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I've looked at the link https://link.springer.com/article/10.1007/s12053-019-09781-3 and it just does not address the ongoing maintenance cost.. it's just more pish written by people that are still learning. That is ok.. but it's your money.. better maybe to take the view of old crusty designers like myself also.. then you can make an informed design choice as tou how you want to spend your own money. How on earth can you attribute any credence to some of this stuff if they can't say.. ok x glazing has a life span of 15 years on average, Y MHVR is this and account for that in the carbon calculation and energy calculation. Until the replacement and maintenance costs are accounted for there is no way you can make a long term choice or take a balanced view. Often many on BH are just trying to get building regs approval. Ok if that floats your boat.. it's your money after all. We need to recognise the true costs of replacing glazing units and mechanical equipment etc if we really want to make good environmental design decisions.

They do. Min size should be, based on number of beds would be 270L. Section 3.5, would say 175 and 210L are way too small for a 5 bed. https://mcscertified.com/wp-content/uploads/2025/02/MIS-3005-D-2025-V1.0.pdf

22mm backbone is fine if there’s a hot return. Otherwise, just painfully slow to get hot water from basin taps. Avoid.

I hate plumbing. It is the cause of the vast majority of defects. I think we should bring back the outside WC. The hidden cistern is probably going to haunt me.

All depends where you are locating the things you talk about. ASHP if this is on an external wall of the house then take the wires through the service void in those rooms. same with car port if it’s fixed to the side of the house then straight through the wall, if it’s down the garden then you will need a duct. why is the solar coming in via a duct unless it’s a ground mounted array down the garden. solar panels from roof to an isolator switch then armoured cable to inverter. all depends on final location. I have every item you talk about and it takes up 4-50mm ducts for electric stuff and 2 for comms in and comms out. .

Yeh - strange on the cylinder, with 5 beds I thought MCS would insist on bigger but the optional cylinder upgrades are only 175l or 210l ?? There is no specific mention of whether they would be using a plate heat exchanger rather than the existing coil. Our loft hatch won't fit a standard cylinder so keeping the current one has advantages.....

Not the best decision, but yours to make, as long as the size of cylinder complies with MCS regs - which it may not unless your in a 2 bed property - your worst case is short cycling doing DHW. Plate load as a minimum, ideal skip it and a suitable sized heat pump cylinder.

yep roses and a couple of distribution boxes too!

Thanks Dave, yes that was all covered in the deeds and planning consent. The reason I wanted more info about surrounding landowners was to check how robust some of the agreements are. I'm sorry that I can't say any more at this stage and am being a bit cryptic, but I'm not wanting to give the location away! There's nothing there that's causing me concern re the water, drainage or services though. I know it all needs checking to make sure it's still current but it seems good so far.

Are they proposing to plate load the cylinder? Even then, as an MCS installer myself (with the full Heat Geek training) I'd be seriously suggesting a cylinder upgrade, especially given the existing one is 15 years old and having lived with high storage temps, and given you've got them in on BUS Grant and zero VAT now.

Yeah, currently we do immersion set to 70c heated overnight at 7p per unit which gives us 5 showers, at say 45C we would need to reheat during the morning shower period but should be doable at say 7kw reheating. [Say cold water is 10c, 70c x 180l gives us 360l at 40c whereas 180l at 45c only gives 210l so I will then need another 5.25kwh - say 45 mins - to heat the remaining 150l of 40C water needed each morning] Either way we also then need to reheat for evening showers. Zero disrupt - I have already changed enough rads that I know we stay warm with a flow temp of 45 (it went a bit higher when we were -5 and below outside but not over 47C) Plan is also to not change the DHW tank and accept the hit to COP.

That's amazing, thank you very much. I totally understand where there needs to be better notation and explanation of the tool. The instructions are one of the next big steps. So too is a methods for importing measurements. I decided against Lidar as the kit is very expensive (if you don't already have the top of the range phones or tablets) and it's still a bit fiddly to work. So I'm working on a way to use bluetooth lazer measures that import into an app and can then export the data, but this may be some time. U-value data is being structured and imported as we speak, so maybe there by next week. And then next step will be the radiator library too. Noted on the links to room below or above as you have to hold that in mind quite carefully while inputting the data. I tried one other app that did this is a semi drawing/semi text way and it fuddled my mind - I found it even more difficult than without the facility, so need to give it some careful thought on implementation. But thanks again for your input.

Are you going for Zero disrupt? How many people is this cylinder serving and do you have any data yourself on hot water usage?

My comments 22mm main run for DHW, will take an utter age to get hot water out the tap. You really want a manifold system. Mine is DHW cylinder - 15mm to manifold central location, then from manifold 15mm run to each wet room and spur from there. No comment on price

@crispy_wafer thanks - we do like some of the more doable DIY and are in need of controlling the budget, so doing this is very much worth our time! I also think I am more focussed on tidy routing of services…

If you have the time and inclination then it’s doable, work out the pipe runs to minimise crossovers and interference from other services if space is tight, go buy rolls of said pipe and clips to keep it tidy and go for it. Many of us have trod this path, and history shows that we do like a good plumbing thread if you are so minded to let others have their 2p worth. Biggest minor issues are how to bring the pipe work tidily into plant room if having individual runs, you can end up with 20 or so individual pipes. And the various wall plate elbows and terminations at the end point. I’m not sure it’s 4 and half grands worth of work in total, but in this day and age where labour costs mucho money then I’d diy it.

