Do i need to flush the central heating system?

scubascuba3

Asking a plumber/heating engineer this question is like asking an estate agent if prices will go up, but anyway I'll give it a go.

My radiators and combi boiler work fine,British Gas pointed out that the water is black so I need a powerflush. So, this isn't a question of Powerflush vs manual flush as that's all over the internet, it's do I REALLY need a system flush? I'm interested in your views.

The combi is generally ok although the pressure plays up every year or two. The motor was replaced a couple of years ago.

Grenage

They get commission on power flushes, so everyone needs a powerflush.

What I would do is drain the system, open the filling loop until the water ran a bit clearer, and add a good dose of inhibitor to one of the radiators before you fill it back up. When I decorated the last house I ran some sentinel cleaner through the system and drained it a few times, took each radiator off the wall and ran a hose through it as I did each room.

I never had any issues, mind you.

scubascuba3

I wouldn't really want to do that myself, so if I needed it flushed out I'd get someone in. So if the water is black you should flush out the system? Or is it normal to have black water and it's only worth flushing out if the combi or radiators are playing up?

EssexExile

I wouldn't bother if it's working fine. I've owned houses for 40 years, the radiator water is always black & I've never flushed a system & never had a problem.

Well I've had lots of problems but you don't want to hear about them.

jaizan

The water should most certainly not be black. I suspect you have been running the system without effective corrosion inhibitor. It needs draining & refilling with corrosion inhibitor.
However, if all the radiators work fine, draining it yourself should be enough.

Draining it yourself is very easy, although you must also remember the bleed valve inside the boiler as well as the ones on the radiators. This should be fairly obvious & near the top of the boiler. If not, just download a boiler manual.

Crinkmeister

Black water indicates iron oxide, so something is rusting away slowly. Given that modern combi heat exchangers are either ally or stainless, the rusting iron will be from the inside of your rads. I would get some inhibitor in there after flushing thoroughly. A magnetic filter would prolong pump life.

pmartin86

As stated above, assuming all is working fine as is, you would probably be best placed to drain the system yourself, flush with water for a few cycles until the water clears then add and inhibitor. I had to do the same a few years back, and it's really not as scary as it sounds!

scubascuba3

I can't really do it myself I haven't got any equipment so that's not going to happen. I'm just mulling over whether to do it. I've had quotes for 250 for flush and 400 and 500 (British Gas) for powerflush with magnecleanse filter fitted. I can't say I'm overly keen ,i've just paid several big bills.
If I don't do it eventually the motor may break down, thats around 250, less than the powerflush quotes

Grenage

The only equipment you need is hosepipe, a spanner, and a funnel; two of which you can get in a pound shop. The inhibitor will cost a bit more.

scubascuba3

How about the pressure across the system / combi boiler?

Grenage

Just drain the system, refill with some cleaner and put the heating on for a few hours (or leave it in there for weeks, different cleaners have different instructions).

Fill it up and run it for a few hours and drain, repeat if it still looks pretty nasty.

When done, refill with inhibitor.

If you don't have any problems with your heating system, you really don't need to spend hundreds on a power flush.