Marvin

Warm roof!

My guess is 44C

Hi @Terryt Welcome I'm sure there's someone here who has some experience with this sort of thing.

Plus 1 about the loo!

Hi @sylvane Welcome Bit concerned that you will find it difficult to convince Building Control that thinner insulation will pass the requirements. What's the width of the bedroom?

Hi @Larsen Welcome. I know the feeling!!!

Any use: https://www.thorenvarmepumpar.se/images/Pdf-er/users_manual_thor_es-3.pdf

Hi @SDTM Don't know if any of this helps... https://www.varmepumpsforum.com/vpforum/index.php?topic=46451.0

Someone with sense!

Hi @Jimmyjazz Welcome. Always good to have other's thoughts on a projects. We gave up finding a site and went the renovation route. 🙄 I don't know if will ever get to adding to this site as much as I have learnt. I doubt it!

Aim to go APE It worth considering all the AIM and APE elements before making decisions. That is Airtightness, Insulation, Mechanical Ventilation with Heat Recovery OR Heat pump Ventilation, and Air Source Heat Pump, Photovoltaics and Electric Vehicle. Some of these will not work properly without the others, and some will complement others: A MVHR will not work properly without Airtightness. An Air Source Heat Pump will have to compensate for the lack of Airtightness and/or Insulation to the degree that the benefits become questionable, especially during winter, without them. An ASHP uses electricity and Photovoltaics can supply a little during winter and a lot during summer when cooling can be a problem and an ASHP can supply cooling. PV can supply a little to an Electric Vehicle during winter and plenty during summer if your vehicle is at home during sunny days. Extending a property and only doing AIM works to the extension will be no good, you have to do all the property within the thermal envelope. And thinking of running costs: a) Airtightness and Insulation should have no running costs and last (Well, loft insulation lasts over 40 years, in our experience) with the exception of UPVC units for windows and doors, but that being said it will last 30 years? b) Our MVHR unit servicing 100m2 floor sized home uses about 260kWh a year; far far less than would be used to heat incoming cold fresh air in winter, and we clean the filters twice a year. c) ASHPs are, in my opinion, still in their infancy but we are now in the second year of use here. We were very careful to follow best practice in the design and installation of our system, did a lot of bespoke tweaking, and we now have an upgraded 1970’s timber framed bungalow that uses less than 25kWh per year per m2 of floor for heating. d) PV would be a lot less attractive if there is no ASHP or EV (or battery backup) or diverter to the hot water immersion. In my humble opinion, if you have a suitable roof you should install as much a physically possible. Electricity production costs (cost per kWh) are difficult to evaluate because it depends how much is used and how much is supplied to the grid. We decided to go with the PV cost divided by 7 years, which for us works out at £1.60ish per day. Yesterday the PV produced 12kWh all of which we used. Remember, 5kW of PV panels will not produce 5kW because you would have to have: i. No shadowing of any of the panels during sunlight hours (like trees, buildings or chimneys. ii. All the solar panels face exactly the right angle in relation to the summer solstice midday sun for their position on the planet. (Perfect angle facing south and perfect slope) iii. solar panels completely clean iv. the sun is completely unobscured v. the Inverter is 100% efficient vi. all the other losses due to cables, and equipment, and so on. e) Knowing the above PV limitations professional installers often add extra panels to make up for these losses. (Our inverter allows us to add roughly 28% more panels than its kW rating) f) PV panel installations will produce about one sixth of the power in the winter compared with what is produced in the height of summer. g) The electric vehicle and charging from the PV only really works if you can have the vehicle plugged in during the day and supply over 3kW from your PV (or a large proportion of that). This is why we went for the biggest PV that would fit on the roof. We then installed a system which only charges the when the PV is on and generating over 2kW in winter and 3kW in summer. (we have a 13amp charging system). So, if finances cause you to have to consider only a few in my humble opinion AIM first and go APE later. (But prepare the property for the APE works as much as you can). Best of Luck Marvin

Hi @John Jackson No ours is a cold loft but the insulation covers the tank. Yes it's the mix of water sitting for ages and the warm temperature that causes the problem. That's why I only have a small tank and refill it at the end of the day. When completing legionella risk assessments, water sitting in lofts for a long time was one of the problems. We had to make sure that any water connection changes that had been done over the years, removed all defunct pipework, that was still connected. Some buildings had long pipe runs to nowhere leaving water to stagnate for years causing a risk especially with mains water.

Some info: https://www.sciencedirect.com/science/article/abs/pii/S2352710219330190

Most PIR for floors has the same sort of thermal resistance so your really only discussing thickness. I would go for as thick as you can stomach! As @Nickfromwales says save you every year!

I think you will need to replace the lintel. It has to be supported at both ends by at least 100mm so needs to be at least 35 inches (890mm) wide central over the new opening. I like to go 5 to 6 inches each end...

We use an unvented cylinder with no problem....

I think you would only need a header tank that will hold about 2 days water at once. Ours is about 60 gallons. We only use rainwater for loos. held in a underground tank with the header tank filled daily and therefore doesn't sit long in the loft. However we do not use it for washing machines and only pass it through a sand filter.

Hi @Post and beam As @Kelvin says, not difficult to understand once you get your head around it.

Hi @Johh When you upgrade the insulation to a building including the floor, walls and roof, a far greater percentage of the heat loss is caused by poor air tightness. If we were to turn off our MVHR and use trickle vents in winter our energy requirement to replace the heat lost through the air changes (at 6C outside, 20 inside) would rise from 175Watts to 875Watts causing a 67% increase in the energy required to heat our home. (not counting the energy used to replace the warm air extracted by the fans needed to wet rooms and kitchen) IMLHO (in my less humble opinion based on my experience) once the building fabric is highly thermally resistant, airtightness becomes more and more important when calculating heat loss. If you are not fanatical about sealing the building...... Good luck M P.S. When "guiding" the builders when completing the airtightness works on our renovation this sort of phrase was often heard: "What? you want to seal between (whatever) and (whatever) ??? Bewilderment, and a polite-ish look at me like I'm either stupid or nuts. "Never done that before!" Luckily I was on site so it was done.

Nothing has been mentioned about airtightness and wood burners: Are the wood burners room sealed?

Wish I got paid for quoting for work.

Make and model of inverter would help

I don't know what you're all winging about I have it tough! I have a bowl of cold broth and bit of old bread.. Beer! I could only dream of beer. I used to work on site for 10 hours in all weathers with rain dripping down me neck, filling me boots, and when I hit my thumb and went to the foreman (as he was called then) he asked could I wiggle it . Upon showing him I could he bollocked me for not hammering hard enough! Teriyaki? Oo very lar-de-dar Sweet corn I should be so lucky. Southern softies pahh! I'm off to see if there's any gruell left.

I think what was meant is that a property no more than 6 homes away from @Canski's home has gone through the same situation.

Hi @Christiano Interesting. It sounds like an iBoost is more complicated (technologically advanced) than a solic. Unfortunately our solic is in a different building from the batteries and our battery system is off grid.