sharpener

I imagine so. Noise reduction was a claimed advantage of the top exit on the original RED HP. But it's probably goodbye to the patented RED hw tank. I was curious as to why Jason Cassells was simultaneously a director of Harlequin Plastics but this would explain it. Lots of other interesting profiles of their people on the Ocotpus web site too. So it's a bit strange I can't find any mention or pics of the new HP! Even more strange that the entire RED web site is still up more than a year after the Octopus takeover.

Not so much of a problem with a 6kW unit (bigger sizes are said to be in the works).

... will be available from December and is claimed will be installed for free (after BUS) if you do not need new rads or a cylinder upgrade. Presumably since it is made in NI it is a spinout of the RED acquisition. Their own web site has not been updated yet but there is this and more or less identical coverage in many other publications.

Not as such. I plan on having a 200 litre thermal store so that the bedroom rads will run on off-peak heat. All the returns will go back to the HP via its bottom tappings, to give more engaged volume for defrosting. Installer seems happy with this and is considering my other suggestion of having a perforated baffle above that layer to improve stratification when the store is not in active use. We are currently awaiting Vaillant's final say on the schematics. They will do one-offs for individual systems but are not very responsive, I would say first try and find an installer who believes in your ideas. V. will give you a few suggestions if you use their find-an-installer scheme.

Yes I worry but after installing the Evohome BRD91 in parallel with the original thermostat on the landing I have kept it as a frost stat set to 5C. The system is programmed to come on 0200 - 0500 if this calls for heat. And I can control the system remotely as well. In other houses I have left the system running on deep setback just like you @JohnMo. Vaillant recommend using glycol rather than antifreeze valves, this gives total peace of mind and you will not come home to find all the coolant on your driveway. Unlike e.g. Daikin they do not waste a lot of electricity keeping the compressor warm either.

I am planning something similar as I too have an Evohome setup, my house is long and thin and like you there are rooms we do not use much. However my plan is to wire the existing BRD91 to the Vaillant VR71 to act as an overriding call for heat. Doing this would allow you to shut the system down properly when you are away and re-start it remotely before you return. I think balancing the flow through the two pumps might work as you describe but it is notoriously difficult and relies on quite a number of factors to get right. Using an automatic bypass valve with a volumiser on the return flow might be a lot simpler. I am not sure you will get away without a sensocomfort control, much of the functionaility seems to be in that not the HP itself. There is a simulator here and a configuration tool here, which may help. There is also an Arotherm Plus fb group but I have found it not very tolerant of this kind of query, the general Heating Design group is better and there is much discussion there of buffers. Heatpunk website has also got useful info on what can go wrong when you use them, generally they are to be avoided on thermodynamic grounds because the mixing causes an increase in entropy which results in irreversible losses. There is also a Caleffi site discussing different buffer topologies. HTH

Yes. I wondered if mine was using the aircon to keep the battery cool on Monday's journey. Difficult to say because the range readings are not always consistent. But the range is overall much better than it was in winter when I am pretty sure it uses it to keep it warm. Another long hot drive tomorrow, I might be more adventurous in the use of the aircon. Fortunately the LiFePO4 chemistry in my house battery is much more forgiving and doesn't need all the mollycoddling. But its energy density is nowhere near as high.

so on that assumption a 6 hr journey would use 9kWh which is >10% of the battery. Problem solved! The Air Balloon pub was being demolished when I passed by in ?April this year.

Yes, the rotating shaft seals are the Achilles heel of car aircon. Was once quoted £800 to replace the seals and re-gas with new(er) legal refrigerant on an old Volvo. You may find yr "long distance BEV with a/c" becomes a short distance BEV once you actually turn the aircon on. It shortens the apparent range of mine by some 10 - 20% so we did not use it a lot on Monday despite the OAT of up to 28C. In fact though we arrived home with 66 miles to spare so might have had more benefit from it in retrospect.

On further thought this may not work. At wavelengths much shorter than the slat width it might be OK (say 4 ins == 3kHz) but around the 3kHz mark it will act as a diffraction grating and might give you quite marked side lobes (think Yagi antenna) - you could model it and see what you get! For reflections at significantly lower frequencies I think the detail will be unimportant and the orientation of the overall screen surface will be dominant. So it very much depends on the nature of the noise. I remember reading somewhere that Vaillants have an annoying whine resulting directly or indirectly from the inverter drive, I will be asking my prospective installer for a reference site with the same model to check this aspect as well as for general comparison purposes, did you do the same?

