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The DNO is interested in safety of the grid, which includes controlling whats connected to it for the benefit of everyone. You might see them as a pain in the butt but consider a couple of scenarios that G98/G99 ensure dont become problems. One of your family needs sensitive medical equipment and has some in the house. Living down your street are a load of reckless PV cowboys who've connected 10s of KW of PV without giving a hoot about what it might do to the neighbours medical equipment. Sunny day in June and the cowboys PV export pushes the voltage way past the UK limit and your medical equipment shuts down. Another scenario. Same PV cowboys install cheap Chinese inverters that aren't type tested and no one checks because theres no G98/G99. Turns out they dont actually disconnect from the grid when theres a power cut. Come the first daytime power cut and the repair linesmen find theres still 240vac on the faulty lines because of the PV cowboys inverters. Despite having the option to earth the live lines they decide to investigate the source before making a repair. The power is off to your house for significantly longer than it need be until they find the PV cowboys non compliant inverters and shut them down. Both hypothetical scenarios but you'll hopefully see that theres more to G98/G99 than DNOs just being awkward

I’ve only ever used MR PB, tanking the wet areas meticulously and sealing with CT1 where necessary. I’ve got a lot of 1st floor wetrooms under my belt, and still have the same mobile number, and nobody’s ever rung me to say they’ve got a leak ( or that any tiles have fallen off ).

https://www.caleffi.com/international/en-int/catalogue/antifreeze-valve-brass-body-108601

https://www.seconrenewables.com/volano-wall-mounted-buffer-7698-p.asp Not all installer have moved on to use anti-freeze vales.

I'm still on gas but been doing lots of reading, I need a cooling solution as much as anything else. Heat pumps generally run a pressurised system same as combi, so if the freeze valves open the system would loose pressure. If the system is operation ie you have power, the pump would circulate to protect the system. Only in a prolonged power cut would the water drop below 3 deg and the valve open.

It has a lower heat transfer coefficient compared to water, so you have to run a degree or so warmer.

Two types of heat pump Monobloc, everything you need to get hot water is outside, water pipes connect to outdoor unit Split, smaller outside unit, but refrigeration gas pipes connect to indoor unit some of the stem is indoors, water connects to indoor unit. Hex unit, just a plate exchanger and pump in flashy box. Less efficient do to a temp drop across the heat exchanger. Glycol anti freeze, stops water pipes freezing. Without a heat exchanger the whole system has to have anti freeze in it. Split system refrigerant doesn't freeze at normal winter temp. Alternative to anti freeze is freeze valves, these open when they detect water temp at or below 3 deg, dumping water to the floor.

Don't need HEX. Only real reason to use one is if you have glycol in your heat pump circuit, but not in your internal circuits. But even in this case it's easy just to use Glycol everywhere rather than adding costs/complexity and loosing efficiency. That said, as @HughF says, with anti-freeze valves you don't need glycol. I have a Vaillant install with no glycol, no HEX and a 25L buffer.

You don’t need the mixed pump groups. The weather comp curve can be set for the radiators and then you can use a standard ufh blending manifold and pump for the ufh loops. Pick a brand that doesn’t require a hex module for a start, and choose one that includes the room controller in the box. There’s really no need to go spending all that much.

It’s for the TV.

Instructing an architect/designer seems a little over kill if you already have scaled drawings. Why not just submit those along with the other accompanying information? After all, you are only talking about extending a garage.

Tropical fish tank's another 70's fave.....

Yep, knocked one of those out in our first house. Then chased out the wall and rewired the plug socket to get it down to a sensible height...

Yep, that’s a fine period telly stand!

No, the diameters are just dictated by the flow from each of the utilities and coincidentally in this case match the level of challenge to run them through the structure. But as belt and braces you could add AAV at the sink, that way the pipework can equalise pressure if necessary

Looks like my mum's old house. All the rage in the 70's. Agreed - masonry TV stand. Edit: to be fair to dear old mum & dad, theirs was real sandstone and had a superb chunk of teak on top - about 1.5" thick...

To stand your great big heavy 26" CRT television on. Yes seriously. Posh people had a matching one the other side for the gramophone to sit on.

A photo from further back to give context within the room might help. What age is the property?

Well gas is about 10p/kWh. So divide the cost of your battery system by 10 (it should last ten years. Then by 5 assuming you need 5 kWh/day out of it. Then divide by the number is of days you want to use it, say 200 a year. Then add the cost of charging, multiplied by 1.3 to the number. If that is less than the gas price, plug in a fan heater. If not, use the gas.

Great, thank you both!

I paid extra for the non-formaldehyde boards when boarding my loft (cold roof, that one). Logic at the time was that even if I'm not up there much, I'd be cutting and fiddling around with the boards plenty during the installation. Still, it's probably mostly marketing.

