HELP! Vaillant ecoTech plus - pressure drop

[gurgleenglish]

Hi all, any Gas Engineers on MN?

About 3 weeks ago we had a brand new boiler installed - Vaillant ecoTech plus.

The Gas Engineer had excellent reviews on Which and Google etc and seemed very knowledgeable and experienced.

Anyways, in the last 3 weeks since installation the pressure had always been between 1.1 and 1.2 when cold (i.e it was in the normal expected range). I check it daily because I walk past it. It's been left untouched and I've just gone about my normal day, using hot water when needed (shower mainly, heating)

However, Yesterday night is the first time I saw it drop to 0.9. When I use the boiler (e.g. shower, heating), it rises up to about 1.6 and that's normal an expected rise with use.

What concerns me is today in the morning I saw it at 0.9 again.

I've checked all my radiators today for any signs of leaks - there are none. I've checked walls, ceilings , skirting boards and any pipes I have access to under the floorboards - no signs of leaks.

Has anyone had the pressure drop to 0.9 when cold? It's worried me a lot since the boiler is brand new.

The Vaillant manual and website says that it shouldn't need a manual pressure "top up" more than 1-2 times a year so I'm quite concerned about doing this so soon after installation.

Is the boiler faulty?

Can anyone advise? thank you

We have a very old Vaillant GreenTech which has the same problem; but it’s basically because it’s on its list and the pump doesn’t fire up itself to maintain its own pressure.

Is it definitely strong enough to maintain everything you run in the house? I believe that’s the only other reason for it happening.

I wouldn’t be happy with a new boiler doing it, it’s a pain in the arse. We have to repressurise ours once or twice a week, and it’s unreliable in very cold weather.

thanks for responding. I'm actually really worried and concerned since it's only been 3 weeks! Does yours drop to 0.9? or lower? thank you and sorry to read this is a pain for you.

I haven't topped my pressure up yet and have emailed the Gas Engineer who installed it

anyone else? :(

Yeah, 0.8 - 1.0.

Hopefully they’ll come back out and look for you, I’d be worried it’s faulty. Did they recommend the boiler?

When the weather is colder and your house is colder the pressure gauge will drop slightly.

TBH it also may be a slight weep on a valve. You need to check every valve and plug on each radiator when the system is COLD. Use blue roll and push it against each union to see if is leaking.

hi @Clamfoo , how do I Use blue roll and push it against each union to see if is leaking?

I'm sorry, but I don't know what blue roll is, or what you mean by union. Do you mean each join?

Can you kindly send me a link of what blue roll is? thank you

Mine is 1.0 most of the day, and then 0.9 if I haven't used if for about 4 hours. It hasn't dropped further than that over the weekend.

Today, I saw it fluctuating between 0.9 and 1.0 within a second of each other for a good while, now it's settled on 0.9

It's making me feel really anxious because we spent good money on this only 3 weeks ago and we are not wealthy

If it's only been three weeks then get them back to look at it. It'll be under warranty anyway, but as it's a fresh install, the installer should come out quickly if there's a chance it could be faulty.

We had an issue with our new boiler and the installers came out next day and when they realised it was a fault with the boiler, not installation, they contacted Worcester Bosch and their engineer came out the day after.

thanks, that's reassuring!

It is definitely under warranty, so does that mean the installer is obliged to come to fix it. I shouldn't have to pay him, right? Since he installed it only 3 weeks ago and there's already a problem?

Also, 0.9 is definitely regarded as low pressure?

I just don't know anything about boilers and this is my first house purchase

does anyone know what the pressure normal should be when the system is cold?

also @doodleschnoodle did the Worcester engineer that came out fix the issue? Hope it got sorted for you in the end!

Also, I have to add that although the Engineer who came to install seemed experienced, I didn't quite like him. He was a bit rude in his mannerism and after he installed it, I wished we didn't use him. I guess this is adding to the anxiety of all of this too

Is it never above 1.0? 1.0 is the minimum good pressure - it should be between 1.0 and 1.5, so you'd expect a new system to sit around 1.3, so that any natural loss of pressure only took it to 1.2.

I'd be concerned that if it can only get to 1.0, it's not the right boiler for your set up, but I'm not an expert and I'm only going from what I've learnt dealing with our current boiler... It'll be being replaced as soon as it can be!

