marshian

@damspt That looks like a decent sized tank - has it got a declared capacity on the side label? I'm struggling to understand how 3 showers exhaust the HW - we can have up to 4 showers per day from a tank that is 115L and only heated once a day to ~50 deg C Have you got a HW circulation loop running? A loop that ensures HW is avaliable instantly at the taps without running lots of water first - they can be horribly parasitic in terms of depleting available HW if they aren't minimised to "TOU" (Time of use)

Unless you get TRV's on UFH I reckon the comment below confirms it's all rads

Or 1. heat the water to a higher temperature in the cheapest period 2. Change the tank for one with a larger capacity

Ignoring the unusual behaviour the boiler occasionally has........ I've done some changes to the system configuration it was covered elsewhere but I though it would be handy to document it here as well I've replaced all the Drayton EB4 TRV Bodies (6 position variable orifice) with Danfoss RAS-B2 TRV bodies - these are "Pressure Independant" flow regulators with flow rate settings of between 10 L/Hr and 135 L/Hr (max flow rate) The aim of the changes was to convert to fully open system and stop the Wiser TRV's from intervening on the 4 rads where I couldn't reduce the flow enough with the EB4 bodies (even on the smallest orifice setting) Once I've got stable room temps as a result of the correct flow rates for the WC flow temp the Wiser "Smart" TRV's are being removed and replaced with std Danfoss ones - Hopefully I can recover some on the cost with selling on a well known auction site. I also took the opportunity to re-configure the "Plant Room" (OK Airing Cupboard - picture below) 1. London loop on the HW outlet of the tank (early days but it already seems to have reduced standing tank losses) 2. Re-pipe the bypass so it's after the CH zone valve (it was before so when I restricted the flow thro the HW tank coil it opened the damn bypass and defeated my efforts to slow down the flow thro the coil!!!) 3. Combined 22mm Feed and vent for CH (removing the old 15mm feed) - it's solved all the issues with air ingress and got rid of another pipe in the cold loft 4. Generally remove a load of joints (from previous versions being adjusted) and clean up the lagging 5. Replaced a compression fitting with press fit that was used as an emergency fix years ago!! Outside the Plant room 1. Convert all the panel rads to TBOE from BBOE with Danfoss RAS-B2 flow control TRV bodies 2. Covert the vertical rads and towel rails to Danfoss RAS-B2 flow control TRV bodies and reconfigure the pipework

I have wiser too - the app is pretty good - the system is fairly reliable and if you just want the ability to remote switch on or off it's a pretty simple interface - Just one word of warning I went down the route of "smart" TRV's on every radiator - I'm now unwinding that and fitting "dumb" TRV's on every rad (battery life and simplification of the schedule now I'm running WC on the boiler are the main drivers for this - they are just "fancy room temp sensors" once you run a weather compensated flow temp.)

Why is your usage low between 10:00 and 3:30 are you running a set back temp during the day?

get some temp (and humidity) displays for the main rooms - they aren’t expensive and run on cell batteries that last a year

Isn't that what I said??

You don't need detailed apps - you just need to understand the process that is going on regarding your DHW and CH Example if it helps (Gas boiler) I heat my water every day at 6.00 am to 6.30 am - as a result of this I can download the half hourly energy data from Octopus and I know that the duration and energy cost of providing the house with DHW I'm running CH 23.5/7 (with DHWP "Domestic Hot Water Priority so for 30 mins my house doesn't get CH) with WC We still cook with gas but that's pretty much a constant and only amounts to 1% of our annual energy usage

WHS ^ After Council Tax the Central Heating "CH" and Domestic Hot Water "DHW" costs are the biggest expenditures in running a home (excluding food because it's based on household size) Minimising those costs can result in a decent annual saving. @damspt what room temps are you targeting - one of the benefits of a low temp heating regime (be that ASHP, GSHP or low temp gas boiler) is you can reduce room temps compared to traditional UK scheduled heating regime where you blast the house with heat during times of occupancy and then allow it to cool down outside those periods. I'm running Bathrooms at 20, Living spaces at 19 to 20, Bedrooms at 18 to 19.5 and all other areas 17 to 18. Moving from room to room you don't notice the small temp differences and the whole house feels "comfortable"

JFYI No DHW energy usage is included in “total kWh” per day in data above it’s not contributing to space heating so I remove it for HDD calcs - my target is 4.0 kWh per HDD - most of the time heating 24/7 I’m in the ball park (it does trip above when there are significant changes in OAT over a short period of time)

