Vaillant turbomax plus banging noise

[DoctorNick]

We have recently moved into a house equipped with this boiler. When the boiler is working quite hard (eg CH is recently turned on and heating up), turning on a hot tap results in a very distinct bang and vibration through the pipework. Once the boiler has changed to DHW mode, it operates without making excessive noise / banging. Also, when the tap is turned off and the boiler reverts to CH mode, there is no banging noise.

Once the CH is operating at temperature and the boiler is working less hard (once it has been on for an hour or so), the noise does not occur on turning on a tap.

I have bled all the rads and made sure that the pressure in the system is correct. I have also used the "bleed" screw on the expansion tank in the boiler to purge air from that. However, the noise has not gone away.

I am sure that this due to something that happens exactly at the time one opens a tap. Sounds like the pump maybe experiences high back pressure when the diverter valve operates or something like that.

I do also wonder though about the expansion tank. In the install manual for the boiler, the valve on the expansion tank is called an "expansion vessel charging valve". Sounds more like one is supposed to push something (eg air?) *into* the tank via this valve rather than bleed air out. The valve also looks like a bicycle tyre valve rather than a rad bleed valve. Unfortunately, the install manual makes no further mention of how to use this valve.

Hence, anyone got any thoughts? Anyone know about how this expansion tank charging valve works? I also wonder whether I should see what happens if the pump speed is reduced (I think it is one "3" at the moment, but can be set to "2" according to the install manual - but the manual does not recommend this).

Any help much appreciated. I have used an on-line form to ask Vaillant about this, but got no answer.

 

[emphasis303]

Hi

Ive got ur same problem but i have an ecotec 630e, i thought it was my cylinder as the problem wasnt there before i installed my cylinder but the cylinder was installed a year after the boiler so now im thinking its my boiler too as the problem only happens when the boiler is fired up and heating water.

Im not sure if there is a fix for this, but ive begun to wander that it could just be becos not all of the pipes are clipped to a wall or joists and are somewhat free

 

[petit_pablo]

I have also used the "bleed" screw on the expansion tank in the boiler to purge air from that.

I do also wonder though about the expansion tank. In the install manual for the boiler, the valve on the expansion tank is called an "expansion vessel charging valve". Sounds more like one is supposed to push something (eg air?) *into* the tank via this valve rather than bleed air out. The valve also looks like a bicycle tyre valve rather than a rad bleed valve. Unfortunately, the install manual makes no further mention of how to use this valve.

Hence, anyone got any thoughts? Anyone know about how this expansion tank charging valve works? (/quote)

The expansion vessel should indeed have air in it and is not supposed to be bled out! Is the system pressure higher than normal now by chance? see FAQs for how to remedy.

(quote)
I also wonder whether I should see what happens if the pump speed is reduced (I think it is one "3" at the moment, but can be set to "2" according to the install manual - but the manual does not recommend this).

Leave pump speed on 3.

Its most likely to be the diverter causing the noise but hard to say without hearing it doing it.

 

[fazedup71]

is this like a thump on start up? not to be confussed with water hammer. When you turn hot tap on does the pressure gage jump? if it does a partial blockage of the expansion vessel could be the cause thats if it is just a thump on start up. The divertors on these boilers have had problems tho. You also need to re pressurise your expansion vessel that is not a bleed screw! you shouldnt have touched that

 

[DoctorNick]

It certainly is not water hammer (cavitation caused by boiling in the heating vessel). It occurs immediately the tap is opened and the boiler switches from CH to DHW supply. Certainly it causes the pipes to rattle and I am sure that they are not all fixed perfectly. However, I also worry that if they are all fixed hard to joists etc, then this might actually be more likely to cause a joint to split when the pressure wave moves through the pipework (I am certain that this is a pressure change affect).

Okay, so I should not have released the air from the valve on the expansion vessel. Any idea what it should be re-pressurised to? A regular foot pump will work to pressurise it, I just need to know what it needs to go up to....

Sounds like I might need to look into the diverter valve as a possible cause of the noise / pipe movement.

 

[kevplumb]

Okay, so I should not have released the air from the valve on the expansion vessel. Any idea what it should be re-pressurised to? A regular foot pump will work to pressurise it, I just need to know what it needs to go up to....

.8 to 1 bar with the boiler empty

 

[fazedup71]

well think you need some clips on that pipe work where pipes go up wall to meet boiler, as long as the pipes are sitting in notches on your joists then they are ok and are supported, if you clip the hot you will get annoying click and ticking sounds, without being harsh i wouldn't play with the divertor as you did not understand the expansion vessel, i would test the incoming water main pressure tho.

 

[DoctorNick]

Found the FAQ on expansion vessels, so understand them now....

Been used to open systems before.

I was not planning on fiddling with the diverter. if there is something actually wrong with the boiler, it will be a service call out. I don't mess with that sort of level of work; just simple things.

Will follow FAQ and repressurise expansion vessel. Might also see if I can restrict mains flow into boiler a bit (just a bit), since we do seem to have high pressure here (have needed to do this with loo cisterns and the washing machine already, since when the valves close in these, the mains pipes rattled. Could be connected).

