sharpener

Open one valve to be in line with the pipe and just crack the other open a bit until you hear water flow. Then adjust the flow rate while watching the pressure gauge. If you open both valves fully to begin with the "whoosh" sound will swiftly be followed by the pressure relief valve going off and possibly water over your feet or elsewhere before you can react, particularly if you have not played this game before.

Depends on the contractual arrangements between the three parties. If you run it and it provides heat you are effectively commissioning it. The Grant guy may not be best pleased particularly if you don't do something that needs to be done in sequence, or fail to spot something which needs to be rectified before it causes a worse issue. I was very annoyed when before I got there the plumbers fired up a new type of boiler which I had specified but they had not installed previously. And when I was a laser systems service manager I could instantly tell if someone had been on site before me and tried to make things "better". In the extreme you could end up voiding the warranty.

Don't see why it wouldn't work from the heat transfer point of view. But the various sensors and software may view it as an error condition and it will be difficult to hack that. As a less elegant solution you could fit an external heat exchanger to do the HW and plumb it up as a second heating zone, then the boiler would not be able to tell the difference. Except you wouldn't want the WC to function when there is a demand for HW. I have had to get round that with an external relay as Vokera did not have a solution for this.

I have used the Fernox citric acid based cleaner for this with good results, need to neutralise well afterwards, don't know if it's still available though.

Nothing wrong with that - I used to specialise in analogue circuit design. The solar immersion diverter I made in 2011 has an analogue multiplier IC to compute the true rms value of the chopped waveform and close the feedback loop to achieve <100W export.

It's not an ideal location though, I have Pylontecs in a lobby on the N side of the house, even so I see cell temps of 28C on occasion. Also have fitted a linked smoke alarm, and on the other side of the kitchen door a fire extinguisher. Insurers don't mention battery systems so I imagine they are regarded as mainstream now. without a BMS how do they get balanced if they need it?

Fair enough. My first ones have silver frames but the later ones are all black, not too bad on dark grey slates. And I realised this week that a house near us has black panels on black slates, so inconspicuous I had no idea they had been fitted. Yes its the batteries that tilt the economics a good deal, the PV on its own would have a lot quicker payback.

When I got the system put in in 2009 the Vokera was the only small (20kW) boiler I could find that had it. The plumbers had never heard of WC, or Vokera (since acquired by Riello). I think the internal expansion vessel needs replacing now but other than that it has needed no attention. The HX is an extruded finned aluminium pipe hydroformed into a coil, which is quite neat. In the house before that there was an Ideal Mexico, I found an aftermarket WC box from Danfoss which allowed/prevented the boiler firing according to the measured return temperature and OAT. With zone valves it cut 1/3 off the gas bill.

I think solar installers are pushing batteries hard bc the panels have become a commodity item and there is comparatively little profit in them. Margins on the batteries are better (for now) and you can install them in the warm and dry. The economic case for the customer is harder to establish, though now e.g. Octopus Cosy will allow you to make three full cycles in 24 hours which is a big improvement. And if you can achieve round trip efficiency >80% you can even make a margin selling their own electricity back to them. But I can't quite.

Sounds like a soft error, you might be able to recover by doing a factory reset (having carefully recorded all settings first!).

You can't generalise, it all depends on their size and how the system is configured. The rads in our sitting room were already quite big enough and the room heats up in 30 mins using stored energy from cheap electricity. Previous UFH was extremely slow to respond and the carpet didn't help either. We had 6 other rads upgraded and they are now fine too. We do not heat all the house at the same time, bc it is a big house and we move about it in a well-defined pattern so it is easy to programme the system accordingly. With PV as cheap as it is now I would have thought that it would be a no-brainer to cover all available roof space.

Worth saying that in another house we have had WC on Vokera gas boiler with Drayton TRV4s, and once set up it hardly ever needed adjusting. Apart from when I had to replace the outdoor sensor (I bought a selection of commercial thermistors for a few £s not their £50 replacement part). Added a trimmer to the circuit for good measure, mfr provides gain adjutment but not offset.

I think it's more a question that unless a recent model and specially designed for it you shouldn't run them in condensing mode as the combustion products (?oxides of sulphur?) in solution will rot the heat exchanger and flue. We used to have a Kidd oil boiler and despite the min thermostat setting being 65 and it only condensing at start-up the aluminium condensate tray in the economiser section had to be replaced twice (albeit in 29 years), all the other "permanent" parts were fine.

