Sparrowhawk

@nod Is there a quiet time of year for render companies when they may want to price more reasonably? The summer?

IME they're not hugely effective either. Build your own tank enclosure and fill it with insulation of your choice. Paint it any colour but red

Blower door in action for the first time. I was pleasantly surprised by how airtight the main rooms downstairs were (I sealed the dining room door into the hall, and mounted the blower door into the lounge doorway into the hall). Even on the slowest setting the fan created enough pressure difference to find the major leaks, with the next speed up used for the smaller ones. Now to start sealing the 40ish leaks we identified!

Welcome @limecc. I'm curious about these two, do you find they provide something over the supplier's own app? I completely agree. I've been next to one this morning at an outdoor centre and it was bliss. It is a shame that none of the alternatives can capture the level of radiative heating and brightness.

I have no idea what the warrant stage is. Don't royalty hand them out? 😛

I hadn't heard of them before so thanks for the name, that looks good as an option for us. Are there any other fixture suppliers you've found are good without being hugely expensive? We're particularly on the look out for doors, handles and flooring but I'll take every recommendation going to uplevel us from the father-in-law's Howdens catalogue...

@jack I'm reading Yvonne's post as saying she's doing a second build, and in the first the MVHR was noisy and she wants to avoid that in the next. But the warranty bit confuses me. @Yvonne who designed and specified the system for the first house?

Welcome Mike, you're not the only one here with an expensive to heat/cold house! I've had great help from the folk here and you could do worse than to peruse their replies in my thread Have you chimneys in the property as well as sash windows?

What would you say is a reasonable sqm cost for UFH?

I like, nay love, the feel of IR heating on my face. Those who compare it to being out in sunshine are right. (I also notice radiative heating from radiators et al so if you don't YMMV). I have been entertaining myself by asking IR panel companies, particularly those who talk about "academic research done" to provide basic information, like how much energy is output at different wavelengths to show conversion efficiency beyond "heat". They go very silient when pushed for substance behind their marketing. I have evidence that a UK manufacturer who advertises widely has taken their 'research' out of context and the organisation that carried it out is... distinctly unhappy with how it's being misrepresented. If your friend's family would like to share any research they have had done, I would be very interested. On costs, what do you think the annual heating requirements for your house will be? Are you building a Passivhaus? How long do you expect to live there? Calculate the annual running costs and see how they stack up.

I'll take some. It gives me a great excuse to go for a walk and stare at people's properties.

A couple of houses round us which are of simialr style to your (pre-extension) house have gone for a colour near sage green. They look really good. It suits the creamy brickwork and landscaping around the properties.

If I depressurise I can feel the draughts with my hands. If using smoke I might pressurise. Yes that is the million dollar question. I've found https://www.builditsolar.com/Projects/Conservation/BlowerDoor/FlowRates.htm but not gone into the details yet. Checking if I reach 50Pa should be simple(!) with a U-shaped tube through the door, fill it with coloured water and measure the height change. Volume of air shifted - well Screfix are out by a factor of 10 in their quoted l/s for this fan so no idea.

My house is so draughty that yes I'm planning to depressurise a room at a time to start with. I do have a second fan so if I need more oomph I can mount two in the door. Why a door? This was free and wood's expensive at the moment. Old doors are also cheap on FB Marketplace.

This is my blower door that's awaiting commissioning. My house has 4 5 different doorway sizes so plan is to tape plastic sheet at the sides/tops to seal it in. I am frustrated how oval the hole I cut in the door is. Am thinking of filling the gap or putting the fan in a tunnel (don't know what the technical term is) to guide the airflow.

Which is the other drawback with UFH on a suspended floor I guess (compared to a floor slab) - the cold side has a bigger range of temperatures say 10C more, and the rate of change is faster than the temperature of the ground.

@JohnMo Good timing, I was just searching for a post of yours I'd seen previously which I think will help quantify this. Found it: and also found I thought ∆T was inside air temperature -> outside air temperature, but here the ∆T is the difference between the water going in to the UFH pipes and the temperature of it coming out? If so 6-8C sounds sensible for a hypothetical system where the input temperature is unknown. Taking your calculation from the first linked post, and it looks like delta T here is the temperatures in the pipes/below the floor(?) if it's a suspended floor and the air underneath is a mimum of -2C and indoors is 20C and the water in the pipes an average of 35C, then won't ∆T by 37C? Trying not to butcher it (edits in bold):

Let's say the whole of the downstairs so (excluding internal wall thickness) 10.5m x 5.8 = 61m². I'm guessing at a suitable ∆T as 20 - -2 = 22K?

Since I got buy-in from my wife about lifting floors and disruption she's started coming up with ideas like "we could remove this wall, and that wall, and what about...". We're planning to get a structural engineer round to say which are load bearing and what would be needed to take each out (I think they're the right person to ask?). Her ideas are great but this could all turn into a bigger job than I anticipated 🤑 She also keeps bringing up underfloor heating. I am not convinced I can get enough insulation between (and under?) the joists to make it worthwhile - not without digging 10cm deeper below the joists anyhow. Modelling the floor: 100mm mineral wool with λ 0.038 and 18mm chipboard: U-value 0.27 150mm mineral wool takes it to 0.19 - but ventilation space is likely tight. 100mm PIR with 18mm chipboard over the top gives a U-value of 0.18 assuming perfect fitting between joists (hahahahaha) 150mm PIR takes it to a U-value of 0.12 What do you think? If not feasible this will feed into the 'removing walls' conversation as if the back of the house is opened up there are fewer places to locate radiators.

And the same supplier sells via eBay without the £8 (IIRC) postage charge on a single can of foam. Makes the pennies go further!

They said bills of <£200/month so that could be combined heating and living. Our annual DD is (was) £200/month for gas & elec. 90kWh/day in an older house for heating only isn't unreasonable in cold spells. We have been over that for 8 days in February, and December/January had more days. Averaged over the year... yeah that would be high. We need more info.

Hi Ant, there is a way to meet regulations with mineral wool: build wider cavities. @nod is an expert here and if he says you need more than a 10 mm gap then he'll be right. Though @nod why not just go for full-fill cavity instead of leaving a gap in new construction? No, it's the difference in the materials. Mineral wool can't compete with the U value of PIR boards. So you have to use much thicker mineral wool to get the same effect. Got it in one. If you use Kingspan or other PIR boards, be aware that the quality of installation makes a difference (from the data: seemingly quite a big difference) to the thermal performance. Gaps between the boards let air circulate, negating the benefit. This paper on thermal bypass is well worth a skim through to get the idea of the effect. If you care about how well the insulation works, figure out a way to ensure your builder spends time installing it properly. Then patent and sell your approach, as controlling builders is like herding cats

I saw that Gapogroup tape at NSBRC, one of those "why didn't I think of that?" moments. Feels like a thin latex foam with sticky foil over it. I do wonder how many decades it will last & stay springy.

I've also used Soudal flexifoam (which Toolstation sell) and it's good foam but the blue colour makes it hard to hide stains or spills. 3 hours it took to get an accidental drip off the middle of the wood floor in our lounge...

Illbruck FM330. If you want one or two cans, I found eBay is the best place to get it as the major company that sells it direct also sells there, and doesn't charge postage if you buy via eBay.