Pretty pissed off and scared

[hendriQ]

We had a new air sealed stove installed about 6 months ago. We used it the day it was installed to check it worked (and also because the installer told us we needed to run it for a few hours for the powder coated paint to finish curing). Appeared to work well.

 

Have not used it since… until tonight. 30 minutes after lighting it, our fire alarms start going off and I see that smoke is pouring out the join between the stove and the first bit of pipe. The stove was blazing with a roaring fire, so there wasn’t much I could do to stop the smoke other than block off the air feed and open all the windows and put the MVHR on max. The heat of the smoke also caused the powder coated finish of the pipe to blister near the join which caused a rather horrible smell throughout the house.

 

I have a video of the smoke egress and will use it to complain to the HETAS installer. But I’m now really concerned that there could be other pipe joints that are defective. The flue goes up into my son’s room, through his wardrobe then up into the chimney stack which starts in the floor above. 
 

There is a smoke alarm in every single room of the house, and now I will also triple the number of CO alarms we have. But it is still scary to think that a flue pipe could leak.

 

Really scary thing to have happened and just so appalled by the rubbish install. Can’t believe this was signed off as safe.

 

Sorry, rant over, just very angry and scared right now.

[Jilly]

OMG that's awful. 

[markc]

This sounds like a blocked chimney, not necessarily an install problem. Birds nest in the cowl? Very possible if it hasn’t been lit for 6 months

[Russdl]

8 hours ago, hendriQ said:

The stove was blazing with a roaring fire,

 

8 hours ago, hendriQ said:

The heat of the smoke also caused the powder coated finish of the pipe to blister

Could the fire burning too hot have caused the flue joints to fail?

 

Do you have a flue thermometer?

 

I would have thought it would be difficult to get a blazing/roaring fire going with a blocked chimney and plenty of evidence that it was blocked whilst trying to light it (unless the lighting process was ‘accelerated’).

[JohnMo]

Couple of things to think about.

 

The flue is a low pressure region, the natural way for thing to occur is not for the smoke to leak out, but room air to leak in to the flue.

 

Has you MVHR been commissioned yet? Could you be extracting more air than you are supplying causing your room to be depressurised.  On the same theme, combustion air coming from the room in a relatively air tight house, will also depressurise the room, causing smoke to leak in to the room. 

 

Two things to check, does your stoves primary and secondary air come from outside air supply (assuming you have one installed).  Not all stoves do, some will take air from the room also.

 

Is your outside air duct correctly installed and not blocked?

 

[JohnMo]

The other thing could a bird have nested in the flue, the nest dropped down and then caused a flue fire.

[Radian]

New build? The test happened when it was warmer. Since then your floor may have settled a little and the flue pipe etc. is colder so thermal contraction adds to the problem. It may all need reseating now the building fabric has stabilised.

[ProDave]

Get the installer back, get the flue swept and get him to test it with a smoke candle.

 

As above, the joints in the flue are not necessarily sealed because a flue should be drawing air, so any leak will suck in air from the room, not expel smoke.  I would be looking at the MVHR setup or just turn it off to rule out depresurisation of the house.

 

Is the stove room sealed? or does it draw air from the room?  if so is there an adequate air vent close to the stove?

[hendriQ]

Thanks all. So a couple of things:

 

The stove is designed for an MVHR house. It has a direct air feed pipe that brings in fresh air from outside. It does not take air from the room.

 

The MVHR had already been commissioned at the time the stove was commissioned. The MVHR was set up to have a slightly positive pressure in the room where the stove is, as a bell and braces approach. I’m therefore quite confident this issue has nothing to do with the MVHR.

 

By blazing hot, I didn’t mean that hot. All I had in there was kindling, made mainly of very dry hardwood, and two small solid fuel firefighters. All the kindling was alight, the firefighters had combusted and I was about to start loading the stove with logs.

 

@Radian’s suggestion is a possibility. Although not technically a new build, it might have well as been. Apart from the walls, everything else is new. The stove is sitting on a steel tabletop which is supported by a reinforced concrete cast plinth, and that is sitting on a screed floor, which is sitting on a new insulated slab. It is right up against the party wall, which must be almost 90 years old. I need to go back and check my notes, but I think the screed was poured in early October last year. And the concrete plinth was cast in February this year. Then both the screed and the plinth were covered in microcement in late March.

The stove, which weighs 90kg, was placed on top of the plinth in mid April to rest for a bit. That "bit" ended up being some 6 weeks because there was a delay in sourcing a connector. It was finally installed and commissioned in June. Some settlement is theoretically possible. Against that however is the fact that nowhere in the entire ground floor (which is the floor the stove has been installed in) is there ANY sign of movement. There are no cracks in the microcement, for example. No cracks in the ceiling plaster work either. No cracks in the clay tiles installed on the party wall behind the stove.

