SimonD

I just assumed it was the same slightly yellowed conduit in the close up shot, but maybe not?

The Hive will go straight onto the black wall plate you've shown in one of your photos. You then need to either bridge the existing thermostat behind the stat - use a simple wago connector - or rewire elsewhere if preferred. However, if you're experiencing strange behaviour it's worth getting someone in to test the system as there can sometimes be other issues causing the boiler to turn on or off when it shouldn't - for example, a faulty motorised valve can sometimes cause a permanent live to the boiler. Process is install the hub > Install the receiver > Add the Thermostat > Complete online setup through the app. Hive customer support is very good and responsive to setup queries - they have a phone number and answer it too! HTH.

Your installer should either have done a self certification for building regulations compliance (through an appropriate competent person scheme) or registered the install through your local building control to notify them of the installation - that's down to him not you so your BC will want this, not just your commissioning certificate. With just an commissioing certificate you may have to pay BC for an inspection and sign off for it.

Time suggests that this approach, especially in older buildings build with stone rarely stands up to the hype and inevitably fails - it is incredibly difficult to detail this to ensure it doesn't fail, hence why so much conservation now proposes using materials that work with moisture. Are you keeping the external cement render, or is this being removed as part of the works? Can you share the full specification of the buildup proposed by the architect and the alternative proposed by the tradesmen? Your other option, which I think works best in exposed areas is to design in a break between the elements and the interior. This could either be a rain screen to the front of the exterior or a ventilation gap between the external wall and a sheeps wool stud wall inside. That way the sheeps wool/woodfibre buildup can buffer excess moisture without the risk of getting saturated if the exposed wall does get wet to the inside.

Ah, so he was spot on then. And people questioned his theories.... Yep, I know that one, but also parallel universe. I saw myself in a video about my build and knew it wasn't me, couldn't be, it was only 2 years ago but a lifetime. Then my wife says it was 8 years ago surely....because she's waited at least 8 years even though we didn't start near 8 years ago, rather I broke ground in Jan 2019. 🤷‍♂️🤷‍♀️ (me and my wife) As for what type of screws, only on buildhub could you find a 2 page thread on needing to see and feel the screws to decide before buying and spending loads of time on time on an internet forum to decide what type of screws to buy - now that's quantum mechanics for you...

I now use ForgeFast torx screws by default. Readily available from Toolstation at a good price and in large trade tubs.

Alpha Pneumatic Supplies sell full round head annular ring stainless steel nails suitable for 34 degree framing nailers. I think they probably do them for 21 degree nailers too. Brand is normally Beck fasteners. https://nailers.co.uk/ Usually best to call them.

It's 40C for ufh on the Vortex exactly as you say to prevent corrosion of the water jacket. For normal rads they recommend 70/50.

These are brick walls with a small infill extension having used dense blocks

It's been suggested to me to dot & dab the plasterboard over Gyproc Soundcoat plus parge coat where I'd planned battens with service void. How might I regret dot & dab versus battens as dot & dab is going to be both cheaper and quicker. Anybody else able to share some pros and cons?

I've used hardwall plus multifinish on high suction clay bricks. DIY and no cracks. The way I approached it was to liberally spray the bricks with water, let it soak in and then spray again before applying hardwall. With the hardwall, I keyed it and left to set, then wetted and applied the multifinish24 hours later. No need for pva or anything like that, just hardwall and multifinish.

Not in mine. Can hardly hear it now even when very heavy. Once we've got the final 50mm in the service void nobody will really notice. Ours is a good few hundred mm of Sheepswool insulation which is also a good acoustic insulator.

I doubt it. That's exactly what I meant in my post 😁 I studied 'proper' engineering at degree level too; aerospace engineering. I was drawn to aerospace engineering because I'd been influenced by members of a gliding club I used to fly at where they built their own planes, then got turned off aerospace engineering because it was so much about mathematical modelling and it just didn't inspire me, so I changed paths. I also worked at what used to be Foster Wheeler for about 5 years. I tend to think that a proper engineer includes those who can make, build and work on the stuff they're designing.

