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  1. We are building a pretty conventional Potton SIPS house with ground floor wet UFH, heat pump, insulated raft, triple glazed, MVHR..... Most of the time there will be just two of us in a 3 bedroom, 3 bathroom house; so only one bedroom & bathroom in regular use. For the first floor our plumber and project manager both want to install wet UFH. It will be in some sort of grooved or clipped panels as it will go in after the first floor flooring is down. Here's my question. I've read quite a few times on here of people who installed it but don't ever turn it on, people who didn't install and don't regret it. I haven't seen any examples where someone chose not to install it, but wishes they had. So, are you out there? thanks in advance
  2. I am in the process of building a timber building in the garden and am looking into electric UFH instead of an electric heater. For context, the building is a suspended timber frame on 16 individual concrete blocks. I currently have 100mm Celotex insulation between joists and have placed 11mm OSB3 on top to give me my flat floor. I then plan to use laminate flooring on top. What are my best options here… 1 - do/can I lift up the OSB and place the UFH directly on the celotex insulation and screed over? 2 - do I install on top of the OSB and then screed? 3 - do I need to add another insulation board on top of the OSB and then the UFH with screed? Any advice would be greatly appreciated! Regards, Dan
  3. Thanks in advance for any help and guidance. We will shortly start on a 3 bed 3 bath SIPs house with wet UFH downstairs, ASHP, MVHR, solar PV - maybe SolarWatt battery. Mostly 2 retired active adults with frequent visitors. As I work through so many decisions, I'm currently stumped with this one. It's really 2 separate questions but they are related for me. So bathroom floors will be porcelain tile. I'm torn between electric UFH or a zone on the UFH? If the latter should each bathroom be a separate zone or just put all 3 on one for simplicity. If electric - which we have currently - each bathroom would be independent. Towel rail needs to be big enough for 2 damp bath sheets, preferably side by side. I've seen examples 1000mm x 600mm. Again if wet, each on its own or one zone? I'll post some of my other dilemmas in the relevant sub forum. thanks
  4. I've messed up and set the block and beam too high, I now only have 150mm to the top of the bi-fold reveal and am concerned that a ufh system will leave the room permanently freezing. The back wall is only 6.66m and 3m of that is Bi fold doors but space is tight and a radiator will really make the modest dining section too small. We wanted a tiled finish, so allowing 20mm for that I've got 130mm for pir and screed; Is that a bad idea or will the room be ok? I don't want to freezing every time we sit down to eat.
  5. Hi All, I was hoping to run past you all our situation with our first floor 200mm concrete slabs. We are being recommended liquid poured TLA insulation on the floor from our builder mainly due to the slab being at some parts ever so slightly uneven, so the poured insulation will work to level out the floor before the screed goes in place. I have on my notes that the architect mentioned with the 200mm concrete slabs you don't need insulation, just lay the UFH pipes and screed over them - which I may have noted wrongly. What have you done on your upstairs, or from experience what would you recommend for depth of insulation and screed? Thanks and as always, I appreciated everyones feedback. This forum as helped me so much in the last few years from an non-subscriber to now a member.
  6. Hello, I’m living in a new build, approx 6 years old, with underfloor heating. Up to about a month ago everything was working well, and the house was toasty. Over the last month, the downstairs floors are failing to heat up. When I look at the manifold, there is hot water at 50 degrees coming from the boiler, but all the return flows for all circuits are cold. All of the circuits are calling for heat and never get up to temperature. I got a plumber out, he replaced the pump on th manifold, that has made no difference at all. Next I flushed all of the circuits to remove any air, again this has made no difference. As a final test, I have closed all but one circuit and am waiting to see if that heats up. Failing that I am at a loss as to what the problem could be and am looking for some advice. regards, matthew
  7. We just received drawings from MBC showing that they will cut expansion joints in the passive raft foundation. This then had me asking the question what happens to the UFH pipes when they cross the expansion joints? Waiting to hear back from the foundation engineer, but it doesn't seem like it would be an unusual issue, so has anyone come across this before?
