Old Rads and Sludge

[mravant]

Hi Guy's,

about four years ago we had an old potterton floor standing boiler (conventional) 30 years old replaced with a new Heatline condensing Combi (I know they are not the best boiler).
At the same time we had the the system powerflushed.

Now the boiler is struggling to get the water hot and only comes out slightly warm. We had a similar problem two years ago when the system needed a new diverter valve, I think either the heating was not getting hot or the water was not getting hot but it was not both together.

I had an engineer around and he stated that the heat exchanger in full of sludge from the system and he recons it is because the radiators are 35 years old the sludge is being produced from the rads rotting away from the inside.

He has suggested a Power Flush and to replace all the rads!

Could this be the case?

thanks

 

[dcawkwell]

Old radiators are by their nature more rusty.
You will need to flush the system out again.
A mains flush with cold mains water will be ok in fact I actually prefer
this.
The plate heat exchanger will need removing and flushing out similarly.

Since the boiler is fairly cheap I would be inclined to simply flush the system drain down and refill once a year to remove sludge.

Also fitting a magnaclean or spiro magnetic cleaning device in the return
the to boiler should trap the dirt. This can easily be cleaned out without
draining down the system.

When the boiler is next up for replacement consider replacing the radiators.

 

[mravant]

Thanks.

Do you mean just empty the system via the drain valve and then refill via the filling loop on the boiler and then empty again untill it is clean?

 

[simond]

The only alternative to using a Powerflush machine on an old system with known sludge problems, is to take each radiator off the wall, take outside and hose it out.

If you don't believe me, do the mains flush suggested above and then take a rad off and see whats left.

Your boiler sounds like it has been mullered by dirty system water and the only long term solution is replacement and a proper powerflush. The system wasn't cleaned properly or at all when the Heatline was fitted - and I only hope you paid buttons for it.

Generally speaking, most 'budget' boilers are lashed up, because this is all customers want to pay for at this end of the market. Ironically, the 'quick and dirty' installers earn just as much out of the job as the ones who Powerflush and fit decent brands.

Any decent Powerflush will be done with quality chemicals, hot water, and will involve the operative opening just one radiator at a time. It is time consuming, dull, but it pays dividends.

A dodgy powerflush will entail;
- the machine being used with no heat if the orig boiler is dead, and more likely no internal heater (only Norstrom Proflush machines have one).
- The installer will hook it up for an hour or two while he gets on hanging the boiler, fitting the flue, wiring the thermostat.
- The rads are all in parallel across the pump, not individually turned on one at a time, massively lowering the flow through each rad.

I know all the dodges, but too many customers just aren't interested in the difference between a worthwhile job and one where the chickens will come home to roost in 2-3 yrs.

If the Heatline has a Giannoni primary heat exchanger you have almost zero chance of cleaning it out, as there are multiple parallel paths inside.

Expect endless grief or a new boiler.

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[mravant]

Thank you Simon. An extremely useful post

You are right the powerflush done when the boiler was installed was done without heat and only for a couple of hours so its probably just built up and now put me in the situation.