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  1. I am in the process of designing (with architects!) and commissioning a small low-energy house which will rely mainly on solar pv for energy. There is no gas at the property. I have over 15 years experience of solar thermal and solar pv. My current house uses solar pv exclusively for hot water for more than 7 months per year, uses gas for ch & backup hw for colder months. My current 3 immersion design cylinder has proved very effective. I have trawled through various heating and dhw designs including thermal stores and multi-tank solutions but cannot reconcile the different requirements (eg thermal stores need a good temperature gradient to provide dhw - heat pumps provide 55º as a working maximum). I have also noted comments on this forum. (“Hot water and heating are different – keep them separate!”) However I’m still looking for an efficient & effective solution. I am considering using a large unvented cylinder (say 500 litres) which will also act as a buffer for a heat pump and a thermal store for underfloor heating. For at least 8 months of the year the total input would be from solar pv through immersion heaters. For the colder months there would be the possibility of input from a heat pump. Primary heating would be through 3 immersion heaters. I have included a diagram. I see the following as advantages : 1. A single tank with straight-forward plumbing. No complex valves or diversions. 2. Separation of circuits for input/output. Antifreeze needed only in the heat pump circuit. - Better heat transfer to UFH with water than with antifreeze mixture. (and much less of it) 3. Ability to maximise use of solar pv (8kW) throughout the year. 4. Possibility of running as a fully electric system without heat pump - under consideration for at least one year to assess relative costs. Also provides alternative heating if heat pump fails. 5. Typically : we boost heat in the mornings (before 9.00) and in the late afternoon/early evening. Background temperature maintained at other times (although with a good store in the slab this will become less pronounced). Best efficiency from an ASHP will be when the outside temperature is highest and the best use of solar pv will be between 9.00 and 17.00. So having a facility to store heat at these times will maximise both efficiencies. I recognise one potential problem: In our current location, with excessive water hardness, cylinders frequently deposit more than 0.5kg calcium salts per year. We have completely avoided this by quality water softening and would do so in the new location. Although the physical design is simple the efficiency will depend on the control circuits. I propose to design & program these myself rather than rely on the current commercial provisions which seem to be over-complicated but still limit options to those provided by manufacturers. All of the plumbing would be installed by G3 qualified tradespeople. So I would welcome constructive guidance … 1. Is there any commercial system which already follows these lines which I’ve missed? 2. Has anyone on this forum taken a similar line – with what results? 3. Are there any genuine down-sides which I’ve missed?
  2. My planning permission contains commitments for installation of solar PV, air-source heat pump and rainwater harvesting. I'm not wanting to go through another round of planning variations so I will install them. However, I suspect if I'd done a full cost benefit analysis then it would be difficult to justify the rainwater harvesting in particular. The solar PV hardware appears to be getting much cheaper (haven't looked at install yet) but the Smart Export Guarantee tariffs don't look particularly attractive (5.6p/kWh). ASHP makes sense I feel as there is no gas supply available to site although some of the installed prices appear astronomically high (e.g. £11-12k). Does anyone have any evidence that these eco features more than pay for themselves in purchase premium on a house sale making them "no brainer" territory?