  8. Hi everyone I’d welcome your thoughts please, especially on heating. Wanted to reach out to you all as I’m finding it’s tough to get unbiased advice and personal experience. We’re just about to start a renovation and extension project to a bungalow. The existing building is a time capsule from 1979 with a stunning avocado bathroom suite so we need to do the works: heating, ventilation, electrics, skimming, new flooring etc. So we have a blank canvas. We’re trying to work out the classic air source heat pump vs gas, and UFH vs radiators conundrum. The existing property is 60m2 with a concrete floor (the very fashionable original self-adhesive tiles are below an equally fashionable retro carpet). Ceiling height is c.2.3m. We need to plasterboard the ceilings before skimming, so are losing a touch of height there. The extension will be 30m2. Attic insulation is going to be increased, there’s cavity wall insulation, and we’ll be putting in new windows. We’re looking at installing MVHR. The existing property’s radiators need replacing anyway and the pipes are all currently mounted on the walls, so if we went for rads here it would be a big job including all the pipework chased through the walls, etc. Even if we couldn’t afford a heat pump now, we’d want to make it as ‘heat pump ready’ for the future as possible by using low flow temp rads, etc. Because of the expense of this scenario, we wonder the actual cost difference with the alternative, which is a low-profile retrofit UFH system? I’ve been researching and awaiting quotes - I’ve heard back so far from Nu-Heat for their LowPro Max. I’m concerned with appropriateness for the existing building, cost, additional lost ceiling depth (although I’m pretty short!), and if there’s a building regs issue with presumably having no insulation with the original concrete floor. We’d like to do UFH in the 30m2 extension and have been quoted so far for Nu-Heat’s relevant system. The grant from April closes the financial gap between a heat pump and a new gas boiler, as if we went for old school gas there would be extra costs to replace the ancient combi as well as moving the gas supply (crazy money!), required to accommodate the new floor plan. So as there would be a relatively minor jump in cost to a heat pump, we’re wondering if the time is right now? And if so, how this would influence the choice of UFH vs rads in the existing part of the house? Would really appreciate your ideas, observations and experience. Big thanks
  9. The general view on this forum appears to be that GSHP and ASHP with UFH should in the ideal conditions be on for most of the time and the room temps set to the required level and not changed. While I understsand the processes and calculations involved in heat transfer and heat loss and the time taken to heat a room with low and slow as opposed to high and quick, what I am failing to understand is why I have been sold as "Ideal for control" for my GSHP supplied UFH a set of expensive all singing thermostats with internet connection that I can set any range of setting from anywhere in the world. When the companies commissioning process recomends all the features are turned off and reduced to a basic stat setting am I correct in thinking I have been ripped off?
  10. Desperate Advice Required!. My current set up is: 1. A 24w combi condensing boiler 2. 150Lts buffer tank. 3.Google Nest Thermostat The UFH pump is connected direct to the buffer tank, and the controller in the tank is linked to the pump and is set to only pump water around the system when the water in the tank is at 40 degrees. The boiler itself, when heating is being called by the Nest is set to 60 degrees. There is no mixer value installed currently. Firstly, is this a correct set up? Secondly the problem is, this set up means that the boiler is continually running and our gas consumption is huge, approximately 35 kgs over 3 days; and also, when the temperatures outside at 1/2 degrees or lower, the system really struggles to heat the house up to 20.5 degrees. The tank never seems to heat to more than 45 degrees despite 60% water being added to it, unless the UFH is switched off completely. Can someone please explain the need for the buffer tank and whether it is better to have this than have the UFH connected direct to the boiler, which can then be set at 40 degrees for the UFH. Also do I need a mixer valve fitted in the system somewhere? I look forward to any advice. Thank you.... Chantal, a complete beginner when it comes to UFH systems!
  11. Ater a good dicussion with a local plumber it is pretty certain that we will be putting 2 ashp systems in to supply 2 zones, but they will both be in one area next to one plant room. The idea is that 1 big pump (15kW)would be working very hard, whereas 2 x 10 would be coasting and much more efficient. Therefore the feed from the plantroom will need long distribution pipes to the manifold. Ground floor concrete with ufh. Partial First floor is largely in the roof space with timber floor and will be big rads. There will be a convenient void between low walls and the outer wall, through which services can run, and we can insulate inside the stone wall. I think we must take the feed pipe to the first floor so that it can be insulated or we will lose too much heat in transit in the concrete floor. Is it normal or wise to use the specialist insulated pipes, or simply to use normal pipe then pipe-wrap (the superior one) then also wrap in mineral wool. This looks great but is £50/m, and it might be difficult to get round corners. Have used it previously outside from distant ashp to building but is it too much for inside? .
