jack

I had grand plans to bring control of the ASHP into the home automation system, but I suspect that would cost several hundred quid due to the cost of the interfaces that are required for both the ASHP and the home automation system. In the end I just went with the bog standard controller that came with the unit. The instruction manual (which is available online) told me in advance everything I needed to know about connections, programming and info like temperature ranges. Have you narrowed down the likely unit(s) yet? I must say I found Panasonic's tech help line very helpful (we went with an Aquarea)

Nope, I don't have one and have never planned one. The only tank I have is a 250L UVC for DHW.

Excellent question, with a simple answer: "I don't"! If you only ever supply, say, 25C water, then the hottest your rooms can possibly get is 25C. Warmer than ideal, but not the end of the world. If that were to happen I could back off the amount of time per day the system is running (or find a mixing valve that allowed for a lower temp, ideally one that's controllable via my home automation system). It goes back to someone's earlier comment about unstable systems - this system can't go out of control because it has a hard limit on its upper temperature that is acceptable (if not ideal). My recent introduction of a weather compensation curve may possibly challenge this, because the water temp starts increasing from 25C when its 8C outside, until it reaches a maximum temperature of 28/29C (can't remember exactly) at 0C. Once the insulation is back in the roof, I'll be turning this down a bit, because we really don't need the slab to be sitting at 23-23.5C as it is at the moment. That said, it's presently -3C outside at 9:30am, and has been even colder the last couple of nights, so it's lovely coming back into the house at the moment! In case it helps, when we turned on our heating a few weeks ago, the slab was at 18C. It took just under 12 hrs to raise that by 0.5C, which was the fastest rate at which the temperature increased. The maximum temperature change is therefore pretty-well bang on 1C per 24hrs, with 25C water (no weather compensation) Once the system is up and running each heating season, and ignoring weather compensation, the temperature differential will generally be lower, so the rate of temperature change should be lower too. What rate of change did your concrete people recommend? If it's okay for "ordinary" UFH systems, surely it should be fine for a well insulated floor which should have far slower temperature fluctuations with lower temperature differentials?

PMSL - genius! "the constraint is the planning system".

Welcome to the forum!

When I first started looking into this, I'm sure I found a supplier that did mixers that went below 25C, but I don't recall who they were, sorry. I thought I'd give it a go with the standard setup first and so far it's been fine.

At the moment, there are no separate "house heating controls". We don't even have an internal thermostat. While I do monitor the slab temp in a couple of places, that temperature isn't presently used to control whether and when the ASHP comes on. The problem with using house heating controls to call for heat is the huge time constant of the insulated slab. It takes days to respond fully to a significant change in water temp. By the time the house is cool enough to demand heat, you're 12-24 hours away from the slab temp rising in a useful way. At the moment, it's just running open loop for a few hours a day, churning out 25-29C water depending on external temp. The temp range was entirely my decision, and it's easy enough to turn the compensation down or off if desired. Seems to work fine at the moment, even if the slab temp is probably a degree or so higher than it strictly needs to be right now. Once we have the insulation in upstairs I'll likely turn down the compensation. I suspect with most heat pumps you can call for heat easily enough using volt-free switching. Setting the temperature is more likely to be handled via a proprietary bus (even if it's based on a comms standard like RS485/Modbus). Last comment about these "all-on-one" packages: the cylinders are generally pretty poorly insulated, and it looks to me like adding insulation will often be difficult. They are also hugely expensive compared to getting one from a more general cylinder manufacturer. I may be misremembering, but I seem to recall that the Panasonic cylinder would be over twice the price of a generic one, and that's with less insulation and without the ability to specify the location of extra taps for, eg, thermal sensors.

As it happens, 25C is the lowest temp that my ASHP will modulate down to. I don't know how common that is. My longer term plan is to measure the return water temperature at the UFH manifold. That should represent a lower-delay version of the slab temp, because you aren't waiting for heat to move through the concrete and hit your temperature sensor(s). Interesting. Do you know the size of the ASHP? We have a 3.2m2 coil designed for ASHPs, and it works very effectively, but our ASHP is only 5kW heating a 250L tank. This is exactly how we run ours at the moment (in the sense that the mixing valve on the manifold is ignored, and temp controlled by the ASHP). It works perfectly. With weather compensation (water temp up to 29 degrees at zero external temp or below) kicking in over the last few days, and quite a lot of sun streaming through around 10m2 of glass on our south-facing sliding doors, our slab temp is a little higher than ideal, having reached 23 degrees this morning. I haven't adjusted it for the moment though, as delays mean our insulation still hasn't been replaced where we had the leaks upstairs, so it's a bit chilly in those rooms at the moment!

