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Well your water bill is gonna thank you even if the in laws and the fam don't

It's witchcraft - that's all you need to accept - once you accept that it's really easy to understand 😉 I set mine up to target a flow temp which resulted in my house being stable internally at 0 Deg C OAT (I started high and worked down - probably quicker to start low and work up but Mrs Alien was not keen on "freezing her ass off while I fecked around with the heating" (True statement) My slope target flow temp at 0 deg OAT ended up at 33 Deg C which in my case was 0.6 as a slope (with no level correction) Once you have the slope you can then fine tune the level All the level is doing is compensating for the fact that heat loss is proportional to temp differential - higher the difference between inside and outside the faster the heat loss example at -2.5 OAT and 21 deg inside the delta is 23.5 Deg C at 10 Deg OAT and 21 deg inside the delta is 11 Deg C So heat from inside moves slower to outside when the differential is lower so proportionally you need to put less heat in to cover for the escape because the escape is at a slower rate So at 10 deg OAT my target flow temp was 27 Deg C and the house over heated so I needed to drop the level to target 26 When I drop the to -3.0 on the level on a slope of 0.6 it changes the target temp at 0 Deg C OAT to 32 Deg (and I want 33) So I increase the slope to 0.7 and that gets me back to 33 Deg C at 0 deg C OAT Told you it's bloody witchcraft

Some simple science Your floor even on a dull day will not be much hotter than the room, maybe 1 to 3 degs at the surface depending on outside temperature. Let's assume room is 20 degrees, floor surface 23, sun comes out room increases to 23. Now as floor is 23 and room also 23 the floor no longer transfers heat to room. Sun goes away room temp drops, floor starts giving heat to room. With a thick screed (think you have this) the floor just acts as a huge buffer for energy. Thick screed doesn't act like a radiator due to its thermal capacity, think more a swimming pool, once up to heat it isn't cooling quickly. Once you allow to cool it takes an age to heat up. Setting up WC is pretty easy for UFH, start with a gradient of 0.5. so every degree outside temperature drops you increase the flow temp 0.5 degs. Start with a flow temp of around 20 or 22 at 10 degs and 28 to 30 at -5. Ideally let it run for 24 to 48 hrs. Adjust curve up down to suit. Small changes have a big change. System doesn't need to know internal temperature. You set the curve to balance heat loss and heat input. You better starting cool rather than hot. WC is completely open loop.

Panasonic uses the wall mounted controller for internal info. How the feck will yours know what's going on indoors if you don't have one? Other than the difference between flow and return, which would be cruder than a semi-sober welsh plumber.

WC will still prevail. Currently the rads are strangled. One step ahead, my man.........

That's what they have now!!!! 🙄😉 No, it's run on WC, not fixed flow temp, so fixed flow temperature would be completely different, may need a buffer if you are messing flow with TRV etc.

The heat pump is running, it has some teething problems but it works very effectively at warming the slab. The heat Meter (EMON Pi) is also up and running. So now I want to move on to setting up the Weather Compensation and see what happens. Looks like you choose a curve setting as best guess and then observe what goes on to fine tune. One thing I cannot see anywhere in the system we have is an internal temperature monitor the typical systems seem too open loop to me. I get the system does not use a thermostat but I don't get how it can get away without having some sort of measure of the internal temperature of the house because it doesn't know how the house is being used, what is coming in via the sun or indeed if the house is cooling or heating more than the output is providing for. Still the heating period has a few weeks to run yet and I want to make every day a school day learning how to heat the place so I guess I should just give it a go, any definitive advice as to the process I should follow.

Have we proven that L is getting there?

Oops been a long day. not sure how easy this will be to do but here is the picture. Regards. James

I'm not, the OP didn't say there was an issue there

Try again, lol.

1 - Good 2. What the heck is one of them - picture of the pump please or did you mean an auto bleed above the pump in the pipework somewhere? 3. Hmmm - we'll leave that one to one side for now

Boiler probably replaced 10 years ago, old leaky rads replaced for new less than two years ago, no real issue since last week

Sometimes it's easy to miss the obvious - I had a gate valve fall apart internally (cold feed to my loft tank - took me ages work out why the tank used to take bloody ages to fill up after a bath - only after a lot of trial an error and checks did I find it wasn't fully open) another reason why I bloody hate gate valves and why I replace them at the same time as a pump if they been a long time Good point well made If it's air locked there opening a drain under the boiler (if it has one might encourage the air to escape (or cracking the union on the ope of the boiler (more towels)

1.Yes I did open them. 2. auto bleed button pressed and on for a while 3. Well, I’m not sure how to answer that so I guess no. I didn’t test that when I had the pump off, maybe I should have. But the isolators seemed to twist shut and open nicely.

