Draining down CH - some downstairs rads not emptying?

[MickOC]

OK, decided to drain CH system to clean it with Fernox restorer and add Fernox protector after clean because I don't believe it's ever been done in the 6 years I've been here. I have a standard Open Vented with F&E tank and 16 rads, two rads downstairs have drain-cocks (on rads I had installed 5 years ago, one in garage and one in conservatory).

I connected a hose to both drain offs, tied up the Ball cock in F&E and opened all bleed valves in upstairs rads - all worked OK and air was sucked in on everyone. Was fairly surprised to see mostly clean water being emptied out of each hose.

Started to bleed downstairs rads which worked OK on 4 of them (the 2 with drain-cocks and 2 older ones), but other five rads just let water out as soon as I bled so my guess is they were not being emptied as none of them were sucking air in? Does this mean they are on a different loop or something?
After draining down and no more water coming out I check F&E tank and it still had a little amount of water in but it was dirty rust coloured so emptied and cleaned tank. I refilled but left drain cocks open to flush system out and water was clear.

I then refilled properly and added Fernox Restorer and will leave for a few days, then will drain again, flush and add protector - but not sure If it will do any good if 5 rads downstairs didn't empty??

 

[Rico99]

Hi there,

Your never going to get all the rads empty from a downstairs drain off.

You have to individually empty each downstairs rad, the water cannot flow back up.

Rico

 

[MickOC]

Thanks - really? I thought downstairs drain-offs should empty all rads! If I flushed water through using F&E refill and continuous drain, will this be good enough to clean those downstairs ones?

 

[Rico99]

Hi there,

It may have got the old water out. Depend where on the loop the drops are, the water will always that the path of leat resistance, so may well have bypassed the other downstairs rads.

Only 1 way to find out, get the 5 rads off the wall and check.

Rico

 

[Hugh Jaleak]

How are the downstairs rads connected? Some are on a 'drop' system, where the 2 pipes run down the wall from upstairs to feed each (or maybe a pair) of rads. These should have a drain off on each drop. Usually employed when the ground floor is concrete, and digging it up proves too costly.

Alternatively, if it is a suspended wooden floor downstairs, then the rads can be individually piped from under the floor, and the whole lot fed from one point. (Mine is like this.) One drain off fitted will empty entire system.

If you find you have individual drops without drain off's then one idea is to fit a self cutting washing machine tap to the pipework to drain them, then fit drain off's as required, for future needs.

 

[MickOC]

Thanks for responses. I guessing they must be different drops which means they were bypassed when I drained-down - oh dear! Not sure I'm confident enough to take rads off or fit a drain point.