  12. I moved into a 4-bed dormer bungalow (176m2) last summer that had just been gutted, extended and completely renovated, including ASHP for the DHW and UFH. The ASHP is a Nibe F2040-8 (8kW). The UFH is in screed downstairs and on aluminium trays in the suspended floor upstairs (both with 200mm pipe spacing). There is no buffer tank, although there is a volumizer unit. Room temps are set to 18C for bedrooms and 20C for the kitchen/lounge etc (no night-time setback). The UFH downstairs can maintain target room temps with a flow temp of 25-35C. However, the upstairs seems to need a higher flow temp of ~45C to maintain target room temps. The problem with this is that when the outside temp falls below 5C, the ASHP continually defrosts and is unable to deliver a flow temperature >30C (i.e. the opposite of the intended weather effect compensation!). I have attached some screenshots of plots from my Nibe Uplink – the first is when the outdoor temp was ~10C, which shows the flow and return temps oscillating around the target flow temp (which is what I would expect to see) and the other shows the same plot when the outdoor temp is ~2C. In the latter plot, the pump is defrosting so frequently that the flow temp never achieves its target, resulting in high electricity consumption (>£200 p/m), a really noisy pump, angry neighbours, and room temps <18C upstairs. The installer is refusing to investigate this problem and Nibe will only interact with installers. Q: is the impact of the defrosting cycles what you would expect for an ASHP at <10C? If not, any thoughts on the underlying cause – insufficient pump size? Lack of a buffer tank in the design? Anything else you can think of that might cause this…? Looking forward to your expert input and happy to provide any additional details that might be helpful.
  13. Based on info on Buildhub I estimated a 15kW ashp, but a local specialist says it is not enough. Also the floor arrangement requires a secondary feed and manifold to reach the distances. The building will be in the form of a main building and an annex (for us old ones and b&b). Plans below shows the layout, with central courtyard. All the GF to be ufh. The upper areas (front and left wings in roof) to be radiator (headroom is tight). Outside is 21 x 19, inside 18 x 16 approx. Insulation will be very good, to new-build targets, although some trading off for practicality (esp headroom at existing doors), so the floor will be 125 to 150 PIR. Our thoughts are as follows. 1. 2 pumps needed so do they both feed the one plant room or 1 for main build and 1 for annex? 2. If the former, do they work in tandem or split to space heating and water heating? 3. Split the load as 2 identical pumps sharing the load, or large and small? 4. Best to have 2 water tanks anyway, for volume and to avoid arguments between the 2 spaces? 270m2 GIA ground floor, 110m2 upper floor. The plant room is shown, to the left next to the stairs. There is a roof void at bottom right that could house more plant. BTW the current favourite installer seems good, but it is early days and I like to understand and question. Any comments welcome, not just as my 1-4.
  14. Hi All, I hope you're keeping well! I just wanted to introduce myself 'Joe' to the forum as I have been a long time reader and now hopefully getting closer to starting my own build. The forum is such a great resource for information and the knowledge of the users is simply amazing - I really do appreciate everything I have read here as it has helped me so far on my journey. I am hoping to learn as I go and all being well, I'll be able to help others as I pass through each stage of the build and gain my own knowledge and experiences. The house is a two story house with a connection to single story building for the kitchen, dinning and living area which in total is approx 330m2 sitting on 0.8 of an acre. It will have a ground source heat pump, with underfloor heating on the ground and first floor, mechanical ventilation heat recovery system and a PV solar array with battery. Windows triple glazed throughout. The current SAP report SAP rating: 92 A Environmental: 93 A If I have missed anything I will update the above. All the best, Joe
  15. Hi all, We are getting closer to having our UFH pipes laid on the ground floor (in 50 mm liquid screed). My design is as shown in the attached image (150mm centres) , however have been told that its not the best way of having it and a spiral design would be better and give more even heating and less chance of any cracks. Is that right or is my design perfectly adequate? All the runs are less than 80m long, I didn't want to go more than 150mm on the centres as I wanted to improve heat up times on the system and the plan was to run the UFH at as low temperature as possible so that the boiler is condensation mode all the time while the heating is on (If anyone has any further information on system design in that respect it would be much appreciated). Thanks
  16. An issue came up today though is that not sure how to set up a circuit for the two towel rads we're having. Here are the different factors we're juggling: The UFH will need to be kept fairly low temp, because our engineered floor cannot be exposed to a subfloor that is hotter than 27 degrees. So I'm guessing we will run the UFH at 30C - though not sure how to calculate what temp to give 27? And presumably different rules apply for heating screed on a ground floor than for heating a non-screed system on the first and second floors. The hot water cylinder I understand needs to be at 60 degrees minimum to avoid legionella. Our plumber thinks this is a waste of energy, but I don't see a way around it, although I know some people just heat it once every so often to sterilse, but either way the temp of the UVC will be much higher than the temp sent to the manifolds won't it? Then what to do about the two towel rads. Presumably these are fine at 40 to 45 degrees, but that is higher than the UFH and lower than the UVC. Or can each UFH manifold lower the temperature of the water it is getting from the boiler? We are not having buffer tanks for the UFH because we've gone for a broad range modulating boiler and a low loss header instead.
