Euro ducting

Hello all, I am new here and looking to build my first RMH. I am starting to gather materials and draw up plans. So far so good, and reading this forum had provided me with some great tips and advice already.  

My main problem so far is sourcing the ducting.  I notice that most of the American builds have lovely smooth duct pipes. But all I have found so far in Europe have been the twisted type of duct pipes, and usually too small (125mm is common, ~5"). I remember reading a post on here somewhere where somebody said not to use those, because they slow air flow.

Is that really the case, are they really a bad idea?
Has anyone used them? How did you get on?
If not, and you're in Europe what did you use instead.

Thanks
Dan

Years ago when dear hubby was in the duct needing business there were folks who did this for a living and could make ducts.

Have you tried contacting our RMH Gurus who are in Europe?

Peter van den Berg and Satamax Antone are the ones that I know frequent the forums.

There are some others listed here:

https://permies.com/w/rmh-builders-list

These posts by Satamax might help:

https://permies.com/t/39554/Ducting-choices#307863

https://permies.com/t/44806/Cobbling-workshop-heater-cooktop-oven

Thanks. I will check those links out. Contacting other builders in Europe makes a lot of sense.  If I find any product links to suitable ducting I'll post them back here, in case others are looking for similar, as a few of those links are dead now.  +1

I hope this works out for you.

Are you talking about the links here:

https://permies.com/w/rmh-builders-list

Can you let us know which ones are dead so we can fix them?

I was talking about a couple of links in those 9 year old forum posts, which is pretty understandable.  

There does seem to be one broken link on the makers list though. The Walker Stove link is to an index page that is no longer there. It should link to : https://walkerstoves.com/

Hi Dan;
It has been stated many times that the spiral design pipe is more restrictive than the smooth HVAC pipes that we use in America.
I've never used them myself so I really do not know how critical it is.
I suspect if you could oversize your pipes they would work fine.
Did you know you can create tunnels through your mass using smooth clay bricks?
It does not need to be round it just needs the proper area inside for the size system you are building.

Also are you aware that you can skip the piped mass and build a stratification chamber (bell) instead?
I assume you are building a J-Tube design?  They are the easiest to build as your first RMH.
Both of my batchboxes started life as J-tube designs and I later modified them to be batchboxes.

Hi Thomas, Thanks for the information. I was wondering about using brick channels, but thought that would be prohibitively expensive with refractory bricks, although I've not done the math. So it's OK to just use 'standard' smooth clay bricks in these channels.  That was on my list of things to ask about.

Related to that I was also going to ask about using an existing chimney.   I am thinking about building a second RSH as a heat battery for heating water and I have a currently unused brick chimney. This house was built in the 70's before the oil crisis and had been heated using heating oil. That boiler has been removed but the chimney is still there are looks to be in good condition. It also looks to have been built using refractory bricks, but I need to check that. I also need to check what the exhaust temperatures would have been for an oil heating system.  

Increasing the size of the flue could be an option, however that creates another problem on getting large enough insulated pipe to exit through the roof.  I understand that the ideally the pipe size should be consistent, and that would be tricky to do if the pipe in a bench was already large to begin with. At least if I used brick channels I have more control over the dimensions. I imagine getting the channels to gradually slope upwards could be tricky, but I do like the idea of using bricks. They are readily available.

Yes, I am planning to start with a J tube design. I have started reading about batch boxes though, but only briefly. That is one of the two areas that I really need to read more about at the moment. The other being bell designs, and their pros and cons vs a bench design.  So much to learn

Thanks again.

Hi, I would of though that Finland would of been full of wood burning stoves and all the associated materials like stove pipe and insulated chimneys?
All the spiral air con pipe I have seen only has a raised spiral of 1-2mm, I really dont see that as an issue.

You're right it is, but it's also really pricey here, stove pipes especially. That said, I'm happy to pay if I can find the right sizes for the insulated stuff to go through any roofs.

Saving aside, I am keen to use second hand if I can.  No chimney pipes have come up but as luck would have it  I just found some 200mm smooth ducting locally. It's old and is a decent thickness. I snagged ten 50cm sections for €5 each. Happy days.

Hi Dan;

That sounds like a great score on finding pipe!

After the hot 1800F air leaves your riser it is quickly cooling.
Where it enters the pipe system it should be in the 400F  range.
When it leaves your mass and starts its way up your chimney to the roof, the temps are down to 150F-250F range.
Sloping your pipe up through the mass is not necessary.  Heat rising will create a draft

.