Inhibitor on partialy drained system

[masterbodger]

Hi all,

I've recently helped a friend remove some 'dead legs' from the radiator circuit on an open vented system. In order to carry out the above work we needed to partially drain down the heating system (upstairs only).

Question, do we need to add any inhibitor when refilling the system? He has just moved into this property so we don't know if the system has any in already and if it has what make/type it is. If we were to add some and there was already a different type in there could this cause a problem?

I guess the ideal solution would be to drain the entire system, flush through then add inhibitor but there are no drain cocks for the downstairs rads (all on individual drops), so this could be a lot of additional work.

Any advice would be much appreciated.

 

[JohnD]

Do the ideal thing.

You can easily add some lockshield valves which incorporate a drain-off. I have fitted them on all my ground-floor rads as it is concrete floor and they drop down from upper floor.

this enables you to do an entire drain, and to flush out well before refilling with inhibitior.

It is summer now, so a good time to work on the CH.

When you refill, hang the labels which are generally supplied with inhibitor on the pipes, with the date filled.

 

[masterbodger]

Hi John, thanks for your reply.

Is there any easy way to fit these lock shield valves that incorporate drain off cocks? I mean, the drops and rads will still be full of water.

Cheers

 

[JohnD]

put a shallow pan under the old valve and slacken the nuts. Tighten the nut when the pan is full. Don't open the vent until you seem to have drained the pipework.

 

[masterbodger]

Thanks again John

So I need to:

1. Put tray under old lockshield valve.
2. Slacken union nut.
3. Drain water into tray until it stops flowing

Would the above drain both the pipework and the rad or would I need to open the vent valve in order to empty the rad?

Thanks very much for you help.

 

[JohnD]

you will need to open the vent to drain the rad. Then you can take it outside (dripping dirty black water) and hose it through from end to end to wash the sediment out.

 

[JB Gas]

might get away with tray but if the water is black and there may be a lot of it spend a few quid and buy a self cutting drain tap.

 

[oilman]

might get away with tray but if the water is black and there may be a lot of it spend a few quid and buy a self cutting drain tap.

The valves in JohnD's post are a good solution. Self cutting valves/cocks are NOT!

 

[corgiman]

oilman is right

they leave a disc once they have been cut that may cause mayhem, believe I know that they do

 

[JB Gas]

I was suggesting the self cutter to drain the system down then cut out the small damaged section of pipe and replace with a compression tee and drain cock. Just an idea rather than sitting next to a radiator with a tray full of water wishing you had an empty one, as fitting will not go back together.

 

[corgiman]

I was suggesting the self cutter to drain the system down then cut out the small damaged section of pipe and replace with a compression tee and drain cock. Just an idea rather than sitting next to a radiator with a tray full of water wishing you had an empty one, as fitting will not go back together.

what about the disc JB? that probably would have shot of into the system by the time you have drained the system and cut the section of pipe out?

once its in there it, depending on the appliance, it could cause havoc in a heat exchanger?

 

[JB Gas]

never had a problem corgiman, disc is normally still attached to pipe when section is removed, saves time in the long run (no mess to clear up)