Pressure in heating system keeps creeping up

[Chillidog]

We have a 2 year old Valiant EcoTec 832 Combi boiler which was running our CH and hot water.

We recently had some UFH installed and the boiler moved to our new extension.

Over the past weeks the pressure in the heating system keeps creeping up. It goes from approx 1.5 to 3.2 bar overnight. If I do not drain any of the water out it remains at approx 3.2. When I drain the water to bring the pressure back down it creeps back up by the next day.

I have checked the filling loop valves and they are all in the off position.

One plumber suggested (over the phone) that we would need an expansion tank fitted as the pressure rise may be due to the installation of the UFH system?

Is this correct or is it more likely a fault somewhere?

Thanks!

 

[Brambles]

Set the system to the correct pressure, then remove the filling loop and cap the valve ends. Monitor it ( the system pressure) and see what the pressure does over the next 24 to 48 hours with the system running and report back.

 

[Scott_D]

Undersized expansion or filling loop issue.

 

[SJB060685]

As Brambles says above, fill to correct pressure, cap off filling loop to ensure the system isnt further filling and monitor over the course of a day or two.
It could very well be down to the expansion vessel charge or even sizing. With the additional UFH circuit/circuits being added you've increased overall system volume, which could have and often does result in the original vessel being undersized and not man enough for the job.
Really this should have been considered when designing these add ons

 

[king of pipes]

The guys have it covered above it may we need a extra vessel but worth checking everything . Kop

 

[Jam007]

Open the refill loop and check if the valve is letting by

you might as well check the pressure on the expansion vessel

 

[SJB060685]

The other possibility is you have a split in the PHE coil causing cold mains pressure to reach into sealed system increasing the pressure that way if the vessel is sound and filling loop not letting by.

 

[EvilDrPorkChop]

Sounds more like a filling issue to me rather than expansion.

As if it's a 1.5 bar goes up to 3.2 bar but then doesn't come back down when everything cools, if it was an expansion issue it should decrease at least when the heating is off.

If you're having to let the water out yourself it sounds like something is filling the system.....

 

[Chillidog]

Update: Emptied and re-adjusted the pressure on the expansion vessel which was very full of water!

Disconnected the filling loop hose to find that the valves on both sides were leaking! Capped for now and am monitoring. But so far it looks like the pressure is holding.

Will monitor for another 24-36 hours and report back.

Thanks all for the help!

 

[Brambles]

Thanks,

Do you mean that water was exiting the expansion vessel from the Schrader air valve? If so, the vessel needs replacing.

Obviously the filling loop assembly and non return valve also need replacing.

 

[moonlight]

Looks like you have two issues then, at two years old your boiler should be still under warranty. give them a call they are still coming out to warranty work.

 

[Chillidog]

The expansion vessel valve was fine - no water exiting. Since disconnecting and capping the filling loop valves the pressure has been stable.

The two valves either side of the filling loop were both leaking (cold water inlet valve and service cock).

have ordered replacement for both.

thanks for the help

 

[moonlight]

The expansion vessel valve was fine - no water exiting. Since disconnecting and capping the filling loop valves the pressure has been stable.

The two valves either side of the filling loop were both leaking (cold water inlet valve and service cock).

have ordered replacement for both.

thanks for the help

The boiler not under warranty?