MCZ Musa Hydro 15kw - thoughts

cancunia

People don't normally give away their personal details on these forums for good reason, I note that even Specflue did not give a person's name or contact number (yes, I know there's an 0800 number on your website). I called it last week and told whomever I spoke to about the growing concern on this forum and was not exactly overwhelmed with the info I was given about the actual problem the testing or the likely remedial work. If the problems were pureley due to lack of adherence to regulations, I cannot see why the stoves are still suspended by MCS, or why tests are - still ? - being made to fix things.

However, it's good to know that Specflue are finally taking note to the levels of concern being expressed here and will hopefully continue to keep us all informed of progress with the BRE testing and any retro-fit activities that need to take place, either directly on this forum or by posting a link here that can be followed. Point taken about the number of incidents vs the installed base, its a very low number but as a fix has been identified, there must be something about the stoves that can be improved?

Swampy - here's the link as promised, it points to a common failure of a relay on the pump controller daughter board if I recall correctly:

http://www.haustechnikdialog.de/Forum/t/158740/MCZ-Musa-Hydro-15KW-Pumpe-laeuft-staendig

You can put the URL into Google Translate, it's not 100% perfect but I think will give the info needed.

Robwiz

Kudos to Specflue for engaging in this thread.

It sounds pretty appalling that so many trained (and tested) installers have compromised so many installations in so many ways. If Hetas and MCS can't sort the competent from the cowboys what hope does the average consumer have in finding an installer who's prepared to do the job properly without taking short cuts?

This cavalier approach to installation seems to have compromised more MCZ installations than any other manufacturer's. That could be because MCZ is one of the cheapest so it attracts the corner-cutter, or maybe the value-engineering in the product design makes it less tolerant of poor installation practice.

Regardless, this is very damaging for the UK prospects of the biomass heating industry in general and MCZ's reputation in particular.

dotherightthingnow

Remember throughout these recent posts here that MCS has suspended the accreditation of MCZ , I know of no installer who has had accreditation suspended or removed through bad practice in installation of MCZ stove.

Remember too that the stoves that have exploded have done so because of a catastrophic, documented and provable fuel overfill. Not just a small amount but significant quantity which should not be able to happen but has.


I have no means or access to the figures quoted for installations and %'s etc. though have requested this info from MCS on "safety" grounds they have yet to supply it. Even if it were just one though that would clearly be one too many and it is significantly more than one rest assured of that.

Beko had 138,000 potentially faulty fridges out and about. 20 fires reported prior to tragic and avoidable fatality. 20 from 138,000 is a significantly lower % than the heralded 1/5th of one per cent which would be 276 in Bekos case not 20!! Neither would be figures to defend .The other 137,724 were not visited and discredited for poor installation or excessive use of fridge magnets on the door.

EveryMCZ stove installation I am personally aware of has either suffered this explosion and/or been removed and replaced.

[Deleted User]

dotherightthingnow wrote: »

EveryMCZ stove installation I am personally aware of has either suffered this explosion and/or been removed and replaced.

incorrect. I have a 15kw musa hydro and it is functioning perfectly. You need to qualify your statement and perhaps explain exactly which mcz stoves you have personally been aware of, apart from your own.

dotherightthingnow

Kittie , I am not "personally aware" of your installation so my statement stands correct.Equally, I am clearly not going to list names and details of those affected to this board.

Glad yours has proven reliable and fine as indeed was Burnardo's until it suffered an explosion like mine. I hope that long continues to be the case.

We must remember that the figures quoted for failure by Specflue are apparently a small 0.2% figure but in terms of historic failure rates and subsequent product recalls this figure alone is huge and totally indicative of a long overdue recall.

I have quoted the figures for Beko and another sobering thought on previous manufacturing defects,recalls and subsequent accountability is of Ford and Firestone tyres. Similar too that the finger of blame was pointed back and forth prior to the right thing being done.The "failure " rate there was one in 4,149. The 0.2% here would have represented 8 in 4,149 so by Specflues figures alone the situation is a sobering 8 times worse already.

