DavidO

Have you resolved this yet? Handmade/traditional tiles tend to be made by small local operations, so knowing where you are building would be important

Hi Andy The wall uValue was 0.14 and the windows are double glazed (though quite well specced for the time, we do have uValues for them somewhere if you’re interested). The big win for us had been airtightness, which tested at 0.296 from memory.

The problem with both the blue and white versions is that the “ribbed” structure creates turbulence within the air-flow which results in increased noise problems and a higher power consumption to move the volume of air you need to achieve satisfactory ventilation + both of those problems will be compounded if the pipes have a smaller bore. The other longer term issue is that the ribbing tends to result in the accumulation of dust/debris within the pipes increasing the risk of mould/bacterial growth. Basically the smoother the internal surface of your ducting the better. The only advantages I can see for flexible ductwork are ease of installation, which I think is only marginal in reality, and a price differential, which is probably also marginal when weighed against the whole system and long term running/maintenance costs.

Bin them....!!

????

I think perhaps you might have missed the main point I was trying to make (for djcdan rather than you) which is to guard against the potential trap of losing sight of the big picture as a result of focusing on the minutiae of the calculations. Depending on where you start from, and what you’re aiming at, there are usually lots of alternative routes to achieving an acceptable SAP score. The important thing is to make sure that whichever of those routes you consider they work with what you are trying to achieve.

Very sound advice! Agree 100%

Agree 100%......Our build/size/heating configuration is very similar to bitpipe’s and (7years in) our bedrooms are consistently comfortable with no installed heating.

Completely agree with this and other posts suggesting the same/similar. So.....given that you are where you are, spent your money, and presumably don’t want to rip out your brand new ASHP and start again, the first and most practical question is can you do anything about the heat requirements of your house? You don’t mention anything about existing insulation/airtightness in your opening post, but that’s surely got to be the place to start? First seal any obvious drafts. Second investigate/seal less obvious sources of air leakage (almost certainly lots in a 1970s build...... service pipes/wiring which enter through external walls/floors/ceilings....suspended floors, particularly timber, which have almost certainly shrunk/sagged, and all the points at which they meet the walls. Third, can you improve insulation of the external shell? Look at the ceilings first, floors second, and walls/windows third, depending on what you find. The more you can do to narrow the gap between your heat requirements and the capacity of your ASHP (at sensible cost) the more comfortable you are going to feel.

NHBC are a joke....!!!

My wife is a nutritionist, so only modest frying permitted here....! Having said that we redecorated during the summer which involved removal of the vent cowls, which I inspected and cleaned to arms length. There was a bit of dust but no oil/grease to get excited about given that was the first time I’d had a serious look at them for 7 years. Also the vents are approx 2.5m distant from the hob which probably helps.

Our experience is that you shouldn’t need any sort of cooker hood....we put 2 extract vents in the kitchen area and have no smells....no condensation and the boost hardly ever kicks in

Dont get too hung up on the calculations. Remember that, at your stage of the process, they include some important assumptions rather than realities, which, in effect, means they are (hopefully intelligent) guesswork. The prime example in our case, which was where the architects energy consultant slipped up, was airtightness. Her calculations were based on 3 (cu.m/hr/m.sq @ 50Pa) which, as first time self-builders, was the very best she was prepared to believe we could achieve, whereas the actual result was 0.296. Fortunately we had stuck to our guns as regards omitting the bedroom heating (significant cost saving + Yorkshire genetics) but still ended up over speccing the boiler and including a wood burning stove which we have lit less than a dozen times in 7 years.

Turner Timber Frames, based in Hull but have nationwide coverage, did a fantastic job for us. They are timber engineers really rather than just frame builders. First class product. First class service (both technical and practical). And a fair price. One of the most important aspects of self building, which is too often overlooked when wrestling with the technological challenges, is choosing the “right” people to work with. From the architect (if you use one) right down to the brickie’s labourer, it makes such a difference. We count ourselves very fortunate to have worked (mostly) with good tradesmen and suppliers, and some of them were great, a pleasure to work with. Turner’s were up there among the best of them.

