noises after drain and refill

[cbasson]

Hi,

I drained my sealed heating system today as I couldnt find the auto air vent or isolating valves. Changed the valve, all done.

Now on repressurising the system, after bleeding all the rads a couple of times to get the air out, when I use the boiler now I get all manner of noises from it and quite a variation in the pressure.

So I'm guessing that there is air trapped in the boiler, though still cant find the auto air vents if there are any. None on top and the manual doesnt show any.

The boiler is a Potterton 60. Any ideas please?

Thanks

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Moderator's note:
I have split the thread,

You should start your own thread! This one is two years old!

Have you bled the pump?

Tony

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[cbasson]

Ok, go easy (on the stupid question that is)...

Would that be one next to the hot water tank? No, how is that done?

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Gotcha on the rules..

 

[cbasson]

So its not this pump however..... is the pump bled via the screw in the middle of the casing (shown)?

View media item 4001 [/img]

 

[cbasson]

I have bled the pump a couple of times now and after each bleeding I have attempted to turn on the hot water.

On each occassion, the boiler ignites and cranks up in its usual fashion, then after about 60 seconds a couple of bangs are heard and the boiler locks out.

So... (1) Is this the process I should be using to stop the noises and get the boiler working again?
& (2) Is this damaging the boiler/system?

Thanks

 

[JohnD]

I am no plumber and have only worked on open-vented systems so this may be complete rubbish, but...

the boiler ignites and cranks up in its usual fashion, then after about 60 seconds a couple of bangs are heard and the boiler locks out.

sounds like water is not circulating through the boiler.

I find it helps to blow the air out, if you start up the system so the pump is running to circulate the water, but the boiler is not firing. On mine you can do that by turning the boiler thermostat right down, and the wall stat right up. If you have TRVs open them all so that the air can settle in the top of the rads and you can bleed it out.

Can you do that on yours?

You also need to verify that the pump is spinning (by looking at the spindle through the hole behind that big screw in the middle) and make sure you have not absent-mindedly left any valves shut and preventing water circulation. If it was am open-vented system fed by a Feed & Expansion tank in the loft I would be more concerned about a sediment blockage in the feed preventing water getting down, I suppose this is also possible if you have an old sealed system and you have seen signs of sediment or sludge. Sediment can also jam pumps. If the pump tries to run without water in it, or if seized, it will get very hot and get damaged. You can identify this when you find it is too hot to touch.


Presumably you have checked the pressure gauge after bleeding the rads, and it is OK?

 

[cbasson]

On mine you can do that by turning the boiler thermostat right down, and the wall stat right up.

So, boilet temp down, central heating temp up, ill give that a bash.

You also need to verify that the pump is spinning and make sure you have not absent-mindedly left any valves shut and preventing water circulation....If the pump tries to run without water in it, or if seized, it will get very hot and get damaged. You can identify this when you find it is too hot to touch.

The pump seems to be wirring so I assume its working. Prior to me draining the system, it was all working okay.

Though after the last lock out the pump was very warm to touch, under normal operating conditions are they not that warm? After I bleed the pump, I stop when water begins to dribble so it seems there is some water...?

Presumably you have checked the pressure gauge after bleeding the rads, and it is OK?

Yup, pressure is fine, having been topping it up after bleeding rads/pump. Presuure jumps slightly when the noises occur.

 

[cbasson]

I am no plumber and have only worked on open-vented systems so this may be complete rubbish, but...

On mine you can do that by turning the boiler thermostat right down, and the wall stat right up. If you have TRVs open them all so that the air can settle in the top of the rads and you can bleed it out.

Can you do that on yours?

Doesnt seem so

 

[cbasson]

Fingers firmly crossed, but I may have success.....

Seemed like the pump would only start working after the boiler had tripped out, so played around with water and CH to get them on at the same time.

A q on the pump: I'm assuming mine is working okay as the pipes are hot both above and below the pump, though how hot should it generally get during operation- not at all, warm, or melt your skin hot?

Thanks for the help, hoping this is the end of this one...

 

[JohnD]

when working properly, the pump will be about the same temperature as the water passing through it, and the pipes beside it, which should be the same temperature along their length. When jammed or dry it will be startlingly hotter.

 

[cbasson]

Thanks JohnD