jack

Not sure about the Zehnder, but I'm sure several members have installed VentAxia units. Google "vent axia buildhub" and you'll get loads of info. You could try the same with Zehnder.

This is one of the reasons our architect gave when we asked why the per sqm rate didn't fall on larger houses due to economies of scale. That and the fact kitchens and bathrooms are the most expensive rooms to build, and larger houses tend to have more of them, taking up more floorspace per room, with more expensive tiles, appliances, worktops, etc. Looking at your other post, part of the problem may be that you're doing a barn conversion. Perhaps counter-intuitively, converting an existing structure can be more expensive - sometimes considerably more expensive - than knocking down and starting again. There are a lot of unknown and potentially pricey risks involved with conversions, plus it can be a lot more effort working within the constraints of existing structures even if there are no such surprises. One way to approach it might be cost plus pricing: This gives the contractor some protection against unexpected costs, meaning they won't be padding their quote to cover expensive potential unknowns. The risk, of course, then falls to you, but that shouldn't be an issue if you can afford the higher rates being quoted at the moment. I imagine you'd do need to be a lot more on top of what the contractor does day-to-day if you're paying like this.

I believe the drain at the top dumps water into the (much larger diameter) downpipe at something of a tangent, which causes the drain water to form a film over at least a reasonable proportion of the inner wall of the downpipe. The drain and incoming water are counterflow, which would set a theoretical maximum of 100% - not that you'd get anything like that in the real world, of course. Based on the admittedly basic test I did (temp of water in the trap after a shower) above, I don't think you lose that much heat to the tray etc after everything warms up (first few tens of seconds, maybe). The installation diagrams linked above show several installation options, all based on ordinary hot-and-cold-fed showers. To reach the higher claimed efficiencies, you have to connect the unit to preheat both the cold feed to the shower(s) (up to two is recommended with the model I used) and the cold feed to the DHW tank. Agreed that adds to the plumbing faff, but it's a couple of extra runs of pipe and you only do it once. Of greater concern might be how long the pipe run with preheated water needs to be to get to the shower and the cold feed to the DHW tank.

I mentioned that her timing was terrible and she said that "at least the house is clean" and asked if I wanted to turn to dryer off. I mean, we did discuss this yesterday, so she was aware it was going on.

My wife just turned on the dryer. And the washing machine. I am not joking.

As 5pm ticks over, we're using something like 1.3 kW, which is more than we've used all day. I'm working on something urgent for a client, so I can't turn my PC off. Also, my wife has suddenly decided that now is the time to get the house ready for family coming over on Friday(!), so there's cooking, vacuuming and god-knows what else is going on in the background. I know better than to object.

I always use a desktop when photos are involved, so perhaps yes?

I'm the same, but I don't think I'm alone about being serious about what goes on in my house. You don't need to start aggressively. Ask nicely once, instruct more firmly the second time, and then all bets are off if it keeps happening. 50 Meg is fast. We typically only get 32-34 at best, and I don't think that's at all unusual. What I don't understand is how a 50 Meg connection is being dominated like this by one device. My kids have had an xbox for 5 or 6 years and I can't remember once having any issues with it hogging bandwidth. Admittedly they don't do a lot of games downloading, but still, I'm surprised it's never been an issue based on your experience. Still, it seems like something could/should be handled on an out of hours basis. That's the main thing. I took from your earlier post that words hadn't been had, which is what I was reacting to.

I suppose it depends on how interested he is in continuing to have an xbox at your house. Why did you time him for that long? At 10 mins, get your daughter to tell him he needs to get out of the shower. If that fails, turn the water off at the mains. I'm a complete pussy about a lot of stuff, but I won't accept disrespectful behaviour from guests in my home.

@ProDave, I'd have stopped looking for a technical solution once it became clear that my hardware couldn't do traffic shaping. Tell him to only download at times when others aren't using the internet. He can change the settings on the xbox so that downloads don't happen automatically.

