Is flushing a sealed central-heating system a diy job?

[none]

Hi

I have a new boiler and some quite old radiators. The original boiler was replaced when I moved in. I have since found that the system wasnt cleaned very well before the new boiler was installed.

I have heard Sentinel Ferroquest mentioned as a good chemical to clean the system out with. I have tried to find info on the internet about how to introduce this to my sealed central heating system (at least I think its sealed - combi boiler, no water tank, top up braided pipe from mains water to increase the pressure when it drops below 1 on teh pressure scale). The sites I have found that explain how to flush a system say you should get a specialist to flush a sealed system. Is this a d-i-y job - can anyone point me in the right direction?

Should I be just replacing the radiators rather than trying to clean them? If I manage to run this cleaner through the system will the sludge come back again a month later? Or will putting some type of inhibitor chemical into the water keep old radiators in check?

Thank you for your advice.

[Lobster]

should answer all your queries

[none]

Thank you - I will try and find a Sentinal Ferroquest product that allows me to introduce it through one of the radiators.

I am right to do the following:

1.Turn the boiler off at the mains. 2.Drain the water out of the central heating system via the valve in my cellar (as I think there is inhibitor in the system - this may react with the ferroquest if I mix them both up?) 3.Close the drain valve 4.Pour ferroquest into an upstairs radiator via the bleed valve 5.Close the bleed valve and use the 'filling loop' to refill the system, letting air out of the radiators bit by bit as described in the boiler back on and let the system circulate for a day or two 7.Drain the water and chemical out 8.Pour inhibitor into upstairs radiator bleed valve and use the 'filling loop' to refill the system.

I am not sure about how to drain the system. If I open the drain valve I expect some water to come gushing out. But do I have to open all the radiator valves upstairs before or after opening the drain valve. Wont the water coming pouring out of the radiator valves rather than coming out of the drain valve? The filling the system bit makes sense now that I have read the

information.

[Ed Sirett]

Thanks for reading the FAQ you are now up to speed on many aspects of the job. The drain point is invariably a little tap like fitting (called a drain c*ck or drain off point). These are usually very leaky when in operation and you will probably find that the washer in them often stays put in the fitting preventing you draining down as fast as you would like.

You can often get the fitting apart (with out getting flooded) if you drain off "the pressure" first and then prevent any air (remember the auto air vent in the boiler) from getting in.

You should probably aim to refill and drain twice to help get all the dirty primary water out.

Remember to open the auto air vent and close all the bleed valve when refilling.

Chemicals are added either by pouring or syphoning them into through the blank plug on a radiator or by injecting the gel versions though the bleed hole.

In both cases you need a bleed point open elsewhere to let the air out as you put the gear in or you will have a messy experience.

[John Stumbles]

Or you can pump it in (with the system *not* up to pressure) using a garden spray pump suitably adapted to connect to the filling point.