Magnaclean not removing all rust. Insufficient circulation?

[benawhile]

My sealed central heating system was installed 4 years ago. 14 brand new rads. Sentinel100 was added and last year checked professionally as adequate. Have checked Magnaclean annually and hardly any deposit last 2 years.

While decorating I removed a bathroom towel radiator but was disappointed to see the water draining out was black with rust. As a check I inspected the Magnaclean filter, and the water inside that was clear, with no deposit on the magnet shroud.

The system is treated with Sentinel and at a service last year the engineer assured us that the sentinel fluid was at correct strength.

I did the simple tablet check myself on the grey water from the aforesaid radiator, and apart from the grey metal discolouration there seemed to be significant yellow colour as well to indicate the sentinel was getting there.

BUT...We keep the bathroom radiator valve almost fully closed so as not to waste heat. It is drop fed and toward one end of the circuit, but there is another hall radiator at the end of this spur which we haven't checked yet.



Would you advise opening all valves fully and running the pump at high speed to give it a good flush once a year, if so, for how long? Would a few hours be enough to get the rust into circulation so it can be trapped by the magnaclean?

 

[ShaunCorbs]

Towel rails are notorious for being bad quality steel so even on the cleanest of system they still dirty, I think it’s down to there height let’s air build up there and air - steel - water bad mix

 

[warmairnotwater]

Yes you stand the best chance of shifting any muck/deposits in the system operating it with everything wide open, and pump at max speed, as the standard circ. pumps aren't anywhere near the forcefulness of a system flushing pump. Dont expect larger particles of debris/rust to be captured by the Magnaclean, as these dont flow upwards in a pipe, and you may well have a few veryical sections. Water should look black, as that is what happens with the reaction of the metals and the chemical additive.

 

[benawhile]

Yes you stand the best chance of shifting any muck/deposits in the system operating it with everything wide open, and pump at max speed, as the standard circ. pumps aren't anywhere near the forcefulness of a system flushing pump. Dont expect larger particles of debris/rust to be captured by the Magnaclean, as these dont flow upwards in a pipe, and you may well have a few veryical sections. Water should look black, as that is what happens with the reaction of the metals and the chemical additive.

Thank you, would you recommend for a few hours spring and summer, for example, or more often

 

[Chuck]

Thank you, would you recommend for a few hours spring and summer, for example, or more often

If it's a vented system, every five years should be enough. If it's an unvented system, it should only need flushing when the boiler is replaced (to comply with the installation instructions).

I'm assuming, of course, that the system is not leaking to any significant extent and it has the correct dosage of inhibitor.

 

[benawhile]

If it's a vented system, every five years should be enough. If it's an unvented system, it should only need flushing when the boiler is replaced (to comply with the installation instructions).

I'm assuming, of course, that the system is not leaking to any significant extent and it has the correct dosage of inhibitor.

Well normally yes, but my issue is that I found a radiator full of black water and significant rust deposits, but for some reason, I have to guess insufficient circulation power, that water wasn't getting from the cloakroom back to the magnaclean. I would expect that water in all parts of the system would be in the same condition if the circulation was sufficient and the magnaclean working properly. But I have clean water in the magnaclean and dirty water in a radiator at the far end of the system. In the first year after the system was installed the magnaclean did pick up a lot of iron. I mean nearly a cupful of sludge, so I know it's working.
Many thanks for responding but did you read the whole post? I did day at the top that the system is sealed i.e. unvented.

 

[Vip1969]

Sealed or Open vent you are not going to get iron particles from the extremities of any CH circuit where the water flow is slow. And the iron particles which are heavier than water are not suspended in water but lie at the bottom or are stuck to the inner metal. Unless you put mains pressure through, you are not going shift this. A central heating pump is a mere water circulator - it does not have the power to do much and especially at the extremities of water circuits. I have done experiments where I close every radiator except one in a water circuit with the pump in full mode but even then the magnetide collected is very small.

 

[benawhile]

Sealed or Open vent you are not going to get iron particles from the extremities of any CH circuit where the water flow is slow. And the iron particles which are heavier than water are not suspended in water but lie at the bottom or are stuck to the inner metal. Unless you put mains pressure through, you are not going shift this. A central heating pump is a mere water circulator - it does not have the power to do much and especially at the extremities of water circuits. I have done experiments where I close every radiator except one in a water circuit with the pump in full mode but even then the magnetide collected is very small.

Point well made and taken, thank you

 

[Vip1969]

I omitted to mention that the one thing that makes some difference is constant hammering with a rubber mallet (or with an SDS drill attachment) whilst the pump is pushing water through the one radiator. You then pick up say half a tea spoon of magnetide as opposed to almost nothing if no agitation of the radiator is done.