ASHP Base

[richo106]

Hi All

 

I need to install an ASHP base and was planning on doing this out of concrete so it’s nice and solid. Also was going to make it 200mm wider and longer than the unit to give it 100mm overhang all round…is this enough? Or overkill?

What would be a typical build up of a base for ASHP? (weight approx. 140kg)

 

I have attached a picture of the side of my house and a badly drawn sketch of where it’s going. The red arrow indicates where my soil stack is going.

 

The ASHP installer suggested an Aco drain at the back up against the house connected into the soil stack so all the waste water can run into that?

 

Also I was planning on the base to be level with 1 brick down from top of blues? Any reasons why to make it up to blue level or does it not matter at all?

 

Any advice/better ways to do it very welcome as always 

Edited July 5, 2023 by richo106

[JohnMo]

Mine is just sat on gravel, with 600mm deep rubber feet.  Seems happy enough.

[Kelvin]

This is mine. 
 

[crispy_wafer]

here's mine, poured yesterday so still green, polythene covered it when it rained so a little rippled in places but itll do.  I've got rubber mounting feet for the ashp aswell.  Gully in the middle for any condensate to run into, needs an extension/riser piece to make it flush when I get round to picking one up.

 

 

[richo106]

Thank you all

 

I’ve been having a think, and decided to go with a concrete base as originally. It’s  down the side of my house that’s out the way any.

 

@crispy_wafer what is your build up? Hardcore? 100mm concrete? Wood shuttering?

[Canski]

I have been thinking about this recently and was considering putting a 25 Or 50 mm piece of PIR down to the foundation against the wall to prevent any vibration / noise travelling through to the inside of the building. Good idea or not necessary guys ? 

[Bonner]

Just make the slab separated from your house wall/foundation. Don’t forget you need to maintain certain clearance for airflow according to manufacturer’s instructions. 

[crispy_wafer]

9 hours ago, richo106 said:

Thank you all

 

I’ve been having a think, and decided to go with a concrete base as originally. It’s  down the side of my house that’s out the way any.

 

@crispy_wafer what is your build up? Hardcore? 100mm concrete? Wood shuttering?

 

Crushed concrete buildup is very deep on that side, all whacked down so didn't bother with anything else under it.  Knocked up some shuttering from 6*2, bits of it in the background of that pic, screwed where I could still get to them to undo once the concrete started going off.  Sits about 50mm from the wall, with a slight fall to the front.  Approx 2 bags of cement used and a 3-4 barrows of ballast.  As @Bonner says check the minimum clearances, I got too excited about playing with the mixer and forgot 🤫!  But 300mm is needed for mine, which puts it just over the centre line of that slab so It'll be fine.

[dpmiller]

1 hour ago, Canski said:

I have been thinking about this recently and was considering putting a 25 Or 50 mm piece of PIR down to the foundation against the wall to prevent any vibration / noise travelling through to the inside of the building. Good idea or not necessary guys ? 

ours sits on the back step and I slipped a strip of inch EPS along the wall before the guys poured, for isolation.

[JohnMo]

It's fine adding insulation but why? The concrete slab will be no cooler than the air around it, so what does it achieve. If you are touching the wall, the concrete could be wet during and between defrosts, you should consider some DPC between concrete slab and wall.

 

You normally require 300 to 400mm clearance behind the ASHP for airflow, so why does it even need to touch the wall? 

 

You need to also ensure you have a suitable soakaway installed to take away defrost water.

[dpmiller]

the insulation was just as a soft packer to ensure the slab was clear of the wall.

[ProDave]

Two paving slabs.

 

The place it sits needed building up a bit, so a good place to uses up some rubbble , wacker it all down, sand, wacker that again, level it and lay the slabs.

 

It's been there about 5 years no problem.

 

The heat pump is slightly longer than the 2 slabs but at least the feet sit on the slabs okay.

 

[saveasteading]

Firstly I would assume that the fitters haven't read the instructions on position, so a concrete slab will make them set it off the wall.

