Magnetite in heat exchanger in combi boiler

[mandinka]

Hi

6 months ago I had my bathroom completely redone and this included fitting a new radiator in a new position. Immediately I started having problems - baxi combi boiler (3yrs old) reporting overheat error and shutting down hot water. Engineer eventually tracked problem down to magnetite in boiler. He took h/w heat exch out and cleaned it as best he could and boiler was fine again. However, this just keeps on happening. It's fine for about a week then same thing again. I paid to have a magnetic filter fitted but still the problem persists. Engineer says no more magnetite is getting into boiler and we just have to keep cleaning it every time it breaks down until all the gunk is out of the boiler. The amount that comes out each time doesn't seem to be decreasing though and, having put up with hot water failure and no shower etc once a week for 6 months now I'm desperate to find a solution. Surely there must be some way to flush all the magnetite out of the boiler? I don't mean to flush the whole c/h system - just to isolate the boiler and flush it though some how?

Please can anyone help?

 

[bazdaman]

What good will it do to flush boiler only, you need to flush everything

 

[JohnD]

Is the muck that comes out hard and black? Or sludgy?

Are you in a hard water area?

What sort of filter have you got? How much muck comes out when you empty the filter? Is it all soft? How often do you empty it?

Has it been cleaned with acids or chemicals?

Are your radiator pipes 15mm, or the size of a pencil?

 

[mandinka]

Hi JohnD
It's a MagnaClean filter. The sludge is black and hard and there seems to be a lot of it inside the heat exchanger itself each time the engineer comes. He,says it is working its way round insidecthe boiler and then getting trapped in the heat exchanger but that no new sludge is entering the boiler since he fitted the MagnaClean.

Any suggestions?

 

[mandinka]

Oh. It hasn't been cleaned with chemicals or acids and I think the pipes are 15mm

 

[Dan Robinson]

Get a different engineer.

 

[Agile]

Dear Mandika,

the dirt comes from your radiators! Its no use just cleaning the boiler. You need to clean the whole system.

But you have not really said how much dirt is in the Magnaclean filter when its emptied weekly?

Tony

 

[mandinka]

Thanks for your replies so far.

bazdaman - the system was flushed 3 years ago when the boiler was installed and I've had no problems at all until the new radiator was fitted 6 months ago - the engineer says flushing can never totally clean magnetite from rads and pipes and moving pipes etc while refitting the bathroom has dislodged some that was stuck in the rads and pipes after the flush and this has made its way into the boiler.

Tony - I understand that the dirt has come from the rest of the system but the engineer is assuring me that no more can be getting into the boiler because he has fitted the Magnaclean filter now and the stuff that is causing the boiler to stop is stuff that had already got in there before he fitted the Magnaclean. His solution is to keep cleaning the heat exchanger each time it gets blocked until all the stuff in the boiler itself has been removed. - This is what I wasn't sure about - is he right that no more is getting in? He isn't cleaning the Magnaclean each time he comes - he's actually taking the boiler apart and taking the h/w heat exchanger out and cleaning that - there is say qyarter to half an eggcupfull of hard black gritty gunk coming out of it each time. To me it just seems to be a hell of a lot of gunk to be still left in the boiler after all this time and so many visits to clean the boiler out? what do you think?

Dan_Robinson - I suppose the reason I have posted this question here is because I am trying to find out whether a different engineer would do anything different. ie -
1) is there some better way of getting rid of the magnetite that is circulating round the boiler and periodically blocking it?
2) is he right in saying that the magnetite that he is cleaning out of the heat exchanger each time is still the original stuff that got in there before he fitted the Magnaclean?
3) would another engineer be able to come and do something that would actually solve the problem in one go rather than me having to keep coping with no hot water every week or so?

Grateful for any advice and suggestions. I just can't bear to think of going into winter and the kids and I not being able to shower etc for days at a time each time this happens.

 

[Dan Robinson]

Any heating professional that thinks that a system filter stops every particle deserves a slap.

 

[JohnD]

It is absurd to fit a Magnaclean and not empty the dirt out of it. It reduces the circulating particles over time, starting out by collecting a lot, then, as the dirt reduces, less and less. If you empty it frequently you will be able to see the amount of dirt reducing. Eventually it will only need to be cleaned out once a year.

If yours has not been cleaned out then it might be full and no longer trapping debris.

Look up the instructions online. You should have a big ring spanner (preferably hanging up next to the Magnaclean where it will not get lost).

Also ask around for recommendations of a more competent engineer. It must be costing you a fortune to have the HEX cleaned out time and again.

If it was me I would for a simple and inexpensive DIY start add some Sentinel X900 and keep emptying the Magnaclean but if you keep getting blockages you need a complete system clean.

 

[picasso]

I would get the dhw heat exchanger replaced, half an eggcupful isin't enough to block the waterways stopping the boiler working.

 

[mandinka]

Hi JohnD - Thanks very much for your advice. The Magnaclean has been emptied recently as, coincidentally, the boiler was due for a service (ie have a service/call out contract but sadly the one thing that is not covered is sludge in the system ) but I will do as you suggest and check it again and regularly to see how much is building up. I have the spanner thing hanging next to it.

picasso - the engineer did replace the dhw heat exchanger when the probelem first surfaced and only after repeated breakdowns was the magnetite found to be causing it.

So - is there no way to flush the boiler itself whilst still doing the other things you recommend to stop more sludge entering?

 

[JohnD]

there are chemical cleaners that loosen sludge so that the Magnaclean can trap it, or it can be flushed out. They are milder and slower than a powerflush, but are useful for DIY. X900 is a mild chemical that can be left in permanently and will help keep a system clean in this way provided there is a filter to trap the loosened particles..

However you appear to have a more substantial problem, so you will probably need a powerflush, and faster-acting chemicals. Some chemicals are more aggressive and IMO not suitable for DIY use.

But as I say, if it was me, I would start with a chemical, and empty out the Magnaclean frequently, simply because it is cheap and easy DIY job which is likely to do some good.

The hard deposits you mention have been baked on with heat, and may be a combination of hard-water limescale mixed with magnetite. Mild chemicals are not much good on those. A professional might use a strong acid cleaner.

 

[Agile]

A major aspect for diagnosing the problem is to see how much dirt is in the Magnaclean.

I don't understand why the engineer never apparently cleaned it out on his visits.

Easy DIY job to clean though.

Tony

 

[mandinka]

Tony

He seems less concerned with the sludge that is in the main central heating system as he seems to suggest this is already being dealt with by the Magnaclean - ie it is no longer getting past the filter and into the boiler so it is not causing a problem. He is concentrating on removing the sludge that he says is already in the boiler from the initial "contamination" by cleaning the part of the boiler where the sludge circulating around in the boiler is getting trapped - ie the h/w heat exchanger. If he is right (and this was one of my original questions) about the fact that no more (new) sludge is getting past the Magnaclean and into the boiler then getting the sludge in the boiler out seems to be the thing that will stop it getting blocked now? Is this right?