  3. Hi community, Over the last 2 weeks I've been trying to take in lots of info regarding ashp since having one installed in a new build, thanks so much to all the people that contribute with their esteemed knowledge, much of it on here is well above my basic understanding and it seems there are a myriad of things to consider when trying to optimise the systems. Bit of background, 186m2 timber frame kit from a company called scotframe, as a non builder this seemed like a means of eradicating some of the problems with builders as it progressed. Product has been good aside the nordan windows and doors imo, the erectors not so good, wish I'd hired a chippy with lots of new build experience to keep and eye on them but I am where I am now.. if anyone has questions about scotframe always happy to share my thoughts and experiences. Installed I have an ecodan 8.5kw system with ufh downstairs dfor heating and DHW. no buffer tank just the ecodan cylinder with 6 room stats downstairs. Vent axia sentinel mvhr yet to be commissioned / balanced. 75mm screed on top of 140mm celotex. pipe spacings at 125mm (mostly anyway). Been running now for 2 weeks, the house is at a comfortable temp downstairs, 17 deg, and that what's the stats are set at, not lived in yet but in this cold weather seems heating will be needed upstairs with points for electric heaters of some sort ready for the future. After lots of reading on here I've decide to run the ufh at a low flow temp, presently 29 degrees and run it continuously aside from peak pricing times with octopus agile.. . The house seems to hold heat reasonably well but until I move in to a semi building site in around 6 weeks I wont know exactly how it performs. Whilst the heat pump installer / plumber was a lovely chap and had a love for making perfect copper piping I'm not entirely sure how technical he is when it comes to these systems. I have lots of questions but the thing that's initially baffling me is on the control panel for the heat pump when the ufh is running its shows the flow and return temps are very similar circa only 1 or 2 degree loss between the two. From reading on here that seems far too narrow so the lovely heat the pump is generating heat but returning the majority of it . If someone could help me understand the impact this will be having on the heat pump / efficiency and then how I would go about increasing this difference that would be appreciated. The installer left all flow rates at 2.5 which was nothing like the ufh design I've referred back to, so a few days back I reduced these to what the design recommended, but this hasnt affected these flow and return temps which I assumed it would have. As said for many on here with knowledge in this area it may well be like pulling teeth trying to get me to understand what's going on but I'm game for the challenge Thanks.
  4. There have been so many little problems Ive asked for a break with the builders so I can do more research. Do I recall people discussing that UFH and ASHP might not be a great idea for a rental property? I'm not planning to rent the stables right now but its not impossible in the future. Is that because of the PITA factor and the chance of poor installation/incorrect sizing etc etc
  5. Hi I really appreciate all the advice and information on this forum so have finally registered with a question of my own. I have bought a house with no heating. We are going to install an ASHP behind an outbuilding and have already put in a heat main (twin 50mm pipes) from the outbuilding to the house, a distance of about 20m. What size pipe should we step this down to for routing through the house to the DHW cylinder and UFH gubbins? Is 28mm big enough? Thanks
  6. 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.
  7. Calling all owners of Samsung Gen6 ASHP (maybe others too). I have found on my system that when the exterior temperature drops to 2deg or below, if the pump is not working for heat/DHW, it enters a frost prevention programme where it runs the main circulation pump and operates the DHW valve. This means it is sucking heat out of your hot water tank to prevent the external unit getting the shivers. Quite why is the good question when mine and I suspect everyone's is filled with antifreeze protector. We've posed the query via our contractor to Samsung as the contractor is as puzzled as I am as to why it should do it. I discovered this by accident as I set the internal overnight temps back a degree or so at 22:00. One frosty night walking past the kit cupboard at 24:00ish I heard the circulation pump running and discovered this. On a fully cold night it takes around 8 to 10 degrees # out of the hot water tank (400l). I've now bypassed the DHW valve with a switch so it pulls it out of the buffer instead whilst we wait for Samsung to reply. Note the pump runs several times a night for around 5 mins a time. #We're passive insulated and EPC A, so room temps barely fall a degree overnight. It seems mad to me to have this put in the programme with no way to adjust it. If it could be set to only do when say the outside temperature falls towards the freeze point of your mix then fine, but otherwise this is just wasting heat.
