Size of chip for biomass boiler

[farmer rod]

The Eta feeder should be ok for 6m of chip stacked over according to the brochure, I dont think you need anything to hold the chips back, they do that themselves but go steady when loading to a\llow the arms to get tucked away

 

Do not walk over the pile, you can fall into the beehive (or so ive heard )

[Pierre_robbo]

Here's the pit woodchip fans

[farmer rod]

Will you have a ramp and tip trailers in? Nice job by the way

[Pierre_robbo]

. Although it doesn't seem like it the pit will be at ground level, see top left of the image. 61cu/m capacity hopefully means it should need filling twice per year.

[neilharrison]

Interesting looking install, and right choice of small commercial boiler if you're looking to burn arb-sourced chip (ETA have a single-chamber rotary valve with a chipper blade that can cut through oversize with the cross section of a chair leg).

 

Things to watch out for (just going off the photos)...

 

Recovery auger should be at a maximum of 15 degrees.

 

Fuel store walls and floor need to be 100% watertight - your panels should

have butyl rubber seals between them.

 

Make sure your installer fits the ETA access doorway above the pressure relief point where the auger leaves the store.

 

Make sure that the panel on the top of the sealed auger section can be removed to clear any chip blockages (that auger looks to be at the maximum of what's sensible/possible with the ETA HACK).

 

Not sure of the size of your store, but the spring arms on small chip boilers can be a bit gutless at their limit - consider asking your installer to go up 500mm on the arms (will cost you a couple of hundred quid). Fit hardwood strike plates where the auger teeth meet the walls to avoid taking chunks out of the concrete over time.

 

Be sure to board out the corners with something non-woody to ensure full recovery.

 

Finally, board out under the agitator to avoid issues with the initial load of chip turning to soil over a 2-3 year period and causing problems.

 

Neil

[farmer rod]

Interesting looking install, and right choice of small commercial boiler if you're looking to burn arb-sourced chip (ETA have a single-chamber rotary valve with a chipper blade that can cut through oversize with the cross section of a chair leg).

 

Things to watch out for (just going off the photos)...

 

Recovery auger should be at a maximum of 15 degrees.

 

Fuel store walls and floor need to be 100% watertight - your panels should

have butyl rubber seals between them.

 

Make sure your installer fits the ETA access doorway above the pressure relief point where the auger leaves the store.

 

Make sure that the panel on the top of the sealed auger section can be removed to clear any chip blockages (that auger looks to be at the maximum of what's sensible/possible with the ETA HACK).

 

Not sure of the size of your store, but the spring arms on small chip boilers can be a bit gutless at their limit - consider asking your installer to go up 500mm on the arms (will cost you a couple of hundred quid). Fit hardwood strike plates where the auger teeth meet the walls to avoid taking chunks out of the concrete over time.

 

Be sure to board out the corners with something non-woody to ensure full recovery.

 

Finally, board out under the agitator to avoid issues with the initial load of chip turning to soil over a 2-3 year period and causing problems.

 

Neil

 

Definitely agree about boarding the floor, but I was told the cheapest option for the corners was to fill it with woodchip.

 

Do your installers recommend any ventilation in the pit?

[openspaceman]

Interesting looking install, and right choice of small commercial boiler if you're looking to burn arb-sourced chip (ETA have a single-chamber rotary valve with a chipper blade that can cut through oversize with the cross section of a chair

 

I do like the look of that valve, mine has suffered badly from hitting " contraries"

[neilharrison]

It is certainly cheaper to allow the corners to fill with woodchip, but it will degrade over time and cause problems - someone, at some point, will have to climb in and shovel it all out. Far better to avoid this in the first instance by boarding out, after all, the RHI is very generous and you are making an investment in equipment that is intended to last for 20 years.

 

You can, under certain circumstances (particularly if using chip at the extremes of what's classified as G50), have an issue with something called "cohesive arching", which may result in the chip-filled corners forming the pillars for an arch which bridges the rotary agitator, and which requires manually breaking-down.

 

Absolutely you need ventilation for the fuel store.

 

Hope this helps.

[Pierre_robbo]

Neil

 

Thanks for your comments very valuable.

 

The auger was at 19 degrees, I've raised it to 16.5 but need to go a bit further yet.

 

Obviously with a flat floored pit what you suggest to mount the gearbox on? I was going to put some shuttering up to lay a concrete slab\box. Probably needs to be 3ft cubed. Would a steel box be better bolted to the pit floor?

 

For the arms, the boiler is on the north side of the pit. The east and west side of the pit have 35cm of clearance between the pit walls and the end of the agitator arms. The west panels has a clearance of 5cm and the north about 1m. As the boiler is a snugg fit I can't move the agitator gearbox only change the agitater arms. Is it correct that they are none adjustable?

 

As for the auger section running through the pit wall, this being changed for some reason, can't remember why, why is this auger housing section special?

 

Concrete panels are sealed and the whole pit had a double layer of visqueen laid in the hole before we dropped the panels it to keep the water out.

 

As for panelling the pit out. I'd like it panelling out but time and cash could be in short supply this year so I might leave it til next summer. I think I'd like to leave a good gap between the arms and the paneling as some suggest the arms need to be able to push oversized pieces down rather than. Catching on the arms on every rotation.

 

Thanks for your useful advice Neil, where are u based?

 

Other than this the install is going well, filling the pit twice per year is going to be a luxury compared with carrying wood into the house everyday (using about 12 cub, per year)

 

So I guess we are still looking for the dream chipper

Chip arb waste to g30

PTO driven 160

For less than £15k

Minimal oversized piece to block up biomass boilers.

Edited April 6, 2014 by Pierre_robbo

[neilharrison]

Hi Pierre

 

Sorry for the slow response - a much needed holiday (now a distant memory!).

 

A quick response to your points/questions (200+ emails to clear).

 

I'd go for a concrete box with appropriate reinforcement. You want it to last the 20 years of the RHI.

 

You should make sure that your agitator arms are sweeping to the full extent of the store on all sides, so worth boarding out (with something non-degradable, e.g. Marmax Stokboard) to ensure you don't get a rabbbit hole in the middle of the chip with a ring around the store that is never recovered (unless you get in there with a pry bar). This is a bit of a fanny on, but better to do it now while the store is empty than a year or so down the line!

 

The agitator arms come in 500mm steps up to 6m, but above 4.5m they are hinged. There is no means/need to adjust them once they're on there (only replace them).

 

Not sure why the through-wall auger section would need to be replaced. It should be the auger section which is connected to the agitator that goes through the wall - not the add-on sections, as if it's these, then it will be impossible to remove blockages from that section of auger. This is perhaps what's been identified as an issue by your installer, who to their credit are doing something about it rather than leaving you to discover this the hard way (this happens a lot!).

 

Sounds like you've got the concrete issue sorted - definitely recommend the panneling. Oversize pieces will find their way into the auger, which assuming they're not chair-legs, will be moved to the rotary valve and 'corrected'.

 

We're based up in Northumberland, but work with installers across the UK, and do a lot of consultancy around fuel supply, due diligence, fault finding, etc... in the wood heat industry.

 

Your dream chipper is probably a Junkkari or Farmi. Finnish-built and very popular with farmers and foresters over there for producing their own chip or chip for local heating schemes. G30 might be a tall order at that price, but a larger ETA is fine up to G50.

 

Make sure your chip is below 30% if you're storing it for 6+ months - you could get issues with fungal degradation, meaning the carbon content (& therefore useful heat) drops and spores become an issue.