Gurgling when boiler only set to Hot Water

[Scarum]

Hi

I recently flushed my CH system after two weeks of Sentinel X400, then finishing off with X100 and X200 on the final fill.

There is no air in the rads, I have bled the pump and the bleed valve off the hot water cylinder.

Here is what I notice, when the actuator turns the diverter valve to hot water only, I start getting the gurgling.

Did I go wrong somewhere when draining and refilling? Can I easily remove the assumed trapped air?

I appreciate anyones help.

 

[Scarum]

Am I allowed to bump my own post?

 

[dinger71uk]

Im no expert but I had a very similar problem and found mine is related to a small leak close to the pump and hot water cylinder on the water circuit. Air was being dragged in to the system producing the gurgling.

Was there a reason why you flushed down, boiler kettling etc.

 

[Scarum]

Thanks for replying.

I initially drained the system as there was sludge, after final rinse the water ran clear. The rads all working fine now. The "gurlging" must be an airlock where the water diverts to the HW cylinder. I am thinking of draining some water off at the boiler but not sure if this will achieve anything, so may as well give it a go. I will also check the F/E tank this evening.

I haven't found any leaks.

 

[dinger71uk]

Dont think the fe tank would be an issue if the rads are filling nicely, it could be a valve issue, do you have a three port valve? this is usually a electrically controlled mech device situated close the the hotwater cylinder?

If you do have this you may be able to manually control this valve and try and see if that makes a diffrence.

Does your system heat any towel rails/radiators when the the water is called in the bathrooms? might be the bleed valves or the trv valves if you have them fitted on these.

 

[Scarum]

Hey Dinger, well I did check the FE tank, no probs there, as you already suggested. The actuator works (I replaced the faulty one only this week). If I set the 3-way valve manually to DHW and the gurgling starts and the boiler can eventually stop (I am guessing no water, only air ). At a 45 turn (DHW & CH) or vertical (CH only) no gurgling problem.

The bathroom has one radiator, I recon it is the first rad in the system as it heats up very quickly (and the airing cupboard in the bathroom is where the pump is). I have balanced the rads and this rad is open by a quarter of one full turn. Is the idea to open up the valve to this rad a bit more?

 

[Scarum]

Nothing like the present, I fully openened the bathroom TRV valve, started the boiler and heard some gurgling but now in the bathroom rad!

So I have learnt something new about my setup, am I supposing the bathroom rad should not be balanced but left fully open at the TRV and heat controlled by the manual valve (as it does not have a thermostatic valve)?

I'll let things settle down and bleed the rad later tonight.