  8. We woke up this morning to no heating and 2 error messages on the Danfoss DHP AQ air source heat pump. The messages are Com Error HP Card and Com Error Exv card. I've looked it up on the internet and it says the HP Card error message is "Communication broken between display card and heat pump card (outdoor)" and the EXV card error is "Communication broken between display card and expansion valve control card (outdoor)" We've checked both indoor and outdoor units for any loose wires but there's nothing obvious. Does anyone have any suggestions as what we could do? Thanks
  9. I'm in the early stages of the refurb of a 1917 property in Kent. The rough downstairs floorplan is below - The floor is a real hotchpotch of suspended floor (45% - Green), Previous extension concrete floor ( 35% - Yellow) and New proposed extension (Orange 20%). The current EPC is a horrible 23 and we're looking at using a combination of internal and external insulation to improve this. This may be an opportunity to seal the house (replacing floorboards?) Trying to bring all the potentially different technologies and solutions together is a challenge and every choice seems to lead to a particular specialist supplier that may have a particular axe to grind/product to sell. There is a wealth of knowledge and experience on this forum that I am very glad that I have found. Regards Tet
  10. Hi, i am a new member, after a quick look on the web for information about ashp, I find myself here, my lodge home is under construction and I am keen to install ashp air to water for ufh and dhw, I came across some info that was 4 years old and has opened my ears, I am not too bothered about the RHI and using MHS certified installers as the general opinion of expensive and a bit of a catch 22 situation. I have good plumbing skills and some experience of electrical installation. My first question is what brands are worth a look and where's best to buy? Cheers Bob
  11. I have had my heat pump on now for over a week and it does seem to be working a lot. I know the house has a large footprint (predominantly g/f with only one room upstairs) but I am unsure how to set it up for the long term. I know @jackhas a similar heat pump and he uses the weather comp curve instead of the direct setting but is this the norm? I had mine set up in the direct mode to start with but changed it later to the comp curve just to see if the amount of time the pump was running was reduced but if anything it has increased the pump running times. I understand each house is different and with this cold spell the house will need more heat to sustain the internal temp but what have people set theirs to? Have you got worked out a more efficient way of running your heat pump? If I was to go onto E7/E10 then I am not sure that there would be enough time to heat the house in the time aloted for the reduced rate of electricity. At the moment I have my heat flo temp set to 35 down to 30 and the outside temp setting -5 to 15 as I tried what @jack (30 and 25 and 0 to 7) had his set to and the house was not getting warm. The house is Passive with ufh pipes laid at 200mm and is all one zone. At the moment I am not sure whether I should have had closer pipe centres to increase the heat output or whether due to the larger footprint my heat load will always be high OR whether my settings need changing to work better? The system is run by a room thermostat set at 21 and the house is lovely and warm so I know I could lower the temp but when you are sitting it can get quite cold. I have had a look at the power consumption and I used 52kw yesterday, 37kw day before and 31kw before that but the weather has turned colder these past few days and the average COP is 2.2. I seem to recall that people run their pumps in segments throughout the day but I cannot do that as the house would not be warm enough. Do I increase the output flow temp to heat the floor quicker(?) or is that not the correct approach as I am then reducing the efficiency of the heat pump but would the heat pump not run as long? I know some people run their heat pump using the buffer tank instead of a room stat but not sure if this would help me? Any advice or insight into how people run their heat pumps would be greatly received as at the moment my elec bill is on a steep upward spiral!! TIA
  12. I am in the process of building a Passivhaus. As there is no gas, I will be using an ASHP for Heating and Hot Water. Heating will be via radiators located downstairs and upstairs. I am in the process of deciding between two Mitsubishi heat pumps - the 4KW QUHZ (CO2) which is matched with a Thermal store and the 5kw PUHZ which is matched with a Hot water cylinder. I have phoned up Mitsubishi and spoken to them about the QUHZ (CO2 air source heat pump). There is no additional maintenance required for the QUHZ. I also asked them about reliability and there view was that as they've had to increase the spec of the QUHZ in several areas to take into account that CO2 is the refrigerant so they expected the QUHZ to be as reliable or more reliable than the PUHZ. I think there is a big difference in the way that it heats up the water as the QUHZ uses a thermal store rather than a hot water cylinder used by the PUHZ. Not an expert in this area, but research I have carried out suggests thermal stores are less complex than hot water cylinders. Idiots guide from Mitsubishi was to use the QUHZ if your hot water energy requirement exceeds your energy requirement. Using the more detailed data for range of temperatures supplied by Mitsubishi the services engineer checked performance in PHPP for specific loads and temperatures for our house. It indicated that the heating is indeed slightly better with the standard unit but hot water is considerably better with the QUHZ which correlates with the feedback from Mitsubishi. These were both modeled at 45 C heating design flow temp and 55 C DHW supply temp. So on the surface it would appear the QUHZ is better suited to my needs. The only caveat is that it is a relatively new technology for Mitsubishi (introduced 3 years ago) and I think in the market place in general. I had an early condensing boiler fitted to my current self build and it was always breaking down, so I am a little cautious of using anything new on the market because of that experience. Heat pumps seem to be tried and tested technology however so maybe I am worrying unnecessarily. I would welcome any thoughts / feedback on this.