Cheers

 

[fazedup71]

could well be, remember tho if you restrict flow at boiler using the service valve it might well end up being just as loud, your problem does not sound that serious just needs a little thought behind it, try turning a cold tap on at another outlet say downstairs if your boiler upstairs and then run your hot water, i don't really think it is divertor related myself, what tends to happen is the little ball inside swells up and sticks the valve normally giving your central heating when you turn the hot tap on, also noticeable with your boiler having pre heat and it starts heating the central heating circuit, keep us posted on it am interested to know if it is just high pressure

 

[DoctorNick]

Job now done... Result...

With the system cold, I drained off 9 and half L of water from the system and pumped in air to the expansion tank until the pressure inside was 0.75 bar (Vaillant spec). Repressurised the system to 1.2 bar using the filling loop and then switched on.

The system seems quicker to warm up now!? Radiators are hotter as well. I didn't change the CH setting, so it looks like the water is being pumped around quicker. I don't understand why this should be the case (maybe the bypass valve is now operating correctly?) but I am not complaining...

The acid test was opening a hot water tap while the system was going like the clappers warming up the CH water. No bang! Switches over to DHW with no noise at all.

When checking the rads, I did have to bleed a load of air out of one and quite a bit out of another. These are the rads that accumulate air in them, but I do wonder whether some of the air that was pumped into the expansion vessel has got into them (ie faulty vessel membrane). Only time will tell on that one, I guess.

I decided not to do anything with the cold water flow into the boiler on the basis that the noise did not occur when the CH was at operating temp and so the noise should not have had anything to do with water pressure.

Keeping my fingers crossed for the longer term.

 

[2point8ghiax]

Had the same problems with mine twice, with heating on sounded like someone whacking a pipe hard when hot tap opened.

Ist vaillant engineer replaced diverter valve (modified!). OK for a while.

1 year later it started again. 2nd vaillant engineer fitted a new bypass, once again a modified/improved one.

Seems to be a common fault with Vaillants

 

[DoctorNick]

I was wondering if the diverter was the problem right at the outset. Still thinking that the PV might be the problem though, since I got water out of it when I "bled" it (by mistake 'cos I didn't know what I was doing!). I stopped when a small amount came out, so I don't know for sure if the membrane is perforated (one comment I saw on a forum said that it is common for a little water to come out the PV charging valve when it is opened).

Certainly if the noise returns, I will need to get the PV sorted out as the first thing to fix. If noises still persist, then it could well be one of the two issues you encountered.

Thanks for the info.

 

[jcorbin]

Certainly if the noise returns

Good afternoon DoctorNick has your banging been eliminated completely ?

 

[DoctorNick]

Thanks for asking.

I think it is about the same as it was before I did anything. This leads me to conclude that the PV membrane is probably ruptured (I did get a bit of water out when I "bled" it). I also got air into various rads when I recharged it and I would not have expected that.

I am living with it at the moment. Pressure in the system is okay and never gets above about 1.5 bar (hot) starting at 1 bar (cold). Hence, there must be enought expansion space somewhere in the system (maybe the PV is still working to an extent and other expansion spaces prevent excessive pressure buildup).

We plan on doing some fairly major work (or probably having some major work done would be a better way of putting it) over the summer - a new rad in one room and replacement of four other rads that had been painted horrible colours, plus changing pipework to a kickspace heater in the kitchen (when it was installed by someone (?competent plumber) they put microbore to it rather than the minimum 15ml pipe that it needs - consequence is that it is pretty useless since the water flow is inadequate). While all that work is ongoing and the system is drained, it will also be possible to check the PV fully and replace it if it is damaged.

Do you have a similar problem or are you just curious?

 

[jcorbin]

Thanks for asking.

I think it is about the same as it was before I did anything. This leads me to conclude that the PV membrane is probably ruptured (I did get a bit of water out when I "bled" it). I also got air into various rads when I recharged it and I would not have expected that.

Good evening DoctorNick this is as per the wiki FAQ ''Some air may have got into the system when you let the water out but most should go out through the Automatic Air Vent and a rad or two may collect some air too"

I am living with it at the moment. Pressure in the system is okay and never gets above about 1.5 bar (hot) starting at 1 bar (cold).

My pressure readings are the same but due to excessive noise hot reading has been reduced to 1.2. A corresponding decrease in noise being emitted from the general location of the diverter valve leads me to believe the valve it self maybe defective.Following several searches of this forum it seems it maybe a common problem and quoting from another forum " diverter and valves and pcb need to be changed together". ChisR from this forum states partial code /part number in a post .Maybe the ''banging diverter valves'' are all from same batch ?

Had the same problems with mine twice, with heating on sounded like someone whacking a pipe hard when hot tap opened.

Ist vaillant engineer replaced diverter valve (modified!). OK for a while.

1 year later it started again. 2nd vaillant engineer fitted a new bypass, once again a modified/improved one.

Seems to be a common fault with Vaillants

We plan on doing some fairly major work (or probably having some major work done would be a better way of putting it) over the summer -

Do you have a similar problem or are you just curious?

A google search " vaillant banging etc " lead me to this forum and this post. The problem is similar but also encompasses hot cold dhw

//www.diynot.com/forums/viewtopic.php?p=893911#893911

As an possible interim solution i have proposed adding x200 to the system until a suitable day can be arranged for another engineer callout.x800 was considered as an alternative with concerns about " particles" causing blockages without the addition of a spirovent or magna clean.I will take this opportunity to wish you good luck with your proposed summer home improvements and hope its a solution to your problem.

PS sorry for long and rambling post this my third attempt at a reply!!

PPS I am DIYER heating engineers please edit out any incorrect information in my reply

Thankyou gentleman