Black crud in new central heating system

[looksexpensive]

Hi,

This is my first post here. I did try searching the forum, but could only find references to old systems so sorry if this has been covered already.

I've recently had a completely new central heating system installed (all new pipes, rads and boiler). After one month of operation, I removed one of the radiators and was surprised to see some black crud (magnettite?) coming out when I drained it. Is this normal in such a new system?

I know the system was cold flushed and that inhibitor was added when installed. I've also noticed that some of the rads were cold at the bottom so could it be that air in the system contributed to the rads corroding already?


Thanks![/img]

 

[45yearsagasman]

What material is the pipework? If it's copper then the system should be flushed hot and with the correct chemicals to remove flux residue, which if not done will quickly attack your system. It does sound like the system was not balanced correctly. You should request your installer to come back.

 

[looksexpensive]

Thanks 45yearsagasman, the pipework is copper. I think the installer did do a hot flush with a chemical to neutralize the flux, but I will check with him.

Would a poorly balanced system lead to air in the radiators?

 

[Agile]

On this forum I was laughed at by other installers because I use X300 to flush a new radiator system. Seems no one else on here ever does!

One of the worst systems that I ever went to was only seven weeks old and the pump had been spoilt by dirt caused by untreated flux having dissolved the steel on the inside of the rads.

Tony

 

[Agile]

Thanks 45yearsagasman, the pipework is copper. I think the installer did do a hot flush with a chemical to neutralize the flux, but I will check with him.

Would a poorly balanced system lead to air in the radiators?

What makes you think it was flushed with any chemical? Do you really have any evidence or its just hopeful thinking?

Corrosion in radiators creates gas and that needs to be regularly bled.

Tony

 

[Whitespirit66]

Would a poorly balanced system lead to air in the radiators?

No.

If you're talking about the rads that are cold at the bottom, this isn't air. Air in rads causes rads to be cooler at the top.

Cold bottoms sounds more like lack of balancing, as already mentioned. Especially if the problem rads are downstairs and/or furthest from the pump.

 

[looksexpensive]

Tony -
A friend did the install (BG contractor 15 years experience). He told me he was going to use something for neutralising the flux, I just didn't actually see him put it in. If he says he did then I'm inclined to believe him, but the black crud is still a problem. I wanted to check here before I go back to him because it's a bit awkward without knowing exactly what I'm talking about and it will be anyway!

Whitespirit66
Sounds like poor balancing might be likely. I'm in a flat, but the problem rad is the furthest from the boiler. I did have some problems to start with with noisy radiators "tinkling". Bleeding didn't help, but I managed to solve this by shutting all but each of the tinkling radiators off (one problem rad at a time), then bleeding them.

I've spent a small fortune on radiators and everything else and to think that it is dissolving away already is annoying to say the least. If I hadn't removed the bathroom radiator to do the tiling, I would be none the wiser.

 

[looksexpensive]

I've spoken to the plumber that did the installation and he did flush and put a cleaning chemical in first, followed by cold flush and then inhibitor. However, I calculated the water content of the system to be close to 100 litres, so I think it is possible that there is not enough inhibitor (1 bottle of Sentinel X100 was used).

My Plan:
Cold flush system
Instal a Magnaclean
Add two litres of Sentinel x100 and refill

 

[ALCPlumbing]

On this forum I was laughed at by other installers because I use X300 to flush a new radiator system. Seems no one else on here ever does!

One of the worst systems that I ever went to was only seven weeks old and the pump had been spoilt by dirt caused by untreated flux having dissolved the steel on the inside of the rads.

Tony

You're not alone Tony. I also do a hot chemical flush to remove flux residue.

 

[Richardthe3rd]

I've spoken to the plumber that did the installation and he did flush and put a cleaning chemical in first, followed by cold flush and then inhibitor. However, I calculated the water content of the system to be close to 100 litres, so I think it is possible that there is not enough inhibitor (1 bottle of Sentinel X100 was used).

My Plan:
Cold flush system
Instal a Magnaclean
Add two litres of Sentinel x100 and refill

I'm not a big fan of too much inhibitor or using X100. Seen too many systems with x100 that are the colour of strong Tea after a few years. If you speak to Sentinel regarding this, they say the system water should be checked annually.

 

[looksexpensive]

Richardthe3rd -

Do you think two litres of Sentinel in a 100+ litre system is too much? I read that too little inhibitor can actually accelerate corrosion in the system. To complicate matters further, today another plumber told me that it is normal to get magnetite even after a few weeks in a new system that has been flushed and inhibited correctly.

 

[ScottishGasMan]

On this forum I was laughed at by other installers because I use X300 to flush a new radiator system. Seems no one else on here ever does!

One of the worst systems that I ever went to was only seven weeks old and the pump had been spoilt by dirt caused by untreated flux having dissolved the steel on the inside of the rads.

Tony

Only time I ever fitted a full system from scratch I used X300, hot flush, then multiple cold flushes till water was colourless, 3 years on I took a sample and it looked like drinking water it was spotless. I sometimes wander if the "Sludge" removal chemicals are that good with flux

 

[Agile]

They are formulated for completely different purposes.

I once did a boiler repair for a nurse and she was worried about the chemical treatment of her system water.

I took a sample and told her it was perfectly clean.

She looked a little disbelieving so I drunk some of it!

Tony

 

[Richardthe3rd]

They are formulated for completely different purposes.

I once did a boiler repair for a nurse and she was worried about the chemical treatment of her system water.

I took a sample and told her it was perfectly clean.

She looked a little disbelieving so I drunk some of it!

Tony

Ah, that explains a lot Tony. And here's me putting it down to your overindulgence in that cheap French plonk......

 

[Richardthe3rd]

Richardthe3rd -

Do you think two litres of Sentinel in a 100+ litre system is too much? I read that too little inhibitor can actually accelerate corrosion in the system. To complicate matters further, today another plumber told me that it is normal to get magnetite even after a few weeks in a new system that has been flushed and inhibited correctly.

System volume calcs;
http://www.fernox.com/problem+solving/how+to+sheets/estimating+water+system+volume

I just don't like their X100, it just appears to be too weak.