Vaillant Ecotec boiler losing pressure intermittently

mossy007

Any update BillG100? I have exactly the same issues and have a engineer out this week. Is the pressure drop worse in cold weather?

BillG100

mossy007 wrote: »

Any update BillG100? I have exactly the same issues and have a engineer out this week. Is the pressure drop worse in cold weather?

The boiler held pressure for 10 days when the auto air vents were closed off and the temperature it runs at was ramped up by turning the dials about 3/4 of the way round.

Since putting it back to how it was and fixing 2 leaks on the 18 month old bathroom towel ring (manufacturing defects rather than installation ones) the pressure holds for about 4 days.

To answer your question the pressure drop seems to be worse when the boiler / water temperature is lower. In other words when the boiler is switched off during the nights.

Alex1983

Did it drop pressure with the flow and returns isolated?

BillG100

Alex1983 wrote: »

Did it drop pressure with the flow and returns isolated?

That has still not been done. However if the boiler held pressure for 10 days what would isolating the flow and return valves off for a few days prove?

Alex1983

From my understanding you have a gradual pressure lose over 10 days.

I dont know what your setting your boiler to initially but if we say its 1.5bar. A Vaillant boiler cuts off at 0.5bar with f75 or f22.

Your boiler is not going to think its the 10th day today Im going to lose all my pressure today, it will be gradually losing it over the 10 days. So from 1.5bar to 0.5bar over 10 days will be around 0.1bar per day.

So logically if you isolate the flow and returns with the pressure set to 1.5bar over the course of 2days the gauge will either fall to 1.3bar proving a issue with the boiler or it will hold the 1.5bar proving a leak on your system, if that happens id guess when you open the flow and returns the boiler pressure will drop.

mossy007

Are you anywhere nearer to sorting out the issue? My boiler is now losing pressure 1 bar every 24hrs for the past 4 days. It has held for 3 weeks on 1.5 bar. It had been much colder for the past week and I seem to be under the impression that it’s something to do with the temperature outside but I maybe wrong. Like yourself Baxi has been out on numerous occasions to check the boiler who have changed the expansion vessel and PRV in the last few visits it was actually better when the PRV was changed and it held on 1.5 for 4 weeks as it was losing pressure every 24hrs prior to that. It then held pressure for a further 4 weeks and then started losing pressure again. The Baxi engineer advised that they maybe a leak in the UFH so he isolated the flow and return to the boiler but it was still losing pressure. No visible leaks anywhere in CH system. The only difference other than yours is that my boiler temps are rising considerably to over 100 degrees when only the UFH is on only. When the HW and CH are on the boiler temps are fine. I am not sure if this will be related to the pressure issue but Polypipe who installed the UFH advised that they maybe a issue with the UFH zone valve sticking and may be affecting the pressure. My heating engineer is out this Fri so I will see what he can diagnose. Do you know what temps the boiler reaches when your UFH is on?

BillG100

mossy007 wrote: »

I am not sure if this will be related to the pressure issue but Polypipe who installed the UFH advised that they maybe a issue with the UFH zone valve sticking and may be affecting the pressure. My heating engineer is out this Fri so I will see what he can diagnose. Do you know what temps the boiler reaches when your UFH is on?

That's very interesting... we also have Polypipe but it was installed by a third party. In our case it's the overlay UH:

http://www.polypipe.com/housing/polypipe-underfloor-heating/underfloor-heating/overlay-system

The boiler temperatures is around 60C. The temperature on the UH can be adjusted using the mixer valve but currently it is set to between 45C and 50C.

mossy007

BillG100 wrote: »

That's very interesting... we also have Polypipe but it was installed by a third party. In our case it's the overlay UH:



The boiler temperatures is around 60C. The temperature on the UH can be adjusted using the mixer valve but currently it is set to between 45C and 50C.

Believe it or not I have the exact same system as yours! I will let you know what my engineer has diagnosed on Friday. The temps you have given seem normal to me.

BillG100

mossy007 wrote: »

Believe it or not I have the exact same system as yours! I will let you know what my engineer has diagnosed on Friday. The temps you have given seem normal to me.

The strange thing is we've now had 3 relatively new valves developing leaks. Both valves on the bathroom towel ring and one on a circuit pipe in the loft. It's almost like there is too much pressure despite what the Vaillant shows (both gauge and digital). I wonder whether there is an issue with the UH zone valve which could be the cause of this. However I don't understand how that could be the case.

mossy007

So you have now located your leaks? Are these the culprits for the pressure loss?