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It’s a fair point, it’s not the most egregious thing now everything is getting warm enough. To be honest the overshooting in and of itself isn’t bugging me, I’m fine with everything getting a littler hotter then I’ve set… though what is bugging me is more the fact it’s staying at 100% of its rated output long after it’s reached target. It’s working way harder than I’ve asked it to and the bottom line is that’s costing me unnecessarily everytime I run it. For every hour it’s running at 35kw it costs around £2. So that will add up a lot through the year if it’s not modulating down when it could/should. as a slight aside. Do you know the best insulation method for pipework that runs in a ventilated, unheated subfloor. The pipes are already lagged but wondering what else I can do to keep them as optimally warm as possible.

So far, simply using online published rates with no allowance for quantity.. celotex or other names all seem to be the same price as listed below, since when I've found cheaper but must check the spec. eps varies by vendor and many don't do it. please excuse that the Tab key doesn't work PIR thickness £/m2 £/m3 25 4 161 50mm 6 121 75 8.4 112 100 10.4 104 Now found approx £88/m3 120 12.7 106 EPS 25 2.16 86 50/75/100 all 86 unfaced pir 90-100 £8.51 £85/m3 as you will see, this bears out what some of you clever people have said about 100mm being the most competitive.

I'm pretty OCD when it comes to pipework/wiring now - If I've had a floor up I normally take a photo of pipework/wiring while the floor is up Then I'll mark out the "unsafe" zones with permanent marker on the floor - the photo is especially useful if you then go and tile the floor and cover the "unsafe" zone markings (Always handy to be able to refer to it if you ever need to put a fixing in) Of course I haven't always done the above - I don't have a picture of the master bedroom floor before it went down - when it was laid I also didn't mark the floor for any pipework or wiring. There is one section that always has a little creak - wakes up Mrs Alien if I've come in late having had a few beers She wanted new carpet so we ordered carpet and arranged for a fitter - day before we emptied all the furniture, cut up and removed all the old carpet and underlay - the morning of the carpet fitting I walked on the creaky bit and it reminded me to throw another screw or two at it - as I looked at the floor it was bloody obvious I'd missed two screws out Creaky floor resolved - new carpet and underlay laid OK you all know what happened next.......... well not actually next as water takes a little while to escape if you've put a self cutting screw thro a copper heating pipe and plasterboard is pretty good at holding water - screws that held it to the ceiling joist not so much

First you need to really understand your heating load at design temperature, so for -3 degs. Your heat load at 7 degs will be half that and at 10 under half. So say it's a 6kW design load, you want to choose a heat pump that does close to or a little over (allow for DHW heating and defrosting) at -3 at your design flow flow temperature. Manufacturer nameplate rating are pretty meaningless. So you need to find the technical data. A few snippets from a 6kW Hiaer R290. So -2 full load it puts out 6.4kW at 30 Deg flow temp and at 45 it's 5.66kW, so if you have radiators it's too small but ok for UFH. It's min output at 25 flow and 12 degs outside, it's min modulation is 1.7kW. pretty much would tick away all day every day. ScoP should be about 5.0 if UFH and an open system on WC, so heat pump doesn't cycle.

Using a multi cutter to channel out plasterboard, and went straight through a plastic water feed. Got a face full of water and a huge scramble dumping the sink cupboard across the floor getting to the stop cock! Then a frantic drive to screwfix to buy everything to resolve before the wife came home.

I guess to some extent it is to do my bit for the environment. As a money saving exercise, it is probably futile. Curiosity is also a factor and as is future proofing.

Here’s the stats for the boiler space heating vs DHW Measured at the boiler and it aligns with actual usage measured by Octopus. My other worry at a change would be how low the ASHP could modulate. We are in winter but although mild (ish) as my boiler does down to 2250kW at a COP of 4 the ASHP would have to go down to 560 watts. The boiler stays at minimum modulation for a while, today it has run continuously for over 15 hours and counting, modulating of course. What decent ASHP at say 7kW can get so low. It would be even more salient as thing starts to warm up to prevent cycling.

Ed on another tangent. So, Rachel says they are getting rid of the ECO4 scheme to reduce bills, and Ed says he is going to load gas with extra cost and increase them. Left hand and right hand and all that. Not that it stacks up anyway, as 13bn, is less than £500 per household. Thats not going to buy you much, and certainly not at grossly inflated grant harvesting prices. Maybe it just for labour party members or some other select group?