  13. Can anyone of our electricians @ProDave please explain how this wiring diagram will work on my Panasonic 9kw Aquarea heat pump?Secon Panasonic H Series rev1.3.pdf I understand that the heat pump will require its own supply from the CU but I am a little unsure as to what cables to put in ready for my sparky mate to connect everything up. I think I need to run some 1.5mm flex to run the heat pump ,diverter valve and controls etc but not sure if the power supply for this is fed from the heat pump supply via some fused spurs or if the heating controls are fed from a different source to the main heat pump supply? I understand it would be ideal to have one isolator for the whole heat pump and assoc controls but just a little confused? The heat pump itself has a back up heater for DHW so this is also confusing me as it shows connections for the immersion heater in the drawings but I assume this is the one on my HW cylinder so not sure if the feed for the immersion heater should come via the main heat pump supply? I am just trying to get all my cables in place ( so I can plaster some ceilings ) plus some spare ready for when my sparky is available to connect it all up next month so we can get moved in before xmas and I still have plenty to do! Hope you can help me understand this? TIA
  14. As part of completion paperwork Building Standards have requested a heat pump installation certificate for my ASHP. Has anyone in Scotland experience of this or have any idea of the regulation where this is cited? I've installed the heat pump myself and I'm not applying for any incentives. Thanks
  15. Does anyone have any experience with the Daiken Altherma ASHP. I'm wondering if they are any good before I go any further. I work for Daiken, although not this area, but if it's any good then I might see if there is any chance of an employee discount.
  16. I currently have an outdated oil fired heating system and I need to replace the boiler, oil tank and pipework etc. I have been in touch with a Air source heat pump provider who quotes a flat £14995.00 install for and ecodan 8kw heat pump, 170 litre hot water tank, 10+ rads etc. Having had a survey done I am due to meet with a sales manager to finalise details. In regards to RHI I have been advised I would receive just under £11K from RHI over 7 years. I have a detached 5 bed house and wondered if this is setup would be suitable and if £15K is about right Any advice would be appreciated, thanks
  17. Afternoon, I wasn't sure if this should go in the renewable section or Scotland section. I was just wondering if there was anyone on here from Aberdeenshire or the surrounding area who has had an ASHP installed. Can you tell me who you used and your experience of the company/installer? Thanks Paul
  18. Hi. I'm a retired (10 years) electrical/electronics engineer and IT Lecturer with too much curiosity probably. I have a 1950's house with upgraded insulation and I'm looking to replace my combi boiler and get rid of gas. A Sunamp unit for hot water and an ASHP for heating are favoured, the idea being to use off peak electricity and installed solar PV to the maximum and minimise emissions etc. Green Home grant and RHI under investigation. Only a shallow knowledge of plumbing, heating and ventilation, so I'm on a steep learning curve. In my early 70s I'm having to get others to do things for me as my DIY capabilities decrease. Very frustrating!
  19. I have finally come to the conclusion that we are going to fit an ASHP and cylinder to our property. Over the years we have been drawn to the Sunamp, Sunamp and Willis heater courtesy of @TerryE but with the recent problems encountered and the uncertainty of how the system works if/when you have a problem does not appeal to us (Apologise to all those Sunamp owners out there). So having chosen ASHP it brings with it the problem of designing/installing the system and even though I have plumbed houses and fitted central heating systems the thought of this seems quite daunting.I have never fitted a cylinder before so this in itself is new territory so I am appealing to people who have done this themselves @joe90 , @ProDavefor any guidance you can pass on to me and may be some more help from @Nickfromwales and @PeterWif you can spare the time. I am struggling to get anybody locally who can just fit this low KW ASHP with cylinder without wanting to double the capacity, have it interact with the space station for telemetry and spend a whole week on fancy control systems. I have looked at the plug n play systems from the likes of LG and Samsung which would be very easy (ish ) to set up but would cost quite a bit more. I know I need an inverter in the ASHP and a blending valve(!) now so you can see I need quite a bit of advice to be able to understand the system and what I require. The house is Passive so will be minimum heating and I intend to keep the DHW temp low like Joe and Dave so I am trying to give you as much info to help with your advice hopefully. I know people have bought their cylinders from Telford but not sure what cylinder to buy? We will be doing solar PV at some point just not sure when. @joe90has mentioned having a buffer tank but he is not sure whether he actually needed it although he has his immersion in this tank I know you can have an immersion in the main cylinder and if I had a Willis heater as an immersion heater this could double up as a stand by if I ever have ASHP problems but how does this all connect together!! Hope you understand my dilemma and hope you can help me design and understand my DHW and UFH system from the start to the finish!!
