Boiler airlock

[neza]

Just after some advice please.
A couple of days I had my central heating drained/cleaned.
Next morning the boiler fired up to heat the water (conventional vented system) and theres lots of sloshing noises coming from the boiler, boiler cuts out after 5 mins then starts back up and on it goes trying to heat the water.
I turned on heating, checked the rads no air when bled , checked pump next to cylinder again no airl came out so all good.

Boiler still making lots of sloshing noises so I expect it's air trapped but don't know how to get it out.
I noticed above the boiler on the flow side there is a drain off valve, if I cracked this open would it expel the air ?
The boiler has worked fine up until now it is old it's a potterton prima f50
Any advice anyone !

 

[CBW]

Who carried out the cleaning and was it vented at this time? Sometimes air can linger in a system, what do you get at a rad when trying to bleed?

 

[fdiddy]

Do you have access to the pump? There is a screw that can be opened like below - very slowly let the air out.

 

[neza]

Who carried out the cleaning and was it vented at this time? Sometimes air can linger in a system, what do you get at a rad when trying to bleed?

Water comes out all the rads, no air at all.
It was vented at the time and plumber did the job, trying to get them back but obviously busy, just thought something simple I could try.

 

[Madrab]

Do you have access to the pump? There is a screw that can be opened like below - very slowly let the air out.

View attachment 316071

Erm, no ... they are gate valves with the heads removed, the screws are for tightening the wheel head onto the valve. They're for isolating the pump if it's being replaced, without having to drain down.

OP, is you system sealed or open vent and is the boiler the highest point in the system? The flow and return head out the top of the boiler so it shouldn't really trap air in the HEX unless it's the highest point in the system.

 

[neza]

Do you have access to the pump? There is a screw that can be opened like below - very slowly let the air out.

View attachment 316071

Yep got access to the pump will try and give that a go, thanks for the illustration.

 

[Madrab]

Yep got access to the pump will try and give that a go, thanks for the illustration.

Don't, it won't do anything and you'll just be wasting your time.

 

[neza]

Erm, no ... they are gate valves with the heads removed, the screws are for tightening the wheel head onto the valve. They're for isolating the pump if it's being replaced, without having to drain down.

OP, is you system sealed or open vent and is the boiler the highest point in the system. The flow and return head out the top of the boiler so it shouldn't really trap air in the HEX unless it's the highest point in the system.

System is vented with 2 tanks in the loft and cylinder on landing, boiler is in kitchen downstairs in 2 storey house

 

[neza]

Radiators all heating up fine, just when do the hot water only lots of sloshing water sound from boiler when on and flame doesn't burn long before boiler shutting down and restarting.

 

[CBW]

Radiators all heating up fine, just when do the hot water only lots of sloshing water sound from boiler when on and flame doesn't burn long before boiler shutting down and restarting.

Could be airlock at the cylinder, maybe releasing air at the air vents there if fitted?

 

[opps]

I recently had to partially drain down a system and had loads of problems recharging the system.

I spoke to the customer and he told me that there was a little vent that needed to be opened on the top of a pipe above the heating pump. Do you have any such vent?

 

[neza]

Will try your suggestions guys, thanks

 

[Madrab]

Are you getting hot water?

As suggested, the primaries (main flow and return pipes) to cylinder may need bled. Do you have 1 motorised valve or 2?

 

[Harry Bloomfield]

Do you have access to the pump? There is a screw that can be opened like below - very slowly let the air out.

View attachment 316071

Those are valves, to allow the pump to be swapped, without draining the system.

 

[Madrab]

Erm, no ... they are gate valves with the heads removed, the screws are for tightening the wheel head onto the valve. They're for isolating the pump if it's being replaced, without having to drain down.

Those are valves, to allow the pump to be swapped, without draining the system.

C'mon Harry ... keep up