As well as Newark you could try Gledhill, their slimline range is only 475mm dia cf the normal 550. If Vaillant would accept a slight reduction to 90 litres it would only be 976 mm high as well.

Since you are going to be buying a lot of quite expensive cedar for this your local friendly timber yard will probably rip 4 x 2 into two bits of triangular cross section for a nominal charge. Or you could use arris rail section in treated softwood and stain it to match. Or use fence boards, which are already slightly tapered, and put packing pieces under one edge of them - it's not as though it has to be structural beyond staying upright in the wind. IME this kind of construction works well. The trouble with it out of doors is that almost anything that is a good absorbent for sound is also a good absorbent for water. Though there are some specialist materials which are not badly affected, there was a thread about this in the spring.

+1, it is what I said days ago. I have in the past had a water tank in my bedroom cupboard and it was unnoticeable. If the buffer is technically necessary and that is the only place it can go then it is a simple yes/no decision for you. If they fit it then if it does make a noise then you have a solid reason to get them back and fix it but if they don't fit it in the first place you will never know and not make any progress.

If there is scope to cant the screen outwards (i.e. rotate anticlockwise in plan) then any reflections would miss the window on the right. In other respects I think you have a good chance of it working. The hit and miss screen will give rise to multiple internal reflections between wood surfaces which should absorb a lot. I don't think scrap iron would be very effective, you have the mass but OTOH the surfaces are reflective and it has virtually no internal damping. Now if only I could remember the handle of the acoustics consultant who was posting on here in the spring...

If you have got a working (boiler) system to begin with you can learn a lot by comparing how long it takes the individual rads and their return pipes to heat up. Ideally they should all take about the same amount of time, then the flow rate is proportional to the volume of each rad which if they are of similar construction will be directly related to the heat output rating.

Even the Vaillant installers themselves don't seem to know about this. Scroll down to the 19 Aug posting by Rob Samuel Kinghan on this site. Total tale of doom and woe, not helped by them also installing a volumiser as per a Daikin schematic! Fortunately they agreed to move it but I doubt there was much profit in the job after that.

Not quite an integrated heat meter but a useful intro here. I used to work for the firm that developed the first u/s gas meters. You have to make assumptions about the flow profile across the pipe, I don't exactly know how they do it.

If you mean the static head between the one and the other that isn't the right figure, you need to take it from the excess head graph for the circulating pump in your HP.

Pressure drop is indeed an important consideration, see this link.

Unfortunately there are good reasons why in a small house you might need a buffer to achieve Vaillant's minimum system volume requirements. Without knowing more about yr existing HP model (type and size) and the proposed replacement it is not easy to know why they are proposing a buffer where none was fitted before. As @JamesPa and I have found, Vaillant are rather inflexible about these things. The installers will only fit systems that conform to their approved system schematics (drawings) and will not depart from them for fear of (i) warranty callouts (ii) loss of warranty cover (iii) loss of their approved installer status. I do not think you need to worry too much about noise from the buffer tank, it has no active components or moving parts. In any case the installer should be able to programme the system so it does not run at all at night. If indeed you plan to run it at all, I am puzzled by your statement that you will not use it for heating, is it for hot water only then?

No it is an expansion vessel.

You would not want the complication of changeover valves in the refrigerant lines or the possibility of refrigerant being transferred from one circuit to the other. So I think you would need two separate coils in fancoil unit C, then pump B (which I assume is the more efficient one) could supply them both when demand is low. Don't know how you would control it. Commercial refrigeration specialist might know, having many units in tandem operation is fairly common, usually they are the same rating and are operated in a cyclic sequence to equalise usage (like the mulitpley redundant pumps in a water treatment plant for example).

Now that Octopus have decided not to require MCS accreditation if you want to sell them your surplus PV do we think the same will happen to the requirement for MCS and heat pumps? Of course they are not involved directly in BUS except as an installer but I suspect they may have quite a lot of clout.

+1, we have 210l, it is fine for four showers in the morning when we have visitiors. I think the key is good stratification, will not be so good with a horizontal cyl.

OTOH I am also with WPD and they required my 5kVA battery inverter to be limited to 3.68kW. Which is why my second lot of PV panels is wired direct into the battery through an MPPT so they don't restrict them as well.