Sounds like this might be a rare case for 3rd party controls, how about Optimise for Zone 1 as above which will be correct for rads but too hot for the kitchen UFH disconnect/disable Zone 2 controls on Ecodan turn down flow rate through kitchen UFH loop(s) until it (almost) requires the same flow temp fit 3rd party thermostat in kitchen to control the actuator(s) and take account of cooking gain etc @JohnMo will be able to tell us if this could work.

Yes, battery combined with a tariff like Cosy is a real game changer. I really struggled to find an installer who would add a second tranche of solar to my Victron battery inverter system. There were various excuses ranging from we only do combined systems to we would not want to face the split warranty liability. But I expect we do not understand why you would want to connect directly to your 48V battery and we would make less profit comes into it too. You might be better off getting it all done together. At least plan it carefully and seek an assurance they will come back and fit the solar later. If they are still trading.

My mistake, according to MIs default is -60 and correct name is Compr.start heat. from. There is a well documented s/w bug which affects yr ability to change this but if yr machine was mfd this year it should be OK. Also you could try reducing Compressor hyster. Heat. from its default value of 7.

If you have it on expanded this is more likely to happen. Energy integral is -90 by default, is in the Appliance Interface settings under "Compr. heat. start from", try changing it to -60. Much discussion on the Arotherm Plus FB page.

When my HP was fitted we discovered that the pressure relief valve on the oil boiler had been vented straight into the utility room for the last 29 years. Previous owner had done a lot of the plumbing himself, filling "loop" was actually 15mm rigid pipe with only one valve as well but I knew about that.

Back on the original topic some further wrinkles that have arisen. 1. I fitted an indicator panel with separate lights for the HW valve and each of the 3 heating circuits so I can see what the machine is doing at a glance. (Very helpful for checking all the different time schedules are set up correctly.) This showed that when in Away mode the heating circuits are energised for less than a minute at 1025, 1030 and 1035 respectively every day (but AFAICS not the DHW). The installers have not responded to my question but presumably it is some kind of anti-blockage routine. 2. System pressure has been varying wildly between 0.6 and 1.5 bar depending on what it was doing. The label on the 25 litre expansion vessel says it is pre-charged to 1.5 bar. I don't think this was adjusted by the installers so with a nominal water pressure of 1.0 bar it will not be doing anything at all. I have changed these round so with the system depressurised the expansion vessel is at 1.0 bar, and then topped the system pressure up to 1.2 when in standby. Now it works properly over the comparatively small range of 1.2 - 1.5 bar.

Just trying to reinforce yr advice - which I thought rather neatly put. Sorry if it sounded bombastic.

If you tell us what make and model you have got someone may come along with more specific detail. If it has performance figures you can read from the display there may be a flow measurement you can see. If it is designed like many to have a delta T of 5 deg C then the flow rate will be approx 3 litres/min per kW of output and you can either read the output power out from the display or infer it from knowledge of the performance graphs and the flow temp and OAT. Even if you know this how will you measure the flow through the secondary pump? Why has your system got a buffer in the first place, they are best avoided unless required to solve a specific design problem?

If it's equipment I installed myself or I am completely familiar with what to expect under the cover and have a good reason to open it while it is live/operating I might consider the risk acceptable. In other circumstances no, too much chance of someone else's hardware mods or wiring springing out or coming apart, with unpredictable results. Miscellaneous tips that have kept me alive for a few decades now include Keeping one hand in my pocket while probing connections above 12V DC. Not wearing a tie (or tucking it into my shirt) when near rotating machinery Asking permission before visiting the shop floor even in my own company and building works in progress even in my own house. Yesterday's hazards may not be today's hazards.

Aim for it to match the HP's internal circulating pump at max heat output so there is no net flow into or out of the buffer.

Was tongue in cheek. But as a starting point for fine tuning I think it has its merits, as quick to do and certainly a refinement on the "open all lockshields fully" approach if you have a variety of rad sizes and pipe run lengths.

Yes. The sodium-sulphur chemistry had the extreme disadvantage for EVs (as we now call them) that if you don't/can't maintain them hot enough to keep the sulphur molten they are completely bricked. For completeness I should have mentioned the bromine-based flow batteries, which I like as a technology as the dimensions of power (size of flow cell) and energy (size of tanks) are determined quite separately.