Central heating stops working after 5-10 minutes (w/ images)

I've been toying with my central heating for over a week but I've no idea what's wrong with it. Before calling a professional, I really would like to learn a bit or give it a try fixing it!

The heating works for 5 to 10 minutes, the radiators seems to start warming up and there are pipes that gets hot. But after that, it starts to cool down even if I cannot really hear any difference in noise from the pump or from the system.

I've been toying with a couple of valves and I did it without checking their original position too so, I am a bit lost here -- especially what they were supposed to do.

Here are some images of the area I've been toying with:

General:

Larger image: http://img16.imageshack.us/img16/5596/p1010257f.jpg

Valves and the actuator?:

Larger image: http://img822.imageshack.us/img822/3874/p1010258w.jpg

Pump:

Larger image: http://img259.imageshack.us/img259/3218/p1010259.jpg

Some pipes going up, left one gets hot when the central heating works and cold when it stops working:

Larger image: http://img202.imageshack.us/img202/1732/p1010260u.jpg

So if you have any idea what I should try or if you have any further questions, do tell me!

Make and exact Model of boiler?

Where is the Myson Aerjec located? I can't see it in any other the other pics.

Which valves were you fiddling with?

How long before the boiler comes on again?

Boiler is a Potterton Suprima 40 L.

Isn't the last image the Myson Aerjec? I can try to look for it if you can tell me how it should look like.

I've played with both valves that appear in the first and second picture. I really didn't know what they did. I just know I've tried quite a few combinations on them. Like, both fully off, both fully on, 1 on and 1 off, both them just half on.

The boiler comes on...I think once in the morning, once in the afternoon and once in the evening. I do have hot water even if my radiators are dead cold after that 5-10 minutes period.

airjecs have a habit of blocking up, try bleeding a radiator with the boiler turned off and see if you can hear the small tank in the loft filling.

andychan2007 said:

Isn't the last image the Myson Aerjec? I can try to look for it if you can tell me how it should look like.

Click to expand...

I know the last pic shows the Aerjec. But where is it in the other pictures.

I've played with both valves that appear in the first and second picture. I really didn't know what they did.

Click to expand...

Saw them after I posted my question.

The valve on the pipe going into the bottom of the cylinder serves two purposes: it can shut of the circulation through the cylinder (this will stop you getting hot water); it will balance the flow through the cylinder so the cylinder goes not grab all the circulation and prevent the rads heating when both HW and CH are on.

Set the valve to 1 turn open to start with. Open the valve a bit at a time if the cylinder takes to long to heat; close it if the rads don't heat up so much.

The valve to the right of the motorized valve is on the bypass circuit. This is a short pipe connecting flow (between pump and MV) to return. It provided a path back to the boiler so the correct flow is maintained through the boiler when TRVs close.

If you have TRV's, set this valve to 1 turn open

If you don't have TRVs the valve can be left closed.

The boiler comes on...I think once in the morning, once in the afternoon and once in the evening. I do have hot water even if my radiators are dead cold after that 5-10 minutes period.

Click to expand...

Are you saying that the boiler runs OK, it's only the rads which stop heating up? If so, the problem is probably in the motorized valve.

D_Hailsham said:

I know the last pic shows the Aerjec. But where is it in the other pictures.

Click to expand...

Look like the Aerjec is in the airing cupboard, above the shelf......

Dan