You've just saved me question on making exactly the same test funnel with some leftover plenum pipe @Gone West. I've got an RS components hotwire bluetooth anometer on order from Ebay (£10.95 including postage and packing) that looks like it came from a bankruptcy auction of a contractors kit (has an asset number sticker on it). Hopefully all that is wrong with it is a missing battery compartment cover 🤞. I'll be happy to lend it to people if it works when I've finished my initial set up (though that's a while off yet). If it doesn't work how do you go about going on the waiting list for the forum one?

Couple of different ways to look at buffer and also what the heat manufacturer states as a minimum system requirements. Some manufacturer will have a minimum system volume and minimum flow rate. Some will specifically demand a buffer of minimum volume otherwise warranty is void. If you have UFH with a mixer valve you have no idea of the volume flow through system will always meet the min flow requirements as the mixer recycles a lot of the flow. Vaillant 8kW demands a flow between a min and max of 380 and 1400 l/h

Lounge yes, 1 terminal opposite corner to the door Agree on hall, maybe retain one? Kitchen defo, not for airflow but to keep things quiet on boost. I’d stick with 2 terminals in the bedroom for the least amount of audibility, but you could go at the head of the ceiling and do as you suggest.

I used a combination. Tile backer boards for the wet room corner and behind the loo, then mrpb everywhere else. Helps they're both 12.5mm thick. It was all tanked: The someone made a hash of the tiling, letting down what would have otherwise been a fantastic job 😤:

Call a heat pump company, not a boiler company… Speak to Chris at CoolEnergy in Grimsby if you want to talk to someone technical. I’ve just added a 5kW Aerotherm plus and a VRC700 to my basket on the first hit I found on Google, with delivery it’s under £4k - where are you getting the other £4k from? Give us a breakdown of your system design and we can see where you can make it simpler and cheaper. Onto the glycol argument - no-one should be using glycol in 2022, a single freeze valve is all that’s required. A decent monobloc doesn’t need an internal HEX unit, just get the flow and return into your plant room and hook it up directly to the system. A buffer allows you to run the heat generator and the heat emitter as separate systems, with a loss of efficiency. Lots of installers use them because it eliminates callbacks for low flow errors when an existing system with too many TRVs have all the heads shutting down. A buffer also provides a large volume of water for the defrost cycle. Personally I have a small house with a simple heating system and we never have any doors closed so have no need for any TRVs downstairs. I’m going direct from ASHP into the rads, using the modulating pump in the ASHP - if I have problems then I’ll add a LLH and put a separate fixed speed pump on the rad side. So yes, a buffer doesn’t make it super easy to throw a system in that will work. The ASHP sees the buffer and controls the temperature of that, the room stats/zone valves/pumps just see the buffer as a ‘boiler’.

Sorry @DavidG, the query re location was for @renovator123. Glad the cost comparisons were useful.

100% get one - I had one on my last build and it was brilliant - the savings on skips alone is worth it. My top tip would be to keep builders bulk bags and separate out waste into wood offcuts (which people will collect together with pallets) other stuff you can take home and put into your bins (general waste and recycle) and then one for the tip. Only once you have a quanitity of bulk bags with waster that has to go to the tip do you pop 'em in the back of the tipper. I only needed to do two tip runs in the end. It never ceases to amaze me that once you have a skip on site, how quickly it get filled up. For aggregates and pallet load collections it was really handy and of course you can drive it right up to the front door for unloading...

Yes I did pretty much everything on the last build I’m now 61 and seem to be doing the same again My wife said I have trust issues 😁

+1 We filled in both sides of a UB then used joist hangers with long tails that went over the top and down the other side. Nailed in both sides.

I finished my class Q build nearly 2 years ago. We actually went for full planning after the initial class Q was granted as we wanted to extend the length/size. However it all had to go to committee to get it through as we have had all out PM stripped pretty much and had to stick to the original footprint and existing structure. It was in a right old state but we had an excellent structural engineer who came up with a clever design. We have a pretty high quality build (air tight, triple glazed, zinc roof, clad) and total all in was 2.9k/m including all the paperwork, services etc.

That's a very short bearing length - minimum of 90mm for an end bearing. (With SE calculation it could be shown to be OK but if there was a knot or something you risk the timber failing anyway.) It's usually easier to go for a bolted timber between the flanges of the PFC, with joist hangers attached to that. With direct bearing the joists you'd still need to put in noggins so you don't save any timber.