  20. Hi all, We just had a ASHP co come out to measure up or extension and original cottage to quote for an ASHP. By the end of it they have we needed around 8.6, then added a 10% buffer which pushed us above the 9kw LG single fan unit they recommend. The 12kw model they recommend is pretty large and a 2 fan system. It is meant to be attached just to side of cottage and I think it is just 2 big visually to fit in there. the extension is around 60sqm and the entire cottage will be 110sqm when complete. I've seen several rather large houses not far from here fitted with a 9kw system by the same company so wondering how such a small cottage, in comparison to some of these large, double story houses, requires such a big system. Can anyone here point me in the direction of some info where I can get myself up to speed with it all please. The ASHP will be supplying UFH and Hot water and the calcs allowed for a 300l water tank. Thanks in advance.
  21. After much heart ache, time and tears I'm looking for some advice from you guys regarding my heating system, which is completely separate from DHW. I plan to directly heat my slab with ASHP using Willis heaters as back up. Hydraulically does this look ok? Input much appreciated.
  22. Hi everyone! We are at the foundation stages of a newbuild. It's a replacement dwelling for a chalet bungalow in the centre of Marlow, Buckinghamshire. Very keen to read about other projects and get some advice on ours. Cheers, Steve 3_Westwood_Road_Design_&_Access.pdf
  23. Left this a bit late and BPC shut for the day. I need to build my external block wall tomorrow on the exterior of the timber frame. I will have to put 3 pipes in the wall to take the flow/return and power for the ASHP so I can seal them from the outside to the frame. I am proposing to use 50mm pipe for the wet pipes to leave enough room to insulate round the pipes afterwards (Passive) and 20mm duct for the power, does this sound ok or would people use smaller pipes? Do not know make of ASHP yet so do not know if I will need 28mm or 22mm pipes. How close can the ASHP be sited next to MVHR vents? I have a low level vent, approx 500mm off the floor and one at 2.2m and they are 1.5m apart and cannot anywhere else. TIA
  24. Just about to put my Norstone cladding on the exterior of the house and need to ensure the ASHP pipes look the part!! I have put in some ducting and now need to decide how to finish the pipes off so it creates a nice junction as it passes through the Norstone. The ASHP will be sited approx 1 metre from the pipes and about 300mm from the wall. I know I need flexi pipes to limit the vibration but can I go with one long pipe from ASHP through the ducting and make the connection to internal pipework inside thus avoiding a right angled union outside or do I need to have a right angled union as the bend will not work without a 90 connection? ( Hope this makes sense) I could site the ASHP nearer than 1 metre if it means I can do away with the 90 union. TIA
  25. Hi all, I have a Danfoss 7 year old DHP AQ 13 ASHP. I am struggling to get local support. For a few years now, Danfoss have outsourced their support to Ashgrove Engineering in Ireland. There’s only so much that they can do over the phone and the problem starts when you try to get local support. My installer went bust during commissioning and my local support (about 8 miles away) withdrew from Danfoss and heating about 3 years ago. Ashgrove recommend an engineer based in Bristol which means that there is an automatic call out charge of £200 before any work has started, not to mention the added time to schedule the work at such a distance. This leaves us feeling very vulnerable indeed and actually giving serious consideration to replacing the Danfoss with something that can be supported locally. I am currently looking at a likely compressor failure (after 10,500 hours pump life) which will cost over £3000 to replace. So should I get the pump fixed and look forward to the next few years losing sleep over the possibility of breakdown (on past experience, we have had breakdowns most winters when the demand is highest), or should I put that money towards a complete replacement which can serviced locally ? BTW, does anyone know whether Danfoss is withdrawing from the UK market ? Our experience suggests that it might be. I’d welcome any thoughts on this.