Central Heating Question

Hi. a new vaillant ecotec plus combi boiler was installed in my 3 bed house after having issues with my condensing boiler and tank.

The combi boiler was fine for a week. Then the radiators downstairs especially sitting room was very low on heat meaning heat is good when the heating is ON for 10 minutes ,then gradually goes down. I called the plumber who installed the boiler and he balanced all the radiators. But still heat wasn't proper to all the rooms.He took the pressure out of the radiators,power flushed too when he initially installed the system. The problem now is that the pressure gauge in the boiler often goes below 0 sometimes to red and heat in radiators comes down. I took the pressure out of the system by adjusting the valve in the boiler and it was fine for a day. Every day now the pressure goes to red or below 0. Also in the bedroom upsatirs where the pipes were taken below the carpet, there is a tapping noise and boiler vibrating sound whenever the boiler starts and also gurggling sound when water starts to flow.When I call the plumber, he isn't responding.I have spent thousands of pounds under the belief that heating issues will be resolved with this installation but all in vain. Why is there heat in raidiators when it is ON for 10 minutes and then heat gradually goes down in the sitting room radiatior?I am also worried about this noise upstairs. Can someone help and try to suggest something to resolve this issue?


9 Answers

Best Answer

Hi, I can help if you post the job! Are you southwest area? was your plumber gas safe registered? Have you had the benchmark filled out in the rear of the install book? And have vaillant been informed ref warranty? i can check all this!

The water following noise is normal,as the pump kicks in, the knocking noise is normal,as hot water creates expansion within the system! pipes just need lagging!! You need someone to go right through it. Expansion vessel needs checking,Trvs checking,presure relief pipe/valve.. but you could have a leak! and installation generally.....


Answered 9th Feb 2012

kelly plumbing Heating & gas

Member since 4 Jan 2012

Sounds like there is a definite leak somewhere ,was the thermostic valves changed or using old ones?whats the roomstat position?

Answered 9th Feb 2012

Paul Caton Gas Services

Member since 23 Mar 2010

The system should have bin fully power flushed meaning all pipe work and all radatiors, once the boiler has bin fitted you may need to top the pressure up once due to a little air in the system but it sounds like you may have a leak on the system somewhere but i cant be certain better off posting a job and getting a recommended heating engineer to take a look an advise further

hope you resolve the problems best of luck

Answered 9th Feb 2012

cm property maintence south east ltd

Member since 8 Feb 2012

with the pressure going down every day there maybe a leak in the system somewhere,pressure needs to be up to the green to help the pumps circulate properly, the tapping noise could be pump vibration in the pipes where they are touching a little, as for the gurgling some trapped air in that area where pipes are not level as well as the pressure being down (not compressing the air) it wants to stay there and not escape, as a resolve you could try shutting down all rads but one upstairs close to the noise and see if you can force the air into that rad??? hope this helps and keep calling the guy to come back

Answered 9th Feb 2012


Member since 28 Dec 2007

sounds like you have a leak on the central heating system and he has not balanced the rads properly if he is gas safe registered ring up gas safe and complain about him if he is not gas safe registered tell health and safety. mdp gas services

Answered 9th Feb 2012

MDP Gas Services

Member since 12 Jan 2012

you have a leak somewhere in the building, when the pressure drops the boiler will stop working , it has to be around 1 bar on the gauge to work,the ticking or clicking noise is pipe exspansion and can be fixed ,the other noise could be because of the loss of pressure,for your peace of mind i recommend calling in a few engineers to quote, all these problems can be solved and think about what to do about the other engineer afterwards,

Answered 9th Feb 2012

sovereign plumbing and heating

Member since 23 Nov 2011


There could be several issues here.

Check the PRV outlet to see if the PRV is letting by, this could be the cause of pressure loss.

How large is the heating system in water volume? You may require a secondary vessel.

What size pipe work is the primary? If retro fit is your system single pipe or twin?

Was the boiler commissioned setting up the primary temperature differentials? What are the differentials when hot?

Was system flushed adequately?

Do you have a magnaclean?

Please reply if you would like acisdence.

I am a member of the Gas Safe register and Vaillant’s advance installers program.

Kind Regards


IJC Domestic Gas Watford.

Answered 5th Mar 2013

Watford Boilers

Member since 13 Jul 2011

could be air trapped in the pipework, although unlikely because the system is pressurised and usually pushes out out automatically. There could be a leak in the pipework under the floor which is causing the pressure to be lost

Answered 9th Feb 2012

Aspire Services

Member since 7 Aug 2011

if the pressure in the boiler is going down you have a leak somewere on the system,or it is the pressure relief valve on the boiler that is letting water out of the system,as for the sounds you are getting one will be loose pipes the other air in the system.try your plumber again if you get no response report him to gassafe as he may be a cowboy,also try vaillant as they may be able to help,i am takeing it that the boiler is new or newish!!! tom clydebank plumbing & heating

Answered 10th Feb 2012

clydebank plumbing and heating

Member since 14 Apr 2011

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