richard_scotland

If its fixed then the flow temperature probably too low to keep your house wam for when its cold as it has been this last week - much better (and cheaper) to have it change flow temperature with the weather. This is something easy to set up yourself using the Daikin menu. I can look later at how you do this. We went to town with large radiators (quite a few K3), but we still needed 43 flow temperature this past week, you might need higher still if your radiators are fairly normal sized. Our design temperature was 55 degree flow at -3 outside (do you have this information anywhere?), but in practice we can run it cooler than that and be fine. This suggests to me that the unit is probably powerful enough. As I said ours is 12 kw and is not operating at max output and keeping our 200m2 single story cottage, half of which has no insulation on the walls, to 20deg. Our unit is mostly very quiet and never makes a noise like you describe, so I wonder if something is not correct here. Also, ours does occasionally 'whoosh' as part of a defrost cycle, but we never have to top up pressure and bleed radiators after this - the fact you have to top up the pressure frequently also suggests something is not quite correct with the pipework or system. when its not heating and its below a certain temperature outside ours does cycle the water in the system every 20 mins or so to prevent freezing - does yours do this? 100kw a day also suggests it is using the backup heater a lot. our 12 kw unit has only been using 55-60kwh a day (it sometimes uses the backup heater for a few minutes at the start of a cycle but they soon switch off). When its milder we are using 20-30kwh a day. I would persist in trying to get the installer back to look at the system as it doesn't sound like its working as it should do.

Hi Tog I have the same model of heatpump and it is working OK to heat our 200m2 house (a not particularly well insulated old cottage) to 20 deg, and is using about 55 kwh a day at the moment to do that (producing 160 kwh of heat). We also upgraded our radiators and pipework. 1. what size in kw is your heat pump? we have the 12kw model which seems to be plenty big enough for us and works out at 60W per sq m 2. does it usually reach the 39 degree set point when its not so cold? 3. Our flow temperature is 43-44 degrees at the moment (-5 this morning), so I suspect 39 would be too low anyway at these temperatures, unless your house is very well insulated. Can you try turning the flow temperature up and see if the room temperatures improve? are the radiators warm at all to the touch? are you running weather compensation (flow temperatures vary with outside temperatures) or fixed? 4. we run our system with only a 1 degree setback at night - if yours is set to turn off overnight it might be that room temperatures have dropped too low and its struggling warm things up? You could use the Daikin menu system to go to Information>Sensors On ours this shows you more information about the actual flow temperature and also the flow rate etc which may be helpful. I think there is also a malfunction log in that menu which might be worth a look at.

thanks. Would the internal part of the gable wall in the loft count as a thermal bridge, if we didn't do IWI? in which case might it be worth putting a little bit of insulation up on the wall in the loft?

bumping in case anyone has ideas on whether it would be worth doing IWI to help with the thermal bridge at the corner, or even if I just did a small section of the wall in IWI (we would like to put a fitted wardrobe here)

Thanks. There is a junction where the cavity wall meets the old sandstone corner of the house. Would IWI be worth doing to help with this thermal bridge and potential cold corner? Or something else?

My only concern about beads is that the cable for the car charger crosses the cavity - its an outside rated cable so perhaps thats provides more protection from plasticiser migration? if not, I could try and wrap it with some sort of barrier tape (foil tape?) where it crosses the cavity.

Thanks, that makes sense. I guess the next question is, if I also add IWI (as the room is having work done anyway for the wetroom), how much should I add? EWI might be trick as there are no overhanging eaves

Hi BuildHub, I've gained a lot of knowledge reading this forum but I have a question about how best to proceed with an upcoming installation of a wetroom into an existing bedroom - whether to add IWI to a partially filled cavity wall, or fully fill the cavity wall Current build early-2000s pitched roof single story extension wrapped around the end of 19th century sandstone single story cottage 3 bedrooms with external partial fill cavity walls external wall length (area in brackets) bedroom 1 - 10 m (2 windows) (23 m2) bedroom 2 - 5.4 m (1 window) (12.4 m2) bedroom 3 - 3.5 m (1 window) (8 m2) current u-value estimated at 0.54 wall construction (from some old plans we found) is plasterboard, 25 mm cavity, 100 mm concrete blocks, 35 mm insulation board (from what i can see looks like PIR), 50 mm cavity, 100 mm concrete block + cement render. We need to subdivide bedroom 1 to create a disabled access wetroom for one of our children (so there will be a fair amount of disruption to this room regardless). Given this work is taking place anyway, I am contemplating whether now is the point to add internal wall insulation. We are rural and near the fife coast fully exposed to the north sea on the east (just open fields between us and the sea), but somewhat sheltered to the west by trees. These rooms are on the west and north side of the house. Overall its a windy location, but not especially cold (-5 is the coldest we have had) These are the options I can think of, would be great to hear the collective wisdom from the forum members. Loft is already topped up to 300 mm. 1. Fully fill the cavity wall e.g. with EPS beads (all 3 rooms) pros -less disruption (and cost?) - more of the house improved at an earlier point cons - u-value still not great - worry about creating damp issues where none exist? - will I be able to find an installed happy to install a partial fill wall? 2. Internal insulation wood board 60 mm (just room 1 initially) an architect involved at an earlier stage proposed this option (to help with managing moisture + thermal mass perhaps) but I am not sure what the benefit is of this approach on what is essentially a modern concrete wall? Seems a lot of disruption for modest improvement in u-value? 3. Internal insulation PIR board (just room 1 initially) - loss of thermal mass? Options 2 and 3 would only be in room 1 initially. We would hope to also do room 2 and 3 at some point but we have 3 small kids so its possible it may not happen for a few years... and it will involve loss of space in what are already quite modest rooms. Any thoughts welcome thanks