Basic question

[Nic]

Can the inlet and outlet pipes for an ASHP go underground and up through the slab or do they come out and go horizontally through the wall? Like I say I’m sure this is one of those basic questions that probably doesn’t make any difference 🤷‍♂️

[BotusBuild]

Yes, they can. Best to install a pipe (conduit) through which you can feed  the pipes at a layer date. This also provides protection to your ASHP piping

[Russell griffiths]

As long as they are in the appropriate insulated pipe and conduit you can stick them where you want. 
if you price up the correct pipe you might find it far cheaper to run it internally. 

[Nic]

6 minutes ago, BotusBuild said:

Yes, they can. Best to install a pipe (conduit) through which you can feed  the pipes at a layer date. This also provides protection to your ASHP piping

I guess that’s a flexible pipe to go round the 90degree turns underground 

Edited November 6 by Nic

[BotusBuild]

Or a long radius drainage pipe (usually 110mm, other sizes may be available) Depends on the external diameter of the ASHP pipes 🙂

 

Think ahead!

[Russell griffiths]

7 minutes ago, Nic said:

I guess that’s a flexible pipe to go round the 90degree turns underground 

You can’t just put any old pipe through under there, needs to be highly insulated. 
you could make you own up, but by the time you have done that you might as well have bought the right thing in the first place. 
 

better off with a drawing with distance on it to get a better answer. 

Edited November 6 by Russell griffiths

[Nic]

18 minutes ago, Russell griffiths said:

You can’t just put any old pipe through under there, needs to be highly insulated. 
you could make you own up, but by the time you have done that you might as well have bought the right thing in the first place. 
 

better off with a drawing with distance on it to get a better answer. 

 

can you show what you mean with the drawing and radius please 🙏 

[SteamyTea]

32 minutes ago, Russell griffiths said:

you could make you own up, but by the time you have done that you might as well have bought the right thing in the first place. 

I just had a look at some 15mm Armaflex pipe, 15m of it was nearly 500 quid.

13 minutes ago, Nic said:

can you show what you mean with the drawing and radius please

Basically all pipes have a minimum bend radius, so any conduit cannot have a tighter bend.

 

As Russel says, knock up a sketch, if it is a simple run, it may just be a case of box filled with expanding PU foam.

Edited November 6 by SteamyTea

[Russell griffiths]

Picture of floor slab from above. 
location of heat pump outside

location of tank or tanks inside

distance between the two things. 
elevation sketch of rooms pipework has to pass through. 

[joe90]

Can I ask why you want to run it up through the slab? I ran mine through the wall, used ordinary un insulated pipes, insulated with thick insulation and wrapped in tape self amalgamating , much cheaper (and shorter straight through the wall).

[ProDave]

If you go down and underground then back up, then there is no way to drain that "sump" if you need to.

[Tony L]

Good point, ProDave, but is this something that ever needs to be done? I suppose you could have the underground pipes passing through one of those cheap plastic inspection chambers if you're concerned you may need to bleed, in future.

 

To answer Joe's question (although it was directed at Nic - sorry, Nic): I'd planned to put my ASHP against the wall on the south side of my house, which would mean it would be a prominent feature in my small patio + back garden area, but these things are so ugly (& there's the noise & cold draught to consider as well), I'm thinking it may be well worth be worth the additional installation, running & maintenance costs to put it out of the way, against the boundary hedge to the east.  That would put it about 4m away from the house. This would mean the pipes would have to go underground, & if they're underground they may as well come up into the house through the block & beam floor.  Please have a go at dissuading me.

 

While I'm on the subject, I'll just ask, do I have to have one of these electric isolator switches, as shown in the picture, below?  Does it have to be outside, near the unit or can it be in the house?  The electrician who made this video explains it must be at least 200mm away, but he didn't mention a max. distance.  

 

 

[Nic]

2 hours ago, joe90 said:

Can I ask why you want to run it up through the slab? I ran mine through the wall, used ordinary un insulated pipes, insulated with thick insulation and wrapped in tape self amalgamating , much cheaper (and shorter straight through the wall).

that makes sense and I guess just tape for airtightness etc but it might be a case as mentioned, it might end up being further away from the house and not next to it . Which is why I was enquiring 👍🏼

[sharpener]

On 06/11/2024 at 16:03, Tony L said:

While I'm on the subject, I'll just ask, do I have to have one of these electric isolator switches, as shown in the picture, below?  Does it have to be outside, near the unit or can it be in the house?  The electrician who made this video explains it must be at least 200mm away, but he didn't mention a max. distance.  

 

They are mandatory or nearly so i.e. electricians will want to fit them citing MCS rules. They need to be outside the prohibited envelope for a R290 (propane) HP which is why in the pic it is just above the top of the HP.

The theory is they are needed so they can be visibly padlocked off for operative safety during maintenance. I don't know why a padlockable isolator, rcd or two-pole mcb indoors is not thought to be adequate, as it is for other appliances. To my mind they mean un-necessary connections requiring an extra outdoor enclosure which is ugly and an extra expense. If they are truly necessary they should be designed neatly into the HP enclosure itself.

 

There is an alternative school of thought that says they need to be next to the HP so it can quickly be switched off in case of fire or other emergency, I believe this is an urban myth. Mine is padlocked on as it is sited right on the path to the house and near a public highway. Mainly as a deterrent, it would be easy enough to break/cut through the plastic to turn it off in a genuine emergency.

Edited November 15 by sharpener

[Tony L]

Thanks.  Something to ask about before I accept a quote then.  I have these switches outside my office, for my a/c, & some kids turned them off a few times.  I didn't realise I may be able to lock them.