I would insulate them, and any other valves bodies and buffer thank bulkhead fittings, etc. not currently insulated. You can't really over-insulate pipework in a non-heated space such as an attic where you don't want to be losing any heat. You could even consider a removable jacket for the buffer tank if you can get or make something suitable. The insulation on it is good, but no harm in adding additional provided it's easily removed. Leave any auto air vent outlets uncovered and open for inspection. The only valves not usually insulated are anti-frost valves on the outside. Some can be insulated, but many manufacturers specify not to. The risk is blocking the valve outlet, which could prevent the valve from functioning. 

@allyfish Many thanks for your reply. I was afraid I am getting too fussy although my installer may still think so!

I am surprised that there are no purpose built covers for the manual air valves as I guess I am not alone in having circulators and buffer in the loft. Something like childrens socks as I guess it has to be easily removable.

The buffer itself feels quite cool so properly insulated except for the manual air valve sticking out the top and the brass connectors!

If you look at the buffer, you will see the brass connectors. Any recomendations on what I should use to insulate? I was thinking of felt pipe sleeving, held in place by tape.

@richard24738 I expect @transparent  could provide much greater detail here but, at least one of the companies that produce the insulating materials have produced ‘tutorials’ on preparing neat insulating ‘caps’ or ‘hoods’ for various shapes or devices; you might find them instructional. Regards, Toodles.

Meanwhile, this may be a starting point:

Regards, Toodles.

Thanks for the nudge @toodles

Yes, Richard, that metal-work all needs insulating.
Let me give you some pointers.

BES provides a range of different sizes of Class-O elastomeric insulation.
Theirs is manufactured by Kaiflex, which is very similar to Armaflex.

I bought 2m lengths of pipe insulation with 42mm and 54mm internal diameter, and a 13mm wall-thickness.
Those can be fitted around a range of different brass valves.

Glue edges together using a standard 'contact' adhesive such as Evo-stik Impact.

Then overlay joins and awkward bends using the 50mm-wide self-adhesive tape.

I don't like to see your existing pipe insulation being compressed by the use of nylon cable-ties.
Remove those if you can.

To support pipe which has outer insulation you can use a Munsen Ring.
These are available in a range of diameters, with or without a rubber 'grip'.
You screw them onto an M10 thread, which in turn gets mounted using an adapter which you screw into timbers.

If there's a timber rafter or joist nearby, you can often fit an M10 dowel hanger:

If you still seem to be losing heat into the attic, then there are more 'adventurous' approaches.

I've seen photos where householders have used PIR Insulation Board, such as Kingspan, to build a 'tent' around all the water tanks, expansion vessels and pipework in the loft.

There's no pre-defined way to approach this.
Use common sense, and treat the insulation materials in similar fashion to a box of LEGO 🙂 

Here's a couple of thermal images of my cylinder and pipework which have turned what was the coldest room in the house (NE corner) into the warmest despite fairly good insulation on the pipework. That heat contributes to the overall heating need so it isn't wasted. Some of it also has made the bedroom above warmer. I wouldn't want to have that heat loss in the attic where it will end up warming any birds that are sitting in the roof. Thermal cameras are very useful for a subjective assessment of heat losses although I don't trust the temperature values provided by mine (a Topdon TC001).

@johnr @transparent Thank you for your suggestions.

Yesterday I found out that the Air Valves are in fact automatic so I have to be a bit more careful when insulating them. Seems daft there not being ready made insulation covers for bottle valves.

A thermal camera would be ideal for highlighting the issues but unfortunately I don't think I can spend something like £169 on a Nano 200 or maybe £129.99 on a HikMicro at this stage. Tempted though! Unfortunately the free Octopus Thermal Camera's are not available.

I am not very handy as such so cutting normal pipe insulation to shape is probably beyond me. What I am going to try is Felt pipe sleeving as this will give me a bit more flexibility without having to be 100% accurate cutting shapes.

Posted by: @richard24738

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I am not very handy as such so cutting normal pipe insulation to shape is probably beyond me. What I am going to try is Felt pipe sleeving as this will give me a bit more flexibility without having to be 100% accurate cutting shapes.

That's a fair point.
The people we really need doing this pipe insulation work have OCD!

"Felt'' may or may not be made from sheeps' wool.
Its thermal conductivity is likely to be greater with a high proportion of 'natural' fibres.

Check out TopSleeve where you can find links to application videos.

You may need to use a lot in order to match the insulation characteristics of pre-formed closed-cell elastomeric tubing.

Consider also what happens if it gets wet, perhaps due to high humidity.
Wet insulation can conduct heat away from the pipe rather than insulating it.

I've only ever used felt-roll to insulate cold water pipes against freezing.
And I then cover it with an impervious outer layer.

Your local Council may well have a thermal camera you can borrow.

In my area it's kept by a local community energy group who also offer free advice.

Councils who have passed resolutions concerning Climate Change often have such arrangements.
It's an effective service, and much cheaper than funding a Council employee to carry out surveys.

Send an email to the District/Borough Councillor(s) for your ward.
That's the level of local authority which has the mandate for Planning and Building Control.

Remember, you need to use the camera at least twice so you can get a 'before' and 'after' comparison.

@transparent Thank you for your comments.

I have insulated my loft Automatic air valves and brass connections by wraping in Topsleeve Sheep wool pipe insulation and the sealing with tape. That was a better solution for me rather than trying to cut traditional pipe insulation. Air valve vents are uncovered. I'll keep an eye on it for condensation.

I haven't managed to locate a Thermal Camera yet (Northampton Area) but will keep looking

Richard - Regarding access to a thermal camera, I suggest you email Cllr Breese at West Northamptonshire Council.
She holds the portfolio for Environmental matters.

If you're not in her ward, the usual protocol is to copy in the Councillor(s) for your ward.

There is also a Northampton Transition Towns group,
But it doesn't appear to have operated since 2019.