See instruction manual for position.

 

For all the cost difference I wouldn't use slabs or just gravel. I wouldn't risk any imbalance when the fan is running.

 

Also they have to fix their rubber feet down. Concrete will be a solid fix.

 

As above, leave a gap to the wall and fill with gravel

[Kelvin]

4 hours ago, Canski said:

I have been thinking about this recently and was considering putting a 25 Or 50 mm piece of PIR down to the foundation against the wall to prevent any vibration / noise travelling through to the inside of the building. Good idea or not necessary guys ? 

It needs to be 300mm from the building (well ours does anyway) so you won’t get any vibration and if it was attached the house and it was vibrating there would be something amiss. Ours is on concrete because if was easy to do when pouring the slab and the ASHP installer requested it. 

[Thorfun]

13 hours ago, richo106 said:

Thank you all

 

I’ve been having a think, and decided to go with a concrete base as originally. It’s  down the side of my house that’s out the way any.

 

@crispy_wafer what is your build up? Hardcore? 100mm concrete? Wood shuttering?

that's what I did.

 

 

with room for the A/C unit next to it (yet to be fitted)

[Canski]

4 hours ago, JohnMo said:

It's fine adding insulation but why? The concrete slab will be no cooler than the air around it, so what does it achieve.

 

 

I was thinking more sound transmission than anything at all to do with thermals. 

[Nickfromwales]

10 minutes ago, Canski said:

I was thinking more sound transmission than anything at all to do with thermals. 

I'd say pointless, if the last few I've installed are anything to go by . Quieter than a mouse whispering and zero movement / vibration etc. Piped with rigid copper too and not a flexi in sight.

[richo106]

Thank you everyone, I am going to read through the ASHP paperwork/installation guidance and work it out using that and the rubber feet I have.

 

I will keep you posted

[Thorfun]

3 hours ago, Nickfromwales said:

I'd say pointless, if the last few I've installed are anything to go by . Quieter than a mouse whispering and zero movement / vibration etc. Piped with rigid copper too and not a flexi in sight.

Ours has been temporarily piped with copper as I didn’t have the flexible hoses. I was going to get them to change to flexible hoses. Is that not worth it then?

[Nickfromwales]

Just now, Thorfun said:

Ours has been temporarily piped with copper as I didn’t have the flexible hoses. I was going to get them to change to flexible hoses. Is that not worth it then?

Don't get "the wrong end of the stick", but "suck it and see"?

[Nickfromwales]

Have you bought the flexis?

[Thorfun]

5 hours ago, Nickfromwales said:

Don't get "the wrong end of the stick", but "suck it and see"?

seems ok for now but it's not been through a full winter of us living in there yet.

 

5 hours ago, Nickfromwales said:

Have you bought the flexis?

no, but our heating engineer has some that he can fit. I'm just wondering if it's worth it! maybe we see how this winter goes. what's the worst that could happen? split pipes and water pissing out everywhere?

[dpmiller]

Jeremy Harris had noise issues IIRC. As far as I'm concerned, if the unit is on flexi-feet of some kind then flexys are a must.

[Nickfromwales]

6 hours ago, dpmiller said:

Jeremy Harris had noise issues IIRC. As far as I'm concerned, if the unit is on flexi-feet of some kind then flexys are a must.

I bolted the Panasonic's down to a concrete plinth and used solid copper, zero issue, and I mean 0.00000. 

 

14 hours ago, Thorfun said:

what's the worst that could happen? split pipes and water pissing out everywhere?

I fitted anti-freeze valves to the most recent one, and used glycol on the one before that. Why would you think these are going to split? I assume freezing conditions?

[Thorfun]

1 hour ago, Nickfromwales said:

I fitted anti-freeze valves to the most recent one, and used glycol on the one before that. Why would you think these are going to split? I assume freezing conditions?

Was more worried about vibrations and solid copper. In case they loosened connectors?