So you are saying to run everything at a fixed temperature, with TRV's on rads and how are you managing UFH room temps, thermostats?

You'd be shot if you didn't, ma' man.... How long has this worked for, to date, without issue?

No you don't. The (then higher) fixed flow temp will arrive at the TMV, and the UFH will see zero change in circumstance or performance. The FF rads will receive x degrees higher flow temp and actually do something. The rads go on TRV's to manage the difference in the size of the spaces that they are now able to satisfy. You balance and attenuate the lift in flow temp degrees at a time, until the happy medium is achieved.

Exactly this. Max flow temp we've seen is 34 degrees through the cold days we've had and the living areas been at a steady 21 degrees since early november

From experimenting with WUFI, the place that experiences the highest humidity is (unsurprisingly) the junction of the IWI and the original wall, so ideal for a temperature-humidity sensor. There could be a moisture build-up behind a VCL (if not very intelligent), so perhaps another there. If a cavity wall has joist ends sticking into it, I'd be interested in what's happening at the cavity to joist-end junction too. You'd expect to see a build-up of moisture during the winter that declines again in spring (cold moisture is generally OK, warm moisture in contact with sensitive materials definitely isn't), without any year-to-year build-up. I've added a handful of sensors on my current project, but at various points above my very non-standard unventilated insulated ceiling, rather than for the IWI. I'm using pairs of DFRobot SHT31-F sensors & LTC4311 I2C range extenders, feeding into a Raspberry Pi via a pair of Adafruit TCA9548A mutiplexers. Until finished I'm just running occasional spot-checks: currently inside = 21.63°C & 49.8% RH, outside = 3°C & 90%, ceiling* = 10.02°C 79.53% - which is good for January, though it has been relatively mild. *above 300mm-ish of hemp insulation, no VCL, directly below timber decking + clay tiles in a very windy loft. Ubacus and similar software just shows a point-in-time, so of limited use. WUFI can throw up some very odd results too, with an incorrect internal environment. Modelling a single element in WUFI doesn't take long, so might only cost a few hundred pounds (but leaving a question mark over the output). I'd be surprised if whole-building modelling cost less than 2K. For someone doing a full-building thermal upgrade the cost would only be a fraction of the total renovation cost, so easy to justify - I can imagine some Architects insisting on it, or doing it in-house. I would guess that it's used too by Housing Associations and the like who have multiple homes to upgrade and/or their own taff to carry out the assessments. Probably not used so much by those on this forum, though there must be some.

Probably an obvious question that you'll already have looked at, but can power be brought to the plot from a different source/direction?

Sounds like loads of PV, battery and generator is required - if you an get mains gas run the generator from that, exhaust heat exchanger, to do the heating while generator is on. And some batteries.

Hi, not sure which forum was the right one so opted for this one. Our new build is in the garden of our existing bungalow, the last property on a low voltage line. Despite over 2 years back and forth with the DNO for quotes for the connection, I've discovered today that they can't do my connection without it going to Parliament (??) to the Secretary of State, under the 1989 Section 37 legislation. The existing bungalow, being the last of the line, and despite having a main electricity line to the pole outside, is not allowed to be followed on by any further build, without said sign off. Which apparently typically takes about a year. I am adding this in as an edit - I don't think it's the Sec of State, reading this from the DNO's own website:- A Section 37 application is a two-part process involving an initial application to the local planning authority followed by an application to the appropriate Ministry:- Scotland - Scottish Government Energy Consent Unit England / Wales - The Department for Business, Energy and Industrial Strategy There are certain circumstances where a supply may be provided to a single customer at less than 33kV without the need to obtain a section 37 Consent. In these situations, it is still necessary to consult with the local planning authority before constructing the line. Where an existing line serving one customer is subsequently required to serve further customers, a retrospective Section 37 Consent will be required. Section 37 consent can also apply in cases where underground cables are being installed from an existing overhead line, where retrospective Section 37 may be required. Where it is necessary to modify an overhead line, Section 37 may be required or in certain circumstances, works may be carried out under the provisions of the requisite Overhead lines (Exemption) Regulations. To say I'm reeling is an understatement. I'm desperate to research whatever I can find now about others who've maybe found themselves in this position, did you manage to deal with it, how, costs etc and what on earth can I be trying next!? Apparently "the quote team should have spotted this" ... but I can see no advantage in my pressing the red button with the DNO, it won't alter the position I'm in now, nor the timescales to overcome it.

Wonder if one of those magicman outfits could effect a repair on something like this. a quick google and this bod has done something with a cast stone corner block https://magicman.co.uk/examples/