Airlock in unvented system?

[Del71a]

Help please!

Our (Gas Safe) plumber drained our unvented system (Vaillant Ecotec system boiler) to replace a radiator valve. He refilled it but said we should bleed upstairs radiators & valves to get rid of air.

Have done that, and heating is working fine, but our hot water is running cold. I bled the valve at the top of the cylinder, and a lot of air came out. Still getting cold water the next day (tank feels cold).

The house is quite big (3 stories...and our 300L water cylinder is on top level) so could there still be air trapped somewhere even if no more air is coming out of the valve?

Pressure on boiler looks fine (1.6 bar) and radiators working fine.

Do I just need to be patient until any air works its way to the top it or can I help it along? Thanks!

 

[terryplumb]

Use your electric immersion heater to give you hot water ,and call the plumber back to sort out the issue.

 

[Del71a]

Have put immersion heater on.

He’s not available over weekend unfortunately. Have had airlocks in the past when work was carried out, but has always resolved itself after bleeding the cylinder valve.

 

[Del71a]

Aaaargh! We STILL have no hot water (it’s running cold). Plumber is stumped!

(Immersion heater not working.)

he has:

1. removed the synchron motor above cylinder and set valve to open
2. Checked all other valves
3. Got us to put all radiators off and crank up heating thermostat to force any air in system upwards

There’s no air coming out of the bleed valve at the top of cylinder. Just water

He asked me to keep bleed valve open whilst opening fill valve slightly yesterday evening. Not worked. The water coming out of bleed valve went from cold to hot but it’s not getting to the cylinder.

Wondering if the valve underneath is faulty/blocked even though it sounds like the pad is moving fine when turned.

If not the valve, can it really take this long for an airlock to resolve?

 

[oldbuffer]

Picture of the cylinder and pipework might help. The coil in the hot water cylinder through which the boiler's primary water circulates is normally about 1/3 of the way up from the bottom of the cylinder. Bit puzzled why you have a bleed valve at the top of the cylinder.

 

[Del71a]

Bleed valve to get rid of any air. It’s what we usually open when system is emptied/refilled to do any work and gets rid of airlocks. It’s a horizontal 300L cylinder (on 3rd leve), unvented with Vaillant Ecotec system boiler (at ground floor)

 

[oldbuffer]

1. If you mean the red valve with the red plastic plastic knob, that is, I think, the temperature and pressure relief valve. It is not connected to the primary coil inside the cylinder.
2. The bleed valve you want is the thumb turn one above the motorised valve. Unscrew it (without losing the screw), you should hear air hiss out.
3. That motorised valve should not, under ANY circumstances, be left like that. It is part of the safety system designed to stop un-vented cylinders exploding. If you plumber does not have a G3 certification (not Gas Safe Registration, although he might be G3 registered with Gas Safe) he should not be working on that cylinder. If he is G3 registered I wonder how he got the certificate.

 

[Del71a]

It is the small thumb valve that I’ve been bleeding, not the red one (not touching that!). Water coming out, not air. Was initially cold, but gets hotter after a bit however the hot water isn’t getting to the cylinder as pipe cold at the bottom despite valve being open. Have been carefully watching pressure too and making sure it stays stable using fill valve whist bleeding thumb valve.

He’s taken the motor off as a cog needs replaced (coming out tomorrow to do it as in another city today).

Have checked Gas Safe and he’s fully registered including work on unvented systems. Has over 20 years experience. Been using him for 5 years on recommendation without any problems.