Wow, that is a tidy job - love it!

Not strictly a requirement for a single dwelling unless you're in a conservation area (and other designated areas), but you'd be bonkers in most cases not to include one. See paragraph 30 here: http://planningguidance.communities.gov.uk/blog/guidance/making-an-application/validation-requirements/national-information-requirements/

The plumber we used wasn't MBC registered so couldn't do the RHI. He said he looked into it but the paperwork and costs of maintaining currency in the legislation itself wasn't worth the hassle. He may not have realised how much of a premium could be involved!

Yes, all of the alarm sensors are fed back into the home automation system, as are the external PIRs (well the wirings there - still haven't got the PIRs up yet!). Once it's all up and running, the "all off" button will set the home automation side of the alarm to night mode.

No, it's just a dumb retractive switch that's wired to the home automation system. It can in theory be used to control anything that's controlled by the home automation system. In fact, the upstairs one was intended to be a lightswitch for a light right beside it, but there's no light installed there yet. The upstairs "all off" function is actually intended to be controlled from the master bedroom bedside switches, but we're still in the guest room while restitution of our ceiling takes place, so I temporarily re-mapped the "all off" functionality to the spare switch in the upstairs landing alcove. Once we finish installing everything, hitting the "good night" switch will turn off the driveway and internal garage/workshop lights (if on), and shut the garage door if it's detected as still being open.

I have one of those. The standing joke (although I'm certainly not laughing) is that I'd come home from work in winter to find literally every single light in the house on! I'd spend the first five minutes going around turning off lights that were on in rooms that no-one had entered for hours. I get that the kids don't pay attention but it drives me mental that my wife just doesn't see this. It's the same with the dishwasher - she'll put it on at 10 o'clock in the evening in summer, when it's dark, rather then the next day when we may have several excess kilowatts being producing from the PV for several hours. Or she'll put it on 75% full right before we sit down to dinner! I've managed to claw a bit back recently by changing the programming on our home automation system. Now, the utility room, bathrooms, and the kids' bedrooms are on timers. Since I'm the only one who can program it, there's nothing they can do about it! Oh, and I've also installed an "all off upstairs" switch in a central downstairs position, and an "all off downstairs" switch in a central upstairs position. Very convenient way of turning off an entire floor's worth of lighting, and something worth considering if you'd doing home automation.

You're using the same plumber I did, yes? He expressed some scepticism in our situation as well. From memory, this all happened around the time of the big discussion on ebuild about the potential chimney effect of an uninsulated (or at least poorly insulated) SVP in a highly insulated house. We didn't use AAVs anywhere, and ended up with everything venting via an SVP on the roof. We did manage to realise what was going on in time to at least limit it to a single SVP - originally there were two. Because we don't have AAVs, I was planning to look into an exterior AAV to try and reduce the chimney effect. Apparently they work okay, although I suspect they quickly end up not completely sealing. Still better than a completely open pipe, I suspect. I'm sure someone (Jeremy?) had a vented a treatment system that satisfied the need for sewer venting without the need for a separate SVP.

We used these guys for our external balcony glass and fixtures. Very helpful (they seem happy to work with self-builders).

The town I live in has been fighting a horrible piece of over-development in its centre for the last 15 years or so. It's had planning approval for years, followed by year after year of amendment to the point where the current scheme bears no resemblance at all to the original. They then faked a start so that they could avoid the planning permission expiring. It's finally gotten to the point where judicial review is the only option, because the council (which, of course, is not located in this town) simply won't follow the law. This is the same council that has recently admitted to separately extending a car park and building a new changing room for a council sports ground without seeking planning permission. But it's okay, because they're applying for retrospective planning permission! Oh, and the new car park breaches a covenant under which the land was donated to the council after the second world war.

