Can_Do

Hi All Thanks for your prompt responses and helpful advice. Apologies for delay in coming back as had a busy week working with the Builder and ASHP Installer together. The Installer originally had brought individual pumps for the two manifolds which gave me the doubt as haven't seen these being used before. He spoke to Mitsubishi Technical Support next day who confirmed that Ecodans don't come with a pump (as JamesPa mentioned above). He has since installed a Grundfos 25-80 180 variable speed pump on the main incoming flow from the heat pump. According to him, this pump would be sufficient to cover flow requirement for both the ground floor manifolds. The first floor manifold already has a pump installed to it along with a Heatmiser UH8-RF controller. He has installed a 3 port valve for water tank/UFH and an additional 2 port valve to the supply line for first floor. In addition he has installed few extra valves which he may need to balance the overall ufh system as the build progresses with the second manifold and more loops are added. His initial install is almost done and tested. Awaiting couple of parts arriving next week which would allow start of heat pump. Looking forward to it now. To be fair, the installer has been very accommodating with the project requirements as the overall ufh system will be build in stages up to next 3-4 months by the Main Builder. The Installer will have to wait till then to fully finish his install. Kind regards

Hi all We are midway through our GF extension adding around 110m2 on 3 sides of our house. After almost giving up on the idea of ASHP, we finally took the gamble to go with a local MCS approved plumber but with little experience of heat pumps installations. The decision was based on low cost and flexibility in choosing pump/cylinder (Mitsubishi Ecodan 11.2kW + Joule 300l high gain cylinder). The original house had radiators throughout, however 4 years ago, I installed wet UFH on first floor covering small bedroom, landing and bathroom with the intent to do the same in the remaining two bedrooms at the time of extension. I used Warmup manifold with mixing valve and grundfos pump which is controlled through couple of actuators, heatmiser app and a single neo-air thermostat. Since then I have been using the heatmiser app as timer to call for heat from the boiler with no other thermostat installed. As part of the extension works, all the radiators are now getting removed and replaced with wet UFH throughout ground floor and first floor. The outdoor Ecodan unit will sit at the corner of the extension with 9m straight run of 28mm copper pipes (elbow at each end) to the Main utility cupboard where the pipes will connect to the water tank and primary UFH 8 port manifold. The total pipe run connected to this manifold will be approx. 750m using 16mm PERT pipes buried in 65mm cement sand screed over 120mm PIR insulation. There will be two Tee off, first one feeding to a secondary 4 port manifold under the stairs on the other side of the house (approx 8m run using 22mm copper pipe). Total pipe length connected to this manifold will be around 350m. The second Tee off will be to the existing manifold in the first floor airing cupboard again using 22mm copper pipes which will feed all of the first floor heating. Based on my research to date, my plan has been to keep all GF UFH as open loop (total pipe length 1100m) which should be sufficient to not need a volumizer or a buffer tank. The main heating setup will be based on weather compensation curve and offsetting function through the FTC6 Controller. I intend to then disable the mixing valve function in the FF manifold and continue to use the grundfos pump and the heatmiser app just to call for the heat for the first floor using the thermostat or timer function which ever will work better. The plumber has started the work today with installation of the water tank. He has brought an ASHP pump pack along with the GF manifolds and other kit. His view is this additional pump would be needed to circulate all the water through the large lengths of underfloor pipes connected to the manifolds. Based on my research (basically watching some Heatgeek videos on Youtube), the pump within Ecodan unit should be sufficient for the GF pipes and the FF manifold already has a pump attached. I am also not sure if this additional pump will have an impact on Frost cycle as there is no volumizer in the system. The chat with him today morning has made it clear to me that we are both bit novice with heat pumps and doing it for the first time which is the reason for this post. Can yo please share any advice on the ideal pipe configuration for all the 3 manifolds e.g. Tee off sequencing for flow and returns, need for additional pumps etc. to ensure that the overall system is balanced and performs the way it should. I have tried to keep the system as simple as possible but it seems there is still scope to get it very wrong. Hopefully it all will work out in the end. Thanks in advance. Kind regards

Thanks for sharing your wall detailing. I just spoke to the BC person he says that if we can show him the calculation with 125mm cavity then it would be okay. Can you please advise which Website/Calculator you used and details of the Ytong blocks as these seems to have too many types. I can then run the calculations and send to BC.

