Triggaaar

These are some of the units I'm looking at: The cheapest, at £222, not including any ducting etc. It's not as efficient as the units I've seen others here use, but I presume it's still better than just having trickle vents? https://www.bpcventilation.com/komfort-d105-a And then a few units for between £770 and £890 https://www.extractorfanworld.co.uk/domus-ventilation-hrxe-mvhr-unit-with-summer-bypass-4556-p.asp https://www.bpcventilation.com/airflow-duplexvent-bv400 https://www.bpcventilation.com/silavent-hrxd https://www.bpcventilation.com/vent-axia-integra Some of these can do more than one room, should I wish to add to the system later. Has anyone got any experience of any of these brands, and any recommendations?

Thank you for the reply, it's much appreciated. I was thinking of a unit that had separate holes in the wall, as you suggest. I was thinking of something like this: https://www.bpcventilation.com/komfort-d105-a and not something like this: https://www.bpcventilation.com/vent-axia-tempra-htp I hadn't thought of just getting a bigger unit and only using two of the connections (1 in, 1 out), so I'll consider that too, thanks. Although I'd like to do as you suggest, and have the extract by the cooking area, and the inlet in the living area, I have an ideal location for the unit in the adjacent utility room, but much of the extension will be cut off from it by large supporting steels (supporting the room above). I can have an extract by the kitchen cooking area, and an inlet 4.5m away, nearer the entrance to the room (the entrance is a few metres after the door). It's not ideal, but I think I have to accept that I can't have the ideal situation, but rather I can hope to achieve something that's better than just having trickle vents in the room. Given that I don't think my situation is ideal, I don't want to spend too much on the unit. I'm hoping for something fairly basic, that does a reasonable job, and hopefully lasts well enough. Are there any actual units anyone could recommend?

The lack of replies is making me wonder if I'm going about this the wrong way, and no one wants to say anything? Is a single room MVHR the wrong solution? Thanks

Hi all I've been building a single story extension, which has enlarged our kitchen into an open plan kitchen/living/diner of about 70m2. The rest of the house is 100 years old, so fairly leaky (I have reduced some leaks, but I haven't been attempting to make it airtight). The room has no windows, but has large glass sliding doors (6.7m x 2.7m). These do not have trickle vents. From reading on here I think the airflow calculation I need to do is internal floor area * 0.3 l/s/m2. So 70 * 0.3 = 21 l/s = 75.6 m3/hr. The building control notes I've received say: Part F 1. Provide 5000mm2 background/trickle ventilation per habitable room and 2500mm2 to kitchen. 2. Provide mechanical ventilation in the Kitchen at a rate of 60 l/s or 30 l/s via a cooker hood. I'm hoping I can replace 1. (the trickle ventilation) with MVHR. I'm planning to have the cooker hood on circulate (just to remove the grease), and hoping point 2 is also covered by the MVHR. Could anyone advice is I'm on track with the 75.6m3 calculation, and what single room unit would be suitable? I'd like to DIY install, putting the unit above the false ceiling in the utility room, and running an inlet and outlet pipe over the new kitchen. Many thanks

Bump. I'd like to have a single room MVHR solution and I'll soon be doing the wiring, so need to decide where the inlet and extract for the MVHR go. Recommendations for the make and model of MVHR would also be much appreciated. Thanks

Cool, thank you. I'll assume that can go between lightweight block and the PIR that the plasterboard is stuck to.

Thank you. I'll start by getting a price comparison from my suppliers. If it is 25% more, then I'll definitely go for separates. Sorry, I don't know what foam bonding is?

Hi Peter One of my builders suggested I use 25mm PIR bonded to plasterboard, and dot & dab it onto our lightweight blocks, instead of fitting the PIR between battens. That way there won't be thermal breaks in the PIR. Why have you gone for battens instead of the method he suggested? Thanks

Although I know close to nothing about MVHR, I was thinking of having it. We have no trickle vents for the room, so I thought about a single room solution. I'd also consider a solution for the whole house, but I've had a brief look at other threads, which mainly highlight just how little I know about it all. I mentioned MVHR as a solution to the BCO and he started asking me questions I don't yet know. Does a single room MVHR usually have separate inlets and extracts, or are they sometimes together? Is the MVHR constantly on, or does it switch on when it detects the need, or what? Thanks

What if you change the extractor to re-circulate the air, instead of extract it?

Thank you. We'll have a direct external air supply straight into the burner. BCO is happy so far, but then he's not the one fitting it. Mmm. We're presumably not the first people to have a log burner in an open plan kitchen - how do people usually get around this issue? Thanks

Thank you all for the replies. I have no idea what the solution is.

Oops, yes, that was a typo. Thanks. Yes, I had actually thought about boiler inefficiency, but thought I'd let it go So if the heating was required to keep the room warm all year, then I could be saving about £2. But then the heating won't even used for half the year, so I'd be lucky to save £1. In other words, don't bother going for the 0.032 over the cheaper 0.036. How about the floor and roof insulation? I'm currently planning on 100mm floor, and 140mm roof (PIR 0.022). Is there much point in increasing either? Many thanks

Thank you both for the replies, much appreciated. I assume the 0.036 is 12.5% better than 0.032. It costs 81% more. But that percentage wouldn't mean a lot if it was cheap to start with. For that one wall, we're talking £70 more. Thanks. You clearly have the answer I'm looking for - now I just need to try and understand it The wall areas I'm taking about total 55m2. So you're saying it would be 55kWh / year. Do I just times that by the cost of our gas (say 3p/kwh) to get a yearly saving of £1.65?

We've just started our kitchen extension (foundations completed, brick and block about to start). The finished room will 7.5m wide x 9.6m long, 2.7m high (internal). The east elevation will be mostly glass sliding doors. to the garden. The south elevation will be brick & block with 150mm full fill cavity. Inside that we'll have 25mm PIR in between battens, and then plasterboard and wet plaster. The blocks are Celcon, with a thermal conductivity of 0.15W/mK. Half of the north elevation will be the existing walls, which are brick and brick, with 100mm cavity, which was filled some years ago with beads. The other half will be new brick and block with 100mm full fill cavity. Again with 25mm inside. The west then joins the rest of the old Edwardian house. The plan is to have a concrete oversite (on top of hardcore) and then 100mm of PIR rated at 0.022W/mK, and a warm roof with 140mm of the same PIR. Do those thicknesses sound alright? I know we'll meet building regs, but I don't know if it's worth doing any more. Re the cavities, do you think it'll make much difference whether the 100mm cavity wall insulation is 0.036W/mK or 0.032W/mK? Since the insulation is thinner than the opposite wall, I wondered whether it would be worth putting a slightly better insulation in. It's not much more expensive, but then the difference might be so negligible it's still not worth it. Thanks