Drain down sealed system

[richierich81]

Hello, I am hoping you kind people can help me yet again.

The problem I have now is that whilst I have been redecorating the bathroom I had to remove a radiator in there. The valves on the radiator are very old but I was able to remove the radiator. Anyway the Pegler valve at one end wouldn't completely close so I ended up with a bit of water coming out - right into the kitchen below.

I have put the radiator back on but the valve is still lightly weeping.

Anyway I intend to replace the radiator with a chrome towel rail, which will need to adjust pipe work and then I can also replace the valves.

To do this I can see that I need to drain down the system.

Am I right in thinking this is the correct procedure?

1) Turn off the boiler
2) Make sure that all the radiators are open
3) Drain the water out of the system using the drain valve
4) Open the bleed valves on the radiators? Starting from upstairs (I'm not sure about this?)
5) Have some towels ready and do the pipework on the radiator in the bathroom and install the new radiator
6) Add inhibitor to the system, is Sentinel the best to use? Do I just add this to the new radiator before I put it on?
7) Close all the bleed valves starting downstairs to upstairs?
8) Close the drain valve and turn the boiler back on and use the key on the Worcester Bosch boiler to refill the system (get the pressure up to 1 bar?).
9) Check that the new radiator is working and check for leaks.
10) One at a time open bleed valves on the other radiators to remove any trapped air in the system, then close the bleed valves.
I guess I'll need to re-pressurise the system again at this point.

Does all that sound ok? Is there anything that can go wrong and that I should worry about?

Incidentally I had a new boiler installed 2 months ago (should have got them to do this all at the same time, but my wife hadn't made her mind up at that point. But when I emptied the bathroom radiator, lots of black sludge came out, should this have been cleaned from the system before the new combi was installed?

Thanks again and sorry to bother you all.

Richard

(By the way I have not tackled the soil pipe yet, I have got all the bits and am ready to go..just waiting for a dry spell.)

 

[Robiow70]

🍰

 

[Robiow70]

Yes turn the boiler off.

You don't need to open all the valves. Unless your going to flush the system through.

Drain down system so your able to connect up the new radiator. If its on the first floor drain just below the working level.

Wrap the PTFE around threads going into the radiator. About 15 times is good. 😉

If it a towel rad no need for a Trv just lockshield valves, as this will act as a bypass

You may want to fill and drain a couple if times, or now could be a good time to clean the system, (sentinel x800) very good stuff.

Some cleaners will need to be running in your system for a few weeks, before flushing out and adding an inhibitor. Sentinel X100

You could also add a Magnaclean or similar if not fitted already.

SLOWLEY top up to 1 bar after fitting, remembering to shut off the blead valve, and check for leaks on new fittings.

Bleed and fill a few times, and some times this can take a bit of time, depending on the size of system,and the amount of hands you have.
And away you go.

I believe that any warrenty you have on the new boiler will be void, if your pipe work/radiators wasn't thoroughly cleaned when fitting the your new boiler.

Hope this helps Rob

 

[richierich81]

Hi,

Thanks for the quick reply.

How do I perform the partial drain of just the downstairs? Do
I lock all the upstairs rads, then take off the 3 dowstairs rads and drain individually? Or do I lock all upstairs rads and use the drain point to drain the system?

I had the new central heating system fitted 2 months ago I am a bit annoyed that this hasn't been done correctly.

Thanks again

Richard

 

[Robiow70]

If your rad is in the ground flow you will need to drain down the whole system.

You can flush each rad individual by closing all the valves to the others, and leave the valves open on the one you want to flush, and turn the water supply and top up to 1 bar.

Bleed the rad you want to clean till water is coming out, then drain from the drain valve. You may want to do this a couple do times.

I personally would just add a cleaner to the system and drain out after the recommend run time, usually 4 weeks.

I would recommend putting in a cleaner if the system wasn't flushed out when you had your boiler fitted. Ask the installer if he/she flushed system.

Hope this helps. Rob

 

[JohnD]

If it is a sealed system, with a pressure gauge on the boiler, you don't need to drain it to change a valve.

If you open the valve first, enough to release the pressure, a small amount of water will come out that you can catch in a bowl or bucket. Once the pressure has gone, as long as you only have it open at one valve, the water wil stop coming out. It can't come out unless you open it at some other place enabling air to be sucked in and water to come out.

(an open-vented system, with a Feed and Expansion tank in the loft, can be done in a different, but comparable way)

This will save you a lot of time, will avoid wasting the corrosion inhibitor that your system (shlould) contain, and it avoids refilling it with fresh oxygenated water that will start corrosion of the insides of the radiators.

Observe what colour the water is, and how much sludge or sediment comes out when you tilt the radiator.

 

[calorific]

JohnD is of course right. However, as you are going to reconfigure the pipework to accommodate a new towel radiator it would be wise to drain down at least the upstairs circuit (assuming the bathroom is there).