The main reason for not using an AD was feedback from couple of friends who didn't had great experiences. The SE my builder had used in past turned out to be similar when i met him so decided to not use any. I needed flexibility as the internal layout and details have been changing few times as myself and family making our mind gradually. This wouldn't be possible with fixed fee professionals. The other reason was I felt confident to do it myself based on great support available online from a Forum like this. Will ever be grateful for all the Forum members sparing their time to help others.

Thanks all for your quick responses and suggestions. I have tried couple of proprietary U value calculators. Another middle option between 100mm and 150mm cavity could be 'Partial Fill Insulation'. As per Celotex Calculator, a combination of 100mm facing brick + 50mm air gap + 85mm CW4000 + 100mm light weight blocks with wet plaster gives U value of 0.18 as required. This option reduces the cavity to 135mm and the cost of 85mm CW4000 appears to be similar to 150mm DriTherm 32 insulation and much cheaper than Kingspan K106 or Celotex Thermaclass. The Calculator doesn't give me the option of reducing the airgap from 50mm to see if I can try other combinations of insulation thickness to reduce the overall cavity bit more. Also, the Lambda values for both Celotex CW series and GA series is showing same as 0.022 on their website. Would this mean that I can possibly use GA4090 instead and achieve the same U value. GA series is further cheaper as well but would require some extra cutting on site. Not sure if the partial fill cavity is a practical option though and if BC would agree to it. I might have to settle for Celotex Thermaclass 90mm with overall cavity of 100mm in the end. Looking forward to further suggestions and thoughts. Thanks.

Hi All We have just started our side and rear extension with foundations poured yesterday. The BC Person while approving foundation depths mentioned that if the external walls are going to be with 100mm cavity then Kingspan K106 90mm interlocking cavity wall insulation (or similar) with 10mm air gap has to be used. Or else the cavity needs to be increased to 150mm and then wool batts type insulation can be used. I checked with the Builder later and he says that it would be impractical to use rigid insulation with only 10mm gap considering the mortar dropping, wall ties etc. There are few 90 degree bends in the walls as well. He also mentioned that rigid wall insulation is very costly and it will cost me dear considering the total combined area of external walls is around 75 sqm. I am planning and designing the build myself and don't have an Architect or SE engaged. My layout plan is based on 300mm thick external walls with facing bricks + 100mm cavity+ concrete blocks. I would like to keep the cavity to 100mm as the layout design is tight in some areas and also to maximise my internal usable area. So even if I decide to pay a lot more for rigid insulation, it may still not deliver the required thermal performance in real life based on Builder's view on practicality. So wondering if there are other economic and practical options with 100mm cavity which I can take back to BC to consider. Any advice on this will be greatly appreciated.

Apologies it took long to respond and thanks for the wise advise above. The relationship has not been great with the neighbours so for our peace of mind we decided to use the the Party Wall Surveyor route. We didn't have a SE hired as well. Luckily the neighbour agreed for our surveyor for joint representation and it was in the end a smooth process. The Surveyor recommended hit and miss approach for laying foundation adjacent to the neighbour's garage in his party wall award. We are now looking forward to start the construction. Hopefully no more issues with neighbours at least.

