mattgibbs

@SimonD what would be an example of room influence controls and how does it differ from zoning? Will the MVHR not just negate any differences in room temperature anyway. For context I'm purely looking at downstairs UFH at low temps, air tight house with mostly large open plan areas. Bedroom heating, im hoping will come from heat rising from below combined with the MVHR distributing air evenly and being topped up from electric radiators in the adjoining en-suite's

So my setup will be ASHP and UFH downstairs. In my situation i dont see how having zones and thermostats would help. If there were some solar gain then this would have a quick effect on heating up a room. If there were a thermostat in that room which then stopped heating that zone what would that actually do? the slab would presumably remain a similar tempreture for hours and have no short term effect on the room tempreture. So long as the system is balanced and rooms are heated evenly, is any more control other than weather compensation in the heat pump really needed?

@Conor thats lucky, ive not found a way to merge the upstairs zone with the downstiars one. I know right! ive been getting lost in the world of the fan coil units vs air con debate today but i think i will just go with cooling the downstairs slab and air con for cooling

@Conor Glass is already all in to be fair. its also mostly south facing but fortunatly our overhangs keep to sun off the glass in the summer almost entirly. But no we didnt do a heat gain/loss model did you have any idea on my comment above about Loopcad only accounting for the downstairs heating requirements?

Also does anybody know how i can make LoopCAD count the supply and return pipes towards the room heat. Our plant rooms and hallways show as needing supplemental heating when in reality they are probably going to be hotbox's? Ignore the pipe layout in the triangular room as i still need to space it out. but there is a large amount of pipework in the plant room (lowest room pictured) which is showing as being to cold and same for the hallway but there is no way thats actually the reality.

@Conor It does assume its the only heat souce but it doesnt design the system to heat the upstairs also (unless you have upstairs ufh). see the attached below, the current UFH is providing the 6kw of heat the downstairs requires but the highlighted box shows there is also a further requirment of 6kw for the upstairs. Based on this i would have a 6kw UFH system in a 12kw demand house. Do I double the size of the system to have the full 12kw of heat in the downstairs UFH which would massively overheat the downstairs in loopCAD or just get some electric radiators in the upstairs bathrooms to cover the heat requirments upstairs. @JohnMo Thanks, I increased the flow rate for a total of 16L/m which brought the DT to around 5 and lowered the flow temp to 31 degrees. Jeremys spreadsheet estimated 11,200w heat loss with a 25 degree defecit so its not far off. There is around 200m2 of glazing which is our main heat loss.

@JohnMo yes it’s 300sqm downstairs and almost the same again upstairs. This is my first design in loopCAD. All spacing is at 300mm centres which based on a water temp of 34 degrees keeps most the house the right temp. There is one room overheating which I can just reduce the amount of pipe work in to compensate is 34 degrees a good temp for the ASHP or should Increase the pipework to 150mm centres and run an even lower temperature? I’ve seen on your other posts you’ve run into trouble with short cycling by running the ASHP lower then 29 degrees. total heating load is coming out at 12,000w but I don’t think it shows anywhere how much the UFH is providing out of that total

@JohnMo thanks that’s great to know. And will anything I’m doing with UFH cause an issues with wanting to put radiators in upstairs bathrooms or is that just a job for the plumber to work out when I get to that stage?

thanks for the response. I didn't realise LoopCAD could also calculate heat loss for each room, I would give it a try but the plan that includes heat loss is $1,150 can you do it all with the free trial? Can I ask if you have any pumps or just rely on the ashp flow? our floor area is near 300sqm so I'm wondering if each manifold would likely need its own pump also

