Advice - customer, not plumber

[MarvelousJoker]

Hi guys,

New here but just wanted to crowd source some thoughts on my current home heating issues.

We completely renovated 18 months ago and put in a new boiler and megaflow system - the system was power flushed when it was installed. The way the house is plumbed, it's a hot water priority system so our programmer always runs the water an hour before the heating comes on.

We've obviously been using the hot water all summer and a few weeks back, put the heating on for an hour one evening and we had kettling from the boiler which dissapearred when I turned the boiler off and then back on.

We have a plumber (who installed the system) and he has been back several times now - to change the valves that go into the megaflow tank and to chemical clean the system.

We are still experiencing intermittent kettling from the boiler, which again can be stopped by turning the boiler off and then immediately back on. A useful short term fix, but far from ideal.

Current plumber wants to clean the heat exchanger now - do you think that is a viable solution to the issue?

Just to be absolutely clear - I have no intention on doing the work myself, only via a qualified plumber!

Thanks in advance

 

[ShaunCorbs]

Any chance of a few pics of the system?

 

[MarvelousJoker]

Sure - boiler & MF tank enough? Theres a cupboard where the filler loop sits too.

 

[gmartine]

Heavy scaling seems unlikely in such a period if it had been correctly dosed with inhibitor, perhaps run some cleaner in it for a while (mc3+ or X200?) that might break down some persistent crud/scale that has shifted through the system to the boiler.

Edit...Ah, I see he's already done that.

 

[ShaunCorbs]

Sure - boiler & MF tank enough? Theres a cupboard where the filler loop sits too.

Yep

 

[Best]

I am not a gas guy, but just wondering would the boiler condense trap be silted up and causing a kettling noise?
Or perhaps that would remain fairly constant?

 

[gmartine]

Can do, any type of flow restriction can cause water overheat in the Hex, doesn't have to be limescale.

 

[Chalked]

I am not a gas guy, but just wondering would the boiler condense trap be silted up and causing a kettling noise?
Or perhaps that would remain fairly constant?

Hi Best
Kettleling is normally caused by trapped air in the heat exchanger expanding. Common cause is scaled, or sludged up waterways.

 

[chris watkins]

Why would turning boiler off & back on stop the so called kettleing?
It sounds more like a flow rate problem, what is the system doing when it starts i.e. is the cylinder up to temp? What position is the diverter valve in? is a bypass required to maintain the boilers minimum flow rate?