Very few manufactured products with proven faults will suffer high % failure rates and this leads to the apathy and misguided belief that when faults initially become catalogued,reported and even proven it is somehow worth just soldiering on and trying to ignore the obvious in the hope that the storm will blow over and not worsen and huge compensation bill can be avoided for replacing all the apparently unaffected products.

It is quoted that the final bill to Ford was over 3 billion dollars after they finally recalled the product.Always remember that the vast majority of people will not be affected by or suffer as a result of a faulty product.In Ford and Firestones case 4,148 happy customers and just one affected. ONE TOO MANY.

Silent_Dancer

@dotherightthingnow your post has got things 100% correct regarding Specflue and MCZ's responsibility for product liability. The reported failure with combustion chamber overloading with pellets and the glass smashing due to explosive ignition could prove fatal to the occupants of the property either from fire or more likely carbon monoxide poisoning.

Even if this proves to be just to be a flue installation issue Specflue have a duty of care to write to all installers of their products and consumers with the stoves installed in their homes with advice on how to rectify the problem.

However, this sounds not only may it be linked to flue installation but their are two specific issues with the stoves. First is that the combustion chamber can over fill with pellets damping down the fire. In such circumstances carbon monoxide would be produced which good design should avoid. The second is the glass being broken by explosive ignition. The question to Specflue and MCZ is what are they doing to combat these issues?

In addition I would ask MCS what are they doing to establish the safety of other pellet stoves as most work on similar principles to MCZ ones.

dotherightthingnow

The information below was emailed to me by a company who are very informed about this product and alleged fault. I understand it comprises, in part at least, information solicited by and past on to MCS prior to accreditation suspension notice going out to MCZ on 13th October 2014. If indeed true it is highly enlightening and does nothing to dispel the need for an urgent full product recall rather than further finger pointing as seen in the Ford/Firestone case I have previously highlighted:-

These appliances have a different technology known as the Active System which is unique to these stoves (not used by other manufacturers). It relies on an electronic airflow sensor which is located within the air supply pipe. This airflow sensor directly adjusts the stoves fan rate which affects the combustion of fuel, the airflow through the stove and up the flue. In other words these stoves regulate and adjust the draught using the fan controlled by the airflow sensor. This is why they are desperately trying to get everyone to blame their flue and air supply as being the cause - that is the deception. That is why they are saying to fit a flue draught stabiliser. The possible irregular flue draught which is so unique and sensitive to these stoves, is actually caused by an unreliable component called the active system airflow sensor which regulates the fan rate.
.

When the airflow sensor turns faulty (which will happen with use) it will not be able to measure the airflow into the stove correctly. It then adjusts the fan rate which affects combustion and flame control. The fan rate increases and can accidentally extinguish the flame but the stove assumes it is still lit due to the high flue gas temperature. The water temperature (hydro stoves) drops so the stove pours pellet fuel into the burning chamber at maximum rate (in ratio to the abnormally increased fan rate). The pellets keep pouring in and then overflow into the hot ash pan below. The warming of this very large quantity of pellets gives off gases within a confined space. The flue exit has a manufacturer 3 inch diameter restriction and no flue installation can extract the volume of gases building up within the burning chamber.



Many times the stoves will overfill and fortunately the temperature drops sufficiently for it to switch off and display an alarm. The customer must notice this and empty out the pellets from the burn pot and ash pan before restart. This overfill of pellets is commonly known and photographed for 4 years. Some people have not noticed the error code or the fuel overfill and pressed the restart button. That leads to an explosion with one of the following outcomes...



Outcome 1: The overfill of pellet fuel can reignite due to a heat build-up or a restart ignition. This causes an explosive combustion of the fuel and gases forcing pressure and smoke out of glass seals, the air intake pipe, the flue, the hopper. There is an uncontrollable furnace of flames which remains behind the glass as fortunately there has not been enough fuel deposited to force the glass to explode - this is witnessed by numerous people who remain terrified by the event.



