Biomass Boiler Ongoing Problem - Failed Pellet Lighting - Looking for opinions!

[BenBullen1980]

Hello everyone,

I came across this forum via google looking at another (similar) topic about a biomass boiler failing and hope someone might be able to help us too with their thoughts!
Our saga has been ongoing now for months and months and we don't seem to get any closer to a definitive answer!

As it's been going on for such a long time, I will try to give the background as concisely as possible:

- Grant Spira 6-26kW Condensing Wood Pellet Boiler
- Originally installed approximately 7yrs ago
- Original home was inside a block/timber shed outside (this is relevant later)
- Original pellet store was a separate timber shed in the garden (this is relevant later)
- Pellets used Balcas Brites (We have never changed pellets or suppliers)
- Regularly serviced etc.

For the first 4.5yrs of its life installed in the "shed" outside, we never had a problem with it. Worked flawlessly.

- 2.5yrs ago, we started to build an extension (which is now more or less complete).
- The first phase of the extension was to build a new purpose-built plant room. This is where the boiler now lives, along with a pellet store and all the other heating equipment (hot water cylinder etc).
- The plant room is fully insulated (cavity walls, insulated floor, insulated roof) permanently warm and dry.

That's the basic background out of the way. Now for the problem. It seems that ever since we moved the boiler and completed the extension (all bar some finishing touches) we've had problems with failed pellet lighting.
Initially, the igniter burnt out which I replaced (at huge £350+VAT from Grant which I've since found out can be purchased cheaper elsewhere! - but that's a different story)
But we're still having problems with constant fails.
The trouble is, it's variable. Sometimes the boiler will go 3-4days without a problem. Sometimes it'll take 4-5 resets to get it to fire and it'll happen morning and night.

Being from an engineering/science background, I'm having to think of what the variables are in order to try to determine what's causing the problem, but I'm struggling!
The variables I can think of have been gleaned from conversations with my heating engineer (Grant approved), Grant themselves, and forums such as this.

Variable 1 - The Pellets
I'm aware that bad firing can happen from damp or poor quality pellets etc. I have noticed that we are getting some sort of "coke" (hard black lumps) build up in the brazier. Is it from unburnt or potentially badly burnt pellets?!
Poor quality pellets? - As we've never changed the pellet brand (or supplier) I can't see this as being a cause of the problem.
Damp pellets? - We HAVE moved where the pellets are stored. But they used to live in a little wooden (uninsulated) shed in the garden. Now they live in a nice warm insulated plant room. So it stands to reason that the pellets are being stored in much better conditions than they used to be?!

Variable 2 - Boiler Software/Hardware Malfunction
Regardless of boiler make, I assume the basic setup is the same: Preload brazier > Igniter fires > Wait pellet firing > Lux sensor waits for flame to confirm lighting >burner fires...
In our situation, the igniter IS igniting (ignoring the one event where I had to replace the igniter), and when a flame finally forms, the lux sensor is sensing.
Our engineer is at his wits end and starting to talk about replacing sensors etc. Even the main PCB. But Grant say they've NEVER had a lux sensor fail... and it appears that ours is working - It turns the burner on when it senses a flame.
The problem seems to be the fact that on random occasions, the igniter is struggling to get the pellets to light.
Incidentally, the igniter is confirmed as being the right distance into it's hole which is quite critical according to Grant.
I personally don't think the boiler is malfunctioning in terms of software/hardware.

Variable 3 - Oxygen?
This one is a bit of a stab in the dark, but I wonder if the boiler isn't getting enough O2? The old boiler shed was weatherproof but still drafty.
The new plant room is obviously a much better construction. However, I did install an air vent right next to the boiler, and the entrance door is still not sealed so there's quite a large gap around it for air to get in.
Having said that, I have left the door wide open before and still got failed pellet lighting so think this one could be discounted?!

Variable 4 - Boiler heat load?!
This is one which, after reading various things on this forum, I'm now wondering if we've got a problem with the amount of heat load for the boiler.
We've built a pretty big extension to the house. It was originally 3bed. Now 4bed. We lost 3 small rads from the original and have gained 5 larger rads.
We were assured by the plumbers (who originally comissioned the boiler when we first had it installed) that the boiler was easily man enough to cope with the additional heating demand so never questioned it.

It's true that we're getting this build up of hard black "coke" type stuff in the brazier. The chimney is not tarring up though. We are also getting quite a lot of burnt dust/ash in the combustion chamber too which I don't remember having in the past.
Could this really be due to the boiler not burning the pellets hot enough due to the heat demand being too high and the boiler not being able to cope with it?
I'm struggling with this being the problem to be honest. The boiler isn't even heating our hot water at the moment as it's too unreliable (we're having to use the immersion on a timer for now) and most of our rads (both old and new) are set to low.

