SimonD

Picture please! Like @ProDave says, if it's the flue is expelling fumes into an extension it is IMMEDIATELY DANGEROUS to life - this is was is called a RIDDOR situation and if your builder has left it like this the builder risks getting locked up by the HSE.

You still haven't read the paper have you? You said it was a fact that Lime was breathable, or whatever. The paper quite rightly highlights that the materials behave differently due to their pore structure. As a result, gypsum is both hygroscopic and vapour permeable whilst lime is only vapour permeable. I merely corrected you to highlight the facts are more nuanced and that the term breathable is meaningless. From any perspective of building, you need to select the correct materials for the job. In some instances, due to the behaviour of the materials, it may be better to select one material over another and it's down to the local context. Therefore, clearly lime may be better in some circumstances than gypsum, and in other gypsum will be more preferrable to lime. However, there is also the fact that there are many buildings without a DPC that perform absolutely fine without damp problems so for me it remains the question that the priority is to investigate the excess moisture first and then, if not practicable, take measures that mitigate against the excess moisture. Unfortunately, I get to see many older buildings suffering from damp that have used lime where the lime plaster is also cracking and peeling off the wall due to long term exposure to excess damp, even far up the wall. But then we get back to the issue of layers such as paint, or even wallpaper and the effects they have on the ability of a wall to regulate moisture content. But even in cases where these layers do not contribute, it has been shown that it still takes years for walls to shed excess moisture following remedial works and if there is a continuous supply of moisture the dampness will remain. The only way a wall will be drier is if you remove the supply of moisture and provide it with adequate time to dry out. This is one of the reasons why @SteamyTea 's point about numbers and measures is so important because otherwise you end up going round in circles in conversations because the reference points are unclear and ambiguous, not really helping anybody - what are we referring to specifically here when we speak of a damp wall? How damp?

Or any self-respecting heating engineer. 😉 And agree completely with the rest 😊

I think it's worth a visit. I attended a self-build project management course there before starting my build and stayed at the centre. We also had the time to walk around the whole site and get a proper lowdown of all the experimental builds they've done, including all the pros, cons, and the odd disaster of the various builds techniques - but at least they're honest about them. We also got out to the site on a current build out in the countryside somewhere to have look. We had a discussion about the hempcrete with, IIRC, the only major learning point that they got a lot of movement/shrinkage of thus gaps at a few joints which needed to be dealt with. The question is whether this movement was down to the hempcrete or the timber frame as it settled.

Have you visited the Centre for Alternative Technology and the Wise building? Wall mainly insulated with Hempcrete - https://cat.org.uk/info-resources/free-information-service/building/the-wise-building/ If I had the opportunity again I'd seriously consider it for a build myself. I think that might have been me. From the standpoint of that research, then if you want both vapour permeability and moisture buffering, then gypsum would be preferable to Lime, yes, and gypsum plaster would be preferable to plasterboard on the basis of the more dynamic tests conducted as part of the thesis. With that being said, we also have to keep in mind that as per the discussion part of the paper, the behaviour of these materials and the building aren't static. For example the moisture buffering behaviour of gypsum (with micro-pore structure) increased in variable temperature scenarios but sinusoidal RH variations reduced the moisture buffering behaviour of all materials. The whole research provides some very interesting data, but also throws up alot of questions, particularly about the overall behavour in real world scenarios of indoor and outdoor environments. To me what is interesting is that the concrete wall performed almost as well as the woodfibre in buffering moisture.

This is exactly mine and @SteamyTea 's point - the term 'breathable' is actually completely meaningless and shouldn't really be used at all. But with respect to the facts about gypsum v lime you should read the paper I linked but the TL;DR is: But the fundamental problem you're talking about hasn't really got anything to do with lime or gypsum, it's down to excess moisture. Excess moisture isn't good for any structure, so deal with the moisture.

Don't forget that flow rates change the resistance within the circuit: If you double the flow rate this quadruples flow resistance and requires eight times the power.

This study is quite a good one where they've built some real buildings at Bath Uni https://purehost.bath.ac.uk/ws/portalfiles/portal/218688237/PhD_Thesis_Cascione_compressed.pdf

Yes, this is key. The complete buildup of a multi-layered wall is also critical - you have a nicely designed breathable wall and then someone goes and applies an acrylic based paint, or uses a bonding coat of something - suddenly the whole thing has become a plastic bag and the main material gets the blame. It's one of the reasons I think people incorrectly think gypsum plaster, for example, isn't breathable and it gets a bad name.

At least I'm not alone

Do I half know both of those. I bought a massive load of bolts for fixing timber plates etc. to the steels and doubling/trebbling joists. When they arrived, I went to put them on a shelf in the garage only to find a few boxes already there full of bolts. I'd looked as hard as I could to find what I had before ordering more as I was sure I had them but couldn't find them at the time! Now my head is even worse.....which is why I come here to hide and get some therapy

With this? https://www.screwfix.com/p/mcalpine-boss-connector-white-22mm/719hr Alternatively you could use an adapter like this: https://mcalpineplumbing.com/traps/condensate-traps-and-fittings/r16-blc-reducer-abs to then fit to a normal boss?