Useful stuff, thanks Sensus. I think what was interesting about Joe's case is that the council made some clear errors (errors obvious enough that a non-professional - no offence Joe! - could spot them). It's concerning that people who are paid to know and implement the law could not only get it so wrong, but would then spend taxpayer money fighting it. Bear in mind also that Joe did, in fact, engage a professional at the start of the process. Given how far they got him, I can understand why he took it upon himself to take the process further. Also, Joe already had planning permission to build something. He cleverly used the same footprint for that as for the application he was appealing, so he was able to crack on knowing that whatever the outcome of the appeal, he'd still be able to build, and the appeal wouldn't be holding him up. Perhaps not general advice to go it alone, but I suspect each case needs to be looked at on its merits. I've also little doubt that there're planning consultants and planning consultants. In our case (and I think this is pretty common), there's a planning consultancy directly across the road from the planning department, and it's staffed mostly with ex-planners, including the ex-head of the department. I personally know two people who've employed them with huge success. Poachers turned gamekeepers (or is it the other way around? )

Sounds horrendous, but hopefully all sorted out in the end. Having good workers onsite makes a world of difference to how this sort of thing pans out.

Interesting numbers. To be honest, In the past I've just assumed it's somewhat worse than they say it is, so a very rough 35-40% recovery, on average. If it's probably better than that (as suggested by your numbers), then great!

All of the above, unfortunately. We have some places where the gap is noticeably vertically wider than it is elsewhere. In other places, the edge trim (unfortunately, I now know we should have used a proper profile) isn't completely flush with the edge of the board, so the plaster surface is slightly proud of the underlying skirting board. And then the skirting board just wasn't put on with as much consistent care as I'd have liked. There are a couple of corners where it's out by 5-7mm, which is quite a lot! As I said, by the time we got to this point it was already a long story with the builder we had in to do some of this work. I think he'd basically lost money on fixing the external cladding because he underestimated the amount of time it would take. From then on, he just dug his heels in about everything we tried to call a snag. Irrespective of whether it was a day rate or a fixed price, it was always "I don't have the margin to re-do adequate work just because you're an unreasonable perfectionist" (not those words, but the attitude was pretty clear by the end of it).

I can vouch for that. The guys that did ours didn't do a particularly good job in places, but of course, you couldn't tell until they'd more or less finished. By this time the relationship with the guy supplying the labour had deteriorated and it was pretty clear there was no way he was going to make it good. I have plans to improve some of the worst sections, but this is waaaaaaaay down the to-do list, unfortunately.

Yes, I know you can do all that, but it isn't a linear as, say, measuring how much water is in a bath and determining its temperature. For example, when you first get into the shower, it takes some unknown amount of time to come up to operating temperature. Efficiency is initially zero, and then rises to maybe 50% recovery when it reaches equilibrium. But every day is different - two longish showers in a row will allow much higher average efficiency out of the unit than two shortish showers an hour apart, but you're more likely to run out of hot water with the longer showers. So yes, you can work out some really rough and dirty numbers, but it's a big and complex step to do much better than that. From memory, we have the Recoup Pipe+ HE. It was a toss-up between that and the Powerpipe - I don't recall why we chose the one we did!

I wish I could determine what impact the waste water heat recovery system has. No doubt it makes difference, but I don't know whether it's like an effective 20L or 100L of hot water.

Good question. We don't have E7. My current setup is largely a function of inertia and a long to-do list! When we moved in, there was so much to do that I didn't have time to optimise things. I therefore just set it up to give us a full tank of 55C water in the morning (which is when we typically use more water), with an hour's top-up of the top portion to absolutely make sure we didn't run out. I had grand plans to revisit this and at least reduce if not do away with the boost entirely. Further complicating things, I originally wanted to control all of this via my home automation system, but of course things don't really want to talk to each other. The Panasonic apparently has an RS485 module that I could use to talk to the HA system, but it costs over £500 from memory. I can't see the value in spending £500 to get slightly easier control over hot water! So the whole thing's been put on the backburner, and it's only now I'm starting to find the time to look at things like this. You're right, there's nothing stopping me from doing a top-up during the day with the ASHP rather than the immersion, and that's what I'll likely look to if one tank at 55C is enough for the morning but not the whole day.