jack

Should have said: it's 99p until the end of today.

My architect recently posted about the following book which has just been released by someone he knows: https://www.amazon.co.uk/Right-First-Time-Architects-Successful/dp/178133420X/ I can't comment on whether it's any good, and I'm a bit late in the process to be reading such a book, but it might be worth a look if it sounds of interest.

Correct. I was concerned about energy wastage and overheating rather than cost, but have since learned that these probably aren't large issues. The two main problem areas are our kitchen sink and one of the bathroom sinks. It takes about 45 seconds for the water in the kitchen to start getting warm. If I'm in a hurry and can't wait I sometimes end up using the hot water tap. The bathroom sink is an oddity. The shower in the same room takes less than 5 seconds to start running warm. The sink takes nearly a minute. They're both very close to the plant room underneath, so I have no idea what odd route the sink plumbing must take! The other place I'd have included this is the downstairs toilet, which takes over 30 seconds to start warming up. No-one will wait that long, so it's cold water for hand-washing there.

I think that every time I walk past my ASHP when it's in cooling mode and I feel all that lovely heat being lost to the atmosphere. Even less feasible is using cold air from heating to make refrigeration more efficient. Slightly more feasible might be to divert some of the cold air in summer to keep a larder outside the heating envelope cool.

Not exactly the same as mine on the inside, but possibly some similarities. I'm heading out for the evening now, but if I have time this weekend I'll try and take some photos of the inside of mine to show where I thought it was leaking and what they did to (allegedly, we'll see!) solve the problem.

I had a very similar problem with my Brink Excellent 400, although I don't recall whether I posted about it. Similar location, and similarly no drain designed for that area (although I think that different versions of this model may actually have their condensate drain on this side, looking at the shape of the mouldings). I have a vague recollection that Renovent and Brink have some sort of relationship - might be badge engineering of some sort going on. [Just re-read your post and noticed you mentioned this yourself!] To me, it appeared that condensation was working its way along joins in the internal insulation mouldings after tracking down the side of the heat exchanger. I eventually contacted Brink (in the Netherlands) about it. To their credit, despite the fact that I'd had the unit for 4 years, they sent out a local guy to take a look. He applied a thin strip along the ridge that the heat exchanger sits on, which has flaps that stick out just enough to direct any condensate over the joins and into the drainage area. I haven't noticed any issues since then, although to be fair we haven't had cold weather since the fix. Do you have photos of the inside of your unit?

Especially where a PH has a high time constant (ie, takes a long time to change from whatever temperature it's reached), there's rarely a need to deliver heat quickly. The house tends to stay at around the same temperate with only small amounts of heat. As an example of how thinking needs to change with a PH, our plumber was concerned that the long time it would take our "undersized" (5kW) ASHP to heat up our DHW cylinder would result in the house temperature falling uncomfortably in very cold weather. In reality, it takes a full day without heating to notice much of a change. Certainly nothing noticeable happens in the couple of hours it might take to heat the cylinder.

That's great news. About the best you can hope for out of the inevitable issues that arise.

Same with the one we saw. I was really surprised, given that when we were looking at MVHR units, Paul was just about the most expensive option. That said, this was around 6 years ago, and I think the unit we saw had been in place for several years before that. I have no idea how well it had been installed or maintained. I know others who've had Paul units installed who are very happy. @HerbJ is one, from memory. Our Brink is extremely quiet when it's on its standard background setting.

I stand corrected!

We have Enphase microinverters (per-panel DC-AC inverters, rather than DC-DC converters like SolarEdge), which offer similar advantages in shaded situations. Another advantage microinverters offer is better generation in low light. In a conventional inverter string, the string as a whole needs to generate a certain amount of voltage before the inverter starts working. With microinverters, each panel needs to generate a minimum voltage. In low light conditions - early morning and late afternoon, for example - a microinverter-based system will start generating earlier and continue generating later than a conventional string inverter. I don't know how much this adds over a year, say, but I seem to recall it was good a few percent. Worth looking into whether optimisers do something similar.

Wow, that's not nice at all. All the best for getting it sorted. I do wonder when trades do work like this how they think people are going to react.

We have an ASHP and are very happy with it. I'd need to check, but I think our electric bill for the last 12 months was around £900 for everything. That's for a 289m2 house in the south of England, U values 0.10 floor, 0.11 roof and 0.12 walls, with 0.6 ACH airtightness, and with us paying very little regard to energy saving behaviour (eg, my wife tumble dries virtually EVERYTHING). We do have 8.5kW of PV, and that will certainly have reduced some of what we take from the grid. During the sunniest months, I suspect we hardly use any energy for water heating during the day. One day I'll get around to measuring some of this stuff!

We have two types of brick slips on our house, both extruded. One is an engineering brick. Unfortunately, the extrusion and firing process has left very slight vertical waves that look odd in certain lights. Also, the corner slips are an entirely different colour to the main slips. Unfortunately, the person installing them didn't notice or didn't care, and by the time we realised it was too late. The other was just the cheapest slip they did, because it was going to be painted white. Unfortunately, several of these were noticeably bent, but again, we didn't find that out until they'd been installed. I'm sure extruded slips can be done properly, I'd just look carefully to make sure that what's delivered is exactly what you're expecting. I agree, and this is what we'd have specified had we known a bit better (or thought more carefully).