Edited November 21, 2022 by hendriQ

[hendriQ]

3 hours ago, markc said:

This sounds like a blocked chimney, not necessarily an install problem. Birds nest in the cowl? Very possible if it hasn’t been lit for 6 months

The flue was drawing well. I don't think it's a problem with the flue being blocked. There should be no gaps in the joins that would allow hot smoke to pass through.

[PeterW]

Twin skin or single skin ..??

[hendriQ]

2 minutes ago, PeterW said:

Twin skin or single skin ..??

It's a twin skin flue. But the leak came out of the join between the stove itself and the twin skin flue and I don't think that bit of the stove is twin skin as it is significantly narrower in diameter. There is therefore an adaptor that transitions the narrower part to the wider twi skin flue, and the leak came out of the join between the adaptor and the stove.

[PeterW]

Sounds like the fire cement hasn’t properly cured - there is a process you should follow to cure it.

 

Is it a European stove so has a converter to standard flue.? Any photos..?

[hendriQ]

9 minutes ago, PeterW said:

Sounds like the fire cement hasn’t properly cured - there is a process you should follow to cure it.

 

Is it a European stove so has a converter to standard flue.? Any photos..?

It’s a fairly expensive Dutch stove.

 Photo below, with a sharp focus on the flue paint blistering, which is a couple of mm above the join where it leaked

[PeterW]

Ok so that looks like fire cement painted black. I would hazard a guess that they installed it top down and didn’t get a decent seal on the flue and with the heat it has cracked and fallen out. 
 

In this sort of instance you need an arm up inside the joint and a good smear of decent fire sealant both ends of the joint. 

[hendriQ]

2 hours ago, PeterW said:

Ok so that looks like fire cement painted black. I would hazard a guess that they installed it top down and didn’t get a decent seal on the flue and with the heat it has cracked and fallen out. 
 

In this sort of instance you need an arm up inside the joint and a good smear of decent fire sealant both ends of the joint. 

You are probably right. Installer is coming back to fix. One question I will ask him is how can I be assured that all the other joints in the 9m or so flue above are airtight. This has just taken out all the enjoyment of using the fire. I can’t see myself ever having the confidence of lighting the stove and knowing that I’m not going to poison my son, given the flue goes through his bedroom.

[ProDave]

20 minutes ago, hendriQ said:

I can’t see myself ever having the confidence of lighting the stove and knowing that I’m not going to poison my son, given the flue goes through his bedroom.

You should have a CO alarm in any room that the flue passes through, so that will alert you if there is any leak long before you see anything.

[Nickfromwales]

First fitting off the stove looks to be upside down? Shouldn’t it be female down facing over male spigot? This shows a female union with the socket upwards instead of the spigot upwards. 

[Nickfromwales]

57 minutes ago, ProDave said:

You should have a CO alarm in any room that the flue passes through, so that will alert you if there is any leak long before you see anything.

Yup. The installer should have been shouting that to you from the rooftops!

 

Best to install a multi sensor vs just a CO detector afaic. 

[PeterW]

1 hour ago, hendriQ said:

One question I will ask him is how can I be assured that all the other joints in the 9m or so flue above are airtight.

Twin wall is designed to be air tight installed correctly - essentially it’s a very tight push fit and then becomes tighter when it heats up. 
 

19 minutes ago, Nickfromwales said:

First fitting off the stove looks to be upside down? Shouldn’t it be female down facing over male spigot? This shows a female union with the socket upwards instead of the spigot upwards. 

That is correct - U.K. design is that flue sections should not allow condensate out, so are female up and make down. That is probably a Euro converter required where you have a spigot on a stove. 

[hendriQ]

Installer coming tomorrow. Let's see what they say...
Still pretty shocked this was signed off as safe, but I guess nothing is full-proof in life.

[hendriQ]

Installer came. Turns out the previous installer did not use fire cement to seal the join between the stove and the stove pipe. Instead he used some fire rope. The second installer said that it wasn't best-practice to seal stuff with fire rope - he said fire rope is only really good in limited situations and this wasn't one of them.

simply incredible.

 

 

[ProDave]

Did you light the stove while he was there and did it work okay now?

[Temp]

On 21/11/2022 at 14:53, Nickfromwales said:

First fitting off the stove looks to be upside down? Shouldn’t it be female down facing over male spigot? This shows a female union with the socket upwards instead of the spigot upwards. 

 

No dont think so. I believe its done like a funnel so that any tar/condensate/rain running down the inside of the flue doesn't  leak out of joints but ends up in the stove.

[saveasteading]

1 hour ago, Temp said:

tar/condensate/rain running down the inside of the flue doesn't  leak out of joints but ends up in the stove

I have seen exactly the opposite stated...provide no hindrance to smoke travelling upwards.