Unless anyone can think of other variables that I've missed, please say. Otherwise, if these above are acurate then we're back to a pellet issue?!
As I said, the igniter is igniting. The pellets just aren't lighting. That is to say, they are lighting but not quick enough for the lux to sense the flame in the time its given by the software. Sometimes the pellets will simply smoulder out completely. Which means they haven't finished a burn cycle and therefore the brazier is then left full of debris. When the reset happens and new pellets are fed in, the igniter is trying to ignite the ash/debris rather than fresh pellets. So the only solution then is to manually hoover out the brazier and reset with fresh again.
Incidentally, we have asked Grant if there is a software setting to allow the lux sensor more time to sense a burn - i.e. give the igniter more time to ignite. But there doesn't appear to be...

I'm just at a complete loss as to what to do/try next!
- Grant will come out, but as it's not in warranty anymore, they will charge £100/hr to come out. Bearing in mind each firing cycle is about 5-10mins, we're not going to get very far before spending a lot of money!
- My engineer just wants to change all the sensors etc something which I don't think will help in the slightest

HELP!

Thanks!

[Countrypaul]

I don't know anything about pellet boilers, but one variable that you do not mention and can cause big issues with wood burning stoves is the chimney design and position. Since you have moved the boiler what has changed with the chimney? It is a long shot, but looks like you've considered all the short ones already.

Another possibility not mentioned is could it be a faulty igniter - resulting in intermittant function, such as a dry joint inside it (I have no idea what the construction/design is) since this is a change compared to when it was functioning?

[chasfromnorfolk]

Hello, you’re not alone (welcome btw) in experiencing Grant Spira problems that baffle otherwise competent engineers.
I too recently got a daily dose of “ignition failed” or “pressure error” messages on my 6/26. In my case we first replaced the pressure switch (left hand end of the clear plastic tube that runs across the top of the burner unit) then the ignition fan (other end of said tube, takes a sample to the switch). Advised by Grant , my bloke said only option left was to replace the PCB. As you have mentioned, all Grant spares are eye-wateringly expensive, we’d spent money and this was a too-far step, even spending someone else’s money, so he came up with this: cut the power lead from the pressure switch, twist the two together in a permanent “on” position and see what happens.

What happens is the boiler runs faultlessly again. So far.

Run that past your bloke. If it doesn’t cure the problem you can always rejoin the wires.

Balcas Brites ok btw, though I’ve just been warned there’s a shortage and have to try some ‘Sparklets’ next week.

Cheers, Chas

[Artiglio]

Apologies if this is irrelevant. My mum has a trianco pellet boiler, in the early days we had similar problems with getting it to give a reliable ignition, it turned out to be the exhaust temperature probe, which was’nt registering the heat rise correctly   so the fan and pellet feed didn’t kick in as they should. Only took moving the probe further into the flue a little and problem solved.

This boiler also gets a bit of clinker build up, i chip it out every couple of months, apparently not an issue according to service engineer. For a boiler thats very much on the cheaper end of things and with a very agricultural build, its really not been too bad so long as it gets a good clean and check over every couple of months and its annual service.

In 5 years its needed less than £500 of spares , which included 3 heat guns that burnt out when we had ignition issues, but they are only bosche hot air guns  and cheap. Total pellets burnt to date about 38 tonnes.

[brackwell]

Can you not individually test some of your theories.  eg Can you not see the igniter and try and light some paper. Cause some heat burning paper etc to fool the exhaust probe. Put some pellets in the oven to make sure they are definetely dry and ultimately change supplier. Is clincker coming from low burning temp because you are turning it down.

[chasfromnorfolk]

 Respect to all above, just a better explanation of my suggestion:





1) pressure switch
2) cut and joined end
3) cut stub
4) fan

[Sprinter]

Hands up, i know nothing.

but i would never rule out a product being "not at fault" just because it has been good for some time I.E. The pellets.

Its possible that the pellets that have always been good, are now of a lower quality due to the company being unable to obtain the previous quality of pellets, or even making an active decision to sell lower quality pellets at the same price to maximize profits (or save the company if they are struggling financially).

I dont even know if it is possible to buy a couple of sacks of different pellets from another manufacturer  (they are probably just a re-seller rather than manufacturer) and load them manually to confirm if it is the pellets, you have almost certainly done this but if not its the cheapest and easiest option to test.

but i really do know nothing, other than not to trust previous good products as an indicator that future products will retain the same quality.

[ecogeorge]

Has this been resolved ? love to know the answer .......
George

[DennyB]

I realise the original post goes back some time but as I have the same problem now I would like to find out if a solution was found.

[Fintray]

Try clicking on the OP's name and send him an email.