Noisy boiler and TRVs

[Catherine123]

Hello

I had a new boiler installed (EcoTec pro 28) several months ago and new trv's on all radiators and am having a few problems. I'd had an old Elan boiler for 20 years so just getting used to the differences. I've always had knocking pipes and am used to that but the following are new.

1. The boiler has started making a loud knocking noise about 5 mins after it comes on - only does it with heating, not hot water. It isn't a fast knocking - just a single knock every 5 seconds or so. At first I thought it was something heating up and contracting but am not so sure.

2. Two of the bedroom radiators have to be kept on max or they make quite a loud hissing noise as I turn them down. This hissing goes on for ages and wakes my daughter up so I have had to leave it on full in her room - the other I turn fully on or off as needed. The installers left me with the TRV instruction leaflets - they are bi-directional.

3. My daughter's bedroom radiator also makes a single loud click every time the boiler fires up and this sometimes wakes her up too.

I did have a problem with a weird vibrating noise in her radiator which stopped when I put pressure on the top right had corner. After a few times of doing this the vibration has stopped (hopefully for good). Also I have bled the radiators as a couple of them started getting cold in one top corner- they all seem ok at the moment.

Can anyone shed any light on this before I ring the installers (which I assume I will need to do). Just want to check whether these are "just learn to live with them" things or problems to be sorted.

Many thanks

 

[doitmyself]

I had ... new trv's on all radiators

One rad should have been left without a TRV; this is in the room with the wall thermostat.

1. The boiler has started making a loud knocking noise about 5 mins after it comes on - only does it with heating, not hot water. It isn't a fast knocking - just a single knock every 5 seconds or so. At first I thought it was something heating up and contracting but am not so sure.

The installer may not have adjusted the by-pass in the boiler

2. Two of the bedroom radiators have to be kept on max or they make quite a loud hissing noise as I turn them down.

Rads have not been balanced

3. My daughter's bedroom radiator also makes a single loud click every time the boiler fires up and this sometimes wakes her up too.

Rads not balanced.

I have bled the radiators as a couple of them started getting cold in one top corner- they all seem ok at the moment.

I hope you repressurized the system after bleeding the rads.

Hint: Bleeding should be done with the boiler turned off and, preferably, when the water is cold.

Can anyone shed any light on this before I ring the installers (which I assume I will need to do). Just want to check whether these are "just learn to live with them" things or problems to be sorted.

Definitely problems for the installer to sort out. If he says that you don't need to balance rads with TRVs, he doesn't know what he is talking about. The main cause for rads not working properly is incorrect balance.

 

[AWheating]

all of the above.

 

[GrahamM]

And just to add to doitmyself's.
TRV's wither they state they are Bi-directional or not never work the way they should in my opinion and should always be on the flow side of the radiator(side that heats up first), regardless if they say they can be on return side or not.
I have encountered bi-directional valves on the return side giving issues with circulation.

Was your old system cleaned out thoroughly before fitting new boiler?

 

[Catherine123]

Thank you so much for your replies. I have now called the installer and he said he will come and have a look. He sounded a bit surprised about the boiler knocking so I did some googling - strangely I found 2 videos on YouTube where people had recorded their Vaillant boilers making the exact same noise as mine - and lots of comments to the tune of "mine does this and my installer can't get it to stop". They were saying that it turned out to where some nuts that weren't tight enough (or needed greasing) on an internal part causing expansion movement and noise when heating up. It all went straight over my head but I printed out the response in case my installer wants to check it out.

I feel very embarassed by one of the comments - about "repressurized the system after bleeding the rads". I knew that my radiators needed bleeding as they weren't getting hot at the top so found some advice on how to do it and went ahead. None of the many many guides mentioned repressurizing the system so, no, I didn't do that. I did however, know that the heating needed to be off and the water cold so I did do that bit. The pressure guage on the boiler has dropped my a miniscule amount but seems to still be in the correct range. Is this what you meant Doitmyself? Did I do it right?

Again, thanks for taking the time to reply to my questions. I now feel more confident about asking my installer questions.

 

[doitmyself]

The pressure gauge on the boiler has dropped by a miniscule amount but seems to still be in the correct range. Is this what you meant Doitmyself? Did I do it right?

You did OK.

If there is a lot of air in the system the pressure will drop a long way when the rads are bled, so you would have to bring the pressure up within range by admitting more water to the system. There obviously wasn't much air in yours, so the pressure only dropped a little and was still within range.

 

[Catherine123]

Oh dear, not having too much joy!

Asked installer to look at the radiators. He removed the lockshield valve cover of the radiator making the most noise, looked at it and said that as the valve was fully open, he couldn't see why all the problems were occuring and that I would have to learn to live with it!!!!! I was so stunned I didn't think to ask why it was only that radiator making the noises etc or to mention balancing...

So, looks like I am left with the option of trying to balance the radiators myself or getting someone else in to have a look at it. I'm not happy but he clearly didn't think there was a problem - he was out of the door like a shot.

What do you guys think I should do next....is this something I can sort out myself?

Many thanks

 

[Catherine123]

p.s. the boiler is now sorted so that's good.

 

[doitmyself]

p.s. the boiler is now sorted so that's good.

How was it sorted?

 

[DirksPlumbing]

TRV's wither they state they are Bi-directional or not never work the way they should in my opinion and should always be on the flow side of the radiator(side that heats up first), regardless if they say they can be on return side or not.
I have encountered bi-directional valves on the return side giving issues with circulation.

Generally spoken you are right. But you should have a second look at the Danfoss revolver ones as you turn the valve in the desired position they work greatly both ways. This is perfect if you are doing replacements as you never know what the installer before you did and why.

Sure you can find out but sometimes to correct that would mean simply to repipe the system, possibly rip up the fairly new hardwood flooring or tiled floor.

I am sure you would prefer to be able to just put the valve in it's old position and just turn the insert in the right way and know that it is working perfect from now on.

And you can have the TRV on the flow and still be the wrong way fitted (horizontal/vertical).