PETIT_PABLO, CORGI MAN, CHRISR, NICKSO, GAS4YOU, NAMSAG,etc.

[macgee]

Hi, put my original question on last night. One of you guys must know the answer. Thanks.

Have had problems in the past with the glowworm 30cxi combi. when hot water is running (so burner is at full rate) a howling starts from the boiler after about 30 seconds. After checking everything from gas valve to combustion ratios, came to the conclusion that the heat exchanger was blocked. Question is, which one? is it the DHW HE or the main one. only reason I say that is because glowworm thought it was the main one and I thought it was the DHW one. Come on local boys, help me out.

 

[Terrywookfit]

There is one simple way to find out!!

 

[macgee]

Which is?

 

[Terrywookfit]

Flush them both !!

 

[macgee]

Good point, but that isn't actually finding out. Dont want to remove and flush HE when not necessary, and flushing in situ has proved not to work for me in the past. Thanks

 

[corgiman]

IHMO they will both need it cos they are connected. If one has muck init so does the other

But I dont reckon on flushing HEX as I have often said, I prefer flushing the system and replacing them

But thats just me

 

[ChrisR]

Secondary heat exchangers howl? Can't see hoooooowwwwww they could do that.
Combustion howl, yes, primary hex, just maybe. DOes it stop instantly if you turn the gas off or carry on slightly.

 

[gas4you]

Does it do it continuously whilst running HW, or does it decrease as the burner modulates down?

 

[bengasman]

Secondary heat exchangers howl? Can't see hoooooowwwwww they could do that.
Combustion howl, yes, primary hex, just maybe. DOes it stop instantly if you turn the gas off or carry on slightly.

I said exactly the same thing, but plate hex do on some vaillants (ecomax for sure), when dhw is set very high and they have some blockage.

before you ask, yes absolutely sure, new hex and noise gone. and yes, you are right, it makes no sense.

 

[bengasman]

Op, I don’t know your boiler myself, but if it is one with alloy primary, you can not use fx2 probably.

If the plate hex is a normal one, it can be taken out and cleaned with fx2, or replace it. lot easier and cheaper than the primary, so that is where I would start in your place.

If you give us a bit more detail about your previous flush experience, we may know a couple of tricks that you missed.

 

[ollski]

Why not just quickly take of dhw hx and check it...out and back in 20 mins. Would have thought a blockage in the main would also sound if you set the pot to max on ch

 

[petit_pablo]

The glowworms main heat exchangers do make a lot of noise if they have muck in them.
One we had a contractor install wasnt flushed properly and the main heat ex blocked in 2 months, glowworm replaced it on warrantee though.

As stated already if one heat ex is mucky, the other will be to!

 

[macgee]

Just logged back in. Thanks for all your replies. To give you a bit more information, sometimes on hot water you get no howling although boiler seems to cycle on and off, which may be due to momentary overheating due to blockage. Also when boiler does howl, it continues until tap is turned off so no difference on modulation. Good point about setting CH pot to max to see if same happens though.

On a different point does anyone know if noise reducing agents such as sentinal X200 are worth trying or is this a waste of time. Thanks.

 

[petit_pablo]

On a different point does anyone know if noise reducing agents such as sentinal X200 are worth trying or is this a waste of time. Thanks.

They noise reducers do work in my experience but its covering up the problem really