ProDave

Agree, it would not sound hollow or thin if it was full of water. That's why I suggested call DNO get them to identify it. I dug up a small black unknown cable on my site. The DNO were happy to come and look at it, carefully open it up and determined it was a redundant old telecoms cable. They would rather do that and be sure than risk damage to their network.

Well done on completion. The second most important bit of paper for a self builder (the most important being the planning permission)

I designed mine myself, I would be interested to see if it makes you wince. We are very happy with it.

I saw the instructions for the volumiser and it could be piped as in this case in series with the ASHP, or a slightly more complex way using ports on the side it could be configured as a low loss header. The plumber chose the simple way using the top and bottom ports. Yes there are a lot of terminals in the electrical connection panel so lots of extras and options you can configure, but it could end up with a lot of wiring between the ASHP and the house.

The arch does NOT match the drawing, the glaringly obvious bit being it should have a flat top, i.e. the middle bricks of the arch should be cut shorter than the end bricks to give that flat top. Would a solution be to cut it off level in situ now? that would remove most of the excessively wide joints at the top as well. See how that then looks. Are there more arches like this to do?

You can read off the temperature on the little thermostats on each of the isolator valves, if I zoom in to try and read it, it is too blurred to read the numbers. If you want to adjust the temperature, use the big white knob below the pump, turn it a bit and wait, it will take a while for any change in temperature to register. A pipe won't "feel" warm until it gets above body temperature so above about 37 degrees.

No suggestions but years ago I wired a steading conversion that had just been connected to the sewer and it backed up like you describe in heavy rain and to say the least it "made a bit of a mess" The solution in that case was abandon the direct sewer connection, connected to a higher sewer point which then meant a holding tank and sewage pumping station. Lets hope you find a simpler solution.

I finally have just a little to add to this thread. A few weeks ago I wired the heating of a house having a Grant Aerona ASHP. I believe the one fitted was the 10kW version, though it was not that obvious exactly what power it was. A few random observations not in any particular order. From a wiring point of view it was easy. Mains power, a 2 core cable to connect the supplied controller, and "call for heat" inputs for heating and hot water. A wiring centre was provided to connect the motorised valves, thermostats etc together, all pretty well documented. It also came with a "volumiser" that appeared to just be an over sized willis heater with an immersion heater. I don't quite understand what this brings to the party other than it is a 3kW electric water heater in series with the ASHP that it can turn on when it wants to. It talks about being an emergency heater? I didn't do the plumbing for this and I am not sure I agree with how it was plumbed, no external pump used by the plumber just relying on the pump inside the ASHP to circulate the water around the UFH and to the HW tank. But it did appear to work. I did not spend time delving into settings, so it was left running with default parameters. It heated the 300L DHW tank from stone cold to 50 degrees in 2 hours. By default it gives priority to DHW switching back to UFH when the tank is satisfied. The outdoor unit was both smaller and quieter than I expected, no complaints there. Unlike some other ASHP's it does not have a temperature probe in the HW tank. It only knows the DHW is satisfied by a conventional cylinder stat opening.

The easiest way for the bulk of it, is SAW it to length with a large panel saw while it is still rolled up and bagged. then when you unwrap it, you have rolls of your chosen width to suit your joist / rafter spacing. You only then need to cut to length. The Knauf Frametherm sort is a lot less itchy and irritating than most mineral wolo insulation.

If they do ask for it back, I will refer them to the email telling me "if you joined after December 2019 you must return your kit" If they still insist I will send it back and seek another BT hub with the same USB port from freecycle or not much money on ebay.

BLACK is usually electricity? Unless it is VERY old water pipe. I would call both your local DNO and your local water company and ask them to identify if they are pipes or cables and then ask them to mark their exact course once identified. Try listening either with a stethoscope or just a listening pole, if it's water you should hear some flow.

I have seen that sort of flush where it just opens a valve from the mains water, mostly in the USA, but never seen one in the UK so I assumed our water byelaws don't allow them?

