Noisy central heating system

[TomLane]

Hi All,

First time posting on here so please be gentle with me!

Just wanted a second opinion on a recent call-out I've been to.

Tenant complaining that central heating system is very noisy when it first starts up in the morning. To the point where they can't bear the noise.

My first thoughts are that the system requires a good chemical clean as far as I am aware it has not been cleaned for 10+ years.

The pump is running fine, all radiators have been bled, boiler a little noisy. The loudest noise is from the radiators. The noise is almost as though the flow is restricted due to build up of sludge & limescale. Hence, my thoughts to chemically clean the system.

Does anyone else have any ideas as to what could be going on here?! As I say, I'm pretty certain the problem is restricted flow, but a second opinion is always handy.

Thanks in anticipation

Tom

 

[diamondgas]

What system design and boiler Tom? :welcome: by-the-way

 

[hammers4spanner]

How do you know the pump is running fine?

 

[lbrad02]

ad try and see if any of the trvs have slightly stuck

 

[lbrad02]

when it heats right up does it go or is it all the time ? what kind of noise

 

[Mike Jackson]

Have you checked the lockshield valves? Could be just a case of tweaking them all open a bit.

 

[TomLane]

Thank you all for your quick responses! Much appreciated.

diamondgas It's a conventional heating system (f/e tank, c/w/s tank, halstead boiler, h/w cylinder)

hammers4spanner Have purged what little air there was in the pump when it was running & adjusted the speeds to ensure this part at least was working. (Are there any other indications that it's not working correctly?)

lbrad02 There are no TRV's on any of the radiators (13 at present). Although I do intend to install some when I have drained down to make the system more efficient.

lbrad02 The noise is similar to a restriction of flow or even high velocity flow through the 10mm pipes.

Mike Jackson Haven't adjusted lockshields yet, but would certainly do so once the TRV's had been installed.

Any further thoughts?

 

[TomLane]

Thanks for all your replies everyone. I thought I had posted a reply to the questions that I had been asked but it didn't seem to post for whatever reason.

The system is a Halstead boiler (in kitchen) & hot water cylinder (in airing cupboard on landing)

Purged the pump for any air that may have been in the system, although bled radiators of any air. (None in both)

There are no TRV's on any rads, but I do intend to install them when I chemically clean the system.

The noise is a sort of restricted flow noise, louder than normal but only audible from within a few feet of the rads.

Haven't adjusted the lockshields as yet, would so though when system is balanced etc.

Thanks again for your help.

Any further thoughts?

 

[M.Joshi]

Is the system vented or un-vented?

If un-vented, have they been topping up the pressure over the years without adding inhibitor? This may have caused the build-up of magnetite.

If vented, what does the water look like in the F&E tank?

May be worth running some chemical cleaner through the system for a week or so before draining out. Then proceed with a PowerFlush after that if necessary.

If you do add chemical cleaner, probably best to drain the system first. Try to inspect the water for debris etc.

 

[TomLane]

It's a vented system. The F&E tank wasn't overly dirty, I've certainly seen worse.

My thoughts were to run the cleaner for a week to give it as much chance as possible to clean through.

My only problem is it is in a rented property & the landlord is a little reluctant to spend any money. Although I have explained to him that if he doesn't have this done then it could lead to further problems.

Tom

 

[M.Joshi]

If the landlord is reluctant to spend money, explain to him that adding the cleaner, draining a week or so later and subsequently adding inhibitor is the cheapest (possible) solution. Otherwise it could lead to other major failures in the boiler/pump/valves which will cost more to repair.

I have spoken to Sentinel and Fernox as well as Worcester-Bosch and Vaillant and it is safe to leave X800 or F5 circulating for a week or so in their boilers. Both are strong PowerFlushing/cleaning chemicals. So long as you flush the system out a few times to ensure the chemical is no longer in the system. Best to check with Halstead which product they recommend first.

 

[PlumbBobBob]

i think i remember that some chaps on here have had problems with x800 clogging pumps

 

[diamondgas]

Any further thoughts?

If it's system flow noise you could try fitting an Auto Bi-pass. Set up right it should regulate the flow through the system Tom