Condensate issues with Firebird boiler

[Lalblacknumber]

We have a Firebird oil boiler, 35kw and have recently started getting issues regarding condensate or lack of it. Long story as short as possible.
Boiler running without any issues for 2 plus years, unusual smell from it turns out to be plastic condensate trap melted. Looked into problem and it's common with Firebird so ordered and fitted new metal trap. Flap on air inlet pipe possibly stuck open at the same time so boiler burning too hot? released and check air flap, now all free and working well. Removed burner door and checked all plates and baffles seemed ok, very little soot so cleaned and re-fitted.
Primed trap before running.
All ok but then started hearing noise from condensate pipe when boiler fired up. Gurgling noise as air/gas passes through fluid in trap? Condensate runs to an external lift pump to take fluid out of cellar where boiler is fitted. There is a slight a smell now from boiler, sometimes, and have seen steam from end of condensate hose as it runs to condensate pump. Boiler working perfectly and efficiently but am concerned about fumes.
What might be making the steam / fumes exit boiler through condensate trap and pipe?
Boiler has been running at 60 - 65 degrees and I would assume that that means the return temperature is low enough to condensate and replenish fluid in trap. Flue outlet shows no sigh of smoke just normal smelling clean exhaust.
Any help or ideas much appreciated.

We are in France, as our badge shows, so burner was set up by Firebird to run on 35 sec fuel. No issues with boiler before the last couple of weeks.

 

[SJB060685]

First off those original plastic condensate traps are rubbish, a very common problem which prompted them to rethink and then supply a stainless steel replacement.
Are you sure it's not condensing? Did you check the turbulators in the secondary HEX at the same time as baffles in primary? Both should be checked and cleaned during routine maintenance, when was it last serviced? A FGA will tell if flue gases are too high.
If it is condensing I would check to see if lift pump is operating properly, if its failed you obviously wont pump the condensate away.

 

[Brambles]

If you see or suspect that gasses are passing through the condensate trap and venting into the cellar - which they probably will as you are using a condensate pump - switch the boiler off immediately. It can also be a sign that your flue path is restricted / obstructed.

Any CO2 will fall onto the cellar floor and build up over time. CO will rise to the ceiling and possibly escape, but the CO2 can be there for a long time.

It, the build up of CO2 below ground level, is a serious problem during the installation of ground source heat pumps in the southern uk. Chalk and limestone mixes with acid rain in open trenches - CO2 builds up overnight - it can be a killer for the first person in the trench the following day.

Sorry to be alarmist.

 

[SJB060685]

Once again very informative Brambles, I think hes implying gases aren't escaping into room though, just not condensing? But yes I should of said to isolate immediately if they were.

 

[SimonG]

When was it last serviced by a competent engineer?
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Always thought condensing boilers cannot be run on 35 second oil. I know Worcestershire can't.

 

[Lalblacknumber]

Thanks for the alarm but I have put a CO2 alarm by boiler and had no warning from it so am happyish that it's not venting CO2 in any large amount. I will check flue to see if there is any obstruction.

 

[SJB060685]

When was it last serviced by a competent engineer?
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Always thought condensing boilers cannot be run on 35 second oil. I know Worcestershire can't.

Down to manufacturer isn't it? OP said Firebird themselves commissioned it so surely it is ok. Apart from higher pressures and couple other adjustments and differences its virtually the same

 

[Lalblacknumber]

First off those original plastic condensate traps are rubbish, a very common problem which prompted them to rethink and then supply a stainless steel replacement.
Are you sure it's not condensing? Did you check the turbulators in the secondary HEX at the same time as baffles in primary? Both should be checked and cleaned during routine maintenance, when was it last serviced? A FGA will tell if flue gases are too high.
If it is condensing I would check to see if lift pump is operating properly, if its failed you obviously wont pump the condensate away.