How does it flush then?

The whole thing needs to be accessible for servicing. How about a removable panel system which could include a concealed cistern as well, think of what you see in most public toilets.

Also, watch out you are not on a commercial electricity tariff. If so that won't be capped so even more expensive. Details of the property, age construction, No of rooms etc might help. If large, (9 or 10 radiators suggests it is) oil CH may be an option if no mains gas.

copper will bend as well you know. I don't like using fittings where not needed. My record in our first house was 9 bends in one length of pipe to go round an alcove. It was a little challenging getting the bent pipe out of the bender and then wiggling it into place. Shame I did not photograph it at the time.

I also prefer copper. I took as dislike to push fit when we bought our first static caravan for our first self build and upon connecting the water one by one over the next few days all the push fit fittings blew apart. Yes I know that would have been very old pipe and an inferior cheap push fit system, but it put me off. Then a year or 2 back when i helped a neighbour with leaks, a mouse had got in and was in the inter floor space and by the time the mouse was caught and dispatched, he had gnawed through the plastic water pipe in 3 places. Make your house properly air tight and mice won't get in and that won't be a concern.

So (hopefully) last bit of network reconfiguration done so everything has been swapped to the new provider. I have repurposed the old BT router. All it's broadband and DHCP services have been disabled as has it's wifi been turned off. This leaves it pretty much as just a dumb 4 port network switch, which I need as I have 4 hard wired things on the network and the new router for the new broadband only has 3 ethernet ports. So that is working and all hard wired devices are connecting and seeing the new broadband. but the reason I repurposed the old router rather than replace it with a simple ethernet switch, was I have a HDD connected to the USB port on the BT router and that can be seen by any device on the network as a cheap and cheerful (if a bit slow) Network Accessible Storage, and I wanted to keep that. So that was the reason to keep the old BT router in circuit.

Then you would have to build a bridge (on my list of projects to do) @zoothorn is the Guitar okay in there all the time? it will get cold when the stove is not on. My acoustic goes out of tune on it's own in a constant temperature house, but I rarely play that much preferring the pretend Stratocaster.

I can't help with a replacement valve, but I can help with the actuators. In order to fit them, you have to press down the pin against the spring tension and it is a lot of tension, that's why they appear not to fit. they will if you push hard enough. Alternatively make sure the actuator is energised, i.e. the heating is all turned on and that zone is calling for heat. With the actuator energised it won't need to push the pin down as you fit it and it will screw on easily. do NOT buy the same type of actuator as you have, those have a plastic part you screw on and then the actuator clips on. It is a rubbish design and they are prone to coming unclipped. Instead buy any of this type that have a metal ring that screws on directly, far more relaible. https://www.ebay.co.uk/itm/265207479221 Oh and while looking for the actuator, I saw this that MIGHT be the valve you need as well but check all the dimensions to make sure https://www.ebay.co.uk/itm/265207479221

I don't think any of us have seen something identical to that so taking the cover off to see inside would help. If you have a spare fuse it would certainly not hurt to try changing the fuse in the plug.

Do you feel like unscrewing those 4 (look like allen key head) screws and take a picture of what is inside?

Is that an electric water heater? Is there anything on it any labels to say make or model number? Can we have a picture further out to show what else is there? Is the hot water working?

@Nickfromwales is the HEP20 expert here.

I am not a plumber bit did all my own on the last 2 houses, what little I know my dad (who was a plumber) taught me. I don't think he was happy that I chose electrics over plumbing. What are you planning to use for water? I am old school and like soldered copper. But plenty here will advise on various push fit systems and what are good and not so. Drains can be challenging, they all have to run down hill, and in certain parts of the country certainly here) building control WILL want to witness a pressure test, so no room for leaks or bodges. My motto was test as you go and keep testing, you don't want to find out you have a problem after the plasterboard is all on.