Dreadnaught

In my experience its about 50:50. And to my surprise it is not only the smaller contractors/suppliers who will not provide a breakdown. Some of the big ones do too. I tend to especially avoid them. For the small ones, I suspect its a fear on the part of the contractor is that a breakdown will lead to cheese paring. Quite understandable. For the big ones, I suspect its a wheeze to try and conceal high margins. Personally, I prefer a clear breakdown and tend to avoid contractors who will not. But I have made exceptions for small pieces of work and where I felt the level of trust was high.

Nice solution. Slightly off topic, I am wondering how such a bracket could be mounted to a metal-framed internal wall (MF).

Pretty close, yes. My walls are indeed I-beams with Smartyply nailed on. The joints and nail-heads were over-pained with airtightness paint. Windows were foamed and double-sealed with decent tapes by me. Rooflight were upstands painted with airtightness paint. The joint between wall and roof was foamed for insulation and painted with airtightness paint. The joint between wall and concrete raft foundation was painted with airtightness paint. All penetrations were sealed with decent grommets and tapes by me and mostly also overpainted with airtightness paint too. The OSB flat roof was left un-sealed, with some slightly-worrying gaps between boards were clearly visible but there is a Bauder three-membrane warm roof above. Before the air test, I was ready to spray paint the entire OSB roof deck with airtightness paint (form inside) but fortunately it was not needed and Bauder's claim that their roof build-up was airtight has proven true. Above all, the building has a simple L-shaped form. And airtightness was managed by me personally, so I kept an eye on all the details.

Thanks @Nickfromwales. I have been looking online trying to work out what you mean by a box attenuator. Is is this sort of thing? Or do you mean the round ones, like this?

I chose felt and bitumen after talking through the various options with Bauder. My impression was felt and bitumen was a good solution if you have lots of fiddly bits on the roof. And I had 9x rooflight up-stands to detail in my flat roof. In my case, I was reassured by the independent (and unannounced, even to me) inspections of the installer's work by the manufacturer. Whatever system you go for, make sure you get a 20+ year transferrable guarantee from the manufacturer, not just the here-today-gone-tomorrow installer.

Another point of view. Don't do it. Put them on the same face. The reason is wind pressure. You want it to be roughly equal on both ducts.

Hi, I am in Cambridge. For my windows, I bought from IdealCombi. They have their office in Milton Keynes. The windows are made in Denmark and imported. For my entrance door, I am buying from Spitfire Doors. They are up-North but I have a personal contact with one of the top guys and he lives less than a mile from me in Cambridge.

Hi @Olu, welcome to BuildHub. What type of piles are you using? In my experience, some firms specialise. For example, the company I used only installed screw piles.

Will the "Building Safety Act 2022" impact us self builders? Do I need to rush out and buy a warrant for my part-completed new build bungalow? https://www.legislation.gov.uk/ukpga/2022/30/contents/enacted Section 142 requires a structural warranty, with penalties for non-compliance. Section 138 defines a new build home as "a building the construction of which began after the coming into force of this section" so I assume it won't apply to my build as it has already started construction. … but … this new legal requirement for a structural warranty might affect us in that all mortgage providers and conveyancing solicitors may routinely demand a warranty in practice, even more so than they do already. It may become the norm. Here is an article from Grand Designs magazine …

You make a good point. Yes. Thanks @joe90.

Yes, 1m-length flexible Ubbink-supplied attenuators on both the supply to and extract from the dwelling 👍

Thanks all. I am the sole builder on my project (with occasional hired help) so I can chaperone the MVHR though any dusty phases. And turn it off. My main wish in having the MVHR operational during the winter is for its benefits in retaining heat. I don't currently have any space heating. The dwelling is very well insulated. For example the roof has 200mm of PIR above the deck and 100mm of woodfibre insulation between the posi-joists beneath. I am hopeful that I can sail through the winter with a toasty house and just a tiny bit of supplemental heating from a Dimplex. It will be a good experiment on how the house will perform even before I add yet more insulation to the walls with a layer of insulated plasterboard. For mounting the MVHR, I am currently debating whether to mount it to the wall or to the concrete floor (220mm concrete raft foundation on screw piles). The Brink installation manual says (my emphasis): "The Flair 325 … appliance can be mounted onto the wall with the supplied mounting bracket. For a vibration- free installation, the appliance must be mounted to a solid wall with a minimum mass of 200 kg/m2. A gypsum block or metal stud wall does not suffice! Additional measures such as double panelling or extra studs are required in that case. On request, a mounting support for floor mounting (with the same minimal mass) is available." It now strikes me that bolting the MVHR to the concrete floor, and so without it touching the wall, is probably the way to a vibration-free and quiet life. This is despite the adamant advice from a friend, who has installed quite a few Brink units, saying that wall-installation would be fine in my circumstances. Brink can supply a handsome floor stand but its only 400mm tall. And I was planning to install it at the height of a kitchen counter so that my water softener would fit beneath. So I found myself on Google looking at ways to build a sturdy stand. And stumbled across steel slotted-angle … and then UniStrut. UniStrut looks like it could support the Forth Bridge but it looks rather nicer than slotted angle. Both seem quite inexpensive but only available from online stockists, not from the usual local hardware shops. I am continuing to think. Insights would be most welcome.

