperature) or does the pump kick in when the valve stops making a hideous noise

For about a year now it makes a hideous buzzing sound which it never use to do,

Do you think that there might be something wrong with it and needs some attention?

 

[athlonoc]

Thanks

I'll check in the morning from cold. I do believe it starts when the diverter valve stops making a noise but I'm not 100% sure at this moment.

 

[athlonoc]

OK. This morning it took about 35 minutes to start the boiler when the timer kicked in. Then heated up nicely.

Allowed things to cool down nicely until midday, then switched timer onto constant and hey presto it fired up immediately.

This doesn't make sense.

Could there be a problem with the boiler itself?

I don't understand why first thing in the morning when it's freezing cold, thermostat way above household temperature to make sure it doesn't shut it off, but it doesn't fire up the boiler instantly?
Yet a few minutes ago, when ambient house temperature is warmer than this morning it fired up straight away.

Any help or advice.

Thanks

Lee

 

[Softus]

OK. This morning it took about 35 minutes to start the boiler when the timer kicked in. Then heated up nicely.
This doesn't make sense.

Lee, an increasing number of systems have a motorised valve (or two) that control the boiler and pump - the valve operates a microswitch when it becomes fully open, which normally takes 5-10 seconds. This is as newboy said.

Hopefully you can see that, if you have such a valve that takes 30-60 minutes to open, for whatever reason, that the boiler will not operate for that period of time.

If the valve is faulty then you need to replace it. There's quite a bit of detail on other topics on this subject - let us know if you can't find it.

 

[meldrew's_mate]

It seems to take on average an hour to start when the programmer fires it up for the central heating. I have no issues with the hot water....Could the 3 port myson valve have anything to do with it. For about a year now it makes a hideous buzzing sound which it never use to do, only when the timer kicks in to start everything up in the morning. It doesn't make a noise later on.

Suspect the boiler starts immediately when HW & CH are on at the timer. This points to the 3 port valve failing to drive to the CH only position (munching gears noise?). Check out/replace the Myson actuator or the whole valve.