Cleaning large heating system

[oz-plumber]

Hi Fellas,

Have a larger job that's starting to have flow problems.

The system as 2 - 250 kw boilers servicing probably 300+rads.

The system was installed @ 15 years ago and stated previously starting to have flow problems to sections of the building, particularly the radiators at the end of the mains - furthest run from boiler / pumps.

This year the problems have really shown up and are stating to cause quite significant issues due to inadequate heating of the facility.

What would be the best options for cleaning the system?

There are 65mm in-line filter / strainers at the boilers, which are cleaned on a regular basis, but now don't seem to improve the systems performance.

There also seems to be flow problems caused by air locks at random radiators.

The water bled off from the panels is a black as the ace of spades.
Bleeding the air out requires connecting hose to plug and draining water from piping until constant flow of water.

Some panels have noticeable cold spots - sludge.
Would it just be best to replace those radiators and keep replacing effected radiators or try and clean the entire system

Any feasible suggestions on what's best.

 

[joni os]

If all radiators installed at same time and some are corroded then most will be same.
Assuming client will not pay for 300 plus new rads. I would remove 30 at a time, thoroughly
flush with plenty of plastic hammer, inspect for serviceability and reinstall or replace as necessary. As work progresses the extent of problem will become apparent.

 

[ShaunCorbs]

is the system done out of iron ?

 

[Best]

That's a seriously big system!
I know you said there are filters at boilers, but just wondering is it also possible that pumps are impaired due to build up magnetic scale? I see that on domestic pumps.

 

[joni os]

Agree above, have removed pumps with impellor so clogged it might as well been a flat rotating disc.

 

[Best]

Agree above, have removed pumps with impellor so clogged it might as well been a flat rotating disc.

Exactly! And that just ruins the pumps performance and the furthest few rads heat very little.
Pumps are, as we know a big electro magnet when their motor is on and act like a filter of the black remains of metal.

 

[AWheating]

how is the system sectioned off? is it possible to powerflush a section at a time? what flushing pumps are available to your market?

the inhibitor cost will be huge on refill.

 

[AWheating]

also a thermal image camera will prob help you alot.

 

[lame plumber]

be worth doing a thermal survey of every rad, ascertain if all or just some need cleaning and if its one or two or all circuits affected and take it from there.

 

[Ermintrude]

The pH and water oxygen levels probably through the roof.

System should have active water control and a scavenger.

Drop rads out and use a rems type cleaner on the mains and risers. - the flow in a dirty main is laminar and usually u get deposits building in areas of high friction.

Is it piped up properly? No tees off the bottom of mains etc?

One pipe system? Have u checked the pumps? The seat can become what appears to be carbonised but it's actually very compacted magnetite.

It's not open vent is it? Balancing valves haven't failed or become blocked?

If you know what's in your system u can mix the correct chemicals and burn it clean