Engineer is quite a confusing term for a lot of people, but its formal definition from the Cambridge English dictionary does include: 1. a person whose job is to design or build machines, engines, or electrical equipment, or things such as roads, railways, or bridges, using scientific principles: - a civil engineer - a mechanical/structural engineer - a software engineer 2. a person whose job is to repair or control machines, engines, or electrical equipment: - a computer engineer - The engineer is coming to repair our phone tomorrow morning. So heating or gas engineer, for example, could technically be correct. I personally get miffed by design engineers who somehow believe they're above the engineers that work with their hands. I remember when I was taught how to use metal lathes and mills and my teacher was the head of apprenticeship programme at the AWE. He used to get looked down upon because of his dirty dungarees, until those very same engineers had a problem and were told by the senior design engineers to ask him for help to solve problems - the things he could design and make were incredible. They used to call him a technician.... Probably a little overkill, but I'm not sure I'd let a thermodynamicist anywhere near my heating system......much like how I wouldn't let a physicist anywhere near the design and building of my house.😉

@Kelvin and anyone else in Scotland - a paper that might be of interest highlighting ventilation aspects that affect both MVHR and natural ventilation performance: An assessment of environmental conditions in bedrooms of contemporary low energy houses in Scotland

I'm certainly no designer of passivhaus, but in terms of airtightness and ventilation, you need to look at them as seperate processes (while taking into consideration the ventilation in the house design of course). With airtightness you are looking to minimise as far as possible, the uncontrolled infiltration of air into and out of the house caused by a non-airtight fabric. Once you've done this, you have a more known volume of air that needs to be exchanged within the house to keep it healthy and comfortable. There are a number of calculations that can be used to predict average volumes exchanged through natural ventilation based upon localised climate and temperature differentials between exterior and interior that can then be used to understand the size and quantity of vents required. For example, a Passive Stack Vent would have a calculated diameter based on room volume and predicted pressure differences in order to make sure it neither over or under ventilates the house. Bear in mind here that because a naturally ventilated house does not have constant exchange, you need to consider the average ventilation rates, so there may be times when RH peaks above recommended levels. But this doesn't matter over short periods of time. Mitigation can then be achieved through strategic use moisture buffering materials. Another strategy is of course to supplement the natural ventilation with lets say a mechanical extract vent switched for particular peaks of RH or CO2, for example. In terms of building regulations, I'm in England and with highly airtight buidings I believe that the current regulations permit the use of natural ventilation providing there is a specialist design. In terms of Scotland, they seem to have been more prescriptive and shot themselves in the foot slightly I wonder. However, reading the document, it simply says that for low infiltration dwellings, mechanical systems should be used to "augment, complement, and/or improve natural ventilation." It then gives some examples of systems that can be used. In this instance, if a natural ventilation system is designed by a company specialising in these systems, then first have a discussion with building control and then secondly look to add a something mechanical. In any case the Sottish regs don't appear to mandate MVHR.

No figures as yet. Still to organise a test as I'm really, desperately hoping to actually finish the house this year. However, given the number of hours spent with airtight foam, tapes, sealants, liquid membrane, parge coating, airtight caulk and all the other myriad of products in this space I'm secretly expecting the result to be okay, but we'll see. It's one of the little projects on my list to build my own fan and test rig, so I might soon be on here asking for some help to do this.

I got mine from Rytons: https://rts.vents.co.uk/blog/products/acoustic-aircore-and-airliner-sets-background/

The CIBSE Domestic Heating Design Guide gives the environmental design temp of bathrooms as 20-22C so my assumption has been that 26-27C is an in use figure.

