Dan F

Vaillant top of the range controller is the "sensoCOMFORT" (VRC720). There is a wired version and a wireless version. The wireless version allow for outside temperature sensor, main control panel and remote thermostats to located more freely. For remote control from Vaillant app, or for integration via EEBus, you need to also add the sensoNet unit. The sensoHOME is a slimmed down version of the sensoCOMFORT which has the core functionality, but doesn't support as many heating circuits or weather compensation with more than one circuit etc. If you want to ensure you get best efficiencies out of the system, I'd recommend you use a Vaillant wiring center (e.g. VR71) which allows you to setup mixed circuits meaning Vailant can use a configured heating curves and weather compensation to automatically adjust the flow temperature to optimize efficiency. You can play with the controllers here: https://simulator.vaillant.com/vrt380/gb/#/setup https://simulator.vaillant.com/vrc720/gb/#/setup

What were they planning to install? Was a unitower and small buffer not an option? You could always check with another installer to be sure.

Which suppliers provide pre-settlement tank? Quotes I have don't include this and strongly advise not using water from sedum roof or patio, which is a bit of an issue given only put one set of drainage in.

Fair number of people on forum have installed, or are installing, Loxone for home automation. Loxone can do heating, security audio and lighting and I've personally found it to be sweet spot between more closed systems and more DIY approaches.

Both calculations are wrong aren't they? Gas is neither 1/4 nor 2-3 times the price of ASHP to run. Assuming 92% efficient boiler, ASHP COP of 3 and fuel prices quoted, i get: Gas: £650/yr ASHP: £750/yr

We have a 110mm duct that will bring the supply into the garage (once we move the meter) and next to the meter is the main 3-phase board for PV, batteries, garden room, garden lighting, garage and front gate. Then from garage there is a 63mm duct through the EPS to the plant room to secondary 3-phase board (which I'd intitially thought would be single phase). One word of warning with ducts through EPS though is that given the space is insulated, you need a thicker cable to meet regs. Our electrician said he couldn't get a 5-core 25mm cable through the 53mm duct, so has used 16mm instead. The run is 12m so this gives a maximum of 60A/phase. This is sufficient, but it will mean we'll need to split the house load across phases rather than use just one (and think about what we want to backup). We will reuse the 25mm 3-phase cable currently used to bring 3-phase supply from site kiosk into the garage for future car charger(s). Rather than put car charger next to the garage as you typically see, we plan to but them elsewhere on the drive where you could easily charge two cars without getting in the way of the garage.

@Thorfun. I'm told that Telsa Gateway also leverages vector summation when charging. Yes, I have a 3 phase supply and a single powerwall on L1, let say I’m generating 9kw of solar (so 3kw per phase) the powerwall will charge at 5kw.

Good "thermal mass" article on there too: https://www.heatgeek.com/what-is-thermal-mass/

Don't forget that: - ASHP won't be running at a fan speed that produces 50dB all of the time, it will modulate down. - Most ASHP's have a configurable quiet period where fan speed will be limited. Ours for example (7kW) has sound power of 55dB and sound pessure of 49dB@1m. But, with quiet mode enabled the sound pressure is limited to 42dB@1m. In practice is anyone going to be 1m away from ASHP when it is running anyway?

The question though @Moonshine and @joth is: Does it work? There is a calculator available that takes into account distance, reflective surfaces and barriers and outputs a value and pass/fail. https://mcscertified.com/wp-content/uploads/2019/09/MCS-Heat-Pump-Calculator.xlsm. Look for the tab named "MCS020".

We used ComfoPost, partly given Zehender MVHR. Other option was VEAB CWK. Slightly off-topic maybe, but what ASHP do you have, and how are you triggering cooling mode? Via heat pump controls or externally?

If you have a humidiy sensor somewhere, and the ability to control flow temperature, you can adjust the flow temperature based on relative humidy. Some ASHP controllers will even do this for you with requiring anything external. This will be fine at 7C, you'll just need a condensate drain for the heat battery. Do you have your MVHR ducts insulated though? If you don't you risk some condensation on ducts and it won't be quite as efective. What heat battery do you have BTW?

