Air in sealed system

[alexo]

I'm having an issue with air in a sealed system.  Approximately once every 6 weeks there is enough air in the system to fill one of the small upstairs radiators.  Sometimes I find air in some other upstairs rads.  I'm needing to bleed them all and re-pressurise.

 

Had this sealed system installed in October last year, replacing a gravity fed system.  All radiators were replaced and a new system boiler installed at the same time.  Horizontal unvented cylinder in the loft, 8 column rads, 6 convectors.  Underfloor pipework not replaced, house 38 years old.

 

Initially my plumber reassured us it was just air from the new water entering when it was setup, but it's been going on too long for that to be plausible.

 

In case it's relevant, the horizontal unvented cylinder had the hot and cold labelled the wrong way round by the manufacturer, and it was operated like this for approx 2 months because my plumber was convinced we had a a plumbing crossover issue causing the lukewarm water.  Eventually they realised and plumbed it in the correct way after the manufacturer informed them of the error.

 

Hot water when run is also very cloudy.

 

What's the most likely cause of the air?  Thanks

[Wil]

Have a similar although less severe issue. Still have to bleed our highest towel rail every couple of weeks. 

 

I always understood there must be something open/ letting by for air to enter a sealed system. Do you have a pressure gauge? Is it static? If the pressure is dropping it’s a leak somewhere…

[alexo]

57 minutes ago, Wil said:

Have a similar although less severe issue. Still have to bleed our highest towel rail every couple of weeks. 

 

I always understood there must be something open/ letting by for air to enter a sealed system. Do you have a pressure gauge? Is it static? If the pressure is dropping it’s a leak somewhere…

I always reset the pressure gauge to 1 when the system is off and I’ve had to repressurise.

This time is 2 months later and when the system is not running, the pressure now sits at 0.7.

 

Would this drop be enough to indicate a leak?

 

I always assumed a leak on a sealed system under high pressure would result in a drastic loss of pressure?

 

[SimonD]

42 minutes ago, alexo said:

I always reset the pressure gauge to 1 when the system is off and I’ve had to repressurise.

This time is 2 months later and when the system is not running, the pressure now sits at 0.7.

 

Would this drop be enough to indicate a leak?

 

I always assumed a leak on a sealed system under high pressure would result in a drastic loss of pressure?

 

 

You'll be surprised how even the smallest drip will cause pressure loss in a sealed system. Given it's a new system, this could be in any multitude of places which you can very carefully inspect. The other option is to pour some CT1 miracle seal into the empty radiator before you re-pressurise next time. Then see if it solves the problem.