I want to insulate the microbore (10mm) heating pipes under my suspended floor and as I am hoping to install an ASHP in the future when I can afford it I need a cost effective solution as I expect I will need to change the pipework later.
What would people recommend in this situation?
Is bog standard polyethylene a wise choice or is it worth getting something with a better U value?
Thank you
Jo
So the pipes run in the floor void under the house?
Would you be accessing the pipework via the crawl space under there or would you be lifting the floorboards? If lifting the floorboards then combining the pipe-lagging work with upgrades to the pipe diameter would make sense, as would doing some floor insulation and air-tightness work to the overall floor.
I second @zapaman’s suggestions and add that upgrading the pipework (and radiators?) now will improve the efficiency of your boiler & pump, so help your energy efficiency going forward.
To actually answer your question requires an analysis to determine whether you can get away with the microbore, not recommended.
If there is any plumbing you know will be replaced the cost of superior insulation probably isn’t worth it. Otherwise go for the best you can afford or, failing that, the best that will fit in the available space.
Pipes sandwiched between underfloor insulation and the floor don’t need insulation. By allowing heat to escape you increase the emitter surface area and make it much easier to trace the pipes when doing other work, making accidental damage less likely.
I think what you are suggesting is wise but I am afraid I need a new roof soon and so it is going to take all of my currently available budget for a new warm roof and I am also planning MVHR.
There is no insulation in the subflloor space and it is very humid so another priority is to install more air bricks (only 3 for the whole house)
So as a stop gap I am going into the sub floor to cover as much of the hot water pipes as I can. The question is what with. Is there something better than normal foam type polyethelyne insulation that comes in 1m lengths or is there a reasonably economical better alternative.
What do you think?
On a tight budget go for the standard foam, if it is available with the correct diameter. It isn’t very bendy so you either need to make custom joins at sharp bends, which would mean lifting the floor at each change of direction, or leave gaps in the insulation.
The “standard” 15mm internal diameter foam will not function very well due to air movement against the pipes. This can be improved by sealing all joins and sealing the ends. At least that way air movement can only be within the insulated volume.
Thanks Tim,
screw fix do a couple of thicknesses so I can use the thinner ones if spaces gets too tight. I expect there will be some fiddly bits-- and quite a bit of patience will be needed— and knee pads!