New combi boiler, rads, TRV's on 10mm microbore pipework....noisy rads and loud tapping in ceiling?

[actiongirl5]

Hi Folks,

I am posting in this forum as my Worcester Bosch certified engineer of 40 years has no clue about this and we are at the stage nearly a year on where we are just stabbing in the dark. He says he has never come across this before albeit he his work has spanned new and older home and honestly as the noise is becoming very disruptive and I do not really know where to go with this.

So it is a 1990's bungalow with all of the 10mm microbore pipe work running through the loft and in each room a pipe is dropped for each rad with two auto air vents in the loft. Originally there was a hot water cylinder in a cupboard and a hot water boiler in the garage. The hot water side is fine, no issues.

So now we have this shiny new Worcester Bosch combi in the garage and the single rads have been changed to double panelled but single convector rads in each room with bi-directional TRV's. The heat output is great but the noise is well ridiculous and I am not talking about the standard creaking or movement noises but loud tapping, crackling in the ceilings (no pests) and thumping, loud hissing in some of the radiators. I even hear trickling water (not leaks) both during when the heating is on and off. Worcester Bosch say its nothing to with the boiler.

When you power on the heating you get at least one good month of as you would expect and then the fun and games start, all rads are blazing hot and when we tried bleeding the rads only water was present, so even more weird. All TRV's have been changed by the gas engineer to a totally different brand but still the problems persists. When the rads start thumping it comes from the TRV going like the clappers from what I can tell.

Any thoughts or what on earth is going on, if a gas engineer doesn't know what are homeowners meant to do when they are woken at 6am on a Saturday morning to tapping above your head and crackling like something is about to drop through the ceiling??? That is when the heating hasn't even powered up.

Mandy

 

[88v8]

Microbore is a crap hangover from the 70s... noise in the rads is often excessive pump pressure due to the small pipework.
Try turning the pump speed down.

 

[actiongirl5]

I will agree 110% on that one, it is money savings tactics gone very wrong but thankfully not quite as bad as the polypipe they use these days in new builds. The pump pressure isn't something I can change myself on the WB 4000 combi boiler, unless you know otherwise. The only thing I can change from the control panel on the front of the boiler is the water temperature of the central heating. WB really do not want you messing with their boilers, but it is a real shame even their regional manager for the engineers doesn't have a bloody clue about their gear either. 3/4 engineers later plus the installer and they all have no clue. They keep pointing at the TRV, but two different version of TRV cannot all be broken.

 

[88v8]

I am posting in this forum as my Worcester Bosch certified engineer of 40 years has no clue about this and we are at the stage nearly a year on where we are just stabbing in the dark. He says he has never come across this before albeit he his work has spanned new and older home and honestly as the noise is becoming very disruptive and I do not really know where to go with this.

So it is a 1990's bungalow with all of the 10mm microbore pipe work running through the loft and in each room a pipe is dropped for each rad with two auto air vents in the loft.

Hmm, I would never have installed a modern overcomplex boiler, but you are where you are.

The really baffling part is that it works OK for a month. That suggests a gradual build-up of... blockage?... air?

Is there a header tank in the loft? Or is it a pressure system? If there's a tank, there should be a vent pipe that ends over the tank. Go up in the attic when it's thumping and see if there's water coming out of the vent pipe... should not be... careful it will be hot.

If no go, then change the air vents for a different brand and try to site them higher.

Next step, which is relatively simple as it's in the loft, is to remove all the microbore piping.
Run a loop of 28/22/15 - the 28 may or may not be needed depending on the total heat load.
The radiators will all have to be rebushed to 15mm.

That will eliminate the potential for overpressure and water hammer.

Next step if there is still a problem would be to remove the TRVs and control the heat with one roomstat in... the hall? If the rads are correctly sized that would work OK.

You're thinking... I shouldn't have to do any of that... but you are where you are.
Anyway, keep us posted. Good hunting.

 

[dilalio]

Well, if 3-5 engineers can't fathom it when there, we don't have much chance at distance.

Some first thoughts are trapped pipework being shunted by pump pressure and TRVs getting satisfied and closing down.

