Flue choice in a new house.

[scooby1]

I am currently building a new house. I am going to install an 8kw log burner (Clearview Vision 500) One company is trying to sell me a pumice liner with some sort of mixed insulation backfill between that and the chimney. Another firm are saying don't bother, just put a stainless liner in a clay flue and fill the void with Vermiculite or similar.

I have done the latter on an existing house before using the same log burner but should I go down the pumice route this time since we are yet to build the chimney ?

TIA.

 

[expertgasman]

I don't fit s/f stoves, but I understand that the pumice liner doesn't deteriorate. is that correct?

If so, then, ignoring cost, go for it, as S/S liner will corrode eventully.

I understood that a new clay liner wouldn't have to be lined, though, subject to correct installation and insulation, particularly on an outside wall

 

[mointainwalker]

I would expect a heavier build-up of soot etc on the pumice as it won't be a smooth as a steel flue and would also expect ( no experience though ) that it would score more easily when being swept , making it still rougher leading to even heavier deposits. All speculation though

 

[scooby1]

Thanks guys for your input. The pumice liner is being sold on the fact that it is more heat retentive and therefore the flue warms up quicker leading to greater efficiency. And I can see the advantage of placing the pipes on top of one another while the chimney is being built because it allows the addition of the mix to be correctly placed around the outside of the pipe at the same time.

When we did one before in an existing flue we used S/S and to be honest I wasn't totally convinced that the Vermiculite was getting all the way round the S/S just by jiggling it in from the top of the chimney.

But I am also concerned about the smoothness of each type. Clearly the S/S is better in that respect.

I just want to take the best option. The cost isn't an issue.

 

[mointainwalker]

In this case greater efficiency means removing more heat that you would otherwise be enjoying. I do not feel in this case that greater efficiency is desirable: it only has to be sufficient and I would think that a small diameter flue - rather than the volume of a chimney - would probably meet that criterion without a lot of supplementary insulation.

 

[scooby1]

In this case greater efficiency means removing more heat that you would otherwise be enjoying. I do not feel in this case that greater efficiency is desirable: it only has to be sufficient and I would think that a small diameter flue - rather than the volume of a chimney - would probably meet that criterion without a lot of supplementary insulation.

I'm not sure that I follow that view MW. Greater efficiency surely means less heat loss through the flue resulting in more heat being retained inside the flue. Heat rises and the more heat there is in the flue to rise gives a better draw I would have thought.

Once heat is in the flue I have lost it anyway.

 

[mointainwalker]

the more heat there is in the flue to rise gives a better draw I would have thought.

Correct.

Once heat is in the flue I have lost it anyway.

Also correct but what you are not taking into account is that the quicker the heat in the flue is removed ( by the better draw) , the quicker it is extracted from your room environment to replace it and therefore the more heat you lose.

 

[scooby1]

the more heat there is in the flue to rise gives a better draw I would have thought.

Correct.

Once heat is in the flue I have lost it anyway.

Also correct but what you are not taking into account is that the quicker the heat in the flue is removed ( by the better draw) , the quicker it is extracted from your room environment to replace it and therefore the more heat you lose.

Mmmm. I see your point. I just don't know which option to take. I just want to get it as right as I can.