TerryE

Well the old Tungsten bulbs were rated at a nominal 1,000 hours or about a year at 4 hrs / day. How many bulbs have you got? The weakness with these is that the cheap capacitors(s) in the voltage drop-down circuit can blow. Big Clive on Youtube did a teardown explaining the failure mode.

You could make the same point about the central heating. Is that as valid? We fitted our MVHR ourselves. It cost us less than £3K, IIRC. When I did the heating calcs the air recirc losses on the top 2 floors meant that we would have definitely needed some form of central heating solution for these upper floors without it. This would have cost us a lot more than the install cost of the MVHR. We just leave ours running 24 × 365. The running cost is in the noise compared to the heat recovery energy savings during net heating days. And as @dpmiller points out: fresh air and no damp year-round. And yes, in the summer we open windows as and when desired or needed. The MVHR still keeps the wet rooms and unused bedrooms fresh.

We also set our reveals at 60° see

Your UFH risers are coming very close to the side door. Make sure that you have enough clearance to get the manifold assembly in.

@JohnMo we are talking classic trade-offs here. Dropping pipe diameters significantly reduces both mass-in-pipe and unit-length pipe mass and therefore heating lag. I did my manifold design 7 or 8 years ago and it work well so is not worth replacing. Heat lag on flow-from-cold just wasn't an issue that I considered. TBH even now that I am aware of it, I am not sure how I would change things. I use closed cell insulation for HW pipe runs from the tank to manifold, and the HW manifold itself is in box that is packed with lagging. The system leaks are ⅓°C / min at 40°C as you can see from the plot below of the UVC top and bottom temps, plus the out from the UVC to the manifold, and inside the Manifold itself. You can see when someone ran the hot until "hot enough" at around 1:30, plus a few other mixer runs where there was some hot draw but not enough to reach the tap (e.g. a quick hand-wash after a pee in the night). Jan was doing stuff in the kitchen 10-12:00, enough to get the hot to mid 30s but not enough to need to run hot. No showers or baths in this period. Total heat loss isn't really material. It's just that we don't use H/W that much but when we do want hot, it takes 30+ sec to run to a decent temp. This would have been better if we'd used 15mm main runs but then this would really limit peak flow times (e.g. running a bath or 2 showers on the go at the same time). The one thing that I would have done differently is to drop all low flow hot runs from the manifold from 15mm Hep2O to 10mm.

As I mentioned in other posts, I have replaced my SunAmps with a UVC. All done, but one consequence is that there is now an extra 3m of 22mm copper pipe between the storage unit (the UVC) and the DHW manifold. This has introduced a noticeable additional lag in the time to run hot from cold when I run a H/W tap. The total amount of heat absorbed by the pipe is quite small (1.5 Kg Cu pipe × 0.385 kJ/Kg°C specific heat Cu × 30°C) or 17.3 kJ or roughly 1/200 kWh per "run from cold". Given that we only run from cold maybe a dozen times a day, this heat loss is quite small -- especially as for half the year we are doing heat top up through the slab and this can just be considered another form of radiator. It's the increased delay in flow response that is noticeable. So I thought to myself: would replacing this copper pipe by HEP2O make a noticeable improvement? So I ran the numbers for PeX. PeX pipe is over 4 times lighter but the specific heat of PeX is actually over 5 times higher than that of copper so the heat absorbed works out still more. However the HEP2O barrier pipe also includes an Aluminium layer which drops the overall figure back again. Even so I estimate the heat absorbed to raise the HEP2O by 30°C is still around 18.5 kJ so the bottom line is almost counter intuitive (to me at least) that I am better off (in terms of thermal responsiveness) using copper than HEP2O for these runs. I thought that some of you boffins might be interested in this observation.

A passing scrap metal man noticed the steel and copper / fittings piles and popped in. All gone. Jan is a happy bunny. Sorry @oranjeboom, you timed out.