Hello all, I’ve read through previous posts on this topic and like the idea of having an UFH system that is weather compensated by the heat pump with no individual control or zones. A simple system. Ive contacted a recommended company and they have said this is a good idea but they would need to know the heat loss per sqm for individual rooms in order to make sure smaller rooms don’t overheat and larger rooms aren’t under heated. They also said actuators and floor probes stop the slab from overheating so the manifold should still have actuators presumably all connected to a wiring centre which all goes against the idea of a simple system. Is there anyone that has a simple UFH system that came across these issues? I’m not sure of a way to calculate heat loss on an individual room basis. project details newbuild wet UFH in 70mm screed ashp and mvhr

Well it is not finished yet but I as Nick said I have noticed that if you put your ear to the wall you can easily hear what's being said outside. But we have faced a number of issues. I really dislike having 9mm osb as the thing everything needs to grip on to. We have 85kg per sqm of brick sips hanging on the outside walls and I do worry if 9mm Osb can take it. Also we are currently working on the inside doing an airtight membrane and the battons over the top which is fine, but the moment you try to screw anything substantial to the wall like CLS the screws just won't grip due to how thin the walls are. Ive also noticed our huge sips roof panels dont seem to perfectly line up. Lastly the main benefit of Sips seems to be the build time but once your factor in the year that it takes to really nail down the sips design, get it manufactured and then to site, it really isn't much faster. I would also never touch ICF after seeing someone down my road build one. Timber frame seems to be the most tried and tested sustainable way forwards in my opinion.

I had not thought of doing it that way to be honest. Using the slab as a heat battery is an interesting idea but our heat pump won’t be oversized enough to do this. how do you control the internal temperature if it gets to hot or cold when using weather compensation instead of a thermostat?

I’m glad you saw this post as I have gone back and read many of your comments regarding Loxone which has inspired me to do as much of the system as I can myself. What you’re saying definitely sounds like the simplest solution and while Loxone is great, it does almost seem unnecessary for heating. I suppose I could still use the thermostats in the rooms to control the blinds to prevent overheating

Sorry for the late reply but having a sips build now up and weather tight I would not chose the sips system again. Without a doubt if I were to do it again I would go down the timber frame route mostly due to the many issues that have arised directly because of the sips panel structure.

Hi everyone our self build is pushing ahead and I am now looking into the Loxone system and will soon need to be Installing wet UFH followed by an ASHP. As part of Loxone we will have a thermostat in each room as well as controlled blinds and I am wondering wether to bother with the Loxone value actuators and have Loxone control the heating for each room individually using the stats but short cycling is one of my concerns. Or should I keeping heating and Loxone separate and not complicate something more than required. Im interested to know your thoughts of how you think the best way to control the heating would be if you were using Loxone in your home.

The warranty which was provided by the manufacturer after the job was completed just states that any modifications need to be approved by the manufacturer. I really don’t see why they wouldn’t let me use another approved installer

I could do but I figured this would add a huge amount of weight to the roof and would require some engineering calcs also. I just think the manufacturers recommendation is wrong

We recently have had our Flatroofing membrane finished by an approved installer of one of the ‘big two’ roofing weatherproof manufacturers. Without going into detail, things did not end well with the installer. We now wish to install a solar fixing system that is welded to the roof but the manufacturer have said we need to use the same installer or our warranty will be void. They would not even allow us to use a different approved installer which seems very unfair to trap us to the will of the original installer. our warranty states that modifications to the roof are fine so long as we have the manufacturers approval. Can the manufacturer force us to use the original installer for this addition?

Hi Craig, Sorry for the reply 5 years after you wrote this. My inspector just refused a set of RC2 doors, where did you find out that they should accept RC2 as I cannot find anything on this? many thanks

Thanks for the tip, we had a few quotes and found some included this in their quote and others have said we need to arrange it ourselves

Hello Everyone. My wife and I are building our dream home after purchasing a plot of land inhabited by sand lizards over 2 years ago. We are doing as everything we can ourselves although we have employed a local Sips contractor to construct the frame, followed by professional roofers to ensure we get an IBG for the flat roof. Im excited to be a new member for this forum where I will undoubtedly be spending many hours researching various topics.