Underground connections from loghoiler in boiler house to house: How to do?

[PinkyPerky]

Hi
I want to run underground flow and return pipes from the heat exchanger in the boiler house to the existing heating and dhw pumps in the house.
I will dig the trench for the flow and return pipes, 10mmsq armoured cable and cold water by hand if it ever stops raining. I have bought myself a Newcastle trenching spade but I don't suppose it will be any easier!
I planned to use 28mm copper tube in Armaflex insulation and possibly run the insulated pipes in Ridgiduct twinwall ducting. The distance is 11m with one 135 degree change in direction at 6m and another at the house. The expansion of copper could be 20mm or so. Would this be a problem if the tubing is run in Ridgiduct?
Also I am loathe to break through the damp proof membrane for the connection at the house.
I am aware of Uponor but it seems inordinately expensive! Are there cheaper alternatives and suppliers?
Any advice welcomed.

 

[kimbo]

Why not use 28mm speedfit or hep run then in soilpipe but insulate them first. plastic is more durable underground.

 

[Destroyer2813]

I would run it in plastic lagged in soil then it can be in one continues length under ground

 

[wheeto]

Upnor pre-insulated (with extra insulation and protection) is the only way I'd be happy doing it but I know it's expensive!!

 

[peteheat]

Upnor pre-insulated (with extra insulation and protection) is the only way I'd be happy doing it but I know it's expensive!!

I agree, it's a one off spend, much better than looking at the line where frost or snow always turns to water or light rain always drys out first technical term Heat Loss most often referred to for years after it's installed as the spot in the garden all the local dogs like to sit in winter.

I have used an A.J. beside the wall of the house to change over to ducted pipes so they can be brought into the house above the D.P.C..

I have seen temperature drops of 10c + between the boiler house and the entry point to the house over similar distances using qualpex insulated and run in soil pipe, also it is difficult to push such lengths of 28mm (1") flow and return into a 110mm duct without damaging the insulation.

Before committing myself I would check the prices again, 28mm copper and Armaflex are not cheap by any standard.

 

[PinkyPerky]

Thanks PeteHeat
What is an A.J.?
I have lots of 19mm thick armaflex and 4 3m lengths of 28mm but would still need another 5 lengths
What thickness gave your 10 degree loss?
It would still be cheaper than using Uponor though that would have no joins underground.
Still worried about the expansion.

 

[Gray0689]

Do it right use ecoflex pipe any other way is cheaper but as said it snows you will have a nice clear walkway where pipes are lol

 

[Gray0689]

Upnor pre-insulated (with extra insulation and protection) is the only way I'd be happy doing it but I know it's expensive!!

What you mean extra insulation and protection mate??

 

[wheeto]

What you mean extra insulation and protection mate??

Just that I'd be running them in 4", even if they were suitable for direct burial, and trying to come up with novel ideas for extra insulation on the outside. Hate the idea of heating my garden!!!

 

[Gray0689]

Any insulation that gets wet is useless

 

[peteheat]

Thanks PeteHeat
What is an A.J.?
I have lots of 19mm thick armaflex and 4 3m lengths of 28mm but would still need another 5 lengths
What thickness gave your 10 degree loss?
It would still be cheaper than using Uponor though that would have no joins underground.
Still worried about the expansion.

A. J. = Armstrong Junction, a junction box for sewage or rodding point basically a small manhole available in plastic and probably still available in clay, with the plastic version you can dig down as far as you want and use risers to have the access lid at ground level available in straight through or a number of different connection points [DLMURL="https://www.build4less.ie/product_info.php?products_id=2398"]Here[/DLMURL]

Strange this I am in Ireland and we use imperial the UK goes metric but refuses the Euro LOL (not that I blame you).

Insulation 1" which I expect is your 28mm.

No joints, bends so no problem with your change in direction, Rehau is another brand, just be careful there are cheap look a likes which are a waste of money.

 

[PinkyPerky]

Any insulation that gets wet is useless

But Armaflex is closed cell foam so doesn't absorb water

 

[Gray0689]

Lol try it and see it does eventually
Do it right and do it once

 

[peteheat]

But Armaflex is closed cell foam so doesn't absorb water

Can you be 100% sure that the insulated pipes you pushing into a tight duct over a distance of 11 metres can be done without any damage to the insulation?

You can weld / glue Armaflex joints but the process is useless if water gets into the duct and finds the smallest tear in the insulation because now you have direct heat transfer from the water in the duct to the copper pipes.

I have seen so many jobs that were done your way and every single customer without exception regrets it to the point where some have already changed and the remainder have it high on their "To Do" list.

That is paying twice for the same job.

I presume you are fitting a buffer tank, load valves etc with the wood burner?

 

[PinkyPerky]

Hi peteheat
My two pipes with 19mm armaflex come to 130mm. I reckon with a couple of turns of THINSULEX Silver insulation blanket and wrapped in black polythene and sealed with Gorilla tape I should be able to pass it through. The polythene should protect the insulation while threading the duct.

 

[PinkyPerky]

Lol try it and see it does eventually
Do it right and do it once

I take your point except that Uponor contains the same type of closed cell insulation (1% by volume) and my duct is a similar twinwall to that used by Uponor though it will have one joint at 6m with seals

 

[Gray0689]

You won't get it the way they do
But hey it's your house if your happy with it when you try it then fair play