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Yep. What I meant is that if I oversize the rads and size for lowest flow temp (or size them for more heat loss than I end up with) there's no negative impact apart form rads taking up more space & being marginally more expensive? And when we get a few cold weeks of -5C in winter, I can just up the boiler temp for the cold period. Ask me again next time I lift a floorboard 🫣. The scope changes as we're discovering more about the house and I'm reading up more about efficiency, ventilation, etc. We bought it as a fixer upper and that was reflected in the price, but on moving in, we keep discovering new challenges every week. And we had some challenges thrown at us with selling our old property, so had to change our plans to battening down the hatches and surviving this winter before doing anything major to the new house. Overall, the plan is to incrementally retrofit with minimum alteration to existing fabric unless necessary and maximum energy efficiency per hour of work (which will be mainly done by yours truly). We're definitely sorting out all of the windows before the end of the year so should have fully working pvc double glazing everywhere. In spring/summer I'll be insulating sections of the house where we have suspended wooden flooring. I'll be doing a fair bit of re-plumbing and replacing the rads, but do it incrementally as I move on to each room. Not sure if it's worth switching to a home-run manifold in the end. I need to sort out ventilation. Plan is to go for dMEV, but that's probably a topic for another thread. The bit that's got me checkmated is the suspended concrete floor in two bedrooms, home office corridor & potentially, one bathroom & kitchen. It seems to be uninsulated, but if I understand correctly, adding insulation on top of it is the only option apart from pouring a solid slab, and it means raising door openings, which suddenly becomes a very big job. Ceilings are 2.4m however, so there's space for it. In terms of heating & insulation, we've got an old combi boiler with no water tank, that must be on its last legs and I expect will need to be replaced in the next 2 years. Maybe sooner. Thermal imaging shows that, once I sort out the windows, by far the biggest heat loss is coming from floor voids in rooms with uninsulated suspended wooden flooring. Current rad arrangement is pants and needs to be revised. I'm looking into A2A heat pumps for the living room and, potentially, the far bedroom with 3 external walls and large areas with windows & French doors.

Where does your DPC sit in the mortar bed? If it's about in the middle why not cut under it with an angle grinder with a narrow disc? Don't try to bed in mortar, but use epoxy or similar.

I've just had a look up in the suspended ceiling from the hot press.... No easy way to get pipes through without cutting out big chunks of plaster board. I think we'll just stick with the electric heater until it's time to replace carpets and we'll put in overlay UFH like we should have done at the start.

My build was a timber frame, so I used ledger boards and the metal web joists were hung on them. Very straightforward and good for airtightness.

Legers are soooo much better / easier, I’d never make all those holes if I was making a house. You parge all around them first, and then use the PP or other liquid AT membrane, then tape from wood to PP for movement.

Do NOT do this. You’ll be lucky to get the top 2 rungs warm, the rest will be completely ignored. You’ll have an empty wallet and zero heat. Rads are cheap as chips, so buy a big (enough) double convector and pipe it properly.

Sorry, I can't offer ay advice, but did you investigate the idea of using ledger boards & hanging the posi joists from those? If so, what made you choose the sticking them through holes in the wall method? Just asking, because I'm not at this stage yet, & based on what I've learned, I strongly favour the ledger board method.

You're right John, I'll need to stick a couple AAVs at the highest point. I'll move the one that's on the manifold to get started.

You will need a top point bleed on both pipes otherwise they will.not move any water. The low point bleed at you UFH manifold may not be much help. May work but could just give you a hot top and the rest cold radiator.

Oh I've made a lot of mistakes over the course of my journey!!! My key points Size the boiler for the house/hw recharge Size all the rads for the output required for the flow temp and room heat loss Get a decent HW tank with a 2.3 to 3.0 m2 coil surface area so you can heat water and still have the boiler in condensing mod Use WC and control the flow temp rather than bouncing room temps of TRV limits

We neglected to put UFH into the small office upstairs and have been using a small electric heater. We've a spare (large, not sure of the BTU rating) towel rad that we never installed, so I was thinking of fitting this to the office. The easiest way for me to do this is to take the pipes from the UFH manifold in the hot press, up through the false ceiling, over the hallway, and down to the radiator. It's 1.6m tall, so I was thinking I could just install it upside down, with the pipes coming through the ceiling and into the rad. Obviously I won't be able to bleed the radiator or easily drain or fill it, but the UFH manifold has its own AAV and drain valves. Any issues with this? The wall is ply lined metal stud so I don't really want to attempt to bring the pipes down through the wall and out at the bottom. Through the floor is not an option either as it's concrete / screed. Thanks.

Just to reinforce what John said. Even T30 is high if you are trying to get most efficiency. Both heatpumps and boilers will be most efficient if sized correctly and ran at a water temp <40C. That's T15-T20. That might not be possible in an old property without more major works than you are planning but is something to bear in mind as you plan changes. If you want to dive into what savings can be made here look at: It's a big long thread and I suspect too much to worry about doing right now. But @marshian at various points shows the gains/cost savings made by his changes and might give you an end goal to aim for in a few years and allow you to avoid doing some things twice.

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Sorry below maybe an old response written while I was in the woods walking the dog with nut much signal. You maybe thinking of sizing radiators a little wrong. You are not oversizing for more output, more to allow a low flow temperature from the boiler. Lower flow temp from boiler allows much higher efficiency and less gas usage and same room temperature. But to take advantage you need to follow the same approach with all rooms and not be a system or heat only boiler on S or Y plan. What is your scope of work for the whole house?

Thank you. But I take it sizing the rads for more output, as long as the space allows, is not a problem, is it? A TRV should moderate the heat output and I'll have a bit of extra oomph for the extra cold winters?

