Persistent sludge in radiators

[steve1978]

I had a new boiler installed with a power flush and new magnates filter in summer 2023. Its an ideal LOGIC MAX COMBI2 C24 boiler.

My old boiler was only 6 years old but ended up getting dirty water backed up into the boiler.

Since installation there has been numerous problems. Primarily build up of sludge in the radiators. Since installation the company that fitted it have flushed the system 3 times and put in inhibitor. The problem being solved for a few months each time.

In only this short time they also had to change the diverter valve. Ideal boilers themselves have looked at the boiler a year ago and said it was full of dirty water. They replaced the pressure relief valve and vessel.

Today I noticed the radiators once again are hot at the top cold at the bottom. Bled the rads and cleaned the filter but very little change.

I am now out of warranty with the company that fitted the boiler. I do have a 10 year warranty with Ideal for the boiler. The owner of the company that fitted the boiler gave me his personal number last year and assured me that I won’t be left high and dry with this situation. My big concern being that what killed my old boiler is once again doing the same thing with this new boiler.

Does anyone know of any other problems that could be causing this persistent sludge build up? The company that fitted the boiler - whilst being helpful with flushing the system multiple times under warranty, are maybe ignoring/ not seeing another underlying problem.

Having to flush every 6 months to keep the sludge down seems excessive. But if I don’t it seems my new boiler is heading for the same fate as my previous boiler.

Any help would be greatly appreciated!

Thanks

Steve

 

[steve1978]

When you say flush, what do you mean exactly? There is a specific tool that is used to flush systems. It isn't just draining it and refilling it.

How old are your radiators? How many? You need to drain the system and remove/drain/or replace every single radiator. Sludge doesn't build up that quick and it isn't the boilers problem.

Thanks for your reply.

The invoices say 'Chemical flush to the heating system'. 'Fill with inhibitor'.

The radiators are 14 years old. 5 radiators. Its a 1 bedroom flat.

Im unsure what your telling me? That the company arent doing a thorough job in the flush? Im pretty sure they are doing as you suggest.

So if sludge doesnt build up that quick what is the problem?

 

[steve1978]

A chemical flush isn't a proper flush. If you have sludge it has been there a while and it is because you never had inhibitor or the radiators are just end of life and deteriorating on the inside.

Quick guide: powerflushing

A powerflush can improve the efficiency and lifespan of a boiler and central heating system, but what's involved?

trustedtraders.which.co.uk

A proper "powerflush" is what is required to clear sludge, and even there it isn't fall proof (the crap will be at the bottom of each rad and a bit stubborn, especially if the rads pre-date modern design with baffles etc).

So you can either - drain the system and replace your rads like-for-like.

Or pay for a powerflush that'll be just as expensive and could open up new issues (its at higher pressure than your boiler and can expose dodgy pipework that was ok at lower pressure).

It also has had a Power flush reading the invoices back, when the boiler was installed.

Only back 6 months ago after the last power flush, the rads felt clear top to bottom, no sludge, good heating. 6 months later the bottom half of the rads are almost cold to touch.

It sounds like then that the rads are just completely corroded? Hence my initial concern, that the company that fitted the new boiler ignored the issues that killed my old boiler. 'It just needs a new boiler and powerflush'. I get it companies get their easy money fitting a new boiler compared to solving the problem.

 

[steve1978]

How old was your old boiler?

If you want compo face to get free rads then you're on your own.

Edit: powerflush is about 700 quid / full days labour.

My old boiler was only 6 years old.

Compo face? I never said I wanted free rads? However you must see my point. I have a problem with my old boiler. Company comes round. You need a new boiler and power flush. I do that even though I raise concerns there might be another reason for the problems. Problem persists. Out of warranty. Yeh I could pay £700 for a poweflush but I know from experience over the last 18 months this will only provide a small fix for months not even years.

 

[steve1978]

Problem is that flushing is by no means perfect. The only way to do a thorough job is to remove each radiator and manually flush it with a power-washer. I suppose you could repeat the chemical flush every three months for a year or two but that gets very expensive. Removing the radiators can be tricky too. You really need end caps for them because the sludge stains like nothing else on planet earth.
But no, once it is completely flushed and re-filled with anti-corrosion it will be fine. Even without an anti-corrosion additive it takes a lot longer than three months to corrode enough to form a lot of sludge. Nope, I am sure that is is just re-distributing sludge that is already in the system.

Totally understand flush is not 100%

I’m not totally sure they took off each rad individually I’ll find that out

 

[steve1978]

Problem is that flushing is by no means perfect. The only way to do a thorough job is to remove each radiator and manually flush it with a power-washer. I suppose you could repeat the chemical flush every three months for a year or two but that gets very expensive. Removing the radiators can be tricky too. You really need end caps for them because the sludge stains like nothing else on planet earth.
But no, once it is completely flushed and re-filled with anti-corrosion it will be fine. Even without an anti-corrosion additive it takes a lot longer than three months to corrode enough to form a lot of sludge. Nope, I am sure that is is just re-distributing sludge that is already in the system.

Totally understand flush is not 100%

I’m not totally sure they took off each rad individually I’ll

I highly doubt you received a powerflush. Sludge doesn't build up in 6 months unless your rads are rotting from the inside out.

Pics of rads?

If you need rads, you need to pay for them. Whether your boiler man promised an outcome or simply a scope of work is your problem in how you interpret information.

Appreciate your thorough replies.

However, I find your reply slightly surprising.is it not the job of the plumber to diagnose a problem?

They told me with the old boiler: a power flush may save the boiler it might not.

A new boiler with power flush will resolve all issues and give me a ten year warranty on the boiler

So I went with the second option. However the same problems persist.

Not sure there is any ‘interpretation’ there

 

[steve1978]

Ok well why are you here then and not complaining to your plumber?

In the process of speaking with the plumber now.

As in my original post. I’m on here looking to see if anyone had any other ideas what could be causing excessive sludge. And maybe a solution other than flushing the system every 6 months which will cost me a fortune.