  17. Hello We have built a large extension to an early 1900’s house to be heated by ASHP with buffer tank. We are installing a wet UFH system using 3 manifolds due to the position of the zones. We will also have radiators in the bedrooms in the old part of the house. Looking at various heating system designs online, I am confused as to what valves I need to install and where in the pipework. Do I need a zone valve for the radiator circuit and one for the UFH circuit? Or do I need a valve for each manifold? And should the valves be located at the buffer or at the manifolds? I have also seen some circuit drawings with non-return valves on the return legs of the UFH, presumably to stop the other circuits trying to push the wrong way. Any advice greatly appreciated.
  18. Hi all, We are having some problems with a new Ecodan install and with the heating now on it's clear that it's not performing as expected. I want to check I'm on the right tracks before going to the installer and getting another TADTS type response. 8.5kw Ecodan serving two UFH manifolds: GF - set in flow screed approx 70sqm, 4 zones FF - grooved overlay panels (12mm pipe), 70sqm, 3 zones. When there is a call for heat everything fires up as expected. However if only a couple of zones are calling for heat it will run for just a few minutes before switching off. Not just the compressor cycling on/off but also the heating pump (I would have thought with short cycling that the pump would continue to run and just cycle the compressor on/off depending on return temps?). It then sits dormant for a good 15 minutes before repeating. It often won't run long enough for the UFH return loop to even become warm. I can see from the thermistor readings that the return temp matches the flow within a few minutes. I expect the problem is exacerbated by the small-ish 12mm pipes on the first floor as the flow through these must be tiny compared to the flow from the heat pump. I think we might have a minimum volume problem and/or a flow rate problem. Can anyone confirm if that sounds right and what the correct solution would be? Many thanks, Olly
  19. Hi My first post here - was pointed in this direction by a friend of mine. After months of research (feels like months) I think I have come to a conclusion on which UFH system and I just needed some support on ensuring I had made a right decision (otherwise my wife and kids will kill me in the middle of winter). Background I am doing a renovation project of the ground floor of my house - 95m2. It is a 1930s semi - whole place is being gutted and an extension going in. The current flooring is timber joists and in a bad condition and has no insulation. So first job will be to rip up the flooring and add 100mm of Kingspan or Celotex in between the joists. Now the complexity of which UFH system to go for. I have boiled down to 2 options: Option1: TorFloor by Omnie - I can use these boards as the structural floor, I am hoping a competent plumber can install this and I can get a 9mm plyboard on top and finish the floor with LVT like Karndean. The height build up is 35mm (22m board, 9mm ply, 4mm Karndean). So the build up is pretty similar to what I have with the existing boards and underlay and carpet Option2: Install a pannelling and screed system (like Nuheat or Profix). With this system I would put some 6mm T&G plywood over the top of the joists, put down the castellanated panels, pipes would go in and screed on top. As I cant put Karndean straight on top of the screed, i would need to finish with 6mm ply and Karndean finish on top. So the build up is 80-85mm (6mm ply, 15-20mm panels depending on system, 50mm screed, 6mm ply, 4mm karndean). It is not clear how much screed I need as some systems are different. I am hoping I have described the above scenarios correctly - I am not a seasoned DIYer so all the research has been mind blowing !!!. In conclusion I am tending to go for the Omnie Torfloor system - number of reasons - floor build up is lower and its £3k cheaper. However what I dont know is the output and difference between a screed system and an overlay system. Any opinions on my conclusions?? Please tell me if I have got this one wrong !! Ideally I need a fairly quick heat up and a fairly good output - kids and mrs moan in the middle of summer of how cold it is !!! Thanks for reading
  20. Although planning a building on the East coast in the highlands, I do have a concern for over heating. Heating to be thermal store - ASHP - PV and ( possible Solar thermal)- all DIY, possibly a small wind turbine connected to DC immersion - it is windy all the time....... Anyway I got to thinking about cooling, and read some people use the ASHP and buffer tank to cool the UFH. I plan to have 6000L rainwater tank ( it also rains a bit), this tank will be underground and relatively cold, so I thought a couple of three port valves and a dedicated loop of pipe running through the tank would provide all the cooling needed and a possible heat dump for the solar. Any thoughts , problems you see.