Try turning boiler flow temp down... If your rads get blazing hot, then maybe they don't need to be, in order to heat rooms to target temps, try 55°.

How many rads do you have?
An additional, external expansion vessel might also help or even be required! Does boiler pressure go very high when system fully up to temp?

Just a couple of remote ideas.

 

[gas112]

A combi will initially be banging a lot more heat into your system than your old conventional system so the pipes will be expanding a lot quicker so will show up tight spots that your old boiler wouldnt . As for hissing in rad valve although they are bi directional are they on the flow and not the return as this can make a difference

 

[actiongirl5]

Hi,

Personally I wouldn't say a basic combi boiler is overly complicated especially in the grand scheme of some sets up these days. There was some some form of boiler there already for the hot water and it is installed in a small 2 bed bungalow with only 7 rads. The older system was inefficient and costing us a hell of a lot of run, but also the tanks in the loft had several leaks, both the tanks themselves and the some of the pipework coming from those tanks. I find it was almost the less of the two evils especially when cost and practicality is involved. We aren't all experts and we generally rely on an experienced gas engineer to say what is the best option.

The current set up is a combi boiler and 7 rads...yep basic. Nothing to get excited about at all.

I generally hate mircobore but I didn't realise it would create so much of a nuisance in this system. In an ideal world I would love to rip it all out but if there are a few options to try first I would rather try those as why create more work for yourself if you don't have to...right? More so when you are living in the house and you really don't want to have to surface run 15mm copper as the walls are so thin you cannot chase them in.

Thanks for commenting.

 

[actiongirl5]

Hi,

You thoughts are very similar to mine, so I will be adjusting the flow temperature today as I know it is on 70c at the moment and the rads when they come on they are almost instant and you cannot touch them at all even when the are set to 4 on the TRV's.....boil an egg status on these rads. Also a previous comment by another user mentioned the pump speed and I think that also something worth trying but It isn't something I can tweak from the control panel so that might be an engineer job.

We have 7 rads on the system and mini expansion vessel because we are on a water meter, we also have two auto air vents in the loft from the old system.

Thanks for commenting.

 

[dilalio]

Maybe quote who's post you are replying to!

Then we know what you're on about.

Who said a combi was complex?

Not me!

They're far from it!

 

[actiongirl5]

Hmm, I would never have installed a modern overcomplex boiler, but you are where you are.

The really baffling part is that it works OK for a month. That suggests a gradual build-up of... blockage?... air?

Is there a header tank in the loft? Or is it a pressure system? If there's a tank, there should be a vent pipe that ends over the tank. Go up in the attic when it's thumping and see if there's water coming out of the vent pipe... should not be... careful it will be hot.

If no go, then change the air vents for a different brand and try to site them higher.

Next step, which is relatively simple as it's in the loft, is to remove all the microbore piping.
Run a loop of 28/22/15 - the 28 may or may not be needed depending on the total heat load.
The radiators will all have to be rebushed to 15mm.

That will eliminate the potential for overpressure and water hammer.

Next step if there is still a problem would be to remove the TRVs and control the heat with one roomstat in... the hall? If the rads are correctly sized that would work OK.

You're thinking... I shouldn't have to do any of that... but you are where you are.
Anyway, keep us posted. Good hunting.

Hi,

Personally I wouldn't say a basic combi boiler is overly complicated especially in the grand scheme of some sets up these days. There was some some form of boiler there already for the hot water and it is installed in a small 2 bed bungalow with only 7 rads. The older system was inefficient and costing us a hell of a lot of run, but also the tanks in the loft had several leaks, both the tanks themselves and the some of the pipework coming from those tanks. I find it was almost the less of the two evils especially when cost and practicality is involved. We aren't all experts and we generally rely on an experienced gas engineer to say what is the best option.

The current set up is a combi boiler and 7 rads...yep basic. Nothing to get excited about at all.

I generally hate mircobore but I didn't realise it would create so much of a nuisance in this system. In an ideal world I would love to rip it all out but if there are a few options to try first I would rather try those as why create more work for yourself if you don't have to...right? More so when you are living in the house and you really don't want to have to surface run 15mm copper as the walls are so thin you cannot chase them in.