Outcome 2: The heat build-up or a restart ignition will ignite the pellets and there is an explosive combustion of the fuel and gasses. This time there is enough fuel within the burn chamber so the glass explodes across the room. This is a dangerous force of glass shards, fire and burning pellet fuel photographed to explode over 10 metres distance. Any adult or child standing in front of the glass would be seriously injured. The fire propelled into the room carries obvious serious risks. The stove will spew toxic black smoke into the property. This has been photographed, witnessed and reported since May 2012. At that time the manufacturer knew of previous explosions in the UK and in Europe – but then they changed their mind.



A year after the “first” explosions were reported the manufacturer discontinued the Active System using the airflow sensor located within the air intake pipe (discussed at their own technical training in mid 2013). No reason has been given, but we assume the sensor gets damaged by moisture or dust within the air intake. They reverted to the industry standard of a simple mechanical pressure switch. It does not seem possible to retro fix the active system versions - so a recall would be required. Any changes to your flue will not fix the overfill of fuel fault, therefore your stove will have no guarantee of safety – just ask anyone to sign to say that the stove will not overfill again and cannot therefore suffer from an explosion – they will refuse. The overfill of pellet fuel causes the danger of explosion - not the flue. The stove does not stop feeding in fuel until it has deposited a dangerous, large quantity. The airflow sensor was changed by MCZ or installers under instruction on every stove that exploded or suffered overfill of fuel problems. The manufacturer refused to explain the reason to change the airflow sensor.



These products entered the UK with certification from the MCS. They stated the products and manufacturer were to “standards fit for purpose”. They also stated that their standards would “protect the consumers”.

The overfill of fuel fault and the explosions were reported to MCS and BRE in May 2012. They visited the explosions after waiting for over 2 months then issued a report that did not bother to identify the cause of the overfill fault. They refused to suspend the products in May 2012 with many subsequent overfills and explosions. It has taken a further 2 years and many more avoidable installations to get MCS and BRE to reconsider the safety of these stoves. That is why there is now the long overdue suspension of the stoves and they issued the warning letter to customers and installers on 22nd Oct 2014. The letter did not inform customers or installers of the photographed overfill fault, or the already known symptom of the fuel overfill, or that this had been reported to and “investigated” by MCS and BRE in 2012. The MCS letters and subsequent actions/recommendations dictated by them, has caused customers and installers to remain negligently uninformed that even after any installation changes, the appliance will remain unsafe from the overfill of fuel which causes the actual danger and explosion.

Burnardo

Specflue, thank you for coming on this forum in an open and approachable way, I'm glad you are seeking to understand customers feelings about these machines, and hope that you take the points raised here seriously.
I apologise for the long post, but it is important to deal with each of the points raised independantly.

Your engineers report as to why my boiler exploded listed the following points (in italics), my answers to each are below:

No carbon monoxide alarm.
No flue data plate.
See my comments on these points in a previous post.

The draught stabiliser was installed outside on the flue run..... a flue stabiliser should be installed in the same area as the appliance.
As I understand it, one of the jobs of the flue stabiliser is to prevent a downdraft in the flue (or partial vaccuum due to the venturi effect) from affecting the appliance. A downdraft (with flue gasses) escapes out of the flue stabiliser, a vaccuum is filled, again through the flue stabiliser.
If the flue stabiliser is inside the building as you suggest, the flue gasses would be vented into the room, and a vaccuum will try to suck air from the (possibly well sealed) room.
My stabiliser was on the outside of the building, near the bottom of the flue in still air. So the downdraft is released to (and the vaccuum filled by) the atmosphere outside.
How is the system you propose better than that which I had?

When fitting a direct air kit the installation still requires an air vent into the room with 100cm squared free air.
So you're seriously saying I should have had a 100cm square hole through my insulated cavity wall to let the cold air in?
On the machine I had, the air for combustion came in through a short tube which ran between the back of the machine, through the cavity wall to the open air. The internal diameter of the tube was greater than that of the inlet tube of the appliance, and could not have restricted the air supply.

No fused spur fitted only plugged in to socket above appliance.
So that's going to make the boiler blow up is it?

No ESBE valve fitted
The machine had a thermostatic mixing valve fitted inside it. On start up, the water circulated inside the internal water jacket of the machine until it reached the required temperature (60 degreesC I think), only then did the valve open and circulate water through the thermal store.

