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A bit of an afterthought, but have you costed in the purchase of new tools & machinery? Part of the reason to do it yourself is that it gives you the excuse to buy all the shiny new toys.😇

Hi Folks, Didn't want to create a new thread for another suspended concrete floor insulation question so I hope you don't mind me hijacking this old one. I currently have suspected suspended concrete flooring in a couple bedrooms and the corridor of my bungalow. The exact construction of the floor is unknown, but it's raised, has a void under it, sounds & feels closer to solid concrete and it sure doesn't feel like suspended wood that I have elsewhere in the house. The floor make-up in the bedrooms is a layer of very old tiles, then underlay + carpet. The corridor has been re-done professionally under previous ownership and looks like a layer of screed (possibly over old tiles) + glued-on LVT, which makes it a very cold floor to walk on. I'm eyeballing my options to add some floor insulation before I re-decorate the bedrooms and would really appreciate your advice. Door frame clearance currently is 196cm. Internal walls construction is solid brick, which may make it difficult to raise the clearance to accommodate a raised floor. There's perhaps an extra 10-15mm that I can gain by knocking off the top of the wooden door frame and replacing it with a thin decorative veneer as an easy win. I don't want to mess with the old tiles, as, given the age of the property, tiles & adhesive might be ACM. My thinking is along the lines of 25mm PIR (not sure if I need wooden battens between them), then a layer of 8-12mm ply (is that sufficient?), then 2mm underlay & 4mm LVT or 6mm laminate. Perhaps a DPM needs to be placed below or above the PIR? A total of about 40mm increase in floor level, which potentially sounds like a lot of work for marginal insulation gains and dodgy 193cm door clearances? Are there any sensible alternatives to keep it under 40mm? The fallback option is to just lay new carpet with thicker underlay in the bedrooms and replace corridor 2mm glue-on LVT with something like 2mm underlay + 6 or 8mm SPC LVT which I had in my old house and which felt very warm to the foot, so I'm guessing it's got very decent insulating properties. Or just SPC LVT everywhere. The fallback option results in better door clearances and better quality flooring compared to thinner LVT and laminate. Your thoughts on how to improve this without resorting to a bulldozer or a concrete breaker are very welcome. Thank you.

Very cheap. Well spotted. Though 345 lumen is a bit tight on light output. For all the progress, I have yet to find the perfect GU10 - 800 lumen+, dimmable, 60deg, CCT remotely controllable, CRI>90. I wonder where we would be had they not banned people from using the old ones.

many suggest undersizing heat pump and if needed for those few days supplement heat. id go for 4kw no question. bin the buffer which lowers efficiency (if not needed) adds cost and complecations. you shouldn't need it as you will likely have plenty of water volume.

I know it's not your work but those rads work much better when set up TBOE - I've got 2 of them and the inbuilt baffle is very poor so I converted them to TBOE

I couldn't be arsed with ledger boards on blockwork. I'd rather try tony tray. Ledgers might sound great in practice but fixing and putting them up sounds a pita. What if the walls are out by 10mm on the width.

Nice enough that is. I've had the shell looking ones before but a bit old fashioned now

Bring the pipes down and run behind the center of the radiator until you're at floor level and then bend off left and right? Picture isn't my work but you get the idea.

Combi boiler already gives you room to have CH and DHW at very different temps. If you are adding more insulation your existing rads may be fine or something you sort out later when funds allow. If you replace the boiler get one that allow you run weather compensation (WC). Then with correct sizing you run most the time in the low 30 for CH, cold snap the flow temp will naturally increase to compensate. The idea is you run long and low, you warm the building fabric and that also allows the house to feel warmer at a lower room temp , that also which lowers heat loss. Once return temp drops below 53 degs you are in condensing mode, the further you fall below the more condensation and the more efficient your boiler.

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.