Jeremy Harris

I got a joiner friend to get prices from Howdens for some stuff for our build and the prices were higher than for the same thing bought online. In the case of our doors and door linings, Howdens price was a lot higher than Doordeals, for example.

I can easily believe the amount of paperwork something like this will create in a workplace. Luckily I know the stairs are OK, as I've already hauled a 150kg load up them once, and there were no odd noises from the staircase when I did that. Mind you, I used to work with a chap who weighed more than 150kg, so the point load he applied to a staircase was similar, so I'd guess that stairs are designed to take higher loads than this..

We pre-warm whenever the UFH is on, which isn't a lot of the time (not at all recently) so yes, the first shower of the day has the benefit, if the UFH has been on overnight, of around 1 to 1.5 kWh. I'm not sure how many times the UFH had been on overnight during this time (need to pull the stick from the data logger and check at the end of the month) but at a guess I say there may have been another 100 kWh contributed by the ASHP, so the daily average would have been around 5.2 kWh, perhaps a little more, so a bit lower than the 3 kWh/person used for DHW estimating. The additional cost of the off-peak electricity for the ASHP pre-heat since mid-November 2018 may have been around £3 at the most, so not a lot.

Many thanks, that's really useful to know. If the truth be told, moving our old 70kg Sunamp PV down the stairs on a sack truck scared me ***tless, as I was bloody terrified that it was just going to roll away over the edge. The idea of having to shift 150kg down the stairs just fills me with dread. Pulling stuff up, with a tirfor and timber sled was hard work, but not anywhere near as scary as going down with the sack trolley (yes, I was stupid to try it, but once over the first step, going down, I was past the point of no return).

I really do not ever want to move it again, but it's possible that I may have to. It's not something I'm looking forward to at all, in fact I'd do damned near anything to avoid having to do it, if I can.

I'm pondering on ways to shift a heavy load (~150kg) up and down a standard width, straight run, staircase. Looking around, I've spotted that it's possible to hire an electric stair climber, something I'd never heard of until earlier today. Has anyone here ever used one, and can offer an insight into what they are really like to use, please? The models I've seen look like this: https://www.speedyservices.com/71_6010-h-stair-climber-powered-310kg-swl

Yes, that's how I run ours. It's charged only by electricity, so can either charge from off-peak mains (mainly in winter) or from PV generation (pretty much 100% of our charge for the past few weeks has been from PV). Since last mid-November last year to today, PV charging has used 370 kWh, mains charging (mainly off-peak) has used 341 kWh. We seem to be averaging around 4.6 kWh/day for hot water use, with about 52% of it (so far) being "free" PV generation. That ratio will increase, as between now and the anniversary of me fitting the separate energy meters (mid-November this year) most of the charging will be from PV generation (I'm expecting at least 70% of our hot water to come from PV over the course of a year). In terms of cost, then as mains charging is off-peak (currently 8.148p/kWh here) the daily average cost for hot water is about 27.8p. I anticipate that the annual average daily cost for hot water will be lower than that figure suggests, probably around 15p/day, maybe less.

Very true, and I dearly wish that I'd thought to add a duct behind our bathroom ceiling so that I could fit an air-to-air unit right up near the top of our entrance hall. Being a tall (>6m high) space, with glazing on the South facing gable, this is the part of the house that gets the most solar gain, and being able to cool the air right at the top would be useful. I've been thinking of ways to try and get a duct, big enough to take the pipes from a split air-to-air unit, up behind the ceiling, which isn't easy as the service space 50 x 50 battens run at right angles to the direction I'd like to run the duct.

It's no different, functionally, to the myriad of other electric resistance heating systems available as far as I can see. I installed electric underfloor heating in the bathroom of our old house around 15 years ago now, it was cheap, relatively easy to install (just sat in the time adhesive bed) and reliable.

I believe they paid less than that, as the land was disposed of by the MoD pretty cheaply, for a host of reasons.

Have a read of how PGP (Pretty Good Privacy) works here for starters: https://en.wikipedia.org/wiki/Pretty_Good_Privacy And, for details of how digital email signatures work, see here: https://en.wikipedia.org/wiki/Digital_signature As @Ed Davies writes, though, there is resistance from our government to using encryption, as they view it as being a threat to national security. In essence encryption stops, or makes very difficult, the ability of the state to read electronic communication (at the moment it's pretty easy to read email traffic). They argue that encouraging the use of encrypted, secure, messaging allows terrorists to communicate without the state being able to listen in. This ignores the fact that terrorists are generally pretty switched on when it comes to secure comms (there are several secure messaging apps readily available), so are almost certainly already using encrypted communications anyway. The reality is that discouraging the widespread use of encryption, so keeping email traffic in plain text, without any effective means of authentication, allows email scams and phishing attacks to flourish, something that arguably causes as much public harm as terrorism.

As I mentioned earlier, doubling the concentration of CO2 (chosen because it's the greatest single pollutant in urban areas) displaces less than 0.01% of atmospheric O2, below the capability of a vehicle gas analyser to detect reliably. The biggest single difference between dyno readings I used to see on my old hillclimb/sprint cars was down to variations from one dyno to another (these could easily be around 5% to 10% alone). The next greatest variation was from temperature density, as even with the dyno fan running flat out the air temperature at the intake would vary in line with the weather and with how many runs had been done that day.

