Underfloor heating pipes

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Modernisation work a late 1960’s extension has necessitated repositioning some existing central heating pipes & provide new spurs for a conservatory radiator. The under floor pipes in the existing extension were buried in a 100 x 100 pre-formed concrete duct below a 30mm floor screed & surrounded by some sort of loose, granulated material which looks a bit like used cat litter! I assume this provides insulation & allows for expansion movement of the pipes but what is it? Should I refill the existing duct with this before concreting over or can someone advise a modern equivalent material?

Also, the 2 new spur pipes are not contained within a duct at present; what is the accepted practice for burying pipes in concrete floors? Should I form a new duct & backfill similar to the existing or is it acceptable to just wrap the pipes in Deso tape & concrete them over?
 
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In the days when plumbers did things properly, the builder formed ducts and insulated the pipes in Micafill granuls, and the pipe lived happily ever after in a nice warm house and without any stress or strain on their little joints.

Then along came the cheap skates :- to be continued

Wrap the pipes in denso after testing them, its the next best method. :cry:
 
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doitall said:
In the days when plumbers did things properly
Many still do. And we aren't restricted to using iron or copper these days :rolleyes:
 
dia history has a habit of repeating itself ;) we will see if the newer materials can stand the test of time micky and roland are quite fond of the plastic,but they seem to disappear quite quickly once they have a shower :eek:
 
bripl said:
dia history has a habit of repeating itself ;) we will see if the newer materials can stand the test of time
Sadly, it's not time that erodes copper, but acid and water.

micky and roland are quite fond of the plastic,but they seem to disappear quite quickly once they have a shower :eek:
Who what when why where and how?
 
mickey=mouse
roland=rat, these rodents seem to enjoy a meal of plastic pipe washed down with h2o maybe with a hint of inhibitor,living in a semi rural location come across this problem frequently also badly made joints and leaky fittings are very popular copper/blk iron for me
 
Even if wrapped in Denso they still have to be able to MOVE. Have been shown a tee which pulled apart.
Suggest ducting with a ply lid - BES do it.
 
Im inclined to form a duct around the new pipework & backfill to match the original. In my search to track some of this stuff down, it seems that Micafill & Vermiculite have different properties but neither seems to be specifically recomended for backfilling pipework floor ducts?
 
Both the same stuff and comes in big bags, most builders merchants stock it.

The term Vermiculite was generally used when mixed with cement for benching back boiler flues.

bag of micafill in a dustbin, bucket of cement, and about 10 gallons of water to make a stiff mix, then used to fill in around the flue and up the chimney.
 
polystyrene balls have a good insulation properties and allow movement
 

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