Simply means you have to use a air-to-water heat-pump for heating/cooling and aircon type units are not allowed.

The best place to see what bits you need is the schematics: https://www.vaillant.co.uk/downloads/aproducts/renewables-1/arotherm-plus/all-schematics-wiring-notes-1799366.pdf If you have a very simple system (single zone) this has most of what you need, but doesn't include a buffer tank, no. There are still obvisouly various other things that are needed materials-wise to complete an install.

What size ASHP are you planning go install? Does it need more than standard 100A supply? I've never heard anything about notifying DNO, where did you see this? Our ASHP is rated 15A, the hob however is over twice as much at 32A. Do you also need to tell DNO what you are installing in your kitchen? PV the DNO do need to approve, but this is because it's grid-connected and will export.

There have got to me more than a couple of good installers in your area. I'd get some more quotes until I'm confident about who I'm dealing with. An initial phone conversation with the right person can help rule out suppliers who aren't interested in cooling etc.. We didn't use them in the end, but elite renewables, who aren't that far from you, seemed very comptetent in conversations I had with them.

You don't necesarily need home automation for this. If you have a limited number of zones, you can typically use ASHP wiring center to control a number of circuits, just need to check ASHP controller supports cooling.

If it was me, I'd knock them off the list if they are pushing back on cooling. I had same issue with some PV installers where they pushed back on 3-phase, I simply ruled them out.

I've seen buffer size discussed multiples times on the forum, but did anyone ever come up with any "buffer maths" to calculate buffer sizes based on flow temps and heating circuit characteristics?

Yes, but only on the first-floor if you are only using it for first floor, also only for supply ducts not extract ducts. Not sure how uneffective it would/wouldn't be without insulation. It's not only about avoiding condensation, but also ensuring the right place (the rooms) get cooled and not e.g. loft space. The duct cooler unit needs a condensate drain yes. I'll let @joth or others comment on the fan-coil based approach.

Is this the Pasiv Systems package?

The MVHR will help distribute temperature around the house but the first floor will likely always be slightly warmer on the first floor. Most people live with this using night-time ventilation and with the bedrooms slightly warmer, but depending on the numbers in your stress model and what you comfort requirements are, it may make sense to consider either fancoils or MVHR cooling for the first floor for future-proofing and/or as an insurance policy. Typically cooling via MVHR isn't advisable or practical as the cooling power it can distribute is very low but, if you have i) external shading to protect from majority of solar gains ii) a trust-worthy PHPP model to give you a fairly accurate idea of what your cooling demand is, I would argue that it's easier than adding fancoils to each bedroom and plumbing cold water to them.

Ours uses 0.25 for L31 and 0.0 for P59. What value do you have for L20, I have 0.3? Also check R22 is checked. WARM suggests stress-testing with: - minimum user operated summer shading - MVHR operating in summer at its background rate - no natural vent during the day - 0.1ACH due to night ventilation. In my opinion not allowing for any window ventilation air changes may be OK for stress-testing, but is completly unrealistic otherwise. It's bascially saying that in the summer you'll never open any windows or doors! If I make this value zero in our model then the cooling demand doubles. Your PHPP consultant should know better than to leave this empty if you want any kind of realistic overheating number. On the otherhand night-time window ventialation in zero, may be a reality if for example you live in a noisy area.

The further it is the thicker the cable you need. As does type of charger(s) and how cable gets to charger. See: https://www.elandcables.com/cable-calculator We have 2 x 3-phase boards: - One in garage for PV, Batteries, Car Chargers, Garden, Outhouse, Front Gate etc. - One in plant room for house. Having the board in the garage is practical as Supply/PV/Batteries/Chargers are all close.

We used SolarEdge too and have a 12.5kW three-phase inverter. We didn't use enhabit for PV. I told them what strings to used after working out a scheme (using solaredge designer web tool) that I knew would work for both options.