I think you could have a go at this, but it wouldn't be that easy. It depends on the heat capacity of the heated floor and the thermal conductivity from the pipes through that. Concrete is a reasonably good conductor of heat, so if you know the volume (or mass) of the floor, the heat output the room with varying temperatures and the heat losses, it should be possible to work out how long it takes for the floor to warm up. I know that our slab takes several hours to warm up from cold, but as we've been running it at a near constant temperature for a long time now I can't say for sure exactly how long it takes to go from, say, 20°C to 22°C for any given heat input and room temperature.

For a ventilated space under the floor, then the "under slab soil temperature" needs to be changed to be close to the outside air temperature, as it will vary pretty much in line with that, so will be colder in cold weather and warmer in warm weather. The losses in the heat pump from either the fan power or the circulating pump are pretty small. The biggest impact seems to be from defrost cycling, as in cool, damp, weather, with the ASHP being asked to run at a high heat output, the external evaporator tends to ice up, and ASHPs have a de-icing system that often just runs the heat pump in reverse for a short time, to transfer heat from the house back out to the evaporator to melt any ice. I've found by experiment that if the ASHP flow temperature is kept to 40°C or less, the need for de-icing is dramatically reduced, which improves performance a fair bit. Icing isn't a problem in cold weather, as the air tends to be quite dry then, it's at it's worst when it's cold and wet. I run the UFH with a lower flow temperature, using a thermostatic valve. The ASHP charges a 70 litre buffer tank and the UFH can draw from that as needed. Typically our UFH flow temperature will be around 25 to 26°C.

COP improves if the ASHP flow temperature is reduced, but there seems to be little improvement below about 35 to 40°C, from what I can tell. I run ours at 40°C flow temperature. You can calculate the required UFH floor surface temperature for a given heat output to a room from this spreadsheet, together with the heat loss from UFH to the ground beneath the floor: Floor heat loss and UFH calculator.xls

@Onoff, Just found this info on the Renusol Console mounts: https://www.alternergy.co.uk/renusol-console.html It states that they are OK for a roof that has a reserve from 15kg/m², which isn't massive. Any roof you can safely walk on should have a reserve that's greater than this, I'd have thought.

The fact remains that the best atmospheric scientists in the world are reporting data that's at odds with your ad hoc observations on a garage gas analyser, so which is most likely to be accurate?

It doesn't seem to say in the data sheet: https://uk.krannich-solar.com/fileadmin/content/data_sheets/mounting_systems/uk/ConSole_PB_A05_EN.pdf There's a photo with what looks like six off 400 x 400 paving slabs, which would be around 150kg, but it also mentions calculating the ballast weight from the wind loading, so I'd guess that this might be lower in a sheltered area.

Just shows a constant error, though. Climate scientists have been monitoring atmospheric gas composition changes for decades now, and no one has ever recorded a significant variation in O2 concentration from urban to rural areas as far as I can find, from an hour or two scanning the literature. There are tiny variations as a consequence of displacement by variations in atmospheric pollutants, but these are really tiny. For example, doubling the atmospheric CO2 concentration causes a displacement that reduces the proportion of all other gases in the atmosphere by roughly 0.04%. The pro rata reduction in O2 concentration from this would be less than 0.01%, a change that a vehicle gas analyser wouldn't be able to resolve.

FWIW, vehicle gas analysers are only required to be accurate to +/- 5% of the reading, so a reading of 21% O2 could be anything from ~20% to ~22% in reality. These things aren't by any stretch of the imagination lab quality measurement instruments, they are pretty rough and ready garage tools that give a good enough figure for the purpose for which they were designed.

I was comparing like for like, the quote was for the supply and installation of a 5 kW Mitsubishi Ecodan ASHP, and listed the price of the Ecodan on the quote as £2.348.37. The installation cost was quoted as £2,106.11. I bought a 7 kW Glowworm ASHP (in reality a Carrier) for £1,700, spent around £300 on installation related fittings so my total cost was around £2k..

The ones I have don't have clip on sensors, just probes at the end of leads that can be taped or cable tied to a pipe: https://www.ebay.co.uk/itm/Digital-LCD-Thermometer-for-Refrigerator-Fridge-Freezer-Temperature-FT/113008453181?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D57478%26meid%3Daeca8244fe7141aea66332424431482e%26pid%3D100005%26rk%3D2%26rkt%3D12%26sd%3D182565788871%26itm%3D113008453181&_trksid=p2047675.c100005.m1851 If you don't mind waiting you can get them from China for under £1 each, delivered: https://www.ebay.co.uk/itm/Mini-LCD-Digital-Temperature-Thermometer-Outdoor-Indoor-Meter-Probe-Measuring/123696872545?hash=item1ccce87c61:g:45wAAOSwajRcj5Is&frcectupt=true

I don't agree, as I was quoted a price that was around the same again as the cost of the ASHP, just for an MCS install. I did the job myself in around half a day, and I cannot for the life of me see how any company can justify around £2,000 for half a day's work, no matter what their overheads.

The thing with RHI is that it depends on the assessed requirement, so if you build a well-insulated, low energy house then you get less RHI. The worse the house is, the more RHI you get.

I feel for you, @lizzie, as I'm afraid there are some people around who will take advantage of anyone that they think may not know much about something. Without in any way wishing to be sexist, I'm afraid that tradesmen taking advantage of women who they think may not know what they are talking about isn't that uncommon. My late mother was reasonably savvy when it came to practical stuff (she was a farmer) but even she got done by a plumber and a general builder, and both times I stepped in to sort things out.