Glen Farrow boiler smokey

[Celtictimber]

Here's a few pictures of the boiler burning different stages this morning. Took your advise and burnt small off cuts and kept them below the secondary air valves heaped it up in the middle. Better but still a bit smokey. What's your thoughts?

[Celtictimber]

Then I loaded it up again after lunch and had serious smoke for the first 45 mins as you can see from the first photo, temperatures was at 70 on reload. Second photo taken about 90 mins after - still smoking quite a bit

[cornish wood burner]

That looks bad. If your boiler frame is too cold then you will get condensate and tar around the inside as you have. It looks to me that your boiler needs to run hotter with probably more secondary air.

Can you tell us your return water temperature?

[BARNSLEY BOB]

considering weather , dont look too bad.

 

oak IS the worst wood to burn.

 

should have laid that concrete with a fall on it.

 

your central air pipe going banana shaped.. rotate it,and it will flatten out again.

 

put some birch or sycamore in with the oak to get a better burn of the tannin's.

[openspaceman]

Then I loaded it up again after lunch and had serious smoke for the first 45 mins as you can see from the first photo, temperatures was at 70 on reload. Second photo taken about 90 mins after - still smoking quite a bit [ATTACH]193196[/ATTACH][ATTACH]193197[/ATTACH]

 

That's bad, as you say the oak is dry then the white smoke is unburned pyrolysis offgas, the black is soot from a seriously air starved secondary burn. Looking at the combustion area it looks like the side walls are in direct contact with water?. What's happening is the cold sides are quenching flames before they burn out, also I guess excess air is further cooling the fire. You need some better mixing and a means of upping the firebox temperature, some fire bricks perhaps but this will decrease the heat exchange area, the fire tubes look a bit pathetic. Ideally the combustion should be able to complete before entering the fire tubes.

 

When you say 70 degrees does this refer to the water temperature? Ian has already mentioned back end protection, basically its a recirculation device controlled with a thermostatic valve, just like the thermostat in a car engine to keep it at the right temperature.

 

Have you a temperature gauge on the flue anywhere? The temperature at the bottom of the stack needs to be around 150C

[Duffryn]

Then I loaded it up again after lunch and had serious smoke for the first 45 mins as you can see from the first photo, temperatures was at 70 on reload. Second photo taken about 90 mins after - still smoking quite a bit [ATTACH]193196[/ATTACH][ATTACH]193197[/ATTACH]

 

Pics are a big help. Have you completed a really good clean out :-

 

1) Tubes at top of the boiler ?

2) Removed and cleaned air tubes at bottom of boiler ?

3) Removed the plate and cleaned the fan area at the rear of the boiler ? I suspect that there is some sort of blockage limiting the amount of air going into the primary and secondary air tubes, check that the plate on the lever at the back of the boiler that controls the volume of air has not become detached)

 

The tar build up could be compounding the ongoing smoke issues and needs to be removed before you stand a chance of getting a

clean burn. This can either be done manually by scraping it of ( wearing full mask and protection) or it burning off with a hot burn.

 

As Openspace has said the tar issue / smoke has been caused by a lack of temperature. Your next steps are a really good clean out, a hotter burn and ideally ( just to prove the point) a mixed fuel load ( not just oak). You will get a clean burn after 20 mins but the problem you will face is that you are going to need to reload the boiler every 45 minutes to achieve this and gain anything more than a 50% boiler efficiency.

 

Where about's are you based ?

Edited November 15, 2015 by Duffryn

[Duffryn]

That's bad, as you say the oak is dry then the white smoke is unburned pyrolysis offgas, the black is soot from a seriously air starved secondary burn. Looking at the combustion area it looks like the side walls are in direct contact with water?. What's happening is the cold sides are quenching flames before they burn out, also I guess excess air is further cooling the fire. You need some better mixing and a means of upping the firebox temperature, some fire bricks perhaps but this will decrease the heat exchange area, the fire tubes look a bit pathetic. Ideally the combustion should be able to complete before entering the fire tubes.

 

When you say 70 degrees does this refer to the water temperature? Ian has already mentioned back end protection, basically its a recirculation device controlled with a thermostatic valve, just like the thermostat in a car engine to keep it at the right temperature.

