JohnnyB

Ahh, thanks. We have seen the one with the black dots that are closer together in frames at an exhibition a couple of years ago, and thought they were quite noticable. The samples we have seen with the clear dots that are further apart have only been small samples and it is hard to gauge how they will look in a larger window. They are much more noticable in sunlight than they are indoors. We have discovered that we can't get everything we want in a new build, what we like wouldn't pass the PAS24 tests, so we are going to go for triple glazed or possibly krypton filled double glazing as JohnMo suggested above. We are waiting for prices and U values for the krypton filled units compared to argon 3G and then we will decide which to order. We have decided it isn't worth the extra cost and the distraction of the dots in the vacuum glazing if we can't get windows to look exactly as we want anyway.

Interesting, is krypton filled much more expensive than argon? The vacuum glass isn't a hugh increase, about 9% more than triple glazing on our wooden windows and doors.

@lizzieuk1 Did you use the vacuum glass in the end and if you did how have you found it and have you found the dots are noticable or do you get used to them and they blend into the background? We are having all timber windows as we want a very traditional look, and have 4 sliding sash windows and we are considering the vacuum glass. The cost isn't too much more but my wife is very unsure about the dots, will they stand out to her and become annoying or just get lost in the background. I think the windows will look better for the thinner glass, but not if the dots distract the eye every time you look outside. We have seen the glass with the clear dots, I think it is from PassivGlas not Fineo, but they are still visible and the consistent rows of dots are quite noticable on a small sample, we haven't seen a full window with it in.

The first SAP assessor I spoke to (who doesn't have time to take on my project for health reasons) when asked about the modelling and using PSI values I came up with, or someone else, he said can't see a reason why he couldn't accept my figures. I have asked the person who will probably be doing my calcs if she can use my figures, or those from someone else, but via email and I am waiting for a response. I can't see any 'qualifications' I could gain, just courses for using software, and the below screenshot is from the Elmhurst website I tried to attach a basic DXF of my wall build up above the window but a DXF file isn't an allowed file. How do I post/send it? I have added a screenshot and one of the 3D to show what we have built. I have also attached a spreadsheet with figures I was given to work out the U values. There will be timber fixed to the main timber frame to fix the window in place but it will be in short lengths at 3 or 4 points around the opening to reduce the amount of timber needed and that can conduct heat. There will be an approx 10mm gap between the window frame and the hempcrete that will be filled with Illbruck FM330 expanding foam but gaps don't seem to be shown on the models I have seen so I haven't included it. I would assume that helps the thermals is it is an insulating material and something is needed to fill the gap. U value calculator.xlsx

For me the easy bit will probably be the CAD as I know how to use that. If Therm is fairly easy to use I would be interested in understanding how to use it and work out how good the junctions should be, whatever the EPC shows. I'll see if I can make any sense of it. Would you be prepared to show me a little of how it works, as we are both in Suffolk? I find it easier to learn by doing/watching than trying to understand instructions. I did have a bit of a look last year and hadn't a clue what to do, I think that was understanding where to start, what was needed and feeling like I hadn't got the time to learn what was needed. Thank you, that's very kind. As above I'll have a look and see if I can make any sense of it. Is there a simple instruction set to start out with that would help me start to understanding the software? It was one of the SAP guys who said about proving the method. He and a colleague were looking into software used for thermal modelling to see if they could do it theirselves. He said he needed to be able to prove his models by modelling an approved model first and getting the same results as the approved results. I was reading up since posting and wonder if it is that straight forward. I'll speaking to the two people I've been in contact with about the SAP calcs and I'll ask them both what they need. My understanding is they are responsible for what they sign off (and are happy to prove if they are inspected) and BC are happy as long as they have an EPC. My timber frame isn't standard, using hempcrete makes it quite different so I'm not sure other timber frame models would work for this, I guess it would be a starting point . If I know what is needed for Therm I can draw it in CAD, I might already have it from the BC drawings. Examples of DWG drawings would be helpful to start with.

I don't think that's going to happen for us, we are using hempcrete with a stick built timber frame. The hempcrete is mixed on site by a small company. It's a basic process using mostly natural materials and when we have come up againest these type of questions they haven't been asked them before.

