New rads

[NewhouseOldhouse]

take it to 2 with heating not on

Ok

 

[oldbutnotdead]

If your main runs are doing an up across down loop then good odds the across bits are full of air. 2 ways to address this;
1 mess about for ages at each radiator doing a high volume bleed (you need to make space for the air to get from the across to the down legs- basically defying gravity- bleed vent is too small, take the whole plug out and drain into a bucket with a friend topping up the system.
2 put some manual bleed vents at the high points. Personally wouldn't bother with automatics- you should only have to bleed those tubes after draining and refilling.

 

[NewhouseOldhouse]

If your main runs are doing an up across down loop then good odds the across bits are full of air. 2 ways to address this;
1 mess about for ages at each radiator doing a high volume bleed (you need to make space for the air to get from the across to the down legs- basically defying gravity- bleed vent is too small, take the whole plug out and drain into a bucket with a friend topping up the system.
2 put some manual bleed vents at the high points. Personally wouldn't bother with automatics- you should only have to bleed those tubes after draining and refilling.

So do the high volume bleed is what your suggesting?

Do all rads need to be off with the one working on to be bleed?

 

[oldbutnotdead]

So do the high volume bleed is what your suggesting?

Do all rads need to be off with the one working on to be bleed?

For now yes, longer term I'd be putting bleed valves in the pipework as above.
Yes start off with only 1 rad in circuit, pump not running, any motorised valves latched open (to help with venting the returns, if they're full of air the pump will be pushing it towards the boiler). Once you've got a load of air out, then turn the pump on and repeat as necessary. All fairly tedious, much easier (at this stage before stuff is boxed in) to chuck some manual vents in at the high points- if the across legs are level, make them higher at one end by inserting a bit of extra tube in the up or down.

 

[Harry Bloomfield]

For what they cost, plus the messing about you will save now and to avoid future problems with airlocks, I would fit the bleed valves now. Find the very highest point on the runs and fit them there, where air will collect.

 

[Deleted member 267285]

How do I do that?

https://www.diynot.com/wiki/Plumbing:faq2 As for air, this has already been suggested, by turning off other rads, then bleeding too making sure just water is coming out.

 

[NewhouseOldhouse]

For what they cost, plus the messing about you will save now and to avoid future problems with airlocks, I would fit the bleed valves now. Find the very highest point on the runs and fit them there, where air will collect.

So fit the Flamco valves on flow and return on the new pipe work?

The highest point does it mean furthest point from boiler or pipe in loft?

Also as the flow/return has 5 rads t'ed off at what point in the pipes would you fit the air valves after first rad or before last rad in the run?

 

[Harry Bloomfield]

So fit the Flamco valves on flow and return on the new pipe work?

If both flow and return go up then down - yes!

The highest point does it mean furthest point from boiler or pipe in loft?

Also as the flow/return has 5 rads t'ed off at what point in the pipes would you fit the air valves after first rad or before last rad in the run?

Air is lighter than water and so it will naturally collect at the highest points in the system and cause an air lock. So assess where the highest places are and fit the bleed valves there. If the pipes are generally at a similar level, then anywhere along there will work. Small air bubbles will be flushed along to the radiators.

 

[NewhouseOldhouse]

If both flow and return go up then down - yes!

Air is lighter than water and so it will naturally collect at the highest points in the system and cause an air lock. So assess where the highest places are and fit the bleed valves there. If the pipes are generally at a similar level, then anywhere along there will work. Small air bubbles will be flushed along to the radiators.

Thanks for the advice will install them, fire heating up with all rads of bar the one not working then work back to open them all up.