What are you re-pressurising it to? 1.0?

I have the same boiler and the pressure should be 1.5!

When you top it up make sure you close the valves after you've topped up.

Check that rads don't have air in them, by bleeding the highest one.

You may have to top up again!

Lots of you tube vids explaining how to do it

AFAIK a few tenths of a bar fluctuation is no issue. Maybe the reading is just on the edge of one value and that's why it flicks between the two.

Pressure might have dropped a tenth or so recently when cold due to colder ambient temperatures. There is also the issue it may be airlocks moving their way round the system after installation. Sometimes the systems can be water tight but not air tight, you can leave bleed valves open in this state.

I do find it a bit strange that your system goes up from 0.9 to 1.6 when turned on. I don't see that on mine. Maybe that's because you have a higher volume of heating circuit water in your system relative to the expansion capability. In this respect eveyones heating system is going to be different.

hi @YouveGotAFastCar yes, it's been 1.1 when not used (i.e. a cold system), but drops gradually over the course of the day to 0.9

we haven't re-pressurised it yet as we thought we'd wait for the installer to come round, but he's not really been responsive and will be leaving a complaint

Hi, thanks @hushabybaby yes, I read on the Vaillant website a cold system should be around 1.5. I am really concerned and pissed off too.

I have't re-pressurised them.
I think bleeding the rads would reduce the pressure more and might be a worse situation, so waiting for a plumber to come round

thanks @GasPanic I have no idea about the effect of cold weather on a combi boiler system. Why would the pressure drop in colder weather? The house hasn't been cold cold. unless you'd describe the weather/temperature in England as cold now? I guess it is a bit chillier

I do find it a bit strange that your system goes up from 0.9 to 1.6 when turned on. I don't see that on mine. Maybe that's because you have a higher volume of heating circuit water in your system relative to the expansion capability. In this respect eveyones heating system is going to be different.

I read from Vaillant website that this happens because hot water expands so naturally the pressure goes up when in use/hot

I'm so upset about this

Bleed your radiators and adjust the pressure. Then see if it holds it.

I would imagine that having only been in 3 weeks it's the system settling more than anything particularly as the atmospheric temperature has now dropped.

Particles move closer together when they are cooler as they have less energy and expand further apart when they are warm so it is unsurprising that it has dropped, the atmospheric temperature has decreased considerably over the last 3 weeks as is normal for autumn.

Well why would the pressure increase when you turn the heating on ?

As water is heated the volume of it expands, so if you keep the confining volume constant the pressure in that volume will increase. Similarly as you cool water the pressure will decrease. In fact the overall behaviour across the entire liquid temperature range for water is a bit more complex than that simple rule (see science), but is applicable to most of the usual temperatures you will find in a house.

Going from say 25C ambient to 15C ambient is probably not much of a contraction and therefore not much of a pressure drop - certainly compared with the pressure increase in going from say 20C to 60C. But it still might amount to something noticeable on a larger heating system.

hi all , we had a Vaillant gas engineer come round since our original installer refused to come. The original installer said he thinks it's because the system is still "settling" and can "take several weeks" and refused to check the boiler and see if there is a leak.

We have now understood from the Vaillant gas engineer that this is absolute BS. It shouldn't take a combi boiler system several weeks to settle down, it should happen within a day of the rads/hot water are on/in use. The latter made more sense to us than this BS from the original installer saying it taking several weeks to settle down. With the original installer, we are taking this further with a complaint and will be taking legal action. We are sick of some of these tradespeople and won't let them get away with negligence esp after we've paid them. Just sharing this here incase anyone is getting a new boiler soon.

The Vaillant engineer believes there is a micro leak somewhere in the pipes causing the pressure to drop, he did all the checks on the boiler too. The boiler itself is fine.

Anyways, he has advised we find a good plumber to check the pipes through the house and rads/valves for micro leaks. He did find one site at a rad valve but isn't convinced this is the cause, but recommended we get it sealed anyway.

He also suggested we could use a leak sealant and add it to the rads system. Apparently this can help seal micro leaks from within the pipes, but might be hit or miss.

Has anyone used this or not? We just hoped someone could share their experiences. Thank you