Chimney / fireplace modifications

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

mickthetree

Established Member
Joined
24 Feb 2006
Messages
1,573
Reaction score
0
Location
Tring - Herts
One of the many jobs still to do is modifying our chimney, currently:

21643231390_1abd2faa9b_b.jpg


Have looked at getting a wood burning stove fitted but the costs are just too much. My neighbour (semi detached so our fireplaces back onto each other) has just had his fitted. Looks nice and gives lots of warmth, but cost more than we could afford.

I've looked into doing it myself which is allowed, but seems you need to get (pay) building control to come and sign it off which increases the costs. Has anyone on here done their own?

So we are looking at making a nice open fire instead. We currently use it open since having it swept. I'll need to create a hearth and add a brick facia to the lower half of the chimney breast. If I do this I plan on reducing the opening with some brickwork across the top, over the front of the current lintel. This should increase the draw of the fire (which isnt bad anyway, but its too open) and reduce any smoke overspill when starting fires.

21805534206_957a544e76_b.jpg


As shown in that photo I need to know if I need to support the vertical bricks across the top. Our old victorian house had a slight arch with a strip of bent steel that the bricks sat on. I have seen L shaped lintels but I'm unsure if I actually need one here.

Profile of current and proposed.

21211055383_6b695c920a_b.jpg
 

Beau

Established Member
Joined
23 Mar 2015
Messages
1,877
Reaction score
10
Location
Devon
Sorry for the negativity but I have heard open fires in centrally heated home can have a negative overall effect on heating ie cool the home. Having talked to a few new woodburner users who had open fires they think this could well be true. Basically the convection up the chimney sucks the heat from the rest of the home and all you get is a bit of radiation heating when sitting in front of the fire.

I installed our stove and had BC sign it off but this was easy as the whole place was under BC when I built it. Get a copy of the Building regulations and it's all in there. Heatas installers are making big profits for what is usually a straightforward job. Did our neighbours flue in two hours all done and dusted but everything went like clockwork. A good stainless twin wall flue can be as expensive as the stove but is well worth it for a good setup.

Good luck whichever route you take
 

mickthetree

Established Member
Joined
24 Feb 2006
Messages
1,573
Reaction score
0
Location
Tring - Herts
Many thanks for your honesty beau. I did feel I could do all of the steps myself and we are going to be doing an extension next year which I think will mean building control could cover this too.

We would only need a 4/5kw stove for that room. I was impressed by how much heat next doors stove was kicking out compared to our open fire.

Maybe I should hold off till next year...
 

Beau

Established Member
Joined
23 Mar 2015
Messages
1,877
Reaction score
10
Location
Devon
My advise would be hold off if you can. Modern quality stoves are amazing. The likes of Morso, Woodwarm Burley etc all make great stoves which seem to have made a lot of happy users. I sell logs hence getting to see a lot of stoves. Think if you stay under 4.5 or 4 kWh you don't have to have a gert big hole in in your wall to allow combustion air into the room but also creating a dirty great draft in the process. One possible complication with a self instal is how big you current chiney is. If its narrow or twisty you may struggle getting a twin wall flue in. Then you need a single skin flue but without some form of insulation you get major problems with condensate running back down onto the hearth. With a single skin flue you insulate with something like Leca (think that's the stuff). It's like beads which you pour down around the gap between the chimney and flue to insulate it but you need a very sturdy a well fitted register plate to avoid a right mess. I should add I have not done the latter system to date.
 

Eric The Viking

Established Member
Joined
19 Jan 2010
Messages
6,599
Reaction score
59
Location
Bristle, CUBA (the County that Used to Be Avon)
The issue with room cooling is to do with the volume of air that a stove or an open hearth requires.

Originally, old houses were 'leaky' with air getting in through many small gaps - under doors, round windows, and between floorboards (no wall-to-wall carpeting in the C19th). The regs nowadays require a certain area of non-shuttered vent, so that the fire burns properly and carbon monoxide isn't created, and the flue gases aren't slowed down or (worse) stay in the room. Both CO and CO2 are dangerous, although CO is arguably worse (caused by bad combustion).

If you have a wooden floor, with a decent space below, AND enough area of airbricks or similar on the outside walls (to ventilate the underfloor space), you might consider floor vents by the fireplace. That's what we've done (over a decade ago, though). The big advantage is that there's very little cooling draught across the floor.

Open fires are worse, because the arrangement drags air up the chimney with the combustion gases. Stoves are in part more efficient because a lot less ordinary air is pushed up the chimney with the combustion gases.

I'm not fully up on this, but, as long as the work is done to the proper standard, I don't quite understand why building control should be involved. Is there some new law requiring sign-off?

E.
 

Woody2Shoes

Impressive Member
Joined
5 Jan 2015
Messages
2,133
Reaction score
405
Location
Sussex UK
I've done a DIY install (X4!) in an Edwardian house.

The work is covered by Building Regs (because of the obvious possibilities for burning the house down or, more insidiously, poisoning people with CO). A HETAS registered installer can do the work and effectively self-certify their work as far as building regs are concerned.

More than one section of the building regs applies, from memory B, F and especially J. They cover things like air vent requirements, hearth dimensions and materials, ratio of flue cross-section to hearth cross-section etc. etc. Well worth reading. http://www.planningportal.gov.uk/buildi ... /downloads

I would prefer a log-burner to an open fire every day of the week, because:
- you make more efficient use of firewood;
- you can walk out of the room and not worry about fireguards etc.
- when not in use, they cut draughts in the room.