I'm not aware of there being limitations on new users uploading, plus he managed to upload one yesterday. Size seems fine. Try going to where you have the file saved, then dragging and dropping them from there into the post where shown in the editor:

Yeah, fair enough. Now that I think about the actual time slot, 5-6 pm isn't a great time for us to be reducing energy either. We rarely cook before 6, there's no hot water heating happening at that time of day, and the ASHP isn't likely to be doing any heating at this time until it gets colder. I haven't looked back further, but yesterday we used something like 0.8 kWh between 5 and 6. Short of stopping work for an hour and turning my computer and monitor off, I'm not sure what other easy wins there are. I'm not switching off the fridge or the freezer, as knowing my luck I'll forget to turn them back on again!

What's happening when you try? Are your pics too large (as in file size)?

Same here, but trying to use less during that period is still the right thing to do.

Very much wish I'd gone with CC drivers (using a DC power supply) to begin with. I thought they were expensive at the time, but once you factor in the cost of mains dimmers and a driver per fitting, I'm not sure there's that much difference.

I have one of Mike's 16 channel DMX dimmers. Great quality at a decent price, and as you say, supporting someone local.

Brink (I have one) are more expensive than the Vent Axia equivalent. They're generally considered quiet and good quality. I had a minor issue with some internal water build-up in mine and Brink sent out an engineer something like 3 years after we bought the unit, so I can't fault their support. I know others on here (maybe @Nickfromwales?) rate Brink highly as well. The airflow rates quoted above are overkill imo. They're quoting for 5 bedrooms, 7 wet rooms, and 12 occupants (perhaps that's what you'll have, but it seems unusual compared to typical British living arrangements). From memory, the building regs rate for our 289 m2 house with higher than average volume was 180 m3/h, which in practice is far more than needed. We tend to run it at 80 m3/h year round, and that leaves us with perfectly fresh air (two adults, two teenagers, and a dog). Edited to add: I forgot to mention that some of the Brink units are rebadged under other brands. Envirovent (which might actually be a Brink sub-brand) and Ubbink are two that jump to mind - I think there used to be others. It might take some comparing to make sure you're getting all the same features, but I suspect there may be savings to be had if you can find one of these rebadged units. It's generally pretty obvious from the pics.

Bloody Nora that's a ridiculous amount of money, even if commissioning were included. We had our electrician wire our MVHR unit in (literally just a single circuit with appropriate RCBO), and had the plumber install the appropriate drain (again, very little work). My wife and I installed the manifolds and ducts ourselves. From memory, it was basically two easy days of effort. For the £7k quote, even two guys at £350 a day (a ridiculously high day rate) would suggest 10 days onsite, which seems crazy. I doubt that your builder will have any difficulty. That's an unusual problem to have. Unless it's very high volume, white noise (and other random noise types - pink, etc) tends to quickly fade into the background for most people. It's usually more intermittent or repetitive sounds that cause problems. Even ordinary window vents surely let in far more objectionable noise than any decent, properly installed MVHR unit will cause? Nevertheless, noise shouldn't be an issue with a suitable unit, properly installed. We've been running a Brink Excellent 400 for the last 7 years. It's very quiet. We tend to run it well below the calculated building regs rates, which are massive overkill. At those rates, it's completely silent, to the point that I can't tell it's even running unless I stick my ear right near the duct. Passivhaus-certified units tend to be more expensive, but on average are likely to be quieter than non-certified units. I seem to recall that the Passivhaus Standard places restrictions on the noise output of MVHR units. The two main sources of noise in rooms with ducts are fan noise and moving air. You can reduce the former by including silencers between the MVHR unit and manifolds. You can reduce the latter by making sure airspeed in the ducts is kept low. This can involve, for example, doubling up duct runs and using larger inlets/outlets (e.g., long slots instead of the small "mushroom" type), which will reduce the noise of air entering/leaving the room. Make sure that outlets in places like the bedrooms (where you're likely to be more aware of noise) are as far from the bedhead as possible. We do currently get a little bit of noise from the unit itself. The fans, in particular, are starting to make a small amount of noise after 7 years of continuous use, and I wonder whether the bearings need replacing. Careful siting of your unit will help mitigate the impact of the small amount of unavoidable noise generated by the unit. I've heard rumours of this too, but I suspect they're more related to wide-bore branched (rigid) systems that are more typical with American ducted heating and aircon than with the radial systems installed with most MVHR units these days. I don't recall anyone on BuildHub reporting this, despite a large number of us having installed MVHR in our houses. Perhaps avoid the rigid systems is you're really concerned about this.

