Hi @noburn - so do you know what COP/efficiency you're currently achieving from your ASHP?

Do you have a particular point which you think might be contributing to inefficiencies within the set-up (not necessarily related to the ASHP)?

@transparent COP for water = 2.49 and Heat =3.27.

Unfortunately the main contributor to inefficiencies is my other half lol.

Were you provided with an operational manual for your other half? 😉 

Achieving COP=3 is generally acceptable for an ASHP.
So the space heating looks good.

What sort of tank is supplying the Domestic Hot Water?
At what temperature?
How's the pipe insulation?

@transparent That ‘Operational Manual’ you speak of has not yet been published; I believe it is in its’ 14,285,154th. re-write at present! 😉 Regards, Toodles.

@transparent The set tank temperature is 50c as per installation. It is an unvented 210ltr tank in loft as in photo:

Thanks for the photo @noburn. Here's two comments which might help.

1: You don't need 50`C for DHW.
If you were to install a safety device to prevent scalding, the default setting on those is 42`C.
That's a useful guideline.

2: My graphical answer is this:

@transparent Thanks for the advice.  I'll consider the points you've highlighted on photo and get back to you.

@transparent I don't understand how these kind of loft installs can ever pass muster from an insulation point of view. its basically outside!

@noburn I'd be tempted to think about ways to build additional insulation (celotex boards or similar) in an enclosure around the whole thing, to alleviate heat loss to the outside.  Also for those uninsulated valves, diy fitting of pipe insulation is easy. With a knife and gaffer tape you can make it fit around most valve fittings. 28mm which is what they'll have used for the pipes, as a size is really too narrow for valves (which is probably why they didn't do it) but can be done with patience and a lot of cutting. wider stuff (35mm, 42mm) will fit more easily around valves.

about the system, the thing I noticed was that you have 3 circulating pumps. which is a bit of a puzzle. If you have time, it'd be worth drawing up a system diagram of what is connected to what. just boxes for components and lines for pipes. if you are trying to troubleshoot it or optimise performance at any point, this will be invaluable. I'll counter @transparent's comment on DHW - you don't need it at 50, and heating to 40-something is more efficient in a direct comparison. But if you find that a tank at a higher temp allows you to get through a days usage with one reheat, and the lower temp doesn't, the higher temp may be more efficient (either in money or energy terms) than reheating more than once to a lower temp. This is something thats always specific to the HW usage pattern of the residents, electricity tariffs etc.

@iancalderbank I was thinking of building mine an insulated cupboard in the loft so interesting you said that as was my first thought when mine had to be put in loft.

@joti yep you can't over insulate. my cylinder and all the complex pipework are inside the main body of the house, but some of my primary pipework has to pass through an uninsulated loft space. They have pipe insulation (with lots of carefully trimmed bits around the valves on them), but they also have 2x 150mm of loft insulation roll laid over the top of the insulated pipework. Its easy DIY.

@iancalderbank I'm stillwaiting for my loft to be insulated, long story but logic tells me exactly that so will be doing something eventually. Heat loss was noticeable when my tank had to be moved to the loft.

Posted by: @iancalderbank

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I don't understand how these kind of loft installs can ever pass muster from an insulation point of view.

I think this ASHP installation passes the regulations in the same way that all the others don't.  😥 

A couple of weeks ago, an MCS accredited installer told me that they receive an annual inspection of an installation selected at random from a list of their customers.
I have no idea how that's carried out however.

If MCS only check the aspects which fall within their remit, then the efficiency and levels of insulation won't be evaluated.
There's no requirement for a heat pump to achieve any particular COP,
and the insulation falls within Part-L of the Building Regs. That's outside what MCS have responsibility for.

But hey... what do I know?
I have no credentials to approve what's worthy of an MCS pass.
It's their accredited installers who are 'certified'.

Posted by: @iancalderbank

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it'd be worth drawing up a system diagram of what is connected to what.

Would that be the system diagram which all installers are required to create, and then leave with the customer in order to comply with Building Regs? 😧