Central Heating Sludge...

[wlam]

Hi all,

Recently experienced problems with my conventional boiler (Worcester Bosch Greenstar 15ri) and central heating. Some background:

When on HW only, it would take around 60-90 mins to get from a completely cold cylinder to a hot cylinder. I think the cylinder has a capacity around 180 litres.

When on CH only, after a couple of hours only the loft and 1st floor radiators would get hot/warm. The ground floor radiators would not get even warm, and the feed pipe to these radiators are cold (I suspected some sort of blockage or sludge build up).

I avoid having both HW+CH on at the same time, as it takes 3-4 hours for the cylinder to get hot, and the 1st floor & loft radiator only get midly warm.

I called a heating engineer, and he agreed my diagnosis of blockage/sludge and drained and flushed the system and cleaned out the F+E tank. As the water was been drained and flushed much of it was dark brown/red colour but also sometimes turned black.

He suspected there was also a problem with the diverter valve, and when this was replaced, I noticed that there was a lot of sludge in the valve (see pictures). I'm guessing it's safe to assume the rest of the pipework will be in a similar state?

Unfortunately none of this cleared the problem of the ground floor radiators being cold, though the heating engineer, added some CH system cleaner so we will see if that improves things.

However wanted to hear if anyone had any other ideas or thoughts? based on the pictures, is there anything else worth trying?

20160120_231934[1]

• wlam
• 20 Jan 2016

20160120_232101[1]

• wlam
• 20 Jan 2016

 

[TCCHeating]

Red sludge like this is caused by air ingress. You need to find out where this air is coming from. Pumping over is the most common cause. Post a pic of your pump, feed and vent configuration

 

[shambolic]

Trace the cold feed pipe from the feed and expansion tank to where it tees into main pipes ( probably on cylinder return )
Then touch copper pipe with a magnet if it sticks you have sludge there.
If that's the case cut out and reconfigure the cold feed and open vent and pump properly ( get someone in).

 

[wlam]

Thanks, pic of my configuration below.

The over pumping as the cause of the red sludge, sounds correct, as many years ago (10+) we did notice a problem with water noise and steam going into the F+E tank. I just checked, as our system has been on all day, and the overflow pipe going into the F+E tank is cold, so guessing that's a good sign.

The CH pipework and radiators haven't had any maintenance for over 20+ years, though the Worcester Bosch boiler was put in 5-6 years ago (don't recall if the system was flushed at that time, probably not).

In the picture I believe the cold feed pipe is the one coming down from the top left. Magnet does not stick where it tees into the main pipe.

20160121_194042[1]

• wlam
• 21 Jan 2016