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BarryM

Central heating power flush?

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Hoping for some insight from our plumbing experts :)

 

We recently had a radiator replaced in our bathroom that had developed a tiny hole and leaked, had a cup under it for 6 months and just emptied it every other day but the plumber said the system needs to be flushed as the water was black and probably caused the leak. We've lived here 20 years and have the traditional system: boiler in the garage, feeder tank in the loft & hot water/immersion tank in the airing cupboard and I'm not aware of anything being done to the system when our boiler was replaced maybe 10 years ago by British gas. Apart from this one incident the system seems to work fine with the radiators all heating up etc although the hot water tank doesn't seem to be heating up the water as well as it used to...should I go for a flush or is he just trying to make some money as he's quoted £500 which is the same as BG!

 

TIA

 

 

 

 

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10 years ago when your boiler was fitted the advice by boiler manufacturers was to power flush before installation of a new boiler. In theory British gas should have done it. But I'm sure they wouldn't have bothered and just charged you more than a good independent plumber/heating engineer.

 

You are basically looking at £30 for the chemicals and 3 to 4 hours labour, longer if it's really clogged. If you are NOT getting any cold radiators it's not that badly clogged.

 

Depending how confident you are, it's not that difficult. If you have a drain off that works.

 

Go to a decent plumbers merchants, buy a bottle of flushing chemicals and a bottle of inhibitor (about £30 the pair). With the boiler off Isolate the ball cock on the header tank (turn off or tie up), drain some water from the drain cock (3 to 4 buckets). Poor the flushing chemicals in and turn the ballcock back on. Then turn the heating on. Leave it for a couple of days. 

Then heating off turn ballcock off drain the system completely. Refill and bleed all the rads. Turn the heating for an hour. Turn off heating, turn off ballcock, drain the whole system.

Then poor the inhibiter in the header tank, refill and bleed the system, turn heating on.

 

Job done!

 

This is not a full power flush but it would give your system good clean as long as it's not heavily sludges up. The reason you have the back water it generally because it has been run without inhibitor which keeps it clean.

 

IF YOU ARE NOT HAPPY DRAINING AND BLEEDING THE SYSTEM.    DON'T DO IT.  

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Thanks for the advice 'Stressed'. I'm not sure if this has any impact but all our downstairs radiators are fed via pipes straight down and back upstairs as we have a concrete floor. I'm not aware of the drain cock so would it be by my boiler in the garage?

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Normally the drain cock is fitted at the lowest point in the system. It is sounding more like you have had a new boiler fitted to an old system. A lot of plumbers didn't fit drain cocks on older systems which would meant draining each drop at the radiator valve.

The drain cock/valve would be obvious at the bottom of a drop near or on the radiator valve.

It does sound like you may need a plumber to do this job for you if you have doubts about drain cocks. I would get another opinion on price for a power flush, some plumbers do over price because they don't really want the work!

 

I did used to do a lot of heating and plumbing and may make it sound easy to a non plumber. 

 

As a comparison, Would you happily change the brake fluid on your car, drain refill and bleed? Then trust your safety of your own work? Three times!

Edited by Stressed

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50 minutes ago, Stressed said:

Normally the drain cock is fitted at the lowest point in the system. It is sounding more like you have had a new boiler fitted to an old system. A lot of plumbers didn't fit drain cocks on older systems which would meant draining each drop at the radiator valve. The drain cock/valve would be obvious at the bottom of a drop near or on the radiator valve.

Each radiator on the ground floor has it's own 'drain' point where I guess I can put a hose to drain each individual radiator. The upstairs rads don't have individual drain points hence me asking about a valve near the boiler or where the stop cock might be for the upper rads?

 

53 minutes ago, Stressed said:

As a comparison, Would you happily change the brake fluid on your car, drain refill and bleed? Then trust your safety of your own work? Three times!

I've replaced all the brake hoses on my car and flushed the fluid so comfortable if I know what I'm doing... 

 

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Great on both replies

 

When draining to add the flushing chemical just put a hose on one radiator and drain a few buckets worth off.

Once you've added the chemicals and run the heating for a couple of days I would drain from all downstairs rads one at a time then refill. Then drain all again and refill with the inhibitor. as described in my first post.

When draining you will have to open the beed nipples on the rads starting with the upstairs ones. The upstairs rads will drain when the drain valves are open downstairs. Upstairs rads don't have drains.

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Thanks for your guidance, I guess the difference between this and a power flush is that the DIY method relies on gravity and the power flush forces the crap out so depending on how bad the system is will depend on how successful I can be?

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If you had some radiators that were cold even when bled or radiator that had cold patches at the bottom or middle it would defiantly need a power flush, if all rads are hot and it's just dirty the diy method will give the system a good clean. There is no harm in tipping a bottle of inhibitor into the header tank every couple of years without the need to drain the system.

Happy to have given a little guidance 

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7 hours ago, BarryM said:

the system seems to work fine with the radiators all heating up etc although the hot water tank doesn't seem to be heating up the water as well as it used to...should I go for a flush or is he just trying to make some money as he's quoted £500 which is the same as BG!

 

On the face of it, the only problem is that the water does not get hot as quickly as it used to.  If there are motorised valves in that circuit it may be worth checking to make sure one is not stuck or will not open fully 

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10 hours ago, whiskychaser said:

On the face of it, the only problem is that the water does not get hot as quickly as it used to.  If there are motorised valves in that circuit it may be worth checking to make sure one is not stuck or will not open fully 

 

Well I did see the water that came out of the radiator and it was def black and I have no recall of the system being treated so just trying to pre-empt longer term problems after the leaking radiator. The hot water thing is a bit tricky to be 100% sure about because we had a new 'power' shower fitted that takes a feed direct from the hot water tank so it might just be that the new shower is using a lot more water, maybe I'll try my own flush as per Stressed's guide and then get the plumber back to check the hot water system is working properly with any valves etc all working correctly.  

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