Doing the job properly is not always straightforward and will likely involve working at height (e.g. sometimes easier to insert the liner from above also to check that the chimney pot/stack is sound - I also always install a cowl to keep rain out), and will probably involve several skills including masonry/metalwork/roofing but you can save quite a bit of cash by DIY. I'd look at ClearView stoves as they're UK-made and decent quality - I have Morso but they seem to have become very expensive and although perfectly good, I might choose ClearView if I were choosing again.

I used these people to supply the bits I needed (no connection other than a happy customer): http://www.fluesystems.com/shop/Multi_F ... ner_6.html

Installing a liner (stainless, double-skin - for wood not gas) is an extremely good idea and ideally needs insulation surrounding it. Getting the flue liner down a (potentially kinked, if multiple flues share the same stack) existing flue can be very tricky - I have been seen with an angle-grinder taped to a long stick trying to grind off bits of brick inside the chimney stack(!) and often the flue needs to be opened up.

I think your mantelpiece idea is OK - you'd need a piece of steel angle to support the brick soldiers. One alternative would be to use a nice oak beam as a mantelpiece (perhaps surprisingly, building regs explicitly allows timber in this location).

Cheers, W2S
 

Phil Pascoe

Established Member
Joined
29 Jan 2012
Messages
23,044
Reaction score
3,117
Location
Shaft City, Mid Cornish Desert
I've just had a stove fitted. Literally.. signed off ten minutes ago.£1200 for the stove inc. stainless boiler, and £1730 for the flue and fitting (in a bungalow) - we've postponed the plumbing until the finances are a bit better. This was the most expensive heavy gauge stainless flue. Mine's an 8kw, and the vent is no more than about 4" square and 1" at the most off the wall. don't let that put you off. I had a Clearview before that was good, so I had no qualms about this one - there is no way on earth would I go back to an open fire. Do yourself a huge favour and save up or run up a debt - it'll be worth it.
 

undergroundhunter

Established Member
Joined
12 Dec 2011
Messages
817
Reaction score
68
Location
doncaster
Why not have a wood stove with a back boiler, then you could run the rads off it. One of my work colleagues has this setup and has a central heating pump under a floorboard that he switches on and off as required.

Matt
 

RobinBHM

Established Member
Joined
17 Sep 2011
Messages
7,187
Reaction score
1,382
Location
Wst Sussex
I think building inspectors will say they want a HETAS certificate to prove compliance, preventing any diy option.

My experience is that HETAS engineers will only install flues that they have supplied, so you cant even buy the bits online and save some money.

I realise the need for regulation, flues can be dangerous for a number of reasons, but the installation costs seem to be a case of legislation creating a monopoly.
 

Sheffield Tony

Ghost of the disenchanted
Joined
2 Aug 2012
Messages
2,078
Reaction score
89
Location
Bedfordshire
It would not be so bad if HETAS ensured that their members were competent and followed the regs. But that appears not to be the case.
 

blackrodd

Established Member
Joined
29 Sep 2013
Messages
3,220
Reaction score
1
Location
sunny devon
Open fires can be a pain in the butt, people get at them and then seem forever to refuse to draw or smoke everything out or even both.
You will need one of these, firebacks, (link) which I would say was once fitted to you're opening at some time before the present.
Saving for a good stove or a multi fuel with a boiler is very good advice.
As most things, u tube has some "how to's" on replacing a fire back They come at 18" and 21", widths as I recall.
Regards Rodders

http://shop.vitcas.com/heat-resistant-c ... oCr9Xw_wcB

https://www.youtube.com/watch?v=ZsrhGu58eq8
 

Phil Pascoe

Established Member
Joined
29 Jan 2012
Messages
23,044
Reaction score
3,117
Location
Shaft City, Mid Cornish Desert
"I think building inspectors will say they want a HETAS certificate to prove compliance, preventing any diy option." - Robin.
Not from what my installer said. He moaned that HETAS notify the building control for compliance, but it could be directly obtained by a diy installer from building control - although they have no specialist training to inspect installations, and would would pass things that a HETAS registered installer wouldn't.
 

Eric The Viking

Established Member
Joined
19 Jan 2010
Messages
6,599
Reaction score
59
Location
Bristle, CUBA (the County that Used to Be Avon)
Those firebacks are incredibly heavy. I've shifted the old "Milner" style ones, and was amazed to almost fail to cut one up with a grinder in the back garden. I think it had realy chunky granite chippings as aggregate in it.

I'd want to know if those are steel reinforced, and, if so, that they are guaranteed waterproof. Firebacks get pretty damp (counter-intuitive, I know), and you don't want the concrete spalling. At a guess they're probably done in the same way as they traditionally were - big aggregate.

You can, of course chuck bags of Vermiculite down the back, but you need to finish it with a haunching/flaunching of fire cement, sloping down to the fireback, so it's waterproof. That helps to stop your expensive heat radiating out of the back to the benefit of next door rather than your own house, as the fireback warms up but can only really re-radiate outwards into the room. It's more of an issue with cast iron, and that's a right PITA as you only have a very small hole to get everything through (vermiculite, bricks, muck, trowel, etc).

There's a cast iron one here I ought to do, which I've been putting off for that reason - don't want to have to redecorate afterwards because of the mess!

E.
Edit: just found this handy diagram:
install_fireback.jpg
 

blackrodd

Established Member
Joined
29 Sep 2013
Messages
3,220
Reaction score
1
Location
sunny devon
Some good advice there Erik, I was told that the fire backs were made using lightening or rapid cement, A friend of mine has cast his own as a bit of an experiment in his workshop and still there 12 or more years later
Regards Rodders
 
Top