I personally don't give two hoots about whether someone chooses to install MVHR in a development and everybody is different in terms of what they desire and feel comfortable with in terms of temperature variation throughout their house. I respect your experience of your home, but what troubles me is the use of limited data to come to conclusions that are then stated as fact about how these systems work more generally, without backup from larger scale research. This often feeds into what I think is becoming a bit of a MVHR evangelism that assumes MVHR is the only benign solution whereas it's actually more of a marketplace with vendors trying to sell us more technical kit which may often be unnecessary and costly over the long term, - this is even the case with the utterly poor paper published by the passivhaus trust which @Kelvinlinked to earlier in the thread. So forgive me for a minute if I geek out for a while 😉 If you look at temperature variation in the Chartered Institute of Building Services Engineers, for example, the indoor temperature range between rooms can be as much a 10C. As I quoted above it looks like this: Bathrooms 26–27 °C; Bedrooms 17–19 °C; Hall stairs landing 19–24 °C; Kitchen 17–19 °C; Living rooms 20–23 °C; Toilets 19–21 °C Whatever your beliefs about the extent of temperature equalization in homes, the wider research shows that this kind of variation cannot be provided by MVHR systems and this is found to be an issue for occupant comfort (and control). So, in addition to the limited phrase you chose to hang your coat on in the research I quoted above it says: "Research into thermal comfort supports the view that occupants of free-running buildings experience a comfort band, which relates to external temperatures and is wider than that experienced in mechanically ventilated buildings [15,16,17,18,19,20]." (bold is my emphasis). But to take some quotes from other research: Title: Ventilation Performance and Hygrothermal Conditions in New-build UK Housing (link: https://core.ac.uk/reader/159923279) "Significantly less variation of temperature and relative humidity levels were observed in homes with balanced mechanical ventilation with heat recovery systems (p=<0.001)" Title: Thermal comfort and IAQ in super-insulated housing with natural and decentralized ventilation systems in the south of the United Kingdom. (Link: https://core.ac.uk/reader/220155974) "Achieving thermal comfort in winter is as dependent on the heating system as the ventilation strategy. Decentralized systems tend to create thermal zones with different temperate within a building, while centralized systems tend to provide uniform temperatures in all rooms. " Title: On the oversupply of heat to bedrooms during winter in highly insulated dwellings with heat recovery ventilation (Link: https://www.sciencedirect.com/science/article/abs/pii/S0360132316302657) "The results clearly illustrates that the supply-air temperature and the temperatures in the living room and bathroom have substantial effects on the thermal conditions in the bedrooms. A one-zone MVHR solution, with approximately the same the supply-air temperature to all rooms, has clear limitations regarding the provision of thermal comfort in bedrooms." With the last quote, just wait for the next iteration of MVHR which would unsurprisingly be multi-zone to squeeze even more money out of us, add yet more complexity to the system, and be much harder to commission, run and maintain properly. If you're still tuned in, I could go on because I have plenty more papers I could dig out, but then it would get a bit silly, if it isn't already. 😉 So I'll go back to my original claim with some more specificity in that MVHR (centralised) will provide more uniform temperature through the house than a decentralised natural ventilation system.

This is technically a retrofit so 1st floor is new build comprising a buildup of: Inside Interior timber cladding (to be fitted) Service void 11mm OSB - airtightness taped and no additional vcl 140mm stud wall filled with Thermafleece sheepswool insulation 50mm cross battens filled with Thermafleece (this layer is meant to be on the outside of the frame) Breather membrane Battens and ventilated cavity Cladding Outside Roof buildup similar but thicker insulation and thicker cross batten layer outside the joists. Plywood as ceiling finish Ground floor, mostly existing except for some new extension work: Inside Plasterboard/skim (quite a bit still to be fitted) Service void Gypsum plaster parge coat for airtightness Clay brick Cavity - varies 35-75mm Clay brick or sandstone (depending on which wall) 140mm Woodfibre EWI Lime based Baumit thin coat render Outside Ground floor suspended floor buildup: Inside Floating timber floor Cork underlay TG4 18mm OSB Joists filled with 150mm cellulose insulation Breather membrane Outside Interior volume is about 500m3 Occupancy is family of 4. Wife works mostly from home. I work a lot from home. Boys are around pre and post school minus evening sports clubs. 1 dog. No trickle vents anywhere. I've used acoustic vents through the walls so that I can have both cross ventilation through the house in two directions and have ventilation through each individual room when a window is opened. I have a centrally located staircase acting as a stack with two large tilt and turn windows giving ventilation out of the top of the house sited on the North face. We have large windows on 1st floor which are North and South Facing but use a designed large roof overhang which almost completely shades the windows from direct sunlight in summer. Solar gain right now is brilliant but need to work on something for late spring and autumn as had some heat issues during those periods last year but wanted to leave it a couple of years to see how it goes over time and work something out. I'm currently running with only one vent completely open in the kitchen area and had a peak of 907ppm CO2 in the TV area after everyone was watching TV for a while during the evening, now settled down to 780ppm as I write this. As the weather gets warmer I'll crack open a couple more vents. I've actually still got some to install on the ground floor.

