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Product Details

Removes sludge, scale and debris from new and existing central heating systems to improve boiler efficiency. Suitable for use with powerflushing machines.

Technical Specification
Brand Fernox
Safety Data Sheet click here
Volume (L) 0.5
Delivery details

Covid-19 Update

  • Free Next Business Day delivery for orders over £25 to home and site is available for orders placed before 5pm
  • Saturday and Sunday delivery is now available for orders placed before 4pm on Friday for Saturday delivery and 4pm Saturday for Sunday delivery, see here for details
  • We have temporarily suspended our Pre-12 delivery service
  • Once your order has been dispatched you will receive an invoice email with the courier details and your tracking number
  • Alternatively go to MyAccount, click on your Order History, click on the TRACK icon to link through to the carrier website and the tracking details for your delivery
  • If your order contains more than one item it may be split into two deliveries as we manage volume across our network
  • Due to carrier constraints it is not currently possible to deliver age restricted items. Please use our Click & Collect service for these products
  • Delivery direct from suppliers is now available and specific delivery times will be displayed on the product page
Order Value: Under £25 Over £25 but less than £75 £75 & Over
Next Business Day Delivery (Mon-Fri) usually before 6pm £5 Free Free
Pre-12 Delivery before 12 noon Next Business Day £10 £5 £5
Remote areas standard delivery (2-4 days) £5 Free Free
Saturday Delivery order by 4pm Friday £10 £5 Free
Sunday Delivery order by 4pm Saturday £10 £5 Free

Please note items delivered by our suppliers are not available for the options above. Delivery times may vary.

More about Delivery & Returns
Click & Collect details

Covid 19 Update

Click & Collect

  • Safe contactless collection is available 7 days a week at our branches
  • Our branches are open 7am-5pm Mon-Sat and 9am-4pm Sun
  • Keeping our colleagues and customers safe and well and respecting stringent social distancing requirements is our number one priority – 2 metre rule enforced
  • Our available product range will not require more than 1 person to lift
  • Please see our guide to click and collect below

  • Please ensure that your mobile number is added so that we can text you when your order is ready to collect

Call & Collect

Due to current trading conditions we have suspended our Call & Collect service until further notice.

If you are using our Click & Collect service please note the following:
  • Order online or over the phone and collect in branch from 5 minutes later.
  • Ensure you check stock is available for collection at your chosen branch.
  • Check branch opening hours to ensure you have sufficient time to collect.
  • For items not available for same day collection, place order before 7pm Mon-Fri (4pm Sun) and you can collect Next Business Day (Mon-Fri) after 3pm.
  • If we have your mobile number, we’ll send you a text when your order is ready to collect.
Fernox F3 Central Heating Cleaner 500ml is rated 4.1 out of 5 by 11.
Rated 2 out of 5 by from Not as good as suggested. Instructions suggest "One Hour" would be sufficient to clean the system, I left it in for four days. Brown water came out when I flushed the system but when I removed a motorised valve there was still thick, black sediment stuck to the inside of the 22mm pipework ...not impressed! Added Sentinel X400 for two weeks but similar result. Will stick to taking the radiator off the wall each time I decorate.
Date published: 2020-05-15
Rated 5 out of 5 by from Seems to be making the heating better Impressed with how it’s working within the heating system.
Date published: 2020-05-06
Rated 1 out of 5 by from didnt work too well. used something stronger. didnt work too well. used 2 bottles of it. Ended up using Sential X800 which was much stronger and removed alot more debris from the system after leaving it in for 4 days.
Date published: 2020-05-05
Rated 5 out of 5 by from Heating supplies I purchased this item 2 weeks ago. I have used it and it worked very well. Tthe delivery option work superbly.
Date published: 2020-04-26
Rated 5 out of 5 by from Miracle worker! My open vented central heating system had become very noisy over the previous six months, so I drained the system (the water had been treated with Fernox F1 Protector from the original commissioning and seemed fairly clean) and refilled it, adding the Fernox F3 cleaner. After running the pump for an hour I was staggered by the improvement - the system had become virtually silent. I left the cleaner in the central heating for one week before draining it again. This time the water was quite black - clearly there had been a lot of sludge and sediment lurking in the low points of the system. I would therefore wholeheartedly recommend the F3 cleaner, which worked brilliantly for me and was definitely worth every penny of the cost.
Date published: 2020-04-22
Rated 5 out of 5 by from Great Service Cant really comment on the product but the service was outstanding. Ordered online approx mid day , TS quoting 2-3 days delivery because of Covid, arrived mid day the next day. Superb. Thanks
Date published: 2020-04-15
Rated 5 out of 5 by from ideal soluation bought the 2 items together and did a wonderful job
Date published: 2020-04-11
Rated 4 out of 5 by from Seems to work. new boiler picked up a little bit of sludge even after system flush and this was recomended. Seems to do the job
Date published: 2020-03-30
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