Lofty718

I had this issue on a recent build. SE was pushing for piles, wanted 1k + vat to dessign them, then quotes from piling companies were insane. I also spent about 500 quid messing about with a soil test and investigation. I paid to have the neighbours tree removed, 1100 all in including grinding the stump. It was an ugly unkept oak tree that blocked a lot of light and fllled all the neighbours gardens with leaves Also the tree was actually 12m away but the SE put in the drawings that it was 7m away. Not sure if done on purpose, but removing the tree saved a lot of money and I recommend you do the same way before getting started. check what the nhbc calculator says regarding depth if you remove the tree, it will be significantly less than keeping it, because the calculator assumes the height of the tree and imo is overkill.

I'd recommend a door or screen too. Unless you actually need a wet room for mobility reasons

I recommend Mira Ascend shower enclosures. Very good quality

My local council also applies this rule in their planning guidance, but they generally ignore it so depending where you are you might not need to stick to the 1m rule on the second floor.

Extending at the back by only 2.5metres is totally pointless, once block work and cwi is taken into account you won't be adding that much space. Do a 4metre back extension at a minimum

The quote to install ducting is insane. It's a DIY job imo.

This is interesting, I was also planning to try and make some built in wardrobes out of MDF. Any photos of your progress so far?

I think you put too much emphasis on being 'neurodiverse' you have written it in almost every post of yours. There are plenty of self builders with autism and adhd and a host of other things, you shouldn't let that define you and hold you back and it's not as big of a deal as you think. Neurodiverse people will have advantages when it comes to some things the others do not.

What is the COP of the heat pump? bills seem ridiculously high also is it running on weather compensation? sounds like a bad install

Using a property managment/maintenence company for an extension was your initial mistake. Should of found an actual builder on recommendation. Decent builder won't want to build something that is restricted in height or doesn't work well for the client and would of looked for a work around. You seem pretty on the ball and sounds like you could of managed a builder well rather than leaving it to some shoddy company. You will get this resolved soon and once done and dusted will all be worth it.

Use corefix fixings from screw fix. Best fixings for dot and dab.

Sorry to hear you are going through this. Good advice and professionals at the design stage really are crutcial to a good building project. I think the people you have hired are all crap though, architect, builder, SE and 'project manager' You will have to live with these decisions for a long time so make sure it's right. Consider using a different SE, there are options and solutions for everything. Your SE might be some bozo just punching numbers into a program and coming up with these huge beams.

I've got a Vaillant 630 with weather comp, in winter my boiler runs around 40c I am able to run two different flow temperatures for heating (ufh and rads) and then a seperate temperature for the cylinder on hot water priority I run ufh at 30-35 flow temp and rads not much higher, obviously it depends on outdoor temps. The sensocomfort vrc720 and vr71 are very good. How long a burn time do you get before the boiler goes in anticycle mode? with my 630 I get about a 15minute burn time and the boiler is very oversized maybe double so I"ve range rated it down to 15kw. Mixing valve on the manifold is a no no and old tech. Underfloor heating should be controlled by an electronic mixing valve like an esbe with an actuator.

Closer pipe centres allow lower flow temperatures but I don't think there's much in it. Zoning is bad for efficiency, you have the right idea with just one zone for upstairs and one for down. The companies will try and sell you a load of crap you do not need. Ideally you want your UFH running on weather compensation.

https://www.fishpools.co.uk/garden/all-garden-furniture/c842 This company do some nice stuff

@ggc I don't think you should accept this level of incompetence You're building a mega project and relying on these people to get it right. It's quite a big deal and not a small bodge that you can let slide I'd be pushing to get it all re done and spot on as you'd expect it to be. Rather difficult I know, because I imagine you want to be moving into the house asap and this could cause huge delays

It's mainly a lack of education, they are just doing what they know and is easiest monkey see, monkey do as they say. Being a Vaillant master tech installer, Viessmann certified or gas safe means nothing. But the Viessmann training courses do suggest setting up with weather comp and variable temperature mixing valves so he must not have been paying attention in the course or read their design manuals. With regards to your original question @Adsibob I don't think it will make a huge difference really, could you take a photo of your boiler/cylinder setup? has it been set up as a 4 pipe system? let us know.

@Adsibob as you say your system works and the bills are low so thats all that matters, but thats part of the issue is that a badly installed boiler will still work but as @JohnMo says the only way you will acheive the 100% plus effciency figures on the boiler sticker is with proper controls and weather comp, without it will be 85-90% at best. That's why heat pumps are a problem, because a badly installed heat pump will not work for the customer. Where as a boiler will.