But it isn't logic, it's based upon research and models used to design MVHR, especially in low energy houses like Passivhaus - see for example PHPP. Here is some research with plenty of references regarding variations in temperature if you want to read. As always the picture is more complex than much of the argument on this thread: Link: https://www.mdpi.com/2075-5309/3/1/61

I've just taken CO2 readings and currently in the space I've been doing admin most of the day it's hovering between 650-660ppm and downstairs it's about 430ppm. PM2.5 & 10 are at good levels and HCHO is at healthy level. Having just cooked some dinner and eaten, kitchen RH is 60% and downstairs is 55%. Even though I haven't used a lot of wets in the build, RH was much higher and is still gently on its way down, month by month. In terms of approach, it was mostly a research based with just a few numbers to crunch. I read a lot of material not just on ventilation but also on building fabric, finding some real world research showing the reduction in RH coming from moisture buffering materials that either simply temporarily store excess moisture and/or pass it through the whole fabric of the building (I'm avoiding the terms breathable and vapour permeable on purpose here due to common misconceptions). This fabric approach means that my ventilation requirement is significantly reduced (I can provide a link to recent research showing this in real world buildings if you want). I do wonder whether this is really important for well functioning natural ventilation. In terms of natural ventilation, I was dissappointed by a lack of recent good quality research on the subject specifically in domestic contexts so my starting point was The Handbook of Domestic Ventilation by Roger Edwards: https://www.taylorfrancis.com/books/mono/10.4324/9780080454580/handbook-domestic-ventilation-rodger-edwards In weighing up the evidence, Edward's book comes out reasonably in favour of natural ventilation. After this I found some books from the middle to end of the 1800s dealing with principles of natural ventilation including some specific figures re flow rates etc. These weresome of the best things I'd read. Putting this all together including current recommended ventilation rates, I found some papers using computational fluid dynamics to model air flow through buildings and rooms (almost entirely non-domestic) and drew upon these together with my local climate to size and locate my vents and stack (stack is just for cooling). I also had to make sure they're sized in a way that keeps BC happy. I spent a few years designing motorcycle exhaust systems so although now rusty, I got a reasonably good feel for fluid dynamics basics which, once you've played with some numbers actually becomes quite intuitive instead of computational.

Yes,it is possible, but I'm wondering whether you're missing the point in terms of how this works. You build for airtightness in both scenarios and then in each of those you design for a defined number of air changes per hour to maintain a healthy environment. This means that even if you build a passivhaus that achieves maximal airtightness, you're going to have to change the air in the house with something from outside, even if some of it is preheated using heat recovery. Why not? It's actually about occupant health and the principles were certainly backed up by the architect I spoke to who indicated a review of modern build methods (because they don't work that well in the context) and instead using principles developed and then forgotten from over 100 years ago. It's absolutely relevant to our undertanding of indoor air quality as well as the maintenance of human health. The reason the research is going on there is down to budgets, hence why more work is being done in the commercial construction field - do you think our major house developers would have any interest in funding this kind of research for their builds? Of course not, it's easier to just chuck in a mechanical system, just like defaulting to a gas boiler and using the loopholes to continue doing so.

It depends on how you define control as it works very differently. Essentially you design a certain number of vents to provide a sufficient flow of fresh air, using the natural pressure differences between the inside and outside of the house - e.g. still air within the house has a higher pressure than air moving across the surface of the house, so pressure equalization ensures a flow of air. You can also use the similar approach as per passiv stack vents. The difference is that you have to consider the natural variation in, for example, humidity levels. For example, whilst an MVHR system might be able to clear a peak in humidity almost immediately, it takes time with natural ventilation, but over time, research has shown it to be just as effective. What you then do is design the size and location of your vents to that you are highly unlikely to experience high flow rates, or flow that is perceived by inhabitants to be a draft. Additionally, it's helpful to make these vents controllable so that each room can be managed for its own environment. This is probably one of the biggest advantages of natural ventilation versus whole house MVHR in that you can design in controlled ventilation zones. I have an upside down house that has an 18C downstairs and cooler which is better for sleeping, whereas the living area is 21C. It's almost impossible to zone in this way with MVHR due to the way the system distributes air throughout the house. Interestingly, some major research in Europe found that in housing developments where MVHR failed to provide the forecast benefits, it was because inhabitants preferred to open their windows at night for the fresh air while sleeping! More and more research is going into using natural ventilation in commercial buildings due to the benefits it can provide for energy efficiency, user comfort, control and air quality. This includes hospitals following Covid where they've found old Victorian natural ventilation strategies for hospitals could have reduced transmissions amongst other things - I had a long conversation about this with an architect who designs modern hospitals and how they're looking back to older ventilation strategies to understand how they can improve hospitals.