On the UFFI, after this many years it has long since finished giving off formaldehyde, so it isn't a health worry left in place. The usual problem is that it shrinks and cracks, which can leave cold patches and occasionally lets driving rain track across to the inner leaf. If you've no damp patches or mould on the inside of the exposed walls, I'd just redecorate and leave it. Keep the pointing, gutters and sills in decent order and look at extraction or a top up later when funds allow. Your sums are about right. A room that size needing 1000 to 1200W is plausible with older walls, and at a mean water temperature of around 50C (so delta T 30) a rad gives roughly half its delta T 50 catalogue figure. So you're looking at 2000 to 2400W at delta T 50, which is about what a 600 high by 1400 to 1500 wide type 22 does, or a shorter type 33 if width is tight. Check the manufacturer's correction factor table rather than relying on the rule of thumb. Insulating the walls later will bring the number down a fair bit.

You were right - I've drawn the tall rad way too wide. Adjusted to 600cm for the visual. Double bed just about fits as does a 1.5m-wide Type 22.

Thank you very much, both. As far as future property appeal, the current plumbing for under-the-window rads just runs down from the ceiling & along the wall, out there in the open. The black dot on top of the bedroom wardrobe in the left pic shows where the pipes go down the wall (inside the old wardrobe). Re-positioning the rads means I get rid of the godawful plumbing and put the new pipes through the built-in wardrobe in the home office. Nicely concealed & no chasing required. Windows in this room are decent condition double glazed UPVC. The classic rad position suddenly makes sense though - thank you. I like understanding why people do/did things in a particular way. Re walls, how bad is having old UFFI and is it fine to leave in place for now/forever if it's not actively causing problems? I expect to be very cash-short for the next 6 months, which is a crap position to be in when you just moved into a fixer-upper, but we are where we are due to unfavourable factors outwith our control. I do need to redecorate a couple bedrooms asap though so can't wait a year before I have the funds and the time to deal with wall cavities. I know, it's a bit of a backwards situation, but such is cest la vie. Now rads are starting to really annoy me, the more I read about them (please bear with me). We've got building regulations that require us to have condensing boilers because they run more efficiently at < 55C flow return. That implies rad temp of about 60C when the heating is on. But most rads are advertised with BTU at T50 or T60, implying rad temp of about 70-80C. Furthermore, assuming T35, means we need rads rated for about twice as many BTUs, don't we? But there's bugger all supply of high-output rads out there while the market is saturated with rads designed to run at 85C, almost 20 years after we all got switched to condensing boilers. Unless I'm missing something. How does this fit into the government's plan to hook everyone onto heat pumps at T30? Doing some eyeballing with AI and heatpunk, for a room that's 3.8mx3.2m and 2.4m tall, assuming indoors temp of 18C and outdoors of 0C, I need about 1000-1200W from the rads, which is about 4k BTU at T30, so 8k at T50. This places me into 1800x600cm-sized tall rads, doesn't it? For a type 22 it would have to be almost 1.5m wide, which may be OK as plan B, but is a bit too tight space-wise for my liking. Still possible to find tall rads in this size for a couple hundred £, but is my ballpark calc correct? Thank you.

Octopus intelligent and axle are a no go, as it's not allowed, by Axle or Octopus, your API from Octopus would stop it working.

We don't have three-phase power, but the houses in our cul-de-sac are on different phases. We've been here for 28 years, and when we do lose power, it's common for some houses to lose power whilst others are still live, so I would guess if I had an upgrade to three-phase, I wouldn't lose all phases depending on the circumstances of the fault. We do have occasions where everyone loses power, but that's quite rare and means a substantial issue in the area rather than something more localised. At the end of the day, I would guess whether you'll lose all phases or not would really depend on why there is a fault.

I would leave them too, especially with 14 to change. The trap is not doing much for odour on a separate rainwater run, but it is not worth digging up for that alone. Just keep the leaf catchers clear and check the gratings after heavy leaf fall, because that is what will actually cause a blockage first.

G and J's route is the one I would push for here. Get that detail in writing from your SE and agreed with the warranty provider before you cover anything up, because that paper trail is what saves you later. A liquid DPM bridging up the wall can work, but only if the surface is clean and the lap is continuous, so do not rush it just to get the floor down.

I believe that generally all phases will go. The utility wants to balance the current on all three phases so if things get unbalanced to a significant degree it's likely to cause the transformer protection circuitry to trip all phases. If you are running three phase equipment then detecting a missing phase is important as missing phases can happen due to relatively local wiring issues (not main grid stuff). But there is likely nothing in a home that is worried about this. That is an interesting device, though if you have critical equipment that justifies something like this you likely have a UPS and can use a normal transfer switch (which I would choose in preference due to being able to choose a tried and trusted brand vs relatively new Chinese one).

Does anyone have experience of what happens when there is an unscheduled power cut in the area and they have a 3-phase connection? Do all three phases normally go down? Does the DNO shut off all three phases if they detect one is broken? Alternatively, does it happen that only one phase gets knocked out? Anecdotally, it feels like power goes off to the whole road and, since the DNO share houses across the three phases, that suggest all three phases go down during a power cut. If power cuts often only affect a single phase, then the following product could be of interest. Otherwise, it seems a tad pointless in the UK. GEYA ElectricalGPS6-N4VA2 4P Automatic Changeover Switch - GEYA Electric...The GPS6-N4VA2 4P Automatic Changeover Switch (ATS/ACS) is a high-performance 3-in 1-out phase selector designed to ensure uninterrupted power supply.

looked at that and the octopus intelligent seems best all round import +export for most of the day with a high rate between 4 +7 at night they pay and charge same coming or going and its done automatically by them then i have the axle energy as well so they pay £1 a unit when they want it