The pipe I have ordered is from the US, it claims to meet their standards. I couldn't find a nylon one here for the 3/8 to 1/2 connection. I was able to buy a 15mm to 1/2inch tap connector in nylon here, but It doesn't mention any standards. My thinking is to try it as it is nylon braided and so shouldn't rust. From what I can see nylon ones might be a bit less strong and easier to pinch, but that is pretty much irrelevant as they won't be moving around. One of the ones that failed after just a few years I think might have been twisted during installation. Some places do indeed recommend replacement every 5-10 years. Virtually no one must be doing this in reality. I will certainly check the other pipes in the house, I did this last time I replaced one. Last time I checked there were no other issues and it seemed isolated to certain rooms, it seemed to be all the places where the cistern is on an outside wall and colder, although the cold water coming into the house is pretty cold. It was also the most used cisterns and again I think these have more water running through them so are generally colder.

Going to be less than efficient doing DHW, via a heat pump, as you will have higher flow temperature to get the same cylinder temperature. It also sounds a very small cylinder for the high usage of water you seem to have. There are only two of us and we have 210L and wouldn't want any smaller.

Having once worked in a hotel that experienced at least one connector failing every month - but sometimes every week or more than once on the same day - I can confirm that this is a problem. Twisting them during installation is a known issue, but they do have a limited life even when correctly installed. I tolerate them in a cistern, but have returned to using regular copper pipe elsewhere. Replacement every 10 years is advised if they've been installed. Only buy ones that are made to the relevant European / British Standard (sorry - I can't spot the number right now). The standard isn't very good, but it's better than pot luck.

This feels a bit high - what’s the opinion here? Just before receiving this, I’ve been looking at running the pipework from plant room to the end points, then this came in (I’m now definitely considering running the pipework myself). Approximate scope: First fix plumbing pipework install. Only installing a mains connection point in the plant room (leaving the UFH / DHW / ASHP to others). 260sqm, 4 bed house with kitchen sink, dishwasher, freezer with water/ice dispenser, downstairs WC, washing machine, family bathroom & 2 en-suite. Doesn’t include bathroom installation (just pipes to the correct positions in the wall). Labour cost £2,750.00 for all pipe installation (not bathroom install) Materials cost £1,780.00 For all materials as above based on 28mm copper main to plank room plus fittings and stop cocks plus 22mm hep2o pipe and fittings for the hot and cold runs with 15mm hep 20 and 15mm copper spurs. Also, isolation valves to toilets, sinks, bath and showers. Thoughts? Experience elsewhere?

Yes Australia, typo fixed thanks. We have a 28mm hot and cold loops in the house with all the fittings connected to this using 15mm pipe. The loop was put in months before the bathrooms so I think they did this as they weren't connecting up the toilets. They just brought the mains close to where the toilets would would be.

Indirect 'gas' cylinder Viessmann 180l, about 15 years old

The pipes inside the cistern can be replaced just by taking the flush plate off. All of the inside of a concealed cistern can be removed through the flush plate. This was more difficult as it was a second flex connector connecting the valve inside the cistern to the mains. I used metal cutting scissors to cut the top out of the plastic cistern. Then I pushed my arm up into the wall, getting it all scratched up. Yesterday I did this with a small screwdriver to shut off the valve while I waited for a new pipe to arrive so I could turn the water back on. Today I was about to give up because there was no way to get enough purchase on the pipe inside the wall to unscrew the compression fitting. Then I wondered if I could move the 15m PVC mains pipe, I remembered how flexible they are. I pulled it out of the clip holding it to the wall and was able to pull the pipe out through the cistern. Then I could easily unscrew the compression fitting and replace it before putting it back into the wall. The new nylon flexipipe presumably won't rust. Our last house did not use flexi pipes but the builders had put isolating valves in all the fixed pipes entering the cisterns. After around 10 years these all began to fail and we and multiple neighbours had floods due to this as the cisterns were all concealed and you didn't notice the slow leaks until the ceilings started to drip. The flex pipes burst under pressure so you can often hear straight away when they go.

It’s the hose that fails. The stainless steel rusts and breaks then the pipe pops. If I look at the pipes the rust seems to be mainly on one side which fits in with my belief it is caused by water condensing on the outside of the pipe. I have PVC piping and then they have used 15mm tap connectors at the end of each piece to connect to the fittings. This is the first time one of those has gone. The main problem seems to be the ones inside the cisterns. They are not under water just at the top of the cistern. All concealed cisterns seem to use a similar connector.

We’re approaching the point of having the plumbing first fix done and I’m not getting the confident feeling from our plumber - they’re asking for the design of the plant room and system configuration. It seems they are skilled as the practical work when told what to do, but now I’m looking into what a design should look like. I’m not expecting our principal designer to provide a design of the plumbing pipework, and although I’m looking at alternative plumbers, I now want to see some examples of what to expect as to a design / configuration of the plumbing pipework. If it’s not that complicated (which I don’t believe our system is) then in order to get a neat and tidy install that we’re after, I’m wanting to work out a design even if it’s just a means of me assessing whether the plumber we contract proposes something similar or miles off. Help me educate myself - TIA