Funny you should say that! There is a plot we have been flirting with; but it would be hard to leave all that blood and sweat behind!!

Thanks....Yes it’s a stone called Blaxter, from a quarry in north Northumberland, it’s on the soft side, but we loved the colour.

We'll be having UFH on the ground floor and previously had specified radiators to the upstairs. By installing MVHR, could the upstairs be heated by i) rising heat from downstairs and ii) the MVHR to replace the needs to install rads? - By installing MVHR, this replaces the need for other forms of ventilation to kitchen and bathroom areas, which would typically be extractor fans? I assume this is correct since any additional ventilation system would reduce the airtight seal on the property and decline the efficiency of MVHR. We did exactly what you are describing in 2013 in a 195msq timber frame build. Our architect said it was “brave” and his energy consultant said we were “bonkers”. Both were wrong; it has worked perfectly and 7 years on we have no regrets whatsoever. Omitting the heating, other than heated towel rails in the bathrooms upstairs, saved £1,100 which was a significant contribution to the £2,600 cost of the MVHR system. We also negotiated a £600 discount from our window suppliers as we didn’t need trickle vents and saved another £800 or so as we didn’t need a cooker hood or any bathroom extractor fans, so the “net” cost of the MVHR was pretty minimal. Unlike others our experience is that there is an element of heat redistribution from the MVHR, you can feel slightly warm air coming in through the vents. It’s difficult to quantify, but our bedrooms maintain a pretty constant 19 degrees in winter from the combined contributions from the ventilation system and the “migration” of heat which you mention from the ground floor, probably enhanced by an open plan layout downstairs which is also open to the stairwell. As regards your noise questions, our experience is yes you can hear it when it’s on boost, but not if the TV or radio is on, and in reality the boost level is so infrequently required it just isn’t an issue. We’ve also found that we can run the fans at much lower speeds than recommended by the manufacturers so in reality the system is virtually silent most of the time. Rigid rather than flexible ducts are supposed to help with this, as well as trying to keep your duct runs as simple and free of bends as possible. We located the intake/exhaust ducts on a north facing gable wall rather than through the roof in order to benefit from shaded/cooler air in summer. It’s amazing how hot a dark coloured slate/tiled roof can get with the sun on it, and the thought of sucking any of that heat into the house in July/August was unbearable, even in Northumberland. We also sited the exhaust duct downwind from the intake, which was a no cost option which which we thought might have (unquantifiable) benefits for both air quality and intake temperature in summer. Good luck. Hope it works well for you!

I’m tending to agree with MJN/ProDave.....I wouldn’t give up on the existing MVHR unit too quickly; not familiar with the make but 10 years isn’t that old if it’s anything like a decent piece of engineering. Sounds to me as though it was very badly installed and that you have inappropriate configuration of the air distribution/extraction (rather than the unit itself) which might not be too difficult/expensive to sort in a 55msq 4 room property all on one level, even with 100mm ducting. Something else which is puzzling me is that you make no mention of condensate drainage from the MVHR unit? Is it possible that there is no drainage, or that the drainage system is blocked, and the (inevitable) condensate is accumulating in the bedroom and contributing to the mould problems you refer to in that room (and possibly/probably elsewhere)??

Hello All I don’t think this site existed when we were building in 2012/13. I wish it had!.... I came across it while searching for tips about how to deal with an accumulation of condensate in our MVHR (Ventaxia Sentinel Kinetic Plus B) which I think (hope) I’ve cured now, thanks, in part, to experience shared by other members. We completed our build in June 2013 and have been really pleased with the result. Build route was timber frame/self managed mainly using sub-contractors + our son who is a professional plasterer and multi-skilled DIYer. We’ve had a few minor niggles, of course, and one or two things we would have done differently if we’d known then what we know now. It would have been great to have had access to a site like this at the time, actual real experience is a hugely valuable resource. Having found the site, and benefited from it, if we can contribute with our particular bit of hindsight we will happily do that.