More often than what though? You need fresh air one way or the other. You can bring it in with or without heat exchange. Using heat exchange means less energy consumption for a given rate of ventilation. Interesting, because a Paul unit installed in Totnes was also the loudest MVHR I've ever heard.

A 1dB difference is detectable in A/B testing, sure, but it will make zero practical difference to perceived loudness between two potential real world installations. My point was - and remains - that 3dB doesn't involve a perceived doubling of loudness. Nothing like it, in fact. It takes a 10dB increase for the perceived volume to double. In this case, the difference is 14dB, which is a little more than a factor of two in terms of perceived volume. What's probably of greater interest, and impossible to know without listening to the units in the flesh, is the spectrum of the noise. Some types of noise are perceptually far more intrusive than others. White or pink noise, for example, tend to very quickly fade into the background. Indeed, some people use white or pink noise generators to help them sleep. It's spectral peaks like case resonances, bearing rumble, "beats" from fans, and the like that people find annoying. It's therefore possible that two units with the same dBA figures could have noticeably different levels of perceived noise. We have the Brink Excellent 400. It's fine now it's boxed in, but I was very surprised at how noisy the unit itself was on boost when it was out in the open. To be fair, it's pushing a huge amount of air around at that setting, the noise of which I think would be very hard to suppress. We get very little sound through the vents though, even on 100% power. Was this in a house in Totnes, by any chance?

3dB is a doubling in the amount of energy, but the difference in perceived volume will not be anything like double. Most people can barely perceive a 3dB change in an ordinary setting. @jfb is right. Doubling of perceived volume takes a roughly 10dB increase (depends on the type of noise and other factors).

Even if there's zero cold water being used at the mixer, as long as the system is plumbed to preheat the cold feed to the tank, you'll still recover perhaps ~50% of the outgoing heat. Ah, yes. We were lucky that we were able to have the two most-used showers back-to-back, and close to the main vertical stack. The pressure drop can be planned for, but all the extra pipework will mean that the system will take more time to come up to full efficiency. Not the end of the world, and the longer the shower, the greater the overall efficiency. It's probably at its worst for people taking very short showers, especially if you aren't having people jumping in one after the other. Re: softeners, to minimise pressure drop, make sure that the connecting flex connectors are actually full bore. Our "full bore" 22mm connection kit came with flex connectors that had 11mm restrictions at both ends.

I don't know about the difference between units, other than that the longer vertical ones are quite a bit more efficient than the horizontal under-tray type units. From memory, the one I bought recommends connecting up to two showers per unit. We have three upstairs showers, and just connected the two that are used most often (I think the guest shower's been used two or three times in four years!) I personally think you'd get away with connecting even three showers into the system.

We have them inside and out. We used the system that has vacuum formed horizontal guides glued to cement board. I really wasn't happy with the results, but a large part of that was the tiler and the poor quality slips we were supplied with (some are bent like bananas!) If care is taken with installation, and/or a better system used, I can't see why they shouldn't look fine.

I've had one for the last 4 years, installed with an ASHP. This isn't accurate. First, most people use their ASHP to heat water in the tank to at least 50 deg C (@ProDave takes his to 48 deg C, and that's the lowest I'm aware of anyone on here using). Most people like their shower water to be no hotter than around 43 deg C. So you need to add cold water to bring the temperature down. But guess what - if you add some of the heat from the waste water to the cold water before the mixer, then you can use a higher proportion of that (preheated) cold water to achieve a given temperature at a given flow rate. A higher proportion of cold water means a lower proportion of hot water, hence energy is saved. Even better, to get the nearly 70% efficiency you mention, the system needs to be connected so that the preheated cold is supplied to both the cold side of the shower mixed and the cold feed to the DHW cylinder. Higher temp water into the cylinder means less energy to heat it to the final temperature. In short, the numbers work even if you're using a lower temperature heat source like an ASHP. In fact, I'd argue that waste water heat recovery is particularly suited to ASHP-based systems. There's a big difference in the amount of hot water that can be supplied by a tank at 50 deg C (ASHP) and a tank at, say, 75 deg C (gas boiler). In most households, showers consume a large proportion of all generated hot water. I'd estimate in our case that showers account for at least two-thirds of our usage. Waste water heat recovery increases the effective amount of hot water you can get out of your DHW cylinder. That lets you either use a smaller cylinder, or go for a standard cylinder and get more time in the shower.

@Brickie, any thoughts?

That's what I thought. No idea!

On a slightly lighter note, my parents in law told me that the guys that burgled them last year were caught. They admitted to 40+ burglaries and have been sentenced to several years' jail. Interestingly, both of the burglars have had property seized and sold. The result is a not insubstantial payout to my in-laws. I was quite surprised by this - I assume it's something to do with the proceeds of crime legislation, but I didn't realise that money was distributed to victims.

I agree with all this except for one thing: we have no idea what the builder is actually thinking. He may well be on target to deliver exactly what Zoothorn hoped for and drew, and quite possibly would be stunned that such a straightforward job (from his point of view) has run to 11 pages of discussion on a website before a block has been laid. At the moment, it could be as bad as @zoothorn is worrying about, but from my perspective that worry is based entirely on speculation. I think that unless and until some form of communication with the builder takes place, talk of being stuck with the wrong outcome, or falling out with the builder, or firing the builder (etc, etc) are all premature.