No test point installed so unsure how the appliance could have been commissioned.
I understand the flue gas composition was tested on commision, on a still day through the flue stabiliser, the kit they had certainly looked comprehensive, and the machine showed an efficiency of 93%.

You say you were surprised to find the boiler removed when you arrived at our house.
Did you not consider that with it being December, and a child of two and a half in the house, a speedy resumption of central heating and hot water may have been a higher priority than your inspection?

None of the instalation points you raise should cause the boiler to explode, and yet it did.


You say 'a new safety feature to compensate for possible poor installation and maintenance will be added' .
Why have you waited till now? If there was something that could have prevented an explosion, why was it not fitted to begin with? Is this machine still in Beta testing?

You use my automotive analogy to explain why the machine might not work - If you were to restrict the exhaust so it did not work properly and then restrict the air flow in to the engine, and then kept adding fuel and a spark for ignition, expecting it to be ok, what would happen to the engine eventually?
Apart from the fact that the air inlet was not restricted (see above), and (though I am not overly educated in fluid flow dynamics) I could see from the cleanliness of the exhaust from the boiler and the inside of the flue that there were no restrictions there either, if you did restrict the inlet and exhaust of a car engine, it would flood the engine and stop, it would not blow up!


You mention you have been in touch with BRE. They have contacted me, and once they are back from their Christmas recess I will be giving them a full description of my reflections on your report.

I do however agree with your point that prospective purchasers of biomass boilers should perform plenty of due diligence before deciding which manufacturer to trust with their money and their safety. Though message boards are not the best place to garner such information, I think this message board represents the true feelings of those who have suffered life threatening results of fitting an MCZ boiler.
Caveat emptor.

captainhindsight_2

Burnado you boiler was clearly not installed to building regs or manufactures instructions this is why it malfunctioned.

The flue must have an inspection point above and below the draft stabiliser other wise it is impossible to set it up correctly and then commission the boiler in line with the manufactures instructions.

By your own admission you don't want to install an air brick that meets building regs, the installers fault. The intake you have used can only be used in passive houses.

Also no fuse spur, wouldn't cause a malfunction but again a breach of building regs.

The problem here is, too many installers are doing what the customer wants where with respect the customer doesn't understand the machines or building regs and this seems what has heppened in your case or the installer doesn't know what they are doing.

Spec flue have done well with this issue, these issues have been caused by bad installers before spec flue had exclusivity of MCZ in the UK.

This always comes back to getting a good installer, too many people try and do work like this on the cheap or become Internet experts and try and do it there selves.

Also if this is found to be a problem with the boilers which I doubt it will, the fault is with BRE, they should never have certified the boilers in the first place and thus would never have gone on sale.

cancunia

There's been a lot of speculation about the cause, and intended resolution to the problems experienced with the MCZ 22kw stoves. In order to prevent further speculation, perhaps Specflue or BRE could enlighten us on both points. It's entirely possible that poor flue design plays a part, but if that was all, there would be no testing going on to find a retro-fit solution.

A lot has been written about the need for draught stabilisers, but I cannot find anything that mandates their use on wood pellet stoves, MCZ or otherwise. I am not an approved installer, or heating engineer, so if I missed the document(s) where they are mandated please let us reading this thread know.

Building regulations section J, defines a draught stabilisier and notes : "to prevent excessive variations in the draught" but does not mandate their use so far as I can see.

www.planningportal.gov.uk/uploads/br/BR_PDF_ADJ_2010.pdf

On the MUSA installation manual cover, MCZ state that there's a supplementary installation guide for the UK:
" *Some installation advice given in this manual could contravenes UK building regulations guidelines. A supplementary instruction manual in provided to give correct advice for installations within the UK "

The only online source I could find is here, although the manual looks to be for 'Primula' stoves it is quite generic so I assume is intended to cover all:
http://www.nutechrenewables.com/wp-content/uploads/2013/01/Primula-Wood-Pellet-Boiler-Installation-Manual.pdf

The MCZ guide listed only talks about the use of draught stabilisers in certain circumstances: "If it is found that there is excessive draught in the chimney then a draught stabiliser should be fitted."