Woodstoves, Flues and Building Regs

Who installed the stove in 2013?

Local installer. Signed off as compliant, they didn't want to fit a liner, said it was unnecessary, but I think they were not fitting them so they could undercut the competition.

Were the installers HETAS registered?

Yep. As far as I can tell there is nothing wrong with the current install including hearth size. Although the sweep had a grumble about there being no hatch in the register plate, but I've checked and the opening above would obscure it anyway.  Previous sweep either went through the stove or removed the short flue in the register plate.

Smoke test the chimney, if it passes then no liner needed.

Agreed but I'd like a flue really, I think it would run better with one. It passed smoke test before install and since

Does fitting a flexible liner in an existing chimney require the chimney height to be brought up to spec

I'm not sure but I'd say it's doubtful.

And yes your since probably will perform better with a liner, especially if it's an external chimney.

It's internal, goes through loft and comes out just in front of the ridge on a hip roof.  Last time we had it swept the sweep said there was loads of tar in there and had a tempting price on a flue, then he went AWOL and we never even managed to pay for the sweep as there was some minor mismatch with his name and the name of the account for the bank transfer!
However I just swept it myself and stuck a rodding camera up there and it looks pretty bloody clean to to me, which I'm glad about as I'm pretty fussy with making sure I only burn well-seasoned wood.

The cowl has also rusted out and blown off the pot so me or someone needs to go up there to replace that anyway, hence whilst I'm considering the flue liner now.

I'd try another sweep or HETAS registered installer and ask them.

600mm above the ridge iirc . You really want a liner in there.
Safer as it reduce the chances of an ember somehow making its way through missing mortar onto a joist or lighting some creosote residue in a corner.
Reduces the chances of co poisoning as flue liner chimney are sealed from the stove up to cowl.
Stove will light better as the volume of air is much smaller than in an open hearth square chimney so it heats up quicker, and runs hotter and stays hotter so less chance of making creosote. Easier to sweep as well as the trad round brush is in constant close contact the sidewall.
You might need a 6in flue , the top hat cowl hanger is expensive and so are any rigid elbows you need for offsets or to clear the closure plate

Thanks for the replies.

@andylaightscat I've answered your questions, do you have any expertise to answer mine?!

40 odd years as a Building Control Surveyor, OP, you haven’t said if the original installation was carried out by a HETAS registered installer, it sounds like he wasn’t.

If it wasn’t the new guy doesn’t want to work on what is possibly a non compliant install.

How old is the house? It’s unlikely that a plain brick chimney isn’t leaking. Is there any background ventilation or a fresh air feed to the burner?

I’d get someone HETAS  registered to inspect the current installation and see what they recommend.

personally I'd just fit a liner myself.  thats what I did.  check the regs.  Make sure its close enough.  Drop a liner down

I have also been drinking beer before you take my advice

Andy, I did reply after your Q and said yes.  Sounds like I need to prove it.

I could answer the rest of your questions, but seeing as the best qualified person on this thread still hasn't answered mine...  I can't imagine I can ring up a HETAS guy and get him to pop round for a couple of silly questions at this time of year.

Thanks for all the other useful replies!