severnside

@Gooman Yes, the ducted unit shown suspended from ceiling is the new unit. Original ducting in this image is covered in black insulation. You can see the second picture with original J&S Aquair unit to show original ducting. I believe the unit should be mounted horizontally for condensate tray to work properly. If used only for heating then that will not be an issue. The installer suspended it from ceiling to reduce vibration noise, i did ask him to install on existing base used for J&S unit

I can see lot of activity in other threads about adding cooling options to ASHP. I will update my experience based on recent heatwave to provide reference for anyone visiting this thread Positives + Cooling worked really well and system was working at half capacity most of the time. System maintained temperature around 23C + We only ran cooling during solar generation, so no additional cost of running. We averaged about 12-15kWh usage (guesstimate) + Not much noise from ducts or external units Negatives - Warm Air heating Ducts are designed for heating so downstairs gets more air than upstairs. Cooling needs opposit of that, so upstairs wasn't as cool as downstairs - System was modulating to lower capacity with auto mode even though set temperature wasn't reached. I could override it by chaning fan speed - Need to ask everyone to close windows in summer while AC is running

I can share some details on our install. Air to air ducted unit was installed yesterday. There was very little disruption in the house as Air handling unit was in Garage it was replaced by Ducted unit and old oil tank replaced by external unit. It was 25C yesterday so we tested cooling mode which worked really well. It was modulating reasonably well and consuming about 1.4kw during cooling. At full speed the unit is quite than previous Johnson Starley unit it replaced. Internal controller uses 2 wires (used old thermostat cables) and give access to lot of functionality. There is option to add fresh air to system with one duct connected to outside fresh air and controlled via manual damper

I compared the air flow rates. My current Aquair S20's flow rate is 20m3/min. I never feel or hear the air noise. I have put my feet on ducts to feel it's working but it maintains the temperature. The Ducted AC units airflow rates are from 22m3/min to 48 m3/min. So I believe it should be OK. I discussed condensation risk with the Engineer. He mentioned that all the ducting is metal ducting and wrapped in insulation so risk of condensation is low. Also we won't be running air temperature too low even for cooling. Not many companies were interested to do retrofit so we are doing it on risk. If it works then it will be cheaper than UFH install cost itself.

I can provide some update here. We discussed our situation with a commercial AC company. They have looked at ducting and it's insulation condition. They think a ducted AC unit can work in our situation. We are going to get it installed next month and see how well it performs. We are getting this unit to replace Johnson & Starley Aquair (with Grant Oil Boiler) https://www.orionairsales.co.uk/mitsubishi-heavy-industries-air-conditioning-fdum140vh-ducted-ceiling-concealed-14kw48000btu-r32-a-15031-p.asp AC Company will make some custom Plenum to connect to existing Warm Air ducting. This will also provide option to add some fresh air.

Just checked Valiant 15kW spec. - MAx current 25A - At -5C output is 12.65kW ScoP 3.28 They have a temperature table at Page 28 of brochure which has min temperature to achieve heating in 99% cases. Lowest figure is -3.9 for Glasgow https://www.vaillant.co.uk/downloads/product-brochures/arotherm-brochure-2006193.pdf So if my house can manage with 12.65kW constant input then it should be enough Another question to everyone. Most of our calculations use temperature delta as Indoor Temp - Min Outdoor temp. But the heat degree days concept generally calculates heating below (indoor temp - approx 3.5C). Which is correct method of delta calculations

Our last years Oil consumption for heating was approx 2600litres. DHW is heated with overnight electricity. The house will be extended further but we will also improve on insulation, so need to do final calculations. Back of envelope calculations suggest 10-12kW ASHP. I was thinking 16kW with margin. 16kW ASHP should use 5kW or 22Amps which should be doable on Single Phase

Thanks Marvin, Makes sense to plan for lower than my original -3C. Another questions/input on Science bit of design - At what size does it make sense to have multiple units instead of one large. e.g. is it better to get 2x 8kW for a single phase house than 1x 16kW

Yes, I am using that but we are also doing some extention and improvements so need to do some paper analysis as well. I looked at Met office data near Bristol and minimum is -4C. Also I assume minimum is just for few hours in day not -4C for whole day so average for day should be higher.

Hi All, As mentioned in my previous posts, we are renovating a 70s house and at some point would like to add ASHP. I have read lot of posts on ASHP here and most of the response fall in these camps - House need to be super insulated for ASHP - A correctly specified ASHP will work in any building - ASHP calculations need special considerations and lifestyle factors and it's easy to get wrong system (This is what worries me and most of people I speak to) I want to start this thread to list the key points needed to specifying ASHP for any building. I strongly believe it should be couple for formulas which can be added in a successful repeatable process I would like to hear and compile everyone's opinion on this Science: 1. Do proper heat calculation of building e.g. using MCS calculator, Jeremy's sheet, PHPP. Specify heatpump for worst case temperature for the area (e.g. -3C) with 10-20% margin for DHW 2. Specify emitters based on low Delta T of Heat pump 3. Specify pipe size for low temperature (15mm to radiator seems to be common for most cases) 4. Bigger Hot water tank than heated by fossil fuel 5. Location of ASHP and size/insulation of flow/return pipe 6. Noise vs proximity of neighbours, bedrooms etc Art 1. Noise, placement, concealing of ASHP unit 2. Mono vs split? Thanks

myenergi Eddie comes with a relay extention module. You can configure relay outputs based on certain conditions e.g. Turn on relay 1 when solar output is more than 4kW. Also do it for a minimum of x mins and don't start again for y mins (for proper cycling) https://myenergi.com/product/eddi-relay-sensor-board/