 

Have you a temperature gauge on the flue anywhere? The temperature at the bottom of the stack needs to be around 150C

 

The GF boiler is very limited in terms of control. The primary and secondary air are linked ( no separate control), the 70 degrees refers to the water temperature. The boiler control works off a water temperature setting. You set a target of say 80 degrees and the fan kicks in / cuts out when the temperature drops x degrees either side of the target temperature. This is all the control you have over the boiler ! Fine tuning can be accomplished by adding thermostatic controls as you have suggested but I think the first stage in helping Celtic solve the base problem albeit that will mean he needs to refuel every 45 mins.

[openspaceman]

The GF boiler is very limited in terms of control. The primary and secondary air are linked ( no separate control), the 70 degrees refers to the water temperature. The boiler control works off a water temperature setting. You set a target of say 80 degrees and the fan kicks in / cuts out when the temperature drops x degrees either side of the target temperature. This is all the control you have over the boiler ! Fine tuning can be accomplished by adding thermostatic controls as you have suggested but I think the first stage in helping Celtic solve the base problem albeit that will mean he needs to refuel every 45 mins.

 

Rather simple then, the main problem strikes me is the direct contact with water in the side walls.

 

Also a simple on off switch for the fans isn't sensible, can the thermostat be changed to a programmable one that has a couple of fan speeds?

 

My boiler has primary and secondary fans speeds linked which is daft as you really need more primary air as the wood gets wetter.

 

Does the air simply enter at the back and then exit up the fire tubes? I think I would experiment with reducing heat loss to the side walls even if the is reduces the boiler output.

[Celtictimber]

Pics are a big help. Have you completed a really good clean out :-

 

1) Tubes at top of the boiler ?

2) Removed and cleaned air tubes at bottom of boiler ?

3) Removed the plate and cleaned the fan area at the rear of the boiler ? I suspect that there is some sort of blockage limiting the amount of air going into the primary and secondary air tubes, check that the plate on the lever at the back of the boiler that controls the volume of air has not become detached)

 

The tar build up could be compounding the ongoing smoke issues and needs to be removed before you stand a chance of getting a

clean burn. This can either be done manually by scraping it of ( wearing full mask and protection) or it burning off with a hot burn.

 

As Openspace has said the tar issue / smoke has been caused by a lack of temperature. Your next steps are a really good clean out, a hotter burn and ideally ( just to prove the point) a mixed fuel load ( not just oak). You will get a clean burn after 20 mins but the problem you will face is that you are going to need to reload the boiler every 45 minutes to achieve this and gain anything more than a 50% boiler efficiency.

 

Where about's are you based ?

 

 

Thanks Duffryn

 

Your input on this is most appreciated and helpful.

 

I'm based in Haverfordwest Pembrokeshire

 

I'll follow your above steps on Monday now but just a few questions.

 

When you say hot burn - how can you get it to burn any hotter than when it hits the 80 degree water temperature and shuts off or am I missing something? On a hot burn would you load it as normal etc ?

 

Also would mixing it with larch or beech be any good or would I need a different type of wood.

 

Thanks Again

[Duffryn]

Thanks Duffryn

 

Your input on this is most appreciated and helpful.

 

I'm based in Haverfordwest Pembrokeshire

 

I'll follow your above steps on Monday now but just a few questions.

 

When you say hot burn - how can you get it to burn any hotter than when it hits the 80 degree water temperature and shuts off or am I missing something? On a hot burn would you load it as normal etc ?

 

Also would mixing it with larch or beech be any good or would I need a different type of wood.

 

Thanks Again

 

Sorry poor description on my part. By Hot burn I mean try and keep the boiler at 80-85 degrees for a good 3-4 hours. I.E don't let the demand take the boiler down below 80 degrees for more than a few minutes. What you need to avoid is the water temperature on the boiler going down to say 60 degrees and then slowly building up again ( this should never be allowed to happen in normal use). This should burn off all the excess tar. Its imperative that you check there is no obstruction to the air tubes and the rear fan. Also check the the flap on the rear blower has not become detached. With the boiler cold check the airflow through each of the vents in the tubes, there should be an equal airflow through each. Yes larch and beech will be fine. I've got a holiday home in Cosheston not far from you so could always call in next time i:m down there. I've PM'd you my phone number so give me a call later, we can cover much more ground in a 5 min call.