Base is 16.5 (once daily average temp falls below this heating is required - have a few years data that backs it up) Base temp was worked out using on-line regression tool with 2 years of daily heating data (with HW/cooking energy usage removed) it’s an 1980’s build that I’ve tried to bring kicking and screaming into a more insulated state - biggest issue is it’s shape - fundamentally it’s a T shape so a number of rooms have 3 external walls (north facing frontage being the worst areas for heat loss) I was planning on re-running the regression tool after this winter to see if the most recent improvements have made any difference (loft insulation increased to 300 mm from a depth of 75mm to 150 mm)

Exactly - My house heat loss is calculated to be 4.0 kWh at -2.4 Deg C OAT So if we have 24 hrs of -2.4 Deg C (or that as a average over the whole day) I can realistically expect to use 96 kWh for space heating plus another 5 kWh for HW requirements if I run the heating 24/7 Reality is those days are maybe just a handful of days a year rest of the winter time it's somewhere between 2 and 7 deg C

My overnight electricity usage is pretty much 0.3kWh as a background - it's just the day time increase isn't that large unless there is a reason - like laundry, dishwasher, oven etc

HDD data for my house by day Raw Data below - I scaled the total kWh per day by dividing by 6 (so 25% or the other two (HDD and kWh per HDD get lost at the bottom Either way weather gets colder energy usage goes up or house gets colder - choice we have to make in winter (or a choice we don't get to make) Date HDD kWh/HDD kWh Scaled Total kWh 07/11/2025 3.6 4.34 2.60 15.6 08/11/2025 4.6 3.30 2.53 15.2 09/11/2025 6.9 3.77 4.34 26.0 10/11/2025 5.0 4.43 3.69 22.2 11/11/2025 5.3 6.60 5.83 35.0 12/11/2025 2.8 5.21 2.43 14.6 13/11/2025 3.9 2.02 1.31 7.9 14/11/2025 5.8 1.94 1.87 11.2 15/11/2025 6.7 4.33 4.84 29.0 16/11/2025 8.4 4.50 6.30 37.8 17/11/2025 11.4 4.19 7.95 47.7 18/11/2025 13.1 3.99 8.72 52.3 19/11/2025 12.4 5.17 10.68 64.1 20/11/2025 15.2 4.61 11.68 70.1 21/11/2025 14.0 4.94 11.53 69.2

same here from average of 25 kWh per day to over 70

Blimey - we've never hit that sort of base line on Electric - 3 loads of washing, some with tumble drier (some with dehumidifier) and a load thro the dishwasher and we peak at 16 kWh in a day Average daily for the year is 9.5 kWh but typical base number is around 7 to 8 kWh and I regard that as above average

I do - how on earth can you know if improvements are actually improvements otherwise 😉 Octopus makes life easy from that perspective you can export by 30 min intervals your energy consumption - Add in HDD data and you have an instant bench mark for what ever set up you have

Exactly this ^ Doesn't mater what heat source you are using the colder it is the more energy you will use to keep the house at a constant temp Just over a week ago I was using 15kWh a day on "Space Heating" (OAT was Min 11.3 and Max 15.8) Yesterday I used 70 kWh on "Space Heating" (OAT was Min -2.1 and Max 3.2) Average for November will end up at ~30 kWh I see no point panicking about costs during a cold snap it's just part of the UK weather patterns

Being "super efficient but cold" or being "slightly less efficient and warm"? Me I'll take the cooler option but Mrs Alien would rapidly be Mrs Ex-Alien (Divorces are a lot more expensive than energy) so I compromise and take the slightly less efficient option

On a system with 19 rads that's a good way to get very bored Provided you are on a water meter - Easier way to get system volume is to empty the system with a full drain down - then when refilling read the water meter before and after to get system volume (best done when no-one else is at home so they don't flush a toilet or run a bloody bath!!!) and either make a small allowance for air trapped in system or allow yourself time to bleed out the air before reading the meter In reality most of the inhibitors are supplied in a container with a recommended dose for 100 Litres so if system volume is significantly above 100 Litres add 2 bottles My system is 151 litres so I add 2 bottles

cost of a power flush buys a lot of gas at 6p per kWh - if a power flush us lets say £500 you’d be better of using it to purchase 8500 kWh of gas - that’ll more than cover most of the winter needs.

OK Allen Key in the centre - anticlockwise to open more clockwise to close would be my guess

You don't need to understand WC - It's really not hard Houses lose heat As the OAT drops the house heat loss increases You need to put in more heat to maintain the house temp WC just changes the flow temp with ref to the OAT to compensate for the losses based on OAT Get your curve right and there is no change to the internal temp regardless of the OAT Bingo house internal temps don't change because boiler / ASHP flow temps do

Did it get warm previously? If you haven't fiddled with it since last time it worked why do you think is suddenly become shut It's more likely your issues are with other rads stealing the heat before the flow gets to this rad - decorated any rooms recently?