central heating issues

[Phil_Plumb]

Git called to a custards house today, as he asked me to replace the valves on one rad, and flush system thru and re sentinel it. anywhoo did all of that, and fired system up as you do, rads and the revalved rad worked fine, save one rad in hall, the Main circuit for the rads in house is above the ceiling (its a bungalow) so all the drops come down from above to feed the rads on the ground floor.

Would i be right in thinking that as the pipes come from above there would be a high chance that the vlaves and or rad would be clogged up with crud?

 

[SafeGasInstall]

more likely air lock

 

[plumber0808]

If its micro bore its more than likely you have flushed some muck through it and blocked it.

 

[Phil_Plumb]

no its its 15mm none of that mb crap

 

[Phil_Plumb]

how can air travel downwards? this particular drop was never drained so therefore as water cant travel up (unless being pumped) then i am keen to know how air would get in there!

 

[SafeGasInstall]

did you pf ?
if you go in the loft there will be some manual air vents

 

[Best]

If one of the pipes travels horizontally to the opposite side of rad, i found these can airlock easy. Usually just turning all other rads off etc, gets it going, if it is just air.

Edit, - just read your last posts. Check the pipes above are running level or rising to air vents, as said.

 

[SafeGasInstall]

how can air travel downwards? this particular drop was never drained so therefore as water cant travel up (unless being pumped) then i am keen to know how air would get in there!

air will not travel down , will stay at highest point and you will not get circulation , so you must turn of all other rads of and let that one stay on and hopefully pump will push it around , works 99 times out of 100

 

[Phil_Plumb]

no powerflow, just a drain down and refill with chemical cleaner

 

[plumber0808]

If you have drained the loft area, air is then in the system.
filled back up the air will move along

 

[Phil_Plumb]

thanks SGI, am going back there to pipe up new shower so will give that a whirl next week

 

[SafeGasInstall]

let us know how u get on

 

[plumber0808]

I have had 15mm pipe blocked through doing a powerflush, only once but it can happen.
One rad would not work, I ended up cutting the drop from the bottom upwards in sections while holding the pipe into a rubble bag until I hit the jackpot.

 

[Phil_Plumb]

i will, thank you for your wisdom!

 

[Best]

Surely you will soon know if it is simply air or a blockage with dirt if you open each valve in turn into a hose & let it run for 2 minutes?

 

[SafeGasInstall]

Surely you will soon know if it is simply air or a blockage with dirt if you open each valve in turn into a hose & let it run for 2 minutes?

i will sugest stick a jubilly clip on your hose ......open air vent slowly and run ch , then as pressure go down just top it up .....but must close some of the rads so water has no where to go but on that rad pipe work

 

[jase158]

don't ask me how but if you don't drain a drop it will always air lock, all drops should be drained. I can guarantee this is an air lock. either an air vent in loft or need to close all other rads and leave this one open. if trvs are fitted, may do it by itself

 

[PeteWalker]

If stuck, drain the rad and connect garden hose to the tails, (one at a time like ) Make sure the motorised V is open when you do it, natch.
I bet when you go back you'll find the air's settled and it works anyway, though.