It depends on your pipe spacing and power output requirements. I've run my ASHP at 25 ºC with pipes at 200 mm spacing, with weather compensation pushing that up to 27 or 28 ºC in very cold weather. The house has been perfectly comfortable with only that heat output. That's with a polished concrete slab on the ground floor and no other heating anywhere else. (To be fair, the bathrooms do get a little chillier than desirable, so we've installed some electric heaters to take the chill off in the morning.) The mixing valve on the UFH manifold is set at 30 ºC and is really just used as a safety cut-out in case a valve fails somewhere in the setup and the ASHP tries to deliver water intended for heating our unvented cylinder to the UFH circuit. Your calculated 14 W/m2 isn't that much more than the Passivhaus limitation of 10 W/m2, so I can't see it being a serious issue.

A couple of years ago, running the UFH continuously (in the sense of leaving it to look after itself - it didn't literally run continuously) through winter, we paid around £1000 for the year. That's for a 289 m2 house with decent insulation and airtightness. We do have a lot of PV, so that will have significantly reduced summer electricity costs (eg, we'll have hardly used the ASHP for hot water at all during summer due to the immersion diverter heating the tank with excess solar power). We've now switched to Octopus Go, which gives us 4 cheap hours of electricity overnight. With our 5 kW ASHP having to do DHW duties during that period as well, it's inevitable that some heating will need to take place outside of that time during the coldest months. When it gets properly cold, I'm considering using the immersion to provide a supplementary heat boost to the DHW right at the end cheap period. Although it has a COP of 1, it's still cheaper running the immersion during the cheap period than running the ASHP during the expensive period. One of the issues we face is a fairly dumb interface for the ASHP. I've started implementing some logic via our home automation system, but it's tough going with just a dry contact to call for heating and a temperature sensor for the DHW.

Hi @Euan21 I'm closing off this thread in view of the discussion around the same question (with a bit more detail) here.

All fully open. Might as well minimise restrictions so the pump isn't working so hard.

The mechanical side of our MVHR installation was one of the very few things we entirely did ourselves. It was extremely easy. We had a layout from the supplier, but when we went to do the installation we realised that the open-web joists allowed much shorter routing in some places, by going on the diagonal. In terms of tips, I'd suggest making sure that there are no "closed" routes. We had a minor scare when we realised all supporting joists around our stairwell were solid, even though half of them were shown as open-web on the plans. Thankfully, the savings we made pulling some of the runs on the diagonal left us with more than enough to take a slightly longer route around the stairs to reach the affected room. For pulling through the ducts, you really need two people, as they tend to catch on edges of joist webbing. Where your ducts join the manifold, you should ideally have a reasonable length of straight run beforehand. That is, don't have a duct bending right before the manifold. It makes them harder to join to the manifold, and can really obstruct the paths of adjacent ducts. Think carefully about whether manifold position can reduce your runs. In our case, moving the manifolds by a few couple of metres saved us multiples of that distance in ducts, because nearly all of the runs went in the direction we moved the manifolds. For example, if you have 10 ducts coming out of a manifold and they're all going in the same direction, moving the manifold 1m in that direction saves you 10m of duct. You might not have the option to do that, but we had the space and it worked well. Think about how you're going to support the ducts, as they shouldn't have significant dips along their length. It can be as simple as some offcuts of wood bridging wider gaps, and/or using something like leftover breather membrane screwed to something above to provide support.

Fewer thermostats (perhaps only one), no need for per-loop actuators, no need to worry about changing flow rates as different numbers of zones are calling for heat, possibility to avoid a buffer tank (because you're always using the whole volume of the UFH loops). It works fine in a well-insulated house. We've been running ours like this for 7 years without any issues. If you really prefer having a zone a bit warmer/cooler than the rest, you can just manually adjust the flow rates on the manifold. I just run all of ours flat out though.

A more important one, which I mentioned in another thread, was a fan heater that my son left running full bore overnight in the garage gym. The gym sometimes isn't used for a few days at a time, so that could have been an expensive one. I only noticed it because the display screen for our smart meter is in my office, and it was showing high and persistent energy consumption despite the fact I knew nothing significant should be on.