Unfortunately a lot of people are being caught out by this. My dad had this problem while selling a house and it proved futile to try to argue with buyers mortgage lender. In his situation he just had to stump up the money to have the stuff removed and re-insulated with something else. I haven't really kept up to date with what is happening in the market more recently with this so maybe a wider Google might help?

Is the boiler cycling? No Is the boiler showing a low flow situation - e.g. rapid flow temp rise/low return temp? No Is the boiler showing a low differential temp? No - with rads rebalanced but not quite there it's at about 14C which is pretty good Were/Are all the radiator getting hot? No Does the pump selector setting just apply to flow rate? No, it also applies to the overall pressure drop across the system. So the process of commissioning a system is to balance the boiler flow and return and adjust the pump for adequate flow. If you read the whole thread, you'll find it's not too far out and the answer is a pragmatic one. If I was going to be picky I'd say junk the constant speed pump because that should not have been installed on a system with trvs and a pump with proportional pressure settings should be installed instead -cost is hardly any different. But how often do I come across proportional pressure pumps installed and set up on fixed speed? All the bleedin' time and I set them to proportional...

I don't really like to multi-position ones but I have a Little Giant Velocity ladder which is brilliant:

Okay ta, not much you can do with the pump as it stands.

I'm not sure about the efficiency arguments but it's the size of storage tank you need as a minimum in the loft to feed a vented DHW cylinder when it's pumped that's the pain. Sometimes you simply can't fit them in the loft or through the hatch.

On those bedroom losses, you'll be looking at T22 (double panel) at somewhere around 600mm high x 500mm wide mark Delta 30 so if you went 600 x 600 or even bigger, you could reduce your flow temps by a bit

Sorry, throttle back is to close it slightly Your pump should have some lights on it when it is running. Older pumps will just have 3 fixed speed settings, newer pumps can have fixed speed settings and proportional speed setting. Upload a photo of your pump and we can tell you. This can be for several reasons, but often if the rad is hot during the initial balancing followed by not getting hot, there's too much resistance so you might need to open up the LSV on that rad a bit. It's so easy to close the valve a little too much when the system is hot and onlyfind out when it heats up again. Otherwise it can be down to the pump speed setting. Here you're just experiencing the reality of balancing a radiator heating system - it is almost never as straightforward as a lot of articles or videos suggest - so back to requiring the patience of a saint and praying for a bit of luck. Some systems are just a total PIA with the worst ones I've experienced having tall column designer radiators.

Like I said, you've got room to play with as you've got little drop on some radiators and therefore if you spend a bit more time refining the setup, you should see a lower return temp, which is better for effiency. 40C is definitely feasible here.

So you're not far off. As you've got some rads without much drop, I would be throttling back the flow a smidgen there. You'll only need to turn the LSV a small number of degrees, then wait and repeat as necessary. Then test flow/return temps again. With respect to your pump, do you know what setting this is on?

Measure the temperature of both pipes once the heating has been running for a while as we want to see both temps and the difference between them.

Yes, it'll be the pipes with red/blue tape. The black thing is what looks like a Magnaclean Atom system filter so not your pump. The pump is probably in your airing cupboard with the hot water cylinder.

Great progress! What are your flow and return temps at the boiler? These are going to be the most important because you want to make sure the boiler is in condensing mode for as much time as possible. It needs to be under 54C but just below 50 is better.

You are correct, if they're working on a gas appliance, they only have to be Gas Safe registered which requires ACS qualification and centres on gas safety. There are other qualifications a heating engineer can do such as low temperature heating system design etc. but they're entirely voluntary. The decent ones will go on additional training to know what they're doing and talking about, like to this place https://heatingacademynorthampton.co.uk/ But technically, the engineer should not have whacked up the flow temperature but put it back to where it was when he found it and if he had an issue, provided some recommendations - again not law but etiquette he should have learned while training In the last couple of years additional training material has been added to the curriculum,e.g. recently I was tested for OFTEC and that test now includes heat loss calculations, so it is is at least moving in the right direction, but not nearly fast enough IMHO. Most engineers don't really know how to make the systems efficient - just the other day I walked into a house built recently to fix a problem with the heating where the developer had put in 2 30kW boilers and the whole thing was permanently wired up to room stats through 5 zones all powered by separate pumps with all pumps set to no3 regardless of the size of the zone! All running at 70c flow temp. No timer at all and the stats were relay, so no modulation. I wonder who installed that system? Certainly not someone with good knowledge of energy efficiency, nor heat loss apparently. I've told the owners we can switch off and isolate one of the boilers, add modulating controls, reduce the flow temps and probably lose the huge low loss header and combine the zones to make 2 max. We'll see. But as @TonyT says, balancing and making efficient a system is well beyond an annual service.