👎

So here is what my CH / UVC Immersion control setup looks like finished: The RH Consumer Unit is as-installed by my electrician. I've repurposed some of the circuits: CH, SunAmp 1, SunAmp 2 → Immersion 1, CH, Immersion 2 (I swapped the CH to the 20A circuit, though this could be downrated to 16A.) These radials are routed through to the adjacent small CH on the left. This contains AC→24VDC and 4 Finder 240V / 20A relays(UFH Pump, Willis, Imm1, Imm2). These 4 run radials to fused DP wall plates, and on to the pump / heaters. The small box underneath the relays is a commercial off-the shelf unit discussed in a previous post the runs on 24 VDC and switches the 24VDC input used to control the power relays. This runs standard Tasmota Software (albeit configured with a local autoexec to add a local rule that forces the Willis to turn off (if on) whenever the pump is turned off). The Tasmota firmware is controllable via MQTT. Incidentally above the CU are my BT Infiniband modem, 100Mb Enet patch panel and Wifi hub (this meshes with 3 other Wifi APs to give strong 54Mb Wifi on the 1st and 2nd floors and garden. The CH+DHW upper control used to be hosted in the RPi3 to the right of my Wifi hub, but it is now run on a virtual container on my home Proxmox server (a repurposed Lenovo Laptop which sits on a shelf in the service cupboard that contain my DHW+CH manifolds and used to contain my SunAmps). A bit like a NUC, but with built-in battery backup. It just sits there always closed, as I manage everything over my LAN using SSH and the Proxmox Portal. This hosts a VM running Home Assistant, and currently 8 other containers (LXCs) including Pihole, VPN Portal, IoT stack (MySQL, NodeRED, Mosquitto MQTT server, Zigbee2MQTT), an FTP service for my external cameras, a couple of web-servers and 2 test containers. Above it, the small box is one of my DS18B20 IoT devices, but more of that on a separate post.

@Tom, thanks for the heads-up. I'll double-check the manufacturers datasheet and discuss this with my plumber. If necessary, I will source a compliant alternative and get him to refit it. I'd need a double failure that is of both the following for the UVC to risk venting: so I don't view this as an immediate fix needed: A failure of one or both of the tank thermostat switches My CH / DHW control system will only power the Immersion circuits if the tank temperature (taken by a separate digital thermometer next to the tank thermostat) is below a configured set point. Yes,, these DS18B20s can fail, but I've never had one still respond to a reading request but suddenly start to report a value 30°C lower than previous readings . Moreover if the top of the tank was nearing boiling then both sensors would have to be miss-reporting. So on the scale of risk, I am a lot less concerned about this than flying on a 737-MAX 🙃 BTW, here is a brief plot of my HW sensors:

I've got ~150 Kg of food grade Sodium Acetate Trihydrate to get rid of -- assuming Orangeboon doesn't want to take a couple off cells my hands. It can happily go down the drain in small quantities. I was wondering how good a block paving cleaner / weed deterrent it would be. 🤣

Aaaagh. Literally hours to late, but seriously if you have a SunAmp PV and want a spare then resurrecting one is straightforward plumbing if you have the energy / inclination. I would far sooner it go to another member than scrap. Also if you need to extend the operating life that you'd probably want various spares like a couple control boards, inline heater, PMW pump, etc. Jan put some of the foam in the black bin. If you are interested @orangeboom then let me know by return and I'll sort out a complete set of bits tomorrow.

Well, the pallet with 2×SunAmps is no more. I now have a small pile of steel scrap, a smaller pile of copper scrap, a small pot of eWaste and as with @Cooeyswell a row of 4×SAT Cells and a stack of vacuum panels.

What is crazy is that in terms of physics and engineering it would be really easy for a lot of us slightly more IT oriented folk to "roll your own" using the basic approach used in the PV, but keep it real simple N × PCM cells in a well insulated otherwise passive box with water feed and out. Use a Willis or other reliable inline heater and basic circulation pump, one-way valves, etc. so that you can both do flow through and internal recirc for heating, plus the control board that I discussed in my recent Microcontroller based power switching topic (these sell on AliExpress for ~£50 and you can use a python-like language if you want to implement all of the control logic locally); this plus a couple of 20A SSRs. Keep all of the pump and pipework on the outside so it is easily maintainable, and so you don't need a ticket on advanced laparoscopic plumbing. 🤣 I'd be tempted to do this as a "fun" project except that I don't need this myself now, and I've got other stuff on the TODO list. Even suggesting it might get me a severe blast of dragon fire from someone very close to me. Marital harmony is far more important to me. 😇

I have an all electric passive house. I use Octopus Agile and schedule the slab and DHW heating to take advantage of best prices. Search for my posts and blog entries for more details.