I am looking for something to use under the doors frames in anew build, so there's not a thermal bridge between the brickwork and the screed. 25mm of celotex between the screed and the bricks seems rather thin. The architect is suggesting I use Marmox blocks but that seems overkill to support a door frame. Is there anything else that is suitable for this that will work out cheaper?

I'm having the same issue, needing thermal modelling. If you didn't find it hard to use would you be able to give some help in working out how to use it? I have been told that if we can model a standard junction and come up with the same results as the 'experts' then they can accept our figures. It sounds like there are a lot of junctions to model and I'm getting prices of £150-300 plus vat per joint. It is sounding expensive if I have 5 plus joints to model.

I tried flexible outside and it was nearly impossible to get one ethernet cable through anywhere it wasn't straight so I have only used it to protect cables underground where the cable was pre-pulled through. I wouldn't buy it again but used it as I have already got it. From downstairs to Loft I used 50mm external conduit that is semiflexible and smooth inside. That was easy to get several T&E cables through. I have used 25mm rigid from the ceiling void down to sockets with a draw cord and that was fairly easy to pull cables 2x 2.5mm T&E through, but they are short runs and most bends were bend using a pipe bender for copper pipe which gives long bends. From inside to outside I tried 25mm rigid with glued in bends and it was hard work to pull 2 ethernet cables through where I had 2 bends fairly close together. Try to use a bigger internal diameter and make sure it is smooth, and as everyone says you want long bends, or use a pipe bender on the rigid lengths and join lengths together where you have straight runs.

If you have large enough conduit and a draw cord I would put something in. I have 50mm dia running from ground floor to attic and that was easy to get twin & earth through without a draw cord. If you can break it down into smaller runs it would be easier to pull it through in the future as well. If you can actually lay the cable you need at this stage it wil be easier, but for future proofing if you plan out the runs and how it can be accessed it there are issues, avoiding tight spots etc. having conduit must be easier than nothing at all.

Jumping in on this as I have the same question. I want the floors warm in the bathrooms, and some heat, as we find the bathroom and one bedroom isn't warm enough during the coldest weeks in our existing build, built last year. The plumbers have said we need to heat the whole house with the ASHP for the grant so need something upstairs and it needs to be powered by the heat pump Do electric floor mats not count? I was thinking of installing the usual chipboard flooring everywhere apart from the bathrooms and then installing a routed chipboard floor in those rooms once the house is watertight. I have been told that the spreader plates expand and click as they warm up and cool down. Anyone else have experience of that or is it an occasional thing if the plates aren't installed properly? We are planning to fit radiators in the bedrooms as they will only be used during the coldest months of the year. Edit to add that I have just read other posts about UFH with chipboard needing higher flow temps. In the current build I've not had the LWT temperature above 35 degs and most of the time it is around 30. Anyone have experience of routed chipboard or spreader plates and low flow temperatures

Ours is up for sale for £3500, Thanks @Nickfromwales for linking to it above. I can find out about transport if you are interested in keeping the costs down and doing a bit of insulating yourself. We moved into ours in April and managed to get out by the end of November so we avoided the coldest months, frozen pipes etc. that some people have issues with if they don't insulate it underneath. We used electric heaters and it worked for us. It doesn't have central heating of double glazing, but we didn't want to spend more than £10k on one. WOrking and living on site was great, it made things so easy. I wouldn't want to live in one during the coldest months but for most of the year it was the best place for us. If we hadn't have been far enough forward by Christmas we were going to move in with friends or rent for a couple of months to avoid the worst of the weather. I built a large shed as the first job on site and we used that for extra storage, washing machine, big fridge freezer etc. as well as site storage, tools workshop.

I have a list that are approved by Elmhurst Energy, attached below, and I can use whichever I like. I haven't had time to look at them in any detail yet but some looked like they were aimed at smaller pojects. It would be easier if I only had a few options. I can't see Timemark on this list so there must be other options as well. Are Elmhurst one of many companies the assesments are done through? This is a world I know nothing about. Elmhurst_Photo_Evidence_Applications_List_v1.xlsx

Were you given any idea of cost for modelling? I haven't been yet. I don't think we have anything standard, or near to standard, he was talking about needing to model all the junctions as we have hempcrete walls.