@SarahG Ask yourself what you don’t know, and what stage you’d be comfortable being fully in charge of a construction project, and then have a reality check. Loads of people keep reasonably quiet about the adversities, negatives, stress and losses from what they thought would be a, seemingly, easily manageable undertaking. There are others who micro-manage everything in life, and have the time to do so. Some who are naturally ‘managerial’, regardless of the pursuit, and who will come off better simply due to a huge investment in time / research. They’re usually self employed, semi or fully retired etc, and have this time. Others don’t / aren’t and have to use the gaps in between, and hope that time is suffice. The sacrifice is personal / family life and sanity, and when they get compromised so do you. And that’s if it’s all going well……. Choose a very good general builder and get out of the way up until weathertight, then at that stage see how you feel you’ve coped as a passenger. At weathertight you can relax a bit, bank would have released more funds, if you’re borrowing, and you can pause for thought to plan the final push with fit and finish both inside and out. Much less stress and far less consequences if you make simple faux pas here and there, by comparison, vs what trouble you could get into getting the shell up. Assume nothing, check EVERYTHING, as you will be the only truly diligent person(s) on your build.

A buffer is just an extension of the heating system, it give the system more volume. The heat pump has to run longer to get it from temp A to temp B. Once the return temp of water to the heat pump is at a level to hot for the heat pump, it stops its heating cycle. The circulation pump continues running. When the return temp is within limits again the heat pump starts. There are two ways to manage a buffer. No thermostat Within the period of time from heat pump stop to heat pump start, the heating system draws heat from the buffer, the buffer temp rides up and down within a few degrees of it's set point, the same as the heating system. With thermostat Heat pump heats the buffer to a thermostat set point, this thermostat only managed the buffer temp, this is set hotter than heating system flow temp, works the same as a thermal store. Heating system sucks the heat from the buffer. Buffer is recharged by heat pump it doesn't know or care what the heating system is doing. A bigger buffer gives a longer the run time and longer the off time, less cycles more efficient heat pump operation. Heating system 0.1kW to max HP output, it doesn't care. The heating system is a seperate system, you could have a 10kW heat pump driving a 2kW heating system, with a correctly sized buffer. Down side is slightly high flow temp with the thermostat system, some vessels heat loss also.

YES. I have a pretty standard 4kW panels and 3.68kW inverter, but when I submitted my paperwork (pre G98, I forget which) I got an almost instant reply to disconnect it immediately and apply for approval (what would have now been G99) And telling me there would be a fee for even applying. In my case they had seen the inverter model number which contained "4000" and assumed it was a 4kW inverter not 3.68kW and were demanding prior approval, even though that would only have been slightly over 3.68kW. Sending them the paperwork for the inverter confirming it's output was limited to 3.68kW sorted the issue, but it showed there is no leeway. To date in over 3 years I have only exported just over 300kWh. the fact you don't intend to export is irrelevant, the fact is you could.

you also dont want 400 centres if your planning on using sheet insulation that is cut between the studs.

I bought a Testo 405i and made a cone. https://www.test-meter.co.uk/testo-405i-bluetooth-thermal-anemometer These are the results. I just made a table.

I have 10x Perlite all black 310w panels, GSE in roof trays, growatt inverter, from ITS Technologies. Around £2600 for everything, switches, meters etc except the optimisers, which I purchased separately. Installed myself got the electrical guys to wire as part of electrics install. No MSC cert, but planning to self consume (, immersion heater). Even today its producing 1.8kW, in NE Scotland, sunny but cloudy.

Ha, join the club, I don’t do apps, phones are for talking (and maybe texts) ?

Resurecting this old thread. Are all your problems with Octopus Go sorted now? You mention an APP? I am considering Octopus GO but I am a dinosaur I DON'T want an app. I am happy to manage my account on a web browser on a proper computer. Is having an app on your phone to interface with it compulsory ow will old stuck in the mud people like me still be able to use the web interface?

Hmmm... I've done that at a fairly high level: the rooms link to each other as we want them, more or less, and are mostly biased towards the garden which we also want. I've not really done anything to link them to thinks beyond the house though (patio area, where the other houses are, etc.). One thing I'm wary of is that I'm not trying to be the architect here - I've got the wrong mindset, frankly. What I'm trying to do is - cheaply - generate a design which from a size and complexity point of view roughly matches what we would end up with. I can then cost it out to see if what we want to do is feasible or not. Thing is, I've already done that - or at least I thought I had. From the reactions, I'm starting to suspect that either my requirements are non-standard (entirely possible - my wife for instance will happily work all day long in a darkened room) or that my translation of the sizes on the plan to the real life experience of living in them is flawed.

Good post here from @Ferdinand You want to work out which rooms/spaces/functions you want to use and how they suit different scenarios in your lifestyle then work it into a floor plan, rather than starting with a box and making spaces fit - a smaller, better, more light filled house will be much more valuable than a bigger dark box, and it will be a much nicer place to live too! (which is really the most important bit|)

Yesterday the manager of my Local Costa Coffee got me to download the app because there is an offer in today, and for the next 2 days. 50p s coffee, about the right price. So after a tourtous login process, as I already have an account, I go in today to claim my cheap coffee (this is after a 7 mile walk because St. Michael's Mount us not really open, they just say it is to get people to park at 8 quid). App says it is broken. Try again later. One day, all our apps will say we cease to exist.