Glow-worm 24hxi cycling and banging - help please!

[Catmandoo2]

Thanks mickyg.

The HW Cylinder currently reheats in around 4-minutes, and I often use that feature to top-up the bath (since one fill leaves it too shallow for a luxury soak

I follow your logic re tweaking down the rating of the boiler, but, it seems me that no matter how low I tweak it, it will still quickly heat up a small slug of water and cut out at max temp until it resets and tries again - as it does now. The only difference would be that the slug of water would be slightly larger as it would take longer to heat up with less power.

What seems to be wrong, from your explanation, is the initial firing of the boiler at 70%. On start-up it would be much better to begin at low power and slowly modulate as the water temperature increases. If I am right, I am surprised it does not work in that way.

With systems like mine, the demand will only ever approach maximum in very cold weather, when all the rad-stats are open on initial firing-up. At all other times the demand will be lower, and can be anything right down to a single small rad or even just DHW, and the boiler has to cope with that range of conditions doesn't it?

 

[Tibbot]

As you've mentioned finding large deposits of rusty sludge in your pump, it's likely that the same has settled in the boiler. These heat exchangers are less tolerant to dirty water than Evian's quality controller.

 

[Catmandoo2]

Indeed Tibbot, thanks.

That is why I am so concerned that my installation company don't seem to have addressed it, in merely power-flushing the boiler.

Is there a recommended cleaning procedure for these boilers?

Would a genuine de-scaling procedure also clear any rust deposits?

I believe my boiler Hex is of stainless steel. Can these be chemically cleaned/de-scaled without damaging them?

Any recommendations, anyone?

 

[Tibbot]

Personally, I don't believe they can be cleaned due to their design. The coil is not continuous but a series of batched coils. Water is more likely to pass through the clearest coil only. As they can't be dismantled the best option is fit a new part and Magnaclean. That's if yours is full of debris.

 

[Catmandoo2]

Thanks Tibbot.

I've had a good browse around the Internet and can't find any advice on cleaning these heat exchangers, or even on checking them for partial blockages. I have seen references to de-scaling (and we are in a hard-water area) but presumably some kit such as a power-flush unit would be needed for that - and Glow-worm don't seem to suggest it as a maintenance procedure either.

Having cleared the pump, my system now seems to be operating as designed, as far as I can tell - it has stopped cycling and banging anyway, whether on DHW only or on CH with any load from minimum to maximum.

My ongoing concern is how the pump got into that state; could I be running on borrowed time with the Hex slowly becoming blocked; and should I try and protect it in some way?

I've had a look at Magnaclean, which looks interesting but gets varied reports from users and installers.

My inclination is to just run the system as-is and check-out the pump again in 3-months or so.

Does this seem a reasonable approach?

 

[Catmandoo2]

Well my system seems to have settled down now so I plan to check the pump again in a couple of months.

Meanwhile I am trying to find out what, if any, chemicals have been left in my system following the power-flush.
I believe the installer uses Sentinel X400 and Sentinel X800 when power-flushing.

Checking on the Sentinel Website I see they recommend treating the system, after cleaning,
with Sentinel X100 Inhibitor and Sentinel X200 Noise Reducer.

Are these products recommended by members in here?

And are the Rapid-Dose versions the ones to go for?

Are the test kits worth investing in?

All advice gratefully received - I'm eager to get my system running smoothly and trouble-free before the heating season returns.

 

[Menaceman]

Hi - did you ever get to the bottom of the problem with your system? I've got the same boiler with what sounds pretty much like the same problem?

 

[Catmandoo2]

Hi - did you ever get to the bottom of the problem with your system? I've got the same boiler with what sounds pretty much like the same problem?

Hi Menaceman. My system seems to be operating as designed now, though we'll have to wait for winter conditns to really put it to the test.

The story is pretty well covered in this thread and my conclusion to date is that the problem was caused by the very low flow being produced by the almost solidly blocked pump. Having thoroughly cleaned the pump out full flow appears to have resumed and the system subsequently operated as normal.

I have since also completely cleaned out the F&E tank, which was also badly contaminated, and added some more Fernox Inhibitor. As stated above I am keeping a watchful eye on the system and intend to open up the pump to check it before the heating season starts again.

I hope this helps you sort your problems out too.

Do let us know, won't you?

More details can be found in the related thread:- //www.diynot.com/forums/plumbing/is-the-new-spirotech-mb3-the-answer.330345/

 

[Whitespirit66]

Possibly worth considering fitting a system filter to mop up any corrosion debris. Something like a Fernox TF1. Fit it on the return pipe just before boiler.

 

[Catmandoo2]

Possibly worth considering fitting a system filter to mop up any corrosion debris. Something like a Fernox TF1. Fit it on the return pipe just before boiler.

Thanks Whitespirit66.

That possibility was explored in the associated thread referred to in my last post above:-
//www.diynot.com/forums/plumbing/is-the-new-spirotech-mb3-the-answer.330345/

Worth a browse for anyone interested in opting for filters, perhaps?