  21. Converting a 3 bed very dilapidated 1930s semi into a 4.5 bed modern home. EVERYTHING is being gutted except the joists. Quotes are way over budget, particularly for the underfloor heating. I had specified wet underfloor heating throughout all three floors of the house (ground = 800 sqft, first = 750 sq ft and loft = 450 sqft), with the ground being imbedded into screed and the first and second floors being laid within some high performance extruded polystyrene boards made by Cellecta called XFLO. XFLO is quite expensive, about £26 a square metre, but the reason I had specified them is that they provide good insulation to make sure the heat goes up, are CNC drilled by Cellecta to meet any pipe layout requirements we specify and also feel quite firm underfoot. The other advantage of the XFLO is that you can lay the finished floor directly onto it. Underneath those XFLO boards, I had specified a 6mm dense rubber matting (which comes as a 10m by 1m rolled product, so pretty easy and quick to lay) to absorb impact sound, and underneath that 18mm tongue and groove ply which is nailed directly onto the joists (whereas the rubber and XFLO are just floating). In between the joists I was going to have mineral wool to mute airborne sound travel, and underneath the joists I was going to have the ceiling attached using resilient bars (with market name "Genie clips") to isolate the ceiling from the joists to further prevent sound transmission. The whole system is to be zoned as 9 zones, including one zone for the 3 towel radiators (which will be the only radiators in the house, one for each bathroom), although I'm going to provide Tado thermostats, one for each of the 8 UFH zones and a Tado smart valve for each of the towel radiators. One builder has quoted about £25k plus VAT for all of the above, and the other about £28k plus VAT. These quotes don't include the thermostats (I'm providing those). When I have challenged each of them on why this is so expensive (I was expecting about half the cost) they have said different things. The first builder has said that I could save £2,500 to £3,000 money by losing UFH in the loft and in most of the first floor, and instead having radiators there. The second builder doesn't agree that would save any money and is also trying to respect our reasons for having UFH. Instead he just thinks the system I've specified for the first and second floor is overkill and that I could make two changes which would save about £4k in labour: First, instead of 18mm ply plus 6mm rubber matting plus the XFLO boards (which are about 28mm thick) I should just lay a product sold by theunderfloorheating store calledProWarm ProFloor 22mm pre-routed chipboard. I've looked this up and I see the benefit. Like the XFLO boards, you attach it directly to the joists and it comes routed (though with standard not bespoke routing) and enables you to fix the finished floor directly. It costs roughly the same as the XLFO, but it saves the builder the trouble of having to lay the rubber matting and the ply, so the saving is in the cost of the matting (£6 per sq metre), the ply (about £14 a sq metre) and the labour to fit those two layers. Second, he says that in the bathrooms, I should just lay electric UFH rather than wet. He accepts it's dearer to run, but he says I can have smart timers on it to make sure I only have it on when needed and as there will be wet towel rails in there, I really won't use it that often. I think I'm willing to accept his second point and fir the electric UFH in the bathrooms, but I'm concerned about the disadvantages of the first point, which I see as follows: 1) I lose the impact sound protection provided by the 6mm rubber - is this such a big deal given I have an isolated ceiling and the mineral wool between the joists? If so, can anyone think of a way of combining a fairly cheap but effective sound impact layer with the 22mm pre-routed chipboard? It would only ever be my kids running around, so impact sound is not a major issue, but I want some protection. 2) Chipboard is not as durable or as strong as ply. Although both will feel similar at the outset of their lifespan, what will they feel like in 12 years time? I plan to be at the property for 12 years at least, but hopefully longer and I don't like springy floors. 3) no bespoke pipe channels like Cellecta offer with XFLO. But is this overkill? Maybe I don't need bespoke pipe layouts. Builder says that the 22mm pre-routed chipboard just has channels at 200mm pipe centres and that is a standard construction for first and second floors. Although most of the rear of the house is being extended, so it will have insulated cavity walls, and the loft will also be well insulated, the rest of the house has no cavity walls. Keen to hear your thoughts on the above. Thanks for your time!!!