I'm using the LA. The local guy is fairly good but he has mentioned they can't accept Passive house calculations, I assume he means PHPP. How are you getting on with them? I thought my SAP calcs were all in hand but found out this week that they are not! As I'm not using standard build details I've just been told they will need to model each junction. They have also added in that I need to sign up to an app to submit the photos needed for the calculations.

I'm not going to be able to make it, when I mentioned it yesterday I was reminded that we are away that week. The bar at the crown isn't too large, you find each other easily enough.

Looking forward to meeting lots of you. The Crown is easy to get to from the A14, and fairly close to me so a good choice!

I'm interested, IP14

Where do I find the minimum turn down my unit will go to? My heat load is about 3kW on paper but being a self build I've tried to be careful and do some extras so the actual load should be a bit lower. Also it isn't as cold as the temperature used in the calculations so actual heat load at the moment might only be 1kW. Switching the oven on for half an hour or so increases the temperature downstairs, mostly one open plan area. With a small heat load would it be better to use the thermostat more and just have it off lots of the time? I changed it to 1 hour, the DHW has a max run time of 40 minutes. I've just had a thought that the max run time may only be when there is a call for heat at the same time so maybe I should set it longer. I don't think there was an option for off. There are 4 in our house and I had been getting complaints of cool showers buy the third shower if I have it switched off morning or evening. 2 boys, 19 and 22 who like their sports and gym and my wife is also at the gym regularly so 3 showers close together isn't unusual. It is set to heat overnight to 48 deg, then eco during the day which lets the temp drop by 10 degs, and turned off between the Agile peak of 4-7pm. It does seem to heat up quite quickly but noit in 20 minutes, possibly not in 40 minutes, I'll have to try setting it to a longer time and see if that helps as well. The house should easily go without heat for an hour once the floor is warm.

Thanks all, I think I'm starting to understand it a little. A volumiser doesn't effect the efficiency like a buffer does? My HP has a minimum of 30ltrs and I have 42ltrs in the UFH pipes plus 10ltrs in my F&R pipework so more than the minimum amount before manifolds, HP, other pipework etc, although I have read somewhere that 15 ltrs per kWh output of the HP is good for efficiency. I have increased the flow temperature to about 33 and measured the return temperature which is between 2.5 and 4 deg lower than the floe temperature. I haven't tried measuring the return when the temperature as around 25 and on all the time but I wonder if the difference between flow and return was very close. My pumps are fixed speed, and on the highest setting so the flow rate is about 27ltr/minute. The spec sheet for the 5kW unit says nominal flow rate is 14.5ltr/min. Would this be better running slower? @JohnMo From what you say it doesn't matter which is the slower flow rate, if they are different either way the result is the same. I could have the buffer changed to a volumiser, remove the pump and motorised valve, and run everything from one pump. I think from the video notes in IGP's post it should have been a PWM pump. I did discover last night that the DHW cycle was set so the immersion heater comes on if the cycle goes on longer than 20 minutes. As I have been running it so the water temperature drops by 10 deg before starting to heat I think it is taking longer than 20 minutes most of the time so that wouldn't have been helping the COP.

I don't think I need a volumiser either, there is more than 30 ltrs of water in my UFH pipes and another 10 ltrs in my F&R pipes, plus everything else. Would changing it for a volumiser make much difference to the efficiency? I'm starting to understand there's probably a lot of things in my system that's not needed and it could have been a lot simpler