As others have said, you have not indicated your motivations. So rather a difficult question to answer. As you ask, id just leave it until it breaks. Put the money you would have spent to good use elsewhere.

Apologies for an oversimplified discourse. I meant 'we' as the simple requirements of the regs for a new build, but with BH level of care and supervision. So it will satisfactorily airtight but with the resulting dribbles of air through the fabric, and more at fans and any vents. Good pun on manor/manner. Draughts was a deliberate over-statement. I meant airflow that isn't designed. Every time the front door is opened there will be a few m3 of air in or out, however well mvhr is designed. I don't suppose we will ever know the reality unless we here of a newbuild without MVHR that is failing on air quality, or someone builds 2 otherwise identical houses for comparison... and that won't happen. Plus cynical me says that there is an industry that sells mvhr, but not one that suggests not adopting it. Included in the decision are the weaving of ducts through the structure, the ease of maintenance , and the unknowns. Me? It remains debateable and I have plumped for 'not'.

Where is this cheap PIR you speak of?

It's much more than for a gas boiler. There's virtually nothing in a gas boiler, even a system boiler - gas valve, fan, heat exchanger, circulation pump and pcb with some wiring. Plus it's far less volume and weight. A heat pump, lets say with the output required for the OP at about 5kW for arguments sake will weigh nearly 3x the boiler and have about 3x the packaged volume. From a manufacturing perspective it's far more complex. But over its lifetime the heat pump will produce much, much less especailly as the grid continues to decarbonise. For example, this article: https://les.mitsubishielectric.co.uk/the-hub/carbon-embodied-operational-and-whole-life-cycle

Ive found this very difficult to use on the thicker boards. PIR at least. Works great at 50mm. Useless at 100mm. Better off with a cheap normal saw.

It is the lack of clarity, and ultimately, the judgement of the BCO, that i would not involve then unless its unavoidable. If BCO doesnt agree, tough on you. There is no "appeal" process even if they are wrong. On some of the old house groups, theres been a couple of people running into quite some difficulty with BCO's that seem to be unwilling to relax standards based on it being an older building etc etc. Which the clause that Redbeard highlights specifically allows for. But if the BCO says no, then its no. To the point that one person couldnt insulate his roof to current standard, the BCO just said replace the entire roof structure so you can. All while roof is stripped. Sadly, as the old school BCO's retire and the new breed of box tickers comes in, i cant see it getting any better. OP, hope yours goes smoothly.

I'm aware of that but reminders are no bad thing. I wonder how well a soft packaging eps would fare beneath 100mm or more of PIR and a grand piano on top. perhaps with a big enough dish under each wheel it would be ok. This is whimsical: I am not saving amazon packaging to try it.

Or big enough for a cosy tariff and charge 3x

Could also be old fuel. Unless new dump the fuel and our in new

In that case worth looking at something like octopus cosy as there are multiple cheap rates during each 24h period. As you say though, it’s worth weighing up whether it’s best to not worry about the very coldest of days.

That will be a whopping battery to run an ASHP for 24 hours in freezing weather. Not sure it's cost effective to have a battery that size rather than use peak time grid eleccy for the few freezing days a year most people have???

Something else I didn't know. Seems to be a saw tooth but with a wavy profile to avoid sticking, and produces less dust. Between a saw and a knife. £22 The Bahco insulation saw has been specially developed for cutting various types of insulation material

Neither. For simple white switches, I don't think you will beat Click Mode for quality, value and reliability. But Screweys don't sell them. Toolstation do. https://www.toolstation.com/click-mode-10a-switch/p73508 A little "quirk" of these switches is the switch mechanism can be removed from the plate, enabling you to mix normal and intermediate switches on the one plate. Almost like a grid switch.

The carb was left on the manufacturer's settings. The old carb is long gone.

Unburnt fuel possibly, you changed the carb, are these preset at manufacture? Is the old carb Knicknacked, if not I’d be tempted to pop it back on and see what happens

Currently most cost effective to have a battery big enough to see you through 24 hours in the winter when there is little generation. Charge it overnight to 100% at cheap rate then export any excess solar at higher unit price than you buy in for overnight. If you think you’re saving the planet by using maximum amount of generation on site, then that changes things.

May have a winter summer switch, to change the carb settings. In winter it could be running really lean.