  22. A couple of years ago, I bought a house heated by a 14kw Ecodan ASHP with a Mitsubishi pre-plumbed cylinder system, that was installed in 2015. It has zone 1 to heat 10 radiators and zone 2 to heat 3 loop wet UFH for the kitchen and utility - also heats DHW. During the colder winter months and late frosts this year, it was clear that the UFH was failing to heat the kitchen/utility floor. The input to zone 1 is physically higher on the low loss header, so if both zone 1 and zone 2 are on at the same time, zone 1 takes the heat, and no heat travels down the low loss header to zone 2. If just zone 2 is on, some heat goes into the zone 2, but much of it travels down the low loss header to the return. This causes the return to be almost as hot as the flow, so the Melcloud reports show the return temperature tracking the flow temperature. When it reaches the peak temperature, it cuts out and flushes with cold water from zone 1. This shows as a sawtooth effect of fast cycling - the cycling is very regular, every 10 minutes. If zone 1 is on by itself, this does not happen - the return remains lower than the flow and there is no cycling (I've attached a melcloud report showing this). The system has been serviced, I've flushed the UFH loops out (via hose - a small amount of muck came out but not much and the flow was OK) and inserted more biocide. I've tried altering the pump speeds. To reduce any flow obstructions, I've removed the flow meters and used blanking plates. I've replaced the Heatmiser UH2 with a standard Ecodan wireless thermostat, and Salus THB23030 actuators. I still have the 10 minute cycling. I have a feeling that the ASHP is too big for the UFH by itself - but not big enough to heat both zone 1 and zone 2 together. I've tried asking UFH and ASHP installers and maintainers, but they look even more baffled than I do and offer no help (with all the green deal stuff, they are too busy installing new systems to bother with maintaining existing ones). I just wondered if anyone had any thoughts or ideas as to anything I could try? Many thanks Eric
  23. We’ve recently installed UFH in our first floor extension using Nu-Heats spreader plate system. Long story short, the plumber missed the small print which specified that additional heat sources were required in the bathroom to get it up to temperature, so we’re now looking at the best option for plumbing a towel rad. Plumber wants to simply run a new central heating run in and drive the rad off the main hallway central heating stat, however given the bathroom is setup as it’s own zone with stat etc, that seems a massive waste. Is there a way to run the rad and UFH off the same room stat and zone? Is it possible to plumb the rad into the end of the UFH loop?
  24. I'm taken the general recommendation to use Wunda for UFH design and see they offer a neat solution using aluminium spreader plates to fit regular UFH pipes between the joists for first floor bathrooms etc. This avoids need to install pipes on top of the floor and eliminates the level changes that would arrise. Has anybody had experience of using this system? Seems to be a good alternative to electric systems and I'm guessing a lot cheaper to run form the ASHP. One issue i can see is that the spreader plates and UFH pipes would need to be installed before the floor is laid which may be an issue in practice. Any advice welcome.
  25. We have an old concrete slab, and hope to have UFH. The ex builder placed stud walls onto the floor, sitting on DPM (after initially saying they would lay it onto a brick course). If the visible DPM plus another on the floor in each room is lapped up the walls, it will encase the bottom part of the timber wall in plastic. Will that be ok? It seems to me it will get condensation and rot the wood at the bottom? Said builder will never come back to rectify (I have waited 6 months for other bits and given up). Thank you!
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