how to flush out vented central heating system?

[caesarmanager]

Hey I want to flush out my vented central heating system. I no I need to cap of the expansion vent to the header tank and the feed to the system. Does it then involve taking a radiator off and connecting the valve to the cold mains. Can anyone telling me the correct way to flush out the system thanks for any help.

 

[kevindgas]

alternatively put a hose on a low down drain cock, cap the vent pipe 22mm speedfit usually fits and then join the cold fill to the cold feed in the header tank with an isolator to control the flow . then reconnect header / remove cap afterwards as normal

 

[caesarmanager]

thanks kevindgas I can t do that in this situation cause of the pipework to the header tank begin in such a tight spot. To do it through a radiator do I attach a hose to one of the valves connected to the cold mains and turn on. Do I leave a drain off open with a hose on to a drain at the same time? Thanks for any help

 

[combispecialist]

Just get it flushed out properly mate,a mains flush aint gonna get all the muci out of bottom of rads

 

[caesarmanager]

combispecialist could you tell me how to mains flush it though please thanks for any help

 

[Al-Glasgow]

In your situation

I would drain system, and remove each rad and flush with your hosepipe.

then leaving 1 rad off you can flush the pipework.

Al

 

[caesarmanager]

Thanks its just the pipework I want to flush the rads are all new ones. Am I right in saying to do this I need to take off a downstairs rad. Connect one side (the return) up to the mains via a hose pipe. Then other valve the return connect abit of copper to then a hose to a drain. And let it flow throught with all the rads shut. Is that the coreect way of doin it thanks for any advice.

 

[dextrous]

Pretty much like you say. For what it's worth, you may want to remove one of the bleed plugs (the whole thing or the blanking nut at the other end of a rad) and replace temporarily with a garden tap onto which you can jubilee clip a hose to the mains supply. That means you can flush it out without having to take a rad off, and also flush through via either the flow of return pipework depending on which of the rad valves you leave open/close

Once you have flushed the pipework, then open each rad on the circuits one at a time with the mains pipe still flushing it through - this will clear gunk from the tails and the valves as well as the rads. I know you're interested in the pipework, but there's bound to be some dirty water in the rads also.

As you said in your opening post, isolating the FE tank is important, as is wiping it out when it's empty, as is allowing some clean water to be flushed through this last section of pipework which feeds into the system.

Add inhibitor to the FE tank as you refill it, and not after it is full.

 

[caesarmanager]

Thanks for your replys I have been up to look at the FE tank and seems like I will have a problem isolating the cold feed to the system it comes of the bottom of the tank then straight down out of the loft and runs in the wall of one of our bedrooms. Is the any way it can still be flushed without capping this? as it looks like I am unable to.

 

[dextrous]

Get a pipe bung:

Untitled

• dextrous
• 14 Mar 2010
• 1

From screwfix or any plumbers merchants. Thus block the pipe from inside the FE tank

 

[caesarmanager]

Thanks will these hold off mains pressure though?

 

[yerino]

Take out the pump and connect the hoses to either side.
Cap of the vent to the F+E tank.
Cut a gate valve in on the cold feed coming from the bottom of the F+E tank (and turn it off) to prevent backflow.
Open up any moto-valve manually (into the fully open position)
Close the bypass ( normally a gate valve going into the bottom of your cylinder) to get a better flush on your pipework.
When refilling put some inhibitor in. Sorted.

Liam

 

[caesarmanager]

Thanks I have a problem with this thou " Cut a gate valve in on the cold feed coming from the bottom of the F+E tank (and turn it off) to prevent backflow. "
As I can't get to the pipe as it exits the bottom of the tank. I have been suggested to use a pipe bung will these hold and how much do they cost thanks for any help

 

[Fallout]

Or is there any other way I can flush it as I'm struggling to cap the cold feed to the system?

 

[yerino]

Can you not trace the cold feed from your F+E tank, normally they lead into the airing cupboard and you can just cut a gate valve in there.

How are you planning on flushing your system through? Have you got a machine or just planning to adapt a hose and flush it continually through with mains cold water?

I wouldn't recommend a pipe bung (but everyone to there own). It's just easier to have a gate valve, so you can close it back off when putting the pump back in and QUICKLY close it off if you find a leak after.