If you want a good reliable solution without much admin/config needed then current consumer grade mesh solutions are very good. I use 3 Google wifi mesh devices. These are very easy to manage. You get best results if you can hardwire them but even without that they setup a wireless backhaul channel and work reliably. Also these are not very big so can be put anywhere in a room. I personally find ceiling mounted APs a bit office like.

Generally car charging standard need minimum 1.2kW to work. Zappi charger we have will keep charging paused until it has 1.2kW surplus. Under that it goes into hot water via tank.

Eddie Diverter with relay module provide quite sophisticated control. You can set a threshold for triggering relay. e.g. when excess power is more than 4kWh then trigger relay which starts ASHP. Also you can set minimum time to run as gap between mutliple starts. Also it's wiring support ASHP based immersion control. Check Eddie's manual for examples.

https://www.silicondust.com/dvr-service/?_ga=2.173193187.1177182614.1562599479-1613197336.1562599479#devices This lists devices compatible with Silicondust IP tuners. AppleTV or a cheap Amazon FireTV stick will work. They also have a table showing free and premium app difference. You get 24hr EPG free Amazon were planning to launch a similar device but no news for UK yet

DHW can be solved separately with ASHP integrated Water Cylinders like Dimplex Edel or Ecocent. We are also doing renovation and I quite like the idea of A2A heatpump but first level discussion with installer suggest 3-4 external units (It's a 5 Bed House, 9 rooms). Also Tiles without UFH will not be comfortable

@Hanksy This is interesting information, I was looking into this as well to convert whole house to A2A from Oil boiler. Could you help me with following questions 1. Does having multiple outdoor units affect startup current requirement e.g. too much load when all start at same time. Did it need planning permission? 2. How is the response time of heating? Does it heat up quickly in 1-2 hours if you leave it off for a day or two. 3. Is it noisy for bedrooms? Do you have extra pump or is it gravity drained, I have heard pumps are noisy. 4. How much did it cost, was it comparable to A2W or much cheaper? Thanks,

A little update on this, we requested quote from an AC company. The company owner surveyed the house and he mentioned that exisiting warm air ducting can't be used for few reasons - It will be smaller size for A2A heatpump because current Air handling unit uses higher temperature but A2A will need higher flow rate for low rate - It's old and not very insulated - Condensation will be a problem if used for cooling with current ducting He has proposed multi split system with indoor unit in each room, waiting for quote to see if it would be cheaper than ASHP + UFH solution. It will be a brand new heating system for us so we can choose between - ASHP + UFH Downstairs and radiators upstairs + UVC - A2A Heat Pump with indoor units on walls and UVC with ASHP builtin

@Gone West thanks for GBF reference. I read Owlman's posts and he seem to use a ducted AC system in part of house. He also has other heating mechanism in the house. If we go to AC direction then it will be our only heating option. We can do ducted atleast in part of house, but we are concerned about not being able to control individual rooms and temperatures

It's a 70s house which we renovate to good standard, so I assume it will be far from PH standard. But we can size the unit correctly. @ProDaveEpc is for for future readiness incase Govt change rules, it will be our long term home. We can't extend the ducting so we're thinking of removing it and replacing it with multi split style(duct less) system. Since there will be rewire and other disruptive work as well we can install indoor units and pipework etc.

Hi All As mentioned in couple of previous posts, we are renovating a house with Warm Air heating. We are happy with the system but it will not work after renovation (not possible to extend the system). Since we will update the whole system, one of the alternative is to use AC for heating and cooling. DHW can done by solar, E7. One of the issues we noticed was that EPC system is very limited. Our current Warm Air system has a new oil boiler with 90%+ Efficiency but EPC person couldn't find what to enter in system and entered lowest rating for heating. Few questions: Will we end up with similar issue if we use AC for whole house heating because it's not common in domestic market? Also since Air to air heating should use lower temperature than air->water->air so CoP should be better. Can anyone confirm this. Is anyone using AC for whole house heating, if yes what's your experience? Thanks

Thanks for all the comments. We will use plywood in place of chipboard to strengthenn the joists. I checked joist span tables and it seems with 100mm joists they are within safe limits and also deflection calculation show suitable for porcelain tiles. It could be a generic comment from SE without looking at finer details. I will have another discussion with him.

So far I have opened only one room and found sleeper wall at 1.2m distance. So joist span looks safe. However both Architecture technician and SE made comment solely based on joist thickness (100mm). Our intention is to check if someone has resolved this problem in real life and what are their results. Some of tiler forums suggest overboarding and noggings to fix these issues.