Big Jimbo

Personally, i wouldn't use that. I can even believe that is an approved fitting. Problem, waiting to happen.

@saveasteading I've got that book somewhere.

@iMCaan bloody little rascals. I'd send them home with broken fingers if i caught them.

@Apprentice I think these days very few books get written. You tube seems to hold all the answers, but you have to plough through the bulls41te one's to try and find the decent information.

Don't get me started again @SteamyTea Like that poor fella who was asked to spend a load of cash because he had a flawed Air test. He had some of his uncontrolled air losses taped off for his air test. It might well have been what was required for the test, but it didn't make his result scientifically correct. Luckily, the BCO understood that the test, although carried out correctly, was flawed. Science, i think i went once, and sometimes, logic beats science.

@SteamyTea within 200 watts.

@SteamyTea How blinking close were you at my heat loss calcs. Gold star fella.

Somebody recently wrote on one of the hillbilly off grid sites that he was planning on using the electric battery system from a fork lift truck to store his energy created from his vast array of solar panels. said the capacity of the fork lift truck battery was 50kva (prob got my k's and v's mixed up.) (i will wait for @SteamyTea to tell me off) Said that during the winter he would charge the battery from night time cheap rate electricty. He said the battery would be less than £4k. Food for thought ?

Just to let all the kind people who have contributed to my plight. At an outside temp of -2, inside target temps of 18 degrees bedrooms, 22 degrees bathrooms, and 21 degrees all other areas, i will need 6509.52 watts of energy to heat my house on a bloody cold day. (OK, not a scottish cold day, but those lads and lasses are proper hard) So 6.5kW. So should i now be looking for an ASHP of that size ? My next task will be to try and calculate how much water, and at what temp i will require to store it at, in order to provide enough to run 4 showers at the same time. My thoughts are that, (and i'm not saying i'm right) I don't see the point of storing hot water at much higher temp than i actually need it at the outlets, just to blend it down by then adding cold water. Again with my badly educated mind my thoughts are that the lower temp i store the water at, then the larger the tank will need to be ?

So, happy with my fabric losses as calculated. Re-doing my ACH using .5 Would i be right in thinking that my calculation would be......Volume (LxWXH) X ACH (using0.5) X 0.33 X mytemp for that area added to my outside temp at -3 ? (so for 21 it would be 24 ?

@JohnMo The idea of having simple controls for heating really appeals to me. I've been in houses with thermostats in every room. My idea is to have One zone downstairs underfloor heating. One zone upstairs with thermo valves on the rads.

@SteamyTea I was using 3 ach. I am now redoing it at .5 I will report back. Thanks everybody inc @JohnMo

Most of the losses seemed to come from the air changes, but my concern is how realistic is 1 ? All very well calculating it at that, but if you then score 2 ?

I did try Jeremy's, @ProDave but noticed when i finished that he had the air changes set at .5 I know people on here try and get as low as they can, but .5 seems very low, and if you did a decent job and got 1.5 my worry is that you would not have enough energy being provided to heat the house in cold weather.

I'm building a new house of 2500 square ft. Basically an oblong, internally, 10.2m x 12m with a 2.5m wide glazed porch on the front. The "u" values as designed are, floor .09, walls .16 roof .11 windows and doors .96 Windows and doors are just under 25% of floor area. So, a bit better than building regs, but not a huge improvement. I have done some detailed heat loss calcs on a room by room basis, using the following. Design temp for bedrooms 18 Degrees. bathrooms 22 degrees. all other areas 21 degrees. I used an outside air temp of -3 degrees, and i used an air change rate of 3 per hour. (I will aim for less air changes, but wanted to be safe for my calculations) I got a total house heat loss of 12125 watts. Would anybody have any idea if that sounds reasonable for a 2023 new build of 2500 Square ft ? Thanks in advance as always.

It depends if you have trees, and what your ground is like. Sounds over the top to me . I did a workshop, about 10m x 8m. dug out 6" of mot, then 6" of concrete. 12 years later, it was still fine. No cracks. Nothing.

No problem. Don't take any flannel from them. The fitting is not right. Does not meet the part L regs, and is a huge thermal bridge. Warn them that they don't want to have to have a face to face chat with your mate Big Jimbo. If there are any bodies they are members of "Chas, Trusted trader " etc i would report them. How many other windows and doors have this company fitted incorrectly in the local area.

I'm no plumber however, if the OP's water is coming from a presurised tank, then would both the hot and cold not be delivered to the shower mixer at the same flow/ pressure ? If both the supply pipes are the same size ?

Don't pi$$ about then. Point out the relevant bit of part L that i have given you. Small claim court for a full refund. Clueless twats. Get the boss by the throat up against the wall. "your builders told them" classic.

Part L1a 4.15 d 2 Find that and wave it at the window company.

It was One of the accredited details. Labc, Nhbc, Bre, all now thrown in the bin since the new part L1 came into force. Now saps has to use psi values, or accredited thermal modelling. You did a good job spotting that that is a hideous thermal bridge. Get them back, and get them to sort it.

Sorry, should say "Good reason to set them back further" I'm tired

You need to get them back. Bloody professional window company using fitters that don't have a scooby doo. I'd go bloody mental.

30mm minimum into the cavity. If you are having slate cills then there is no reason to sit them back even further. I would do 70mm into cavity, and 10mm of the frame outside. Best position for thermal loss. Fitted on straps.

Is that a cill on the first picture ? It looks like it is flush with your brickwork. Were these windows fitted by a professional firm ?