Spillage from Flavel Diamond DFE fire - advice please

[mchandler]

Hi all, I'm doing my work placement / portfolio working towards my Domestic Gas ACS. I've just serviced my Flavel Diamond 6.9 kW inset/DFE fire. No problems, pressure, gas rate, flame picture all ok. Came to do spillage test (after 5 mins) and I got some spillage. Re-tested several times, same result - most smoke drawn but about 5-10% comes back into room. I noticed in MI a whole page insisting that the unused gas supply apertures in the firebox bottom must be taped up with foil tape which I did (they were all open). My thoughts are that this may have created falsely large draft and hence passed spillage test on installation (3.5 yrs ago)? I have a pre-cast chimney/flue set-up (house built ca. 1996). Depth of opening to firefront fascia is about 300mm. There is a false chimney breast of blockwork which forms a ledge/possibly lintel in the builder's opening of approx 20 cm depth in front of the flue block opening and directly above (4-5cm) the fire opening. This doesn't seem a good set-up as it must be affecting/slowing draw? (by the way flue flow / smoke test was fine). Clearly the current set-up isn't providing enough combustion air / flue draw. So I've ID'd my own fire!! Would be grateful for advice on options/next steps....?? many thanks.

 

[GQuigley67]

try the spillage test again with the door or window slightly open, are the logs/coals in the correct position ? is there signs of flame chilling i.e soot ? I have had to ID my own inlet fire as I don't have the MI's and my dog keeps eating the coals, now i dont know where they go correctly and i it is showing signs of soot/flame chilling.

 

[mchandler]

Thanks GQ. Will re-do test with window/door open. Coals are laid as per MI. Yes there is soot on the ledge above the fire opnening. I note the MI says additional ventilation is not normally required - but looks like my set up may need it, if I can't improve the flue?

 

[kirkgas]

as you are working on placement and not yet qualified you should not be working on gas without supervision, i appreciate you have made safe, as far as you can, but care needs to be taken when doing work without the back up of the person who is mentoring you, and as you did the work unsupervised this couldn't be used for your portfolio as it cant be signed off as your work wasn't checked. Have you confirmed that this fire is suitable to use in a pre-cast flue, some cant

 

[andyg0507]

and correct me if im wrong kirk dfe's need a 100cm2 purpose ventiliation whether its below 7kw or not.

 

[Billy Bob Bob]

and correct me if im wrong kirk dfe's need a 100cm2 purpose ventiliation whether its below 7kw or not.

yes they do and a 175mm diameter flue so if a gc1 has been fitted.....but mi,s take presidence,i think the op is confusing a dfe with a ILFE

 

[GQuigley67]

I would agree with gasman

 

[Reg Man]

I take it that the inset fire box is sealed to the chimney opening and there is a smooth transition into the pre-cast chimney. Flue flow test good? How about checking the roof space part of the flue where it connects to the ridge terminal, could be partialy blocked with spider webs? Also check for encroachment of cement on each joint of the block flue. Any potrutions will build up the restistance of flow up the chimney.

 

[mchandler]

Thanks for your advice. I'm aware of the 100 vent size for DFEs. This is an inset model but the MI calls it a DFE (?). Also states 'no additional ventilation normally required' and suitable for pre-cast flues. To pick up on Kirkgas's points I did this service with my GS supervisor, last job on Friday. Stopped it at spillage and agreed I'd do some homework and suggest the solution(s). I'm keen to find my own feet and ask the relvant sources of advice, like GS, tech helplines tec., which is what I'll need to do when I'm registered and don't have the supervisor over my shoulder. I'm on placement 1-2 days a week and inbetween these days I look into some of the problems encountered. Thanks again.

 

[mchandler]

Flue flow good.
Flue length clear to terminal, no protrusions.
Firebox sealed to opening with Manuf foam seal.

I suspect it's 1. the sharp transition into the flue and 2. possibly not enough combustion air.

 

[huddster]

100sq cmś unless MIś state otherwise

 

[aceservicing]

Remove fire . On the rear there is a baffle restrictor plate , remove this then re comm , you will find the flue pulls like a steam train , doesn't need ventilation under 7kw osd takes care of adverse conditions encountered , mfi will confirm this . Also when restrictor is removed you loose performance heat ( output ) efficiencies are then around 40% .