With a weather compensated system it's a totally different form of heating. The heat in the house is determined by the outdoor weather sensor which is linked to sensors on the flow pipes, usually one on the common flow pipe (low loss header or CCT) and other sensors for every ufh/radiaor zones that all talk to the boiler and make it modulate accordingly This means that the issue you raise is largley redundant and as mentioned earlier there should never be a need to turn a thermostat up or down once the correct weather compensation curves for the property are set because every room will be very comfortable and you'll barely notice the heating is on because it is constantly providing small inputs of heat at low flow temperatures that exactly matches the heat loss of the house, where as a high temperature system is a lot less linear. e.g room gets cold. the temperature drops and thermostat blasts the room with heat until it's satisfied. Another benefit to a low temperature weather compensated running boiler is that there will be a lot less wear and tear on the boiler, a system with many zones will inevitably mean the boiler is always cycling turning on and off, this will wear the internal parts of the boiller much quicker.

The idea with weather compensation is that you don't mess around trying to control it, you leave it open loop and have everything running at a low flow temperature with the heating constantly running and condensing, the only time it doesn't condense is when there is a call for hot water, which is what hot water priority is, the boiler will go into high temp mode and heat the cylinder as fast as possible, shutting off all flow to the heating circuits and once it is satisfied it will then resume heating the house. The temperature is regulated by a weather curve that is set on the boiler, your Viessmann if you go into the settings will have various curves that can be adjusted. A system boiler not set up like this, run at one flow temperature (minimum dhw temp) will rarely be in condensing mode. I hope what I said makes some sense, I am no plumbing expert but these are things I have learnt. Most boilers are set up incorrectly and not many installers do this. It is the same principle of how a good heat pump system is designed which should always be with weather compensation, you NEVER split a heat pump into loads of different zones and people that do that are the ones that had crap installers and say that heat pumps don't work. 12 zones in anything that isn't a mansion is truly insane. It must of been a very expensive install, it would be cheaper to have done it the way i suggested. Watch this video, it is how i would of set a VIessmann up and he explains exactly the points I'm trying to make about why it would be cheaper

Your gas usage seems crazy cheap compared to mine especially with current prices A knowledgable Viessmann installer would of installed it without room thermostats, zone valves, actuators or a mixing valve on the manifold so it's not much more expensive to do it the german way The main cost is the boiler which you already have, Viessmann have it all built in out of the box other than a few items. I had the same thing with the builders plumber wanting to install a high temp running UFH system but I ripped it out. It doesn't work out too much more expensive because you don't need zone valves, manifold mixing valves, actuators, thermostat or a ufh wiring centre. It would probably only save 10 percent in energy, but will give the house and mainly ufh much more comfortable temperatures and a much more functional how water system, like a combi.

The installer sounds crap, Viessman 200 with a low loss header can be run at 3 different flow temperatures one for UFH, one for rads and another for DHW. Sending 70c water down to the manifold and having the blending valve mix it down is really old tech and highly inefficient. If running at only one temperature you are wasting the boilers huge potential and could of bought something a lot more basic i don't know the best timetable because this is my first unvented cylinder and mine runs as a hot water priority setup. But you should get someone in who knows their stuff about Viessmanns to rejig your system, I bet there's a lot of room for efficiency gains by the sounds of it.

Your Viessmann should be running on PDHW, this is the most efficient way to run an unvented cylinder. It comes with this feature out of the box, has your installer set it up as a 4pipe hot water priority system? Priority Domestic Hot Water (PDHW) Central heating systems comprising of a gas boiler and hot water cylinder using a standard S or Y plan configuration are set to run at one flow temperature which will be the temperature for the cylinder at around 65°C - 75°C operating with a combined heat output for the hot water and heating demand. Running at these high flow temperatures limits the potential for the boiler to condense effectively, if at all, and that's probably for most of the year. Priority domestic hot water installations however control the hot water cylinder and central heating system at different flow temperatures maximizing its efficiency and creating a higher potential for the boiler to sit in condensing mode for longer periods of time. It also reduces the heat output for the whole system saving energy consumption. How does it work? This method of controlling the hot water and heating allows the hot water cylinder to take priority over the heating circuit when there is a demand from the cylinder sensor, the hot water is heated to a higher flow temperature in relation to the central heating flow temperature. Combination boilers also use this method, when the hot tap is opened, the flow switch senses movement and diverts a valve over allowing the boiler to heat the mains water instantaneously producing hot water out of your taps taking priority over the heating circuit, when the tap is closed the boilers diverter valve reverts back to heating mode and reduces the boiler water temperature to the set level on the control panel of the boiler. The Advantage of Priority Hot Water PDHW technology allows the system to be run a two different flow temperatures. The hot water cylinder can be reheated at a considerably quicker time frame using a high flow temperature and operates at the boilers set maximum kW output with all the energy being used to heat the coil in the cylinder. Once the hot water is satisfied the boiler then reduces its flow temperature and kW output permitting the heating circuit to now operate at its designed heat output, the boiler can then start to condense. Controlling and diverting the water would incorporate the use of either 2 port zone valves, a 3 port valve or an integral diverter valve depending on the boiler, set up and control options used for the specific system. Smaller gas boilers can be installed as only heating or hot water will be in operation at any one time.

I've seen that case cited a lot but never in these particular circumstances. So it's rather difficult to speculate

These laws are still being implemented, it's quite vague but I believe it was giving royal assent last year.