Boiler Knocking - Myson Orion

Hi all, my first post but a long time user

I've read the sticky so here goes...

1) Boiler make / model (gas or oil)
Gas, Myson Orion (50 - i think)

2) What is / is not happening.
Boiler knocking when in use and the stat is turned up past '2'.

3) Has ANYTHING else been done or changed recently.
Called in a local plumber regarding a different issue but he mentioned using washing up liquid, tried that and it worked for a few weeks!

4) When did the problem start?
We moved in 12 months ago, its been doing it since about March but only when the stat is turned up past '2'.

5) When does it happen? eg, heating coming on or going off.
Within a few minutes of the boiler firing up.

6) Anything else you feel may be of relevance.
Oh yes...the previous owners were DIY fanatics so i don't trust all the joints to be able to resist the Fernox DS40 treatment. Pipework to rads is only 10mm but they all heat up fine. I flushed the system out 6 months ago using just water.

Oh, and the boiler sites in a brand new fitted kitchen so replacing it with something more modern is to really possible.

Would you recommend the Fernox Restorer as opposed to the DS40, I don't want to end up with leaky joints....

Thanks in advance

Si

With a boiler this old, I would be reluctant to clean it out with any worthwhile strongish chemical, let alone DS40.

Have you check simple things like the pump is circulating correctly and not old and tired? (sounds just like me )

gas4you said:

With a boiler this old, I would be reluctant to clean it out with any worthwhile strongish chemical, let alone DS40.

Have you check simple things like the pump is circulating correctly and not old and tired? (sounds just like me )

Click to expand...

Hi Dave, how about a power flush then? the boiler was installed when the house was new in the early 90's. Would it really be that bad using DS4....or are you just risk averse

It's not the pump, it is coming from the HE, shame they're obsolete now otherwise I would have considered replacing the HE.

Si

If the pump is worn and tired, the knocking would still come from the HE, the point where the water is heated, so lack of flow most affecting it.

I am fortunate that I am able to pick and choose what jobs I take on, being absolutely inundated with work at present (apart from getting over the current bad cold doing the rounds at present).

IF I was ever persuaded to take on the flushing of an old boiler/system like this, it would only be after the customer had signed an appropriate waiver/disclaimer incase the boiler or system leaked.

You would get a power flush included automatically with a new boiler, therefore saving you the possible cost of one now on your existing boiler.

gas4you said:

If the pump is worn and tired, the knocking would still come from the HE, the point where the water is heated, so lack of flow most affecting it.

I am fortunate that I am able to pick and choose what jobs I take on, being absolutely inundated with work at present (apart from getting over the current bad cold doing the rounds at present).

IF I was ever persuaded to take on the flushing of an old boiler/system like this, it would only be after the customer had signed an appropriate waiver/disclaimer incase the boiler or system leaked.

You would get a power flush included automatically with a new boiler, therefore saving you the possible cost of one now on your existing boiler.

Click to expand...

Thanks Dave, I will try adjusting the speed of the pump to see if that makes a difference. I have just had to replace the 3 way motorised valve as the last one had worn out so the Grundfos pump might be next. fingers crossed this will sort it.

Just found out my boiler is a 50B, I think it is one of the simplest boilers ever made.....not much to go wrong hopefully.

Well I have recently seen a 6 year old cast iron HE full of black sludge from a system that did not have inhibitor in.

After the loose sludge was removed, the knocking stopped, only to be replaced by kettling!

2 days of 5% hydrochloric acid descaling shifted most of the very hard magnetite but some remained!

DS40.. for wimps

Stick some x200 in it or fernox boiler silencer , dont just dump it in tank try and get it straight into a rad

Pump seems to be running fine, adjusted the speed down and back up, it responds and sounds like its running normally, all the rads heat up fairly quickly too so how else can I tell if it is low flow rate?

Si