Thanks for all the input. I'm going to have to make time to see is the HP is cycling, watching it for 10-15 minutes it seems to be fine, I assume the fan would stop if it is shutting down. I'm also trying to read up on heat pumps and heating, exactly what I didn't want to do and why I used plumbers who are supposed to know what they are doing but there are so many things you are saying that I don't really understand. I'm trying to build 2 houses and thought this was one thing I could leave to others to sort easily, didn't realise HPs need to know so much just to run them efficiently! I had a message yesterday from the plumber and they have another unit like mine that is getting a similar COP which the client has full monitoring on. They have emailed Samsung for advice and he is going to try to get out to me before Christmas to take a look and see if he can see anything obvious. I have been looking for more info and it seems that the video linked to above, and ringi, aren't the only people saying really low flow temperatures don't equal a good cop. If I set the flow temperature so it's leaving the HP at 30-35deg I would probably have the heating on 2 or 3 times per day to warm the floor up, but that isn't as comfortable as having the flow temperature at 23-25 deg and the floor at 20-22, which kept downstairs at a fairly constant 20deg. The higher temp has helped the COP, it was 2.8 yesterday, but it was off all night and has taken a long time to get the floor back up to temperature this morning. The problem of a well insulated house and floor, it doesn't need much heat. Maybe I can set the system so it uses the floor temperature as the set point instead of the room temperature, put water in at 35deg but switch off when the floor gets to 25deg and come back on when it cools down to 22 or something like that. Should be slow heat and cool down times for the floor. I have 60mm screed with 2 layers of 100mm PIR insulation beneath and it seems to hold it's heat for several hours. By LLH are you referring to my buffer tank and pump? What you are saying is the opposite of what I thought I was understanding when reading on the renewable heating hub forum, that the main pump should be running faster than the secondary pump. I have noticed this valve is set to a low pressure and the water seems to be passing along the shortest distance. I was told this is to allow water through if the valve doesn't open and the pump starts, but I can't see why I even need the valve there as the pump only starts if it is open and it doesn't divert the water, just stops it flowing. I do have a diverter valve on the main F&R the switches the flow between DHW and heating. As mentioned before I didn't want the buffer in there but was told I had to have it. If they can't sort this sufficiently I will insist it is removed. I really can't see the need for it when I can't close the loops, there is no zoning and I have a lot more than 50 ltrs in my pipework without the buffer, they have fitted 32mm flow and return to the HP and the buffer, my DHW cylinder and buffer are 3-4 mtrs apart because of space issue with 32mm pipe between them, must be about 15mtrs of 32mm pipe

@JohnMo If only I had time to sit for an hour and see what the pump is doing, I'm trying to finish off the house! I don't have a smart meter indoor display, but the Samsung controller will show the power being it used by the HP. I'll have to watch that and see if it shows anything interesting. It's a real shame they don't give access to proper data. My pumps are identical and both set on the same setting, plumbers said that was necessary. They are mostly both on at the same time, apart from when the DHW cycle is on or occasionally one to the HP will be on without the other for a few minutes, the HP pump will occasionally start up without the thermostat calling for heat. I've turned the flow temperature up and will turn it off when it gets to 4pm and see what happens to the indoor temperature. (I'm on Octopus Agile which isn't a great tariff for a cop of 2 at the moment!) The plumbers told me the internal thermostat isn't great and that I needed an external one, but in the video @IGP linked to Glyn is using the internal thermostat and it sounds like it is working well for him so that could be an option. Glyn had the flow temperatures basically the same in the WC settings as the COP dropped if the flow temperature dropped below 33 deg.

@IGP Thanks for the link, I watched the video then read he has updated to firmware so it works with a PWM pump and he can drop the flow temperature lower without effecting the efficiency. I don't have a PWM pump but maybe my pump would be better on a lower speed? Something to discuss with the plumber. @JohnMo I only have the Samsung controIs and can't see details of what is running when and how long it is running for etc., is there an easy way to find out cycle times without an energy monitor like you have on your system? We don't have zoning, there are no actuators on the UFH manifold. I've read lots of your comments on here so have been trying to keep it simple, although the plumbers have insisted we have to have a buffer for the warranty and one pump for the HP and another for the UFH pipework so it isn't as simple as you would recommend. I think if I set mine to 35 deg we will be rather warm and our feet will cook, I haven't been above 30 at the water outlet yet and that was already quite warm, although if it only heated the slab to a lower temperature and then switched off we could probably control it that way.

I have recently had a 5kW Samsung gen 6 heat pump fitted, been running about 10 days, and I had a look at the energy used and the energy generated on Friday and I'm getting a COP of about 2 so something isn't right. I've contacted the plumbers who are going to take a look but I wanted to get a few thoughts from here on how I am running it. The plumbers are known locally as being good and only fit heat pumps so they should be able to sort it but always good to have some knowledge before they try to explain things away. It's a new self build with UFH and I have been running it 24/7 with the water outlet at the pump between 23 and 30 deg, regulated by the WC. The temperature on the floor is about 20-22 deg which keeps the house around 20 deg. Is there a point where the flow temperature can be too low so the heat pump is cycling and not running efficiently? Should I be using the thermostat in the house to switch the heating on and off with a higher flow temperature instead of running it low and constant? Anything else I should be asking about?