cast iron rads & sludge problem

[alan_james]

Hi, I searched the forum and couldn't find this issue discussed before, sorry if it was.

I got a new (Sime) gas boiler (with expansion vessel/auto-fill) water central heating system plumbed in 7 years ago to an old 3 storey Georgian terraced house I renovated. It's a mixture of some 100 year old cast-iron rads from a salvage yard and regular steel new ones, 14 in total, done with qualpex pipes and copper running into the rads, boiler etc.

The system worked fine, despite me not trusting the plumbers (they were comedy of errors at times, I had to tighten lots of joints to stop leaks they left behind, etc.). Also against their better judgement I found the old rads worked great, get very hot and stay hot long after the heat is off.

Anyway, long story short, some of the rads are getting blocked with sludge or rust or whatever. As far as I know there was nothing added to the water to prevent this. On some of the top floor (new, steel) rads, if i need to bleed them for air any water that leaks is black. I can dislodge the blockage by ramping the heat up and turning off all rads except the blocked one, the heat/pressure seems to move the sludge, but eventually it happens again.

So, does the system need to be physically "blown out" to clear all this, or can water additives do it? I can do some small plumbing work myself (I moved & re-piped a couple of rads etc.), but not pressure-blowing the whole system or whatever. Are there choices between cheap DIY and professional expensive options? Money is tight these days! ;-)

What do you think?

Thanks,
Alan

 

[Barry98]

sounds a bit of both imho , you could do with a power flush to clear the exisiting problems then add something like a magna clean

 

[fuzzy]

can you take the rads off and flush tehm out? thats worked well for me in the past

 

[aggis]

yeap, as bod said a powerflush would be best, but don't forget to add an inhibitor when done. ie sentinel x100 or fernox f1. then top up at least every 3rd year or if you ever have to drain off a rad.

 

[tipintim]

Hi Alan
You have a lot of different metals all reacting there mate. Steel, copper, alli and cast. (plus flux, sand and solders etc) This will be a constant problem if you dont chemically dose, clean and power flush. On completion you need to introduce at least 6 inhibitors, maybe more. ( guessing the size)

If you are confidant to do it yourself, PM me and I will give you procedure that I would carry out.
If not, you can post your area, and someone on this site can power flush for you. At a price of course.

 

[CES]

I would agree that a flush of some sort is in order. Correct dosage of inhibitor and I personally would fit a Magnaclean or similar filter to contain the black iron oxide that occurs during the corrosion process.

 

[alan_james]

Thanks for all the replies!

So, can a power flush be done without removal of rads? The cast-iron ones are very heavy (not really realistic to remove & flush them out myself)! I guess I'll need to call in the professionals for the flush, and a Magnaclean filter sounds like a good idea.

Thanks,
Alan

 

[jase158]

yes power flush is done with system in position, the pump is connected into system without taking off the rads.

 

[fuzzy]

yeh if removing rads is problematic then power flush is a good idea

 

[alan_james]

I actually have a water pump for the sinks/showers/toilets - would that power a cheap (well, free!) DIY flush, connecting a rad zone up to a tap at one end, a pipe out to a drain at the other, and let the tap run full-tilt for a while?

Or is that just a crazy/dumb idea?! :freak:

Thanks,
Alan

 

[daisysdad]

extreme caution on this mate.A plumber is the best option but make sure you get a written quote.I had same problem 2 years ago and the guy quoted us through his wife who took the call as £300 to flush and fit a Cal Clear filter.
He sent one of his men who had the flu ,didn,t flush the system propely and every valve blocked.
He sent another firm and came his self after 3 hours and finally got it working.
He then sent us a bill for £870 but after an argument dropped to 640.
C.A.B told us we should have gotten written quote.
2 years later after following his original instructions for cleaning the filter its now leaking like a sieve and lost us a house sale.
So be careful of getting a written quote

 

[stevetheplumber]

how could you let a leaking filter lead to loosing the sale of a house, £200 to replace a filter vs the sale £????
in truth its not even the suppliers fault if your filter is leaking after two years take it up with the manufacturers we can only fit whats available on the market
i assume you havent had the boiler service in those two years as then you would have discovered the leak within the warranty period

 

[alan_james]

Written quotes & receipts are always a good thing if the worst comes to the worst!

But anyway, just to ask again - I actually have a water pump for the sinks/showers/toilets - would that power a cheap (well, free!) DIY flush, connecting a rad zone up to a tap at one end, a pipe out to a drain at the other, and let the pump-powered tap run full-tilt for a while?

Or is that just a crazy/dumb idea?! :freak:

Thanks,
Alan

 

[daisysdad]

the boiler was serviced this time last year at the same time as we had the fan replaced .The filter started leaking last month when we were away and some one came to veiw the house.We followed the installers instructions on cleaning it as he said it wasn,t worth him coming out to do it.The filter unit is a Cal Cleear and up to press I have been unable to find any one locally that stocks them or has heard of them ie Grahams Plumbers merchants and PTS.
If it was any other brand the seal kits are complimentary they have told me

 

[mitchellplumber]

plastic pipe- generates sludge in central heating. I have still to work out the cause for sure. Think fittings might let air in. I would change plastic for copper if possible and If your power-flushing use a machine. Best plan- Call a competent plumber.

 

[AmritPedersen]

Actually, I'd say at least 2 or 3 litres of inhibitor. 1 litre does up to 10 standard rads & you have 14 rads, some of which are recycled cast iron rads. Who knows how well they were cleaned by the salvage yard (if at all?).

Absolutely a MagnaClean!

 

[alan_james]

Cheers, looking into hiring a power flush kit too, it doesn't sound too different from my idea of flushing via tap!

Alan

 

[tipintim]

Actually, I'd say at least 2 or 3 litres of inhibitor. 1 litre does up to 10 standard rads & you have 14 rads, some of which are recycled cast iron rads. Who knows how well they were cleaned by the salvage yard (if at all?).

Absolutely a MagnaClean!

These are not standard rads. I would put as much inhibitor in as I could offord. Lot more water in a cast rad than a pressed steel one.

 

[Blackcatgas]

power flush, use a rubber mallet not a drill attachment as they can jack hammer through a corroded rad.