Hi All A quick update. The planning decision was delayed but finally came through as approved with no objections or issues. There are few informatives including advice to follow party wall act. I did couple of holes to check the foundations. The garage wall foundation is roughly 300mm deep adjoining ground level and appears to be original from the time when the house would have been built. The foundation for the extension behind the garage is new and supports the twin wall single storey extension. I didn't check the full depth. I an now getting a structural designer visiting tomorrow to prepare foundation drawings. Will have no choice but to follow the party wall notice route even if it is going to be a lot of money spent for little use. Thanks.

Thanks for the very useful advice. I have looked at the old Google street views and the extension was done apparently around 11 years ago. It would still be covered by Building control though. I will dig holes at the weekend to check foundation details. The planning decision is due next week as well. Fingers crossed.

Thanks both for your responses. The planning seems to be less of a challenge as it is the same person who approved last planning 4 years ago with my walls shown right next to fence. They can either approve the application with advisories to comply with PWA or come back to me with some comments for amending the drawings. I can only wait until they come back and will let you know the outcome. The bigger challenge is that the neighbour would want to keep my new walls as far as away and I would like to do the opposite. We are not on talking terms and their recent behaviour has shown that they will go to maximum distance to get what they want. My frustration (should go away slowly) is that we both have identical properties and he has built more than even maximum without any consideration for their neighbour and now I may not be able to utilise my own land to my benefit. Have done some internet search today and have come to the same conclusion that I will need to go down the route of PWA surveyors with associated costs and delay to start. Trying to learn on the ropes of what is the implications of this route. The first questions for me are 1. How close the new wall can be without risking neighbour's foundations with all the precautions and pre+post condition surveys etc. For example, I can possibly get the joists to rest on other walls to reduce the foundation width and depth. 2. Do I have any obligations under PWA in planning my walls for the neighbour to maintain and repair their drainage in future. The answer to above two will help me understand the 'minimum' I have to give in which I can then offer to the neighbour as a start before engaging surveyors. Also, any views on surveyors will be appreciated. The internet search says that they should act impartial so, will they award the 'minimum' or close to it. Thanks again.

Hi Adsibob Thanks for a prompt response and advise. Ideally I would like to cover the whole area as I have no use of it at all and I do have 1 m wide side access on the other side. I will wait for the planning for department response as you have suggested. I might have to arrange party wall agreement anyway which they are not likely to agree. Any other advice on this challenge would be very much appreciated. Thanks.

Hi All I am looking forward to start a 3 sided 115m2 ground floor extension next month (STPP). Construction will be by a builder friend and project management by myself. Ground floor plans attached here to give you a flavour. The planning decision is due in couple of weeks. The next door neighbour has a mirrored property and has done the similar extension around 7 years ago (see the photos attached). They have objected to the plans on the basis that it will weaken their shallow garage foundations and roof, contravene party wall act (section 6), will restrict/prevent access to their guttering/roof etc., and couple of other minor points. We moved in the property in 2018 and applied a similar planning back in 2019 (kitchen was bit smaller and conservatory was staying) but the garage conversion was the same. That time, the neighbour only objected on the basis that natural light to their window would be blocked (as shown in photo). Their objection was rejected on that occasion as the window was not in a habitable room and planning was approved. However we didn't start the build straightaway and then COVID happened changing priorities. I am not sure what would be the planning department response to the objections this time. They may still approve it with some caveats and advisories or may ask to make some amendments. Will let you know when I have heard back from them. However I am more concerned around the neighbour. They have built their wall touching to the fence which has made part of their guttering actually overhanging on to our side. I would also like to do the same and build as close to the fence on my side but without any guttering as I can plan the roof to drain to the front or back. They are not going to like it and may create problems when the build starts. So trying to anticipate any legal or other challenges they might throw in to stall the build. Any advice on both the planning aspects and how to manage neighbour boundary issue would be much appreciated. I would like to do any homework as needed to prepare rather than just sitting tight until I hear back from Council. I would need plenty more advice when the build starts as this is a massive undertaking for me but let's get there first. Thanks in advance. Existing_Floor_Plan.pdf Proposed_Floor_Plan.pdf