Best efficiency for gas fire using a chimney (avoiding ventilation losses)

[THX1138]

Mum is wanting to have a gas fireplace installed in the boarded up fireplace of her ~1920s terraced house to use as an alternative to the central heating. My concern regards the requirement for constant, unobstructed ventilation (about 200 cm^2), regardless whether the fireplace is in use, which I think will negate any improvement in efficiency over heating the whole house via the central heating.

I've read in a thread on another forum that it may be possible to draw air for combustion via the chimney, in the space surrounding the flue. Has anyone here heard of that? I basically want a room-sealed fire supplied with air via a chimney.

 

[tackleburger]

If it is less than 7KW it doesn't normally need a vent unless it is flueless. I don't do fires so i maybe corrected here and can't be bothered looking this up i am sure that's the rule. That is as long as it is the only open flued appliance in the room

 

[lame plumber]

whatever the manufacturers stipulate.

fresh air is something everyone is forgetting about as lack of it causes condensation and mould, cant have it both ways.

 

[tamz]

I basically want a room-sealed fire supplied with air via a chimney.

Room sealed fires get their air from outside through the flue terminal. You don't need a chimney.

Fires cannot be vented from a chimney. Whoever told you that nonsense is an idiot.

 

[THX1138]

Hi everyone. Thanks for your replies.

Tackleburger: That limitation only applies to "Decorative Fuel Effect" fires provided that the dwelling has a certain air permeability (which ours probably does). I'm not sure what the difference between a DFE and an Inset Live Fuel Effect (ILFE) is though.

This is the forum thread I was talking about: h ttp://www.diynot.com/forums/viewtopic.php?t=226286&start=0

This manufacturer says their balanced flue fires can have a balanced flue inside a chimney (max height is 10 m): h ttp://www.drugasar.co.uk/balanced_flue_system.htm - have any of you heard of that from other manufacturers?

Regarding moisture/condensation, we have a dehumidifier running 24/7 so that this doesn't become an issue. I think this is more economical than increased ventilation.

IN ORDER TO POST THE URLS I HAD TO PUT A SPACE AFTER THE FIRST H IN HTTP. THIS IS PROBABLY TO DEFEND AGAINST SPAM AND I'M NOT A SPAMMER SO I DON'T EXPECT TO BE REMANDED FOR CIRCUMVENTING THE SYSTEM.

 

[tamz]

Well i learned something today. A balanced flue fire using the chimney as the air intake.
Never heard of one before. Reading the bumf on it it seems a good system but one thing for certain, it won't be a cheap fire and flue system to buy or install.

 

[Atouchofgas]

Your right tamz, the Dru fires start at Aprox £2000 for the fire then the flue. When we fit them we normally just drop two liners down 6" then a 4"

 

[tamz]

Thats why i've never seen them. I don't know anyone who would spend more on a gas fire than they would on a full heating system :lol:

 

[Atouchofgas]

I know I put in 7 Dru fires in one property. One of them need a forklift and 9 guys to manhandle it into place. It also takes two of you to get the glass out

 

[THX1138]

Are there other manufacturers (apart from Dru) of gas fires which will allow one flexible liner to be placed inside another to form the balanced flue?

 

[Atouchofgas]

Yes, but they are just as expensive. Why not go for a glass fronted conventional flue fire ( below 7kw). Ie gazco ebox, riva 53 That way you don't need ventilation and they give off a decent heat, tbh most fires on the market these days are only for decorative purposes

 

[tackleburger]

Hi everyone. Thanks for your replies.

Tackleburger: That limitation only applies to "Decorative Fuel Effect" fires provided that the dwelling has a certain air permeability (which ours probably does). I'm not sure what the difference between a DFE and an Inset Live Fuel Effect (ILFE) is though.

This is the forum thread I was talking about: h ttp://www.diynot.com/forums/viewtopic.php?t=226286&start=0

This manufacturer says their balanced flue fires can have a balanced flue inside a chimney (max height is 10 m): h ttp://www.drugasar.co.uk/balanced_flue_system.htm - have any of you heard of that from other manufacturers?

Regarding moisture/condensation, we have a dehumidifier running 24/7 so that this doesn't become an issue. I think this is more economical than increased ventilation.

IN ORDER TO POST THE URLS I HAD TO PUT A SPACE AFTER THE FIRST H IN HTTP. THIS IS PROBABLY TO DEFEND AGAINST SPAM AND I'M NOT A SPAMMER SO I DON'T EXPECT TO BE REMANDED FOR CIRCUMVENTING THE SYSTEM.

