New combi installation 30CDI: pressure drop...

[deejaybee101]

Hi All,

I've just had a new W-B 30CDI combi installed with rads and the heating loop appears to be losing pressure over a period of a 3-4 days . If left completely alone the system drops right to zero, then substantial amounts of air appear in the radiators.

- it isn't the PRV, there is no evidence of leaking through this.

- there's no evidence of weeping from any joints, or apparent damp spots

- could it be the automatic air vent? How long after an installation and start up could I expect the system to be air-free from the AAV? Am I just seeing trapped air venting out of the system, causing a pressure drop, until eventually the pressure drops so low that air gets sucked back in through the same route?

any thoughts, would be much appareciated!

 

[Agile]

That is an effect which occurs in new systems. It usually clears itself after a few days.

For the technical its partly water being removed by an AAV and partly oxygen being dissolved in the system water which is quite quick. The remaining notrogen is not very soluble and takes far longer to disperse.

I would say that if its an average size house then suspect a problem if its not pretty much cleared after seven days. You should bleed any air from rads as evidenced by them being cold at the top otherwise dont touch them. Always repressurise after any bleeding.

Tony

 

[deejaybee101]

I'll ensure that pressure is maintained for a week or so then look wider for an issue if it still doesn't hold..

Kind regards,

Dom

 

[deejaybee101]

so the pressure drop is about 1/3 bar in a 24hr period, for the past two days; does this change the likelihood to a leak rather than expelled trapped air?

 

[qplumb]

If you have new rads fitted sometimes you can get tiny leaks from the blank and vent plugs on the tops of your rads.These are sometimes small enough to let out air but not water,worth giving them a small nip.

 

[deejaybee101]

Thanks for your help guys, I think I have found the problem

- a compression fitting had been installed too close to the floorboards, and when walked on it forces the joint to open, then leaves it weeping.

picked up with just the slightest of shadow on the ceiling below, literally the first floorboard I lifted )

 

[Agile]

Its bad practice to use compression joints close to floorboards because apart from that possibility it looks bad it can make it difficult to lift the boards.

Tony