I would like to jerry-rig the MVHR unit to have it running over the winter months before I finally install it properly next spring. But how to mount it? I have about 6-weeks of cladding to finish off before I can turn to first fix. And then it will take me quite a while to get around to installing the MVHR unit properly. So realistically that won't be until next spring. I am very slow. I often camp on site as I work, treating my build as a (very well insulated) tent. The timber frame is insulated, weathertight, with windows and a temporary front door. Its also airtight (blower-door test of 0.47 ACH (n50) recently). The MVHR unit (Brink Flair 325) is sitting in its box waiting for me. And most of the ducting is already installed (with their valves). Hence, I'd like to temporarily set-up the unit and have it running over the winter months. - How to mount it? - The MVHR unit itself weighs 37 kg. - The walls are 240mm I-beam cassettes, filled with Warmcel and I know where the I-beams are located. - The external wall are currently bare 12.5 mm Smartly but will eventually be covered in 50mm insulated plasterboard. - I could power it from a 240V extension lead. - I could run the condensate drain to local external drain. Any pointers on how to do this would be gratefully received?

Minor comment. That door clash from the Kitchen in to the Utility Room and Plant Room would drive me nuts. Suggest to move the door from Kitchen along to the corner-turn of the units, near the hob, so closer to the outside back-door. This also deals with the issue that corner kitchen-units are tricky to design for usefulness. Move the window and units along in the Utility Room accordingly.

Here's the list for my ASHP (not installed yet):

Good point. I think the third bullet is a typo. It should refer to "Bypass temperature from dwelling". This is how the setting is referred to in the setting menu. It makes sense then. It being a typo is supported by the conditions in the manual for the Brink Renovent Excellent 400, as follows:

The broad "per sq.m" figures are rather general I find. Dividing it between first and second fix might give further insight and would make more sense to me. "Finish" for me implies a relationship with spend on second-fix especially. From your description I would say yours as high-spec but for M&E only. Anything else is difficult to tell. I also wonder if there is an aesthetic component to "low" vs "high" spec finish too asp received by a potential buyer. Does a high-spec finish have a certain look I wonder? ("Single story pavilion style house". Nice phrase. Better than the term I had been using for mine … "modern bungalow". I will steal it.)

On the subject of summer bypass, here are the rules for my Brink unit. I think most units work similarly.

@Nick Laslett, I just heard back from my SAP assessor. He said "Yes, the arotherm products are on the PCDB so we will use this data within the assessment". Edit to add: when I also asked whether MCS certification (or its absence) will affect the SAP result in any way, he said: "We do get an option to tick "MCS certified" but it does not affect the results in any way." So I think I am doubly content with that.

Thanks Nick. No. I won't be asking for this. I wonder if the Arotherm Plus ASHP will be available in the "Products Characteristics Database" for SAP. Does anybody know? I've emailed my SAP assessor to ask. Did you mean "aren't" rather rather than "are"?

Don't count on spending that £5k from the BUS. An ASHP install that would cost £6,000 will magically cost £11,000 under the bus ("there is so much paperwork don't you know"). I am buying the ASHP myself and will use a local air-conditioning engineer to install, 1- or 2-days work max. No BUS for me.

The foil you mention sounds like a likely culprit of the poor signal. In an Amazon review of a foil breather membrane someone commented on losing their Wifi signal once they had it installed. Signal of -68 dB is poor for 4-meters. You have mentioned the possibility that metal objects may cause interference. Alternatively, are there any devices in the vicinity that can cause interference at 2.4 Ghz frequency: microwave oven, old fridge, baby monitor, a neighbour using the same WiFi band as you? Do you have other Access Points (APs) in the house? Are you sure that the Ring doorbell is connecting to the Ubiquiti Dream Router and not another AP, which might be further away? This shouldn't happen but you never know. (I don't have any Ring products so can't comment on those.)

@Dan F, I see that the controls on the VRC720 allows for a given Zone to be controlled by a remote control. Could it be possible to connect your slab thermistor to a remote control in some way and then link it to a zone. That way the controller could target a slab temperature for the ASHP rather than a room temperature and so give you finer control. No use of exotic ebus commands required. Just an idea. @Dan F, with your background in software & technology, I suspect you're more ingenious than I.

Makes sense. Thank you. Sounds like it may be wise to constrain the cooling with a higher minimum temperature and perhaps a shorter cooling window. Not ideal, short of directing the controller to watch a sensor embedded within the slab (or the temperature of the return water in the UFH pipes).

I am following this discussion with great interest. I haven't bought my ASHP yet but was planning to use exactly the same setup as you @Dan F, including with a passive slab. I have had a play with the VRC720 online simulator and read the manual. For controlling the cooling, there seems to be a number of controls available. Do they not meet your needs? It is unclear to me if the cooling circuit uses weather compensation or if that is limited only to heating. If not, then how is the water temperature set in cooling mode? @m0deller, in MENU → SETTINGS → Installer level → Installation configuration → Installation → Automatic cooling. Have you turned this on to automatic and set the two temp setting appropriately? See below.