I suppose it depends on what you want it to do. There are plenty fires under 7kw that will provide a decent heat obviously the size of the room comes into play but as a back up to heating and not wanting a vent then........your choice. The only thing I was ever involved in like that was a baxi condensing back boiler and it was a pig to fit.

 

[Reg Man]

LFE has a heat exchanger. DFE does not.

 

[tackleburger]

It doesn't matter what the fire is surely if it is under 7KW the ventilation rules for open flued appliances apply and will not require a vent, unless manufacturers instructions state otherwise, I don't do fires but have a responsibility when attending other calls and this is all CCN1 stuff. The only difference with a DFE fire is in the event it goes over 7KW you are not allowed to take adventitiuos ventilation in to account so a vent will be required for the full heat input rating.

So in other word DFE fire under 7KW net no vent over 7KW vent required .

LFE fire under 7KW no vent if over 7KW (even if more than one fire) then apply aventitious ventilation rule if still over vent required if not no vent required.

Am I right?

 

[Reg Man]

It doesn't matter what the fire is surely if it is under 7KW the ventilation rules for open flued appliances apply and will not require a vent, unless manufacturers instructions state otherwise, I don't do fires but have a responsibility when attending other calls and this is all CCN1 stuff. The only difference with a DFE fire is in the event it goes over 7KW you are not allowed to take adventitiuos ventilation in to account so a vent will be required for the full heat input rating.

So in other word DFE fire under 7KW net no vent over 7KW vent required .

LFE fire under 7KW no vent if over 7KW (even if more than one fire) then apply aventitious ventilation rule if still over vent required if not no vent required.

Am I right?

Unless the manufacturer’s instructions specifically state that purpose provided ventilation is not required,
such ventilation shall be provided in the room or internal space containing the appliance. Where purpose

provided ventilation is required, the air vent free area shall be a minimum of 100 cm2

Regardless of the kW rating.

 

[THX1138]

How much of the project am I permitted to do myself? Am I allowed to put a flexible liner down the chimney? Part J of the building regulations says that builders can do this for future installation of a fireplace, so I figure I ought to be able.

 

[Mrs Tara Plumbi]

There was a study (canada) that looked at whether it was cheaper to heat you home using gas fire as main source of heating or the central heating.
The central heating system won.

From your question is hard to understand what your mum wants.
If she is looking to reduce heating bills then good central heating system with controls, and loft insullation, double glazing and good curtains are better ways of investing her money than in a gas fire.
But if she already has all that and just wants a gas fire - money no object - then yes balanced flue system great.

You know gas fires are supposed to be secondary heating source not the main source of heating?
Make sure she knows they should be serviced every year.
AND make you need to find a GSR engineer who can do fires.

For any installation job I would always recommend you find an installer FIRST - before you do some of the work yourself and before you actually buy the appliance.

 

[AWheating]

How much of the project am I permitted to do myself? Am I allowed to put a flexible liner down the chimney? Part J of the building regulations says that builders can do this for future installation of a fireplace, so I figure I ought to be able.

the flue would need to be installed by a competent person. ie. gas safe registered engineer.

 

[THX1138]

There was a study (canada) that looked at whether it was cheaper to heat you home using gas fire as main source of heating or the central heating.
The central heating system won.

From your question is hard to understand what your mum wants.
If she is looking to reduce heating bills then good central heating system with controls, and loft insullation, double glazing and good curtains are better ways of investing her money than in a gas fire.
But if she already has all that and just wants a gas fire - money no object - then yes balanced flue system great.

You know gas fires are supposed to be secondary heating source not the main source of heating?
Make sure she knows they should be serviced every year.
AND make you need to find a GSR engineer who can do fires.

For any installation job I would always recommend you find an installer FIRST - before you do some of the work yourself and before you actually buy the appliance.

We don't want it to heat the whole house; we just want it to heat the living room. Turning individual radiators up and down is not a viable option because my mother has arthritis.

I'll look for an installer before I start. Thanks for the advice.

 

[Reg Man]

Flue liner intended to be used for gas, is therfore a gas fitting. Under the GSIUR it requires a competent person to do the work, if employed a GSR engineer. You will have difficulty prooving competance unless you are a qualified gas engineer with current ACS ticket.