Trench for ASHP pipework, electricals - tips?

[oranjeboom]

So after much faffing around with suppliers, Ofgem and installer, it looks as though I now have a date for my heat pump install (Vaillant Arotherm Plus). Now looking to prepare for the install so looking to dig a trench to determined ASHP location and shortest route to house. Due to the nature of driveway (just to left of hedge, see below) and the line of sight from the gate, the best place visually is indicated by spade). 

 

As it'll create a bit of an eyesore and also being adjacent to front door, locating it right next to house is not possible, so I will locate it 9m from the nearest entry point (see rough tape measure line below). Pipework will then go up the wall 2.4m.. through soffit, into loft...1m along the insulated loft...then down through ceiling and into plan room (another 3m), so approx 15.5m in total. The exterior wall is still to be covered by EWI at some point in future so that will cover all wiring and pipework.

 

 

 

 

 

 

So, I have a few questions:

 

1. How deep should trench be dug? 500mm?
2. Armoured cable necessary or can  I just use standard cable in conduit I just bury it below the pipework with warning tape over the top?
3. Obviously heat loss is an issue so wanting to minimise that if I can, so I was going to lay the insulated pipework ontop of some EPS leftovers and add some expanding foam prior to filling in - worth it?
4. Any other ideas?

 

Thanks in advance

[JohnMo]

1. Sounds ok

2.yes and yes

3. I built my own insulated pipe, 110mm flexible hose, 28mm Hep2O and 25mm wall thickness black closed cell foam, had loads of aluminium tape, so taped over the insulation before inserting into flex duct. The ends of the Flexi duct I used stainless steel mesh foamed in place to stop rodents etc. About a 1/10th the price of bought stuff and does just a good a job.

 

I placed mine ASHP behind a shed (insulated) and log store, so ran some of the distance in the shed, and the power supply etc were all housed in there. Near constant flow of air through the log shed help get the wood super dry.

Back of shed

 

[JohnMo]

Front of shed.

Rectangular box is where pipes exit shed to go underground, the come back up by the cream watering can.

[oranjeboom]

2 hours ago, JohnMo said:

I built my own insulated pipe,

Thanks ! I think I may recall reading about your DIY approach on here some time ago, but do you have a link to that post by chance? I'm hopeful that installer is supplying my insulated pipe as I've seen the crazy costings!

[JohnMo]

1 minute ago, oranjeboom said:

Thanks ! I think I may recall reading about your DIY approach on here some time ago, but do you have a link to that post by chance? I'm hopeful that installer is supplying my insulated pipe as I've seen the crazy costings!

I didn't post it direct just in reply to another post. Been looking and I didn't photograph anything either.