Thanks for commenting.

 

[actiongirl5]

Well, if 3-5 engineers can't fathom it when there, we don't have much chance at distance.

Some first thoughts are trapped pipework being shunted by pump pressure and TRVs getting satisfied and closing down.

Try turning boiler flow temp down... If your rads get blazing hot, then maybe they don't need to be, in order to heat rooms to target temps, try 55°.

How many rads do you have?
An additional, external expansion vessel might also help or even be required! Does boiler pressure go very high when system fully up to temp?

Just a couple of remote ideas.

Hi,

You thoughts are very similar to mine, so I will be adjusting the flow temperature today as I know it is on 70c at the moment and the rads when they come on they are almost instant and you cannot touch them at all even when the are set to 4 on the TRV's.....boil an egg status on these rads. Also a previous comment by another user mentioned the pump speed and I think that also something worth trying but It isn't something I can tweak from the control panel so that might be an engineer job.

We have 7 rads on the system and mini expansion vessel because we are on a water meter, we also have two auto air vents in the loft from the old system.

Thanks for commenting.

 

[actiongirl5]

Well, if 3-5 engineers can't fathom it when there, we don't have much chance at distance.

Some first thoughts are trapped pipework being shunted by pump pressure and TRVs getting satisfied and closing down.

Try turning boiler flow temp down... If your rads get blazing hot, then maybe they don't need to be, in order to heat rooms to target temps, try 55°.

How many rads do you have?
An additional, external expansion vessel might also help or even be required! Does boiler pressure go very high when system fully up to temp?

Just a couple of remote ideas.

We had 3 WB engineers out, one of which was a lead engineer who told me they come out to jobs like this when customer refuse to believe there is nothing wrong with their system so they send an engineer in a white shirt. He then left several items of testing equipment in my garage and went home. Then they sent out a regional guy who said its definitely the TRV's they all need changing as they are all faulty, he spent more time talking my ears off about him building his extension and how he didn't rate the new WB boilers, which fills you with great confidence in the product. Then you have our WB registered installer, about 30 yers time served has got to the stage where he does the bare minimum as he can pick and choose his jobs, doesn't like to return to jobs and has no in put at all and has never seen what is occurring in my home in all his years??? His answer is call WB.

So you can understand why I asking for any help and advice on here because when you cannot rely on the pro's to figure this stuff then you do wonder what you pay these people to do. Some time the best advice I get on here, these days all jobs seems to be based solely on time and money......whatever happened to doing a proper job?? Very few trades also take pride in their work and because there is plenty of work about many don't care if they retain you are a customer.

 

[BlueLoo]

Utterly understandable.

Try this.

Get a copy of the cbre domestic heating guide. Freely available on the internet if you do a bit of poking. Perhaps someone can share it here via pm...

Read it.

Or at least, read the bits relevant to you.

Get a pad and pencil and then selecting the same diagrams that match your system, go round your completely and draw it out.

Utterly baffling to me as an engineer that fault finding doesn't start with knowing the knowns first.

What have i got?

As you do this, you might notice a few things

Hmm, is that leaking?
Is that stuck?
Is that stiff?
Why is my fe tank growing a tree out of it?, etc, etc.

Like, when i service my car, i clean it inside and out 1st. I learnt so much about things i would not have seen.

Then, you can look at the schematic and start properly problem solving.

Is it right?
Is it best practice?
Are the calcs correct?
Are the flow rates ok?
Does it have more or less than it should?
Are my pipes lying directly against hard surfaces without being clipped and insulated properly?

Etc etc.

Show the schematic here. You might get a surprise.

Best of luck

 

[Harry Bloomfield]

Turn the boiler flow temperature down.

 

[dilalio]

We had 3 WB engineers out, one of which was a lead engineer who told me they come out to jobs like this when customer refuse to believe there is nothing wrong with their system

WB engineers are there for the WB boiler, not the system. I'm surprised they would even touch the system once they've deduced that the boiler is performing as it should.

Maybe they didn't! But just commented on it instead!

What you really need is a decent independent heating engineer and plumber who can look at the whole system.