The tubulators were all fine just needed a wash, no build up of crap on them etc.
Lift pump is working as tested by pouring water in to it.
The boiler is on it's second winter, we are very remote in rural France and engineers are few and far between. Had a service booked in January but as winter arrived early here the engineer set off on all his priority work so it's not had a proper service and FGA since setup.
I have no worries about it's function just the reason for different smell from boiler and sound as if venting through condensate trap. I will take flue sections apart tomorrow and check for obstructions if that is a possible reason for air venting down from boiler rather than straight out of flue. Flue does appear to be fine from visual inspection outside.
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Down to manufacturer isn't it? OP said Firebird themselves commissioned it so surely it is ok. Apart from higher pressures and couple other adjustments and differences its virtually the same

Burner was set up by Firebird before sending out boiler originally, specified it was for 35 sec oil. All boilers in France run on red diesel.
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If anyone wants a free holiday in the mountains of the Cantal, let me know. We run a B&B (chambres d'hotes) so just pack up your tools and come over before the tunnel is filled in. It is very very difficult to find reliable engineers here.

 

[SJB060685]

35 second is not as common over here these days, years ago it was common, I do believe Aga and Rayburn even experimented with it on their vaporising burners at some point, although this quickly went out the window. It is used more often in commercial appliances than domestic but you still find the odd domestic boiler running it (usually farmers lol). The problems with 35 second is it waxes up easier than 28 second so fuel storage and supply can be affected much easier, the pressure jet burners usually have a pre heater installed to bring the fuel up to temperature before passing through the nozzle and it being thicker than 28 means it’s set at higher pressures on the pump as well. It also has the tendency to burn dirtier and soot up more frequent than 28, so really you should be having serviced every six months or so.
I haven’t seen your boiler but Firebird are a bit different to other oil manufacturers, some of their burners are mounted high up and the flue gases are forced through chamber, down through secondary HEX and then back up and out the flue. I’m assuming it’s a conventional flue that rises straight up? I would check what you can as any obstruction could well impede the flow of these gases and cause what you’re experiencing.

 

[Lalblacknumber]

35 second is not as common over here these days, years ago it was common, I do believe Aga and Rayburn even experimented with it on their vaporising burners at some point, although this quickly went out the window. It is used more often in commercial appliances than domestic but you still find the odd domestic boiler running it (usually farmers lol). The problems with 35 second is it waxes up easier than 28 second so fuel storage and supply can be affected much easier, the pressure jet burners usually have a pre heater installed to bring the fuel up to temperature before passing through the nozzle and it being thicker than 28 means it’s set at higher pressures on the pump as well. It also has the tendency to burn dirtier and soot up more frequent than 28, so really you should be having serviced every six months or so.
I haven’t seen your boiler but Firebird are a bit different to other oil manufacturers, some of their burners are mounted high up and the flue gases are forced through chamber, down through secondary HEX and then back up and out the flue. I’m assuming it’s a conventional flue that rises straight up? I would check what you can as any obstruction could well impede the flow of these gases and cause what you’re experiencing.

Thanks for the extra info. Yes the burner is high up with secondary HEX tubes at the bottom of boiler and flue is vertical for a metre then out through wall. Weird thing is that we only get an odour sometimes, not dependant on load of boiler or wind direction etc. It is defiantly condensating, although not as much as I would expect. I have checked flue which exits building and no sign of obstruction so will look again in bottom of boiler when a new door seal kit arrives from UK.
Still have an offer of a weekend in the mountains if anyone wants to service it for us.

 

[SJB060685]

Thanks for the extra info. Yes the burner is high up with secondary HEX tubes at the bottom of boiler and flue is vertical for a metre then out through wall. Weird thing is that we only get an odour sometimes, not dependant on load of boiler or wind direction etc. It is defiantly condensating, although not as much as I would expect. I have checked flue which exits building and no sign of obstruction so will look again in bottom of boiler when a new door seal kit arrives from UK.
Still have an offer of a weekend in the mountains if anyone wants to service it for us.

Hi. Your posts have to be approved before they're visible to us so I'm only just seeing your comment. As we've said above isolate immediately if you're experiencing products of combustion venting into cellar and install new door seals and check everywhere else for possible leaks before re igniting. There are a number of reasons why a condensing boiler might not condense, it could be a problem with the boiler, it could be a problem with the system ie, return water temperature too high etc etc.
Your offer to visit is a nice one but I'm currently off work due to health reasons and although I would enjoy the journey I have respectfully decline. Others might take you up though