Sludge in System - Replace Rads?

[chaoticj]

Hi,

The central heating has never worked well - only the rads nearest to the combi boiler in the kitchen get hot.

The others get warm around the top, upstairs is even worse. The boiler has been repaired a couple of years ago under a fixed price by the manufacturer but it's now on the blink again.

I bought a Flir One thermal camera and walked around pointing it at the pipes and rads.. they all seem to show as hot with no cold spots, but the weather is obviously a lot warmer now so less difference between rads & pipework vs ambient temperature.

I've been advised by a heating company it would be best to replace ALL of the 18 rads at a cost of over £3K as they will be rusting inside. They say the different ages of rads will have a different metal composition that cause each other to rust more.

There are 3 different ages of rads, most look 1980s and have imperial sizing, a couple seem 1990s and some are fairly modern 2010's in the extension.

Just wondering if it's right that they all need changing. Had 2 others quote to replace boiler and none of them mentioned replacing rads.

I'm not experienced in plumbing DIY, draining down, refilling etc. and some of the rads are ginormous but any advice and help would be really appreciated.

Many thanks in advance.

 

[Mottie]

If it's only the ones nearest the combi boiler are getting hot, it sounds like a balancing or pump problem.

 

[HERTS P&D]

Do you have a magnetic filter? Turn off the hot radiator and see if the heat is pushed round to the other rads.

Andy

 

[chaoticj]

Hi,

The heating has always worked like this since before boiler repaired @Mottie but it has not been balanced. Is this difficult?

Unfortunately @HERTS P&D there is no magnetic filter as the boiler is now 16 years old so wasn't a requirement back then.

I will try turning off the thermostatic valves of the rads in kitchen & utility later.

Many thanks!

 

[Mottie]

The heating has always worked like this since before boiler repaired @Mottie but it has not been balanced. Is this difficult?

https://www.diynot.com/wiki/Plumbing:faq2

 

[Mike13]

Balancing just requires a bit of patience to let temperatures settle down after each change. A magnetic filter can be fitted to an older system, ours is definitely keeping things cleaner after it has been in for a while now. Some of ours is well over 20 years old and did not need to be replaced when the extension went in.

 

[chaoticj]

Do you have a magnetic filter? Turn off the hot radiator and see if the heat is pushed round to the other rads.

Andy

Hi Andy,

The kitchen and utility rads were set to almost full, turned them to 0. After an hour of CH on, they are both stone cold along with pipes each side.

So now the large rads in the living room and lounge are piping hot.. at the top and edges.. in the middle and bottom they are cold. Both pipes are piping hot.

The boiler is set to 75 degree CH and shows 55 degree on the display.

Many thanks.

 

[HERTS P&D]

The best Diy job to do is to drain down the system and remove each radiator and flush them in the garden, you won't believe the black/dirty water coming out. It may be best to do this with a plumber or someone who is confidante at diy. Also fit a new magnetic filter. Then refit the rads and re-balance.

You will find videos of flushing radiators with a hose in the garden on youtube.

Andy