ASHP Location - Pipe Heat Loss?

[Barney12]

I thought I had decided on the location of our ASHP but now I'm reconsidering as its fairly close to the front door and frankly they are "butt ugly".

So I'm now considering moving it but that would involve a circa 10m insulated pipe run into the plant room.

I appreciate that's not "ideal" but what would the real world losses be? Can I "super insulate" the pipes?

[le-cerveau]

Are you using a Mono-block or Split?  the impact will be different for each type.

For a split there will be a drop off in performance related to pipe length (see the extracts from the Panasonic handbook below):

 Heating  Cooling

7m seems to be the optimum length.

If you are on a Mono-block, then it will be down to heat loss/gain in the pipework and that will depend on insulation, temp difference, flow rate.....

This can be mitigated by (as you say) super insulating, keeping the flow temp as low (heating) / high (cooling) as practical and large a pipe as practical as losses are (generally) lower through larger pipe (less surface area by volume).

[Barney12]

5 minutes ago, le-cerveau said:

Are you using a Mono-block or Split?  the impact will be different for each type.

For a split there will be a drop off in performance related to pipe length (see the extracts from the Panasonic handbook below):

 Heating  Cooling

7m seems to be the optimum length.

If you are on a Mono-block, then it will be down to heat loss/gain in the pipework and that will depend on insulation, temp difference, flow rate.....

This can be mitigated by (as you say) super insulating, keeping the flow temp as low (heating) / high (cooling) as practical and large a pipe as practical as losses are (generally) lower through larger pipe (less surface area by volume).

 

Mono-block. Probably the Samsung 5kw unit.

 

[jack]

We have around 9-10m from our Panasonic 5kW ASHP to the tank.  However, nearly all of that run is in the middle layer of 3*100mm of EPS, so highly insulated.  I obviously can't compare to any other way of doing it, but the tank reaches nearly bang on 55 deg C (the highest temp of the ASHP in DHW mode) nearly every day.  We used Hep2O 28mm barrier pipe, from memory, to keep resistance low and minimise losses.

 

The way I figure it, if you're doing UFH, the temp is low enough that the losses won't be that high.  For DHW, the temps are higher, but (depending on your setup) you only have it running once or twice a day for a relatively short period of time.  

 

I did some calcs ages ago that I now can't find, but I concluded that with decent insulation the losses weren't that great.

[Barney12]

5 minutes ago, jack said:

We have around 9-10m from our Panasonic 5kW ASHP to the tank.  However, nearly all of that run is in the middle layer of 3*100mm of EPS, so highly insulated.  I obviously can't compare to any other way of doing it, but the tank reaches nearly bang on 55 deg C (the highest temp of the ASHP in DHW mode) nearly every day.  We used Hep2O 28mm barrier pipe, from memory, to keep resistance low and minimise losses.

 

The way I figure it, if you're doing UFH, the temp is low enough that the losses won't be that high.  For DHW, the temps are higher, but (depending on your setup) you only have it running once or twice a day for a relatively short period of time.  

 

I did some calcs ages ago that I now can't find, but I concluded that with decent insulation the losses weren't that great.

 

From the above do I assume you ran the pipework through your MBC slab? bringing it outside the house in the location the suited best? Thats a plan that might work for us.

How did you insulate once outside or did you go straight to flexi's?

[Alexphd1]

We picked up a off cuts of this uponor pipe on eBay for a 6 meter run.

[jack]

18 minutes ago, Barney12 said:

From the above do I assume you ran the pipework through your MBC slab? bringing it outside the house in the location the suited best? Thats a plan that might work for us.

How did you insulate once outside or did you go straight to flexi's?

 

Correct.  After MBC had laid the second layer in the area where we were running the pipes, I cut two channels about 300mm apart in the second (middle) 100mm layer, large enough to take 50mm polypropylene pipe (solvent weld stuff for drains, I believe it was).  The pipes were wedged in place with EPS offcuts and then foamed in.  I used an airgun to heat and bend up the end that came up into the plant room.  Drawcords were put in place.

 

When we eventually got around to installing the ASHP, I used self-adhesive foam tape along the required lengths of 28mm Hep2O barrier pipe (2 * 50mm covered the outside with no overlap).  A bit of detergent to lubricate and the insulated pipes pulled through the polypropylene ducts easily enough.

 

The temporary external pipework done up with Hep2O is still working fine.  I do have flexis and will install them at some point.  Even they will be heavily insulated, unlike my parents-in-law's 15kW ASHP which seems to be insulated with something like 8-10mm armaflex!

[jack]

17 minutes ago, Alexphd1 said:

We picked up a off cuts of this uponor pipe on eBay for a 6 meter run.

 

Well done.  I liked the look of that stuff but it's eyewateringly expensive at retail.

[MikeSharp01]

On 28/03/2017 at 11:37, jack said:

We have around 9-10m from our Panasonic 5kW ASHP to the tank.  However, nearly all of that run is in the middle layer of 3*100mm of EPS, so highly insulated.  I obviously can't compare to any other way of doing it, but the tank reaches nearly bang on 55 deg C (the highest temp of the ASHP in DHW mode) nearly every day.  We used Hep2O 28mm barrier pipe, from memory, to keep resistance low and minimise losses.

Hi Jack. Did you have to go through the DPM. I have looked at ducting it / using duo insulated duct  but have concluded its a non starter as the turns would be difficult if I come in through the slab former side then through the DPC and along in the EPS layer then up I think it should work. 

[jack]

On 25/05/2018 at 15:38, MikeSharp01 said:

Hi Jack. Did you have to go through the DPM. I have looked at ducting it / using duo insulated duct  but have concluded its a non starter as the turns would be difficult if I come in through the slab former side then through the DPC and along in the EPS layer then up I think it should work. 

 

@MikeSharp01, we didn't go through the DPC. We just lifted it out of the way where the ducts disappear into the EPS upstand at the side of the slab.

 

The ducts go through the EPS upstand and ring beam at the level of the middle insulation layer (of three x 100mm).  Let me know if you need a diagram.

[MikeSharp01]

4 hours ago, jack said:

The ducts go through the EPS upstand and ring beam at the level of the middle insulation layer (of three x 100mm).  Let me know if you need a diagram.

I may have confused DPM with DPC where the DPM is below the slap concrete while the DPC is below the sole plate or up a few bricks. Diagram might help as the DPM must go up and somewhat over the EPS upstand so on the inside of the upstand the pipes would go through the DPM in our design.

 

 

[jack]

Right, I understand now. Yes, ours went through the DPC at the inner surface of the upstand, like this:

 

 

I believe we cut a circle in the DPC (see arrow) so that the duct was a tight friction fit, on the assumption that there was nowhere for the water to track to this point once the outer DPC was sealed around the ducts anyway. If you were paranoid, you could use a sheet grommet of some sort attached to the DPC to provide a more resilient seal, but that felt like overkill to me at the time.