In theory it's easy to drain and refill, but you can run into problems getting all the air out. The Scottish Gas guy working on mine had problems bleeding the pump - so much so that he was about to fit a new pump thinking mine was faulty. Tread carefully.
Flushing Central Heating Radiator
- Thread starter kofi2003uk
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Thanks. I will leave it as it is. Working fine so am not risking it. I will talk to my service guy when he comes in to do the yearly service which is due in February. Thank you for all the info. Appreciated.
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Best approach, if it is working leave it for now.
Could always add a bit of this: https://www.toolstation.com/central...k3fmXDj9QnEAQ369YbXGWJtk56GinwGYaAolsEALw_wcB I’ve used it ones, and it did improve the system, nd no need to drain it out 
don’t know what other’s views are on it?
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thanks 'The Novice'.
my plumber added Fernox F3 central heating clearner 500ml x3 bottles over a period of about a month and left it in the system. am not sure if it was supposed to be drained after a while but i believe its has been in the system for the past 5-6months. i have not noticed any problems with it being left in the system though. Boiler works fine. Plumber also attached a MagnaClean to the system which catches a lot of dirt from the system. i still check it every 2 weeks or so and clean it out. used to catch loads of black gunk but it has reduced as the system gets cleaner i believe. the Fernox F3 is still in the system though and i intend to leave it there.
can the Calmag product you mentioned be added as well? i dont intend to drain the system. i can easily add it to the tank in loft but wanted to check if its ok with the Fernox F3 already in there or not necessary as the Fernox F3 is already in the system?
thank you
my plumber added Fernox F3 central heating clearner 500ml x3 bottles over a period of about a month and left it in the system. am not sure if it was supposed to be drained after a while but i believe its has been in the system for the past 5-6months. i have not noticed any problems with it being left in the system though. Boiler works fine. Plumber also attached a MagnaClean to the system which catches a lot of dirt from the system. i still check it every 2 weeks or so and clean it out. used to catch loads of black gunk but it has reduced as the system gets cleaner i believe. the Fernox F3 is still in the system though and i intend to leave it there.
can the Calmag product you mentioned be added as well? i dont intend to drain the system. i can easily add it to the tank in loft but wanted to check if its ok with the Fernox F3 already in there or not necessary as the Fernox F3 is already in the system?
thank you
Wait until the warm weather returns and you don't need your heating so much...probably better to wait until end of next summer, just before you switch heating back on, then...
Open a drain point, which you'll hopefully have down low on the system and connected to a hose to outside, let the f&e tank keep running for about 30mins or so so that clean water flow down through the system and out of the drain point. Then shut off the drain point and add some cleaner/inhibitor into the system (I use calchem) which can be left in. Add this to the f&e as it flows down the outlet into your system.
Open a drain point, which you'll hopefully have down low on the system and connected to a hose to outside, let the f&e tank keep running for about 30mins or so so that clean water flow down through the system and out of the drain point. Then shut off the drain point and add some cleaner/inhibitor into the system (I use calchem) which can be left in. Add this to the f&e as it flows down the outlet into your system.
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