How can I effectively cover my Air-Source Heat Pump without compromising efficiency?

Others may have different opinions, but I would say that the only part of the outdoor unit to cover should be the top !! You’ve blocked the airflow in and out, and I would say it’s not the required one metre from your fence, which is a requirement as @Gingernut49 has found.

This is where the installer has placed the unit. P.s the cover is larger than the unit. 

I am also considering a design change with widening the slates to allow more air flow through. 

To note the 1 meter I have had auditors comes out and they didn't comment on that. 

My auditor didn't comment at the time but has notified the installation company that it has to be moved one meter away. Mine looks as near to the fence as yours now, about a foot. (Same colour fence too.)

This is the unit without cover. Just shy I think now looking at this

Hi @juliamc thanks for that. We are doing some alterations today. One of them is making a hole for the fan. There are no slates at the back of the unit. And it's the same spacing on 3 sides. Also drainage below so water doesn't puddle. 

We are still deciding what to do for the left side. Possible doing some more opening aswell. 

I think @juliamc is correct in everything she writes here. She’s rapidly becoming the group’s expert on the right way to install Heat pumps.

It was @nealmurphy who specifically mentioned the 1-metre from the fence rule in this other topic. It can be reduced, but you first have to obtain planning consent from the local council.

As for the wooden cover…. very attractive styling!

But the distance between the rear of the Heat pump and the wall is calculated to allow sufficient air-flow to be drawn through the heat-exchanger. The cover has significantly restricted this.

The slats on this cover also impede the out-flow. Thus the line of least resistance is for the rear input port to simply suck the air from the front and push it through the heat-exchanger again. It is effectively a partial ‘short-circuit’ of airflow being recycled within the cabinet.

Hiya. 
I'm afraid my opinion on the cover is it’s going to hamper the performance of the pump quite significantly. You’ll need to make the gaps much wider and you need to get decent air flow through the system as @juliamc has said. 

You can buy heat pump covers to disguise them a bit but they are a bit like the camouflaged covers you get for wheelie bins and not as nice as the cover you’ve made. 

Hi all I have modified the wooden cover. Please note the rear has no slates. Only 3 sides. The top is also decking boards which have the grooves under. But also 5mm gaps on the top. Again to allow air flow. Thoughts? 

I just did a quick google and it looks like you aren’t far away from some designs. 
https://www.pumph.co.uk/product/wooden-guards/

From my research the key is to not have the cold air being expelled to be able to recirculate back through the heat pump, one the of the issues with the first location of my pump was it being in low point of the garden and the cold air couldn’t escape (it was also boxed in by walls and fences). If the area where the fan is blowing the cold air allows it to escape from the pump then the design should work. 

Have you also kept the side to the left of the pump free? 

Personally if I was going to box it in I’d make the slats further apart but I’ve got no idea what an optimum design is. The design on the link I shared above doesn’t specify what gap they’ve used but you might be able to find details on another website. 

We are adapting the side tomorrow to make a larger opening. On the left closes to the fence. We going to adjust to help suit this.

Wow - great-looking design for your ASHP cover, @48havelock  - loving the improvements made on the back of the community advice here.

So nice to see such great knowledge sharing (particularly from our emerging expert @juliamc!) I sense that this could make a great tutorial for others that might be looking to build something similar - have you been tracking the efficiency of your system since installing the cover? If you haven’t already found it there’s advice in how to calculate your Coefficient of performance (COP) figure in this thread. 

Would be really interested to hear how you get on with tweaking the design, keep us updated!

Thanks Jess. I am also speaking with daikin about the design. Which they have shown me thr 250mm round the edge and back as well. So really need go get the left side off to give it that space. 

Alot of concern about the closeness to the fence and I have have read the MICs which states one meter from a living window. Which this is well away from any of that. So the fence not the issue. 

Will keep the community updated. P.s there is also a Facebook group who were helpful but not as kind as you guys. 

We’re on the lookout for some great heat pump guides we can share with the world and remembered this great DIY heat pump cover discussion.

Any updates on the design tweaks, @48havelock?

Would everyone be happy with their comment made here being moved over to a public topic? (see the edited best answer for an idea of the collaborative guide we could put together) @juliamc, @hydrosam , @Transparent, @Gingernut49 

Fine by me. I'm not covering mine.

Hi Jess, Yes we have redesign, the whole unit. to make iit more breathable. we are just ordering some new grills to provide vents to the top and left side. Its an improvement to the last picture. 

Great to hear, @48havelock - we’d love to see some progress pics when the new grills arrive! 

Looking forward to seeing that @48havelock 

Does it light up at Christmas?  

@Transparent dont give my other half ideas, its already going to be a windy bar. 

And we’re live! Thanks for all your great contributions Heat Pump trialists.

This guide will make a really valuable resource for anyone looking to build a similar heat pump cover. Think we’ve missed something important? Comment below and we can make sure to get it included in the ‘Best Answer’ above. 

I just stumbled on this thread and wondered how the cover turned out in the end? I’m looking to do a similar cloaking effort on our Mitsubishi low temp ASHP

Great question, @hambrook!

I believe @48havelock is the only ASHP member to have tried out a cover so far, any updates on the effect this had on your heat pump’s efficiency, @48havelock? Did you make any further adjustments to the design if so?

Hi all, ot was a project I started and redesign a number of times, the. Winter caught up, so it's been half completed. But which what had been covered no I have not notice any performance issues. As long as you make sure you have plenty of breathing space and your not blocking the fan at the front. This was the last photo before we took it apart and change the design to increase more air flow around the unit. Now the weather is getting warmer we will aim to have this completed soon. 

Ah still a work in progress then, @48havelock ? (Bring on those sunny DIY weekends!)

Was this something like what you had in mind, @hambrook?

Looks pretty tidy to me, so wondering if this might have inspired others to plan something similar. @nealmurphy, @juliamc, @sylm_2000 - Have you got used to the outside unit appearance now, or would you consider a cover or disguise of some type if the efficiency isn’t an issue?

I am so tempted by the design by @48havelock as I do woodworking as a hobby however no way as stick as the design above. Well done!

However I am tempted to leave the ASHP as is allowing it to breathe and work as the design intended. Also in our case it is on the side of the garden out of view making it less of an issue. Did I say I have a few more exciting wood working projects in the pipeline before I take on the heat pump? :)