Paene Finitur Posted October 16, 2023 Share Posted October 16, 2023 Hi, after moving into our new house last winter and experiencing horrendous heating bills for the first few months, I'm looking at ways to keep the bills down this winter. We have a 16KW Nibe ASHP with UFH in the basements and ground and rads on the 1st/2nd floors. The usage was coming in at around 650KWh per week over last Christmas/new year period. Partly this turned out to be a fault with a hot water tank thermostat that was causing the immersion to kick in, but even when this was resolved the costs were still very high. Since about March, I've had the room thermostats set down to frost override to keep the bills down. I'm currently with Octopus and we're on the Flexible Octopus tariff which is 35.37p per kWh during the day for electricity and 14.84p per kWh at night (2am to 6am I believe) This doesn't seem great for a ASHP really since the accepted way of using them is to have them running all the time, so I get precious little benefit from the night rate. I recently found out about the Octopus Cozy tariff, which seems to have been designed with ASHPs in mind. Despite Octopus telling me that I was already on the best tariff available, I did some basic calculations downloading my usage and applying the rates from both tariffs. It looked to me as if it would be from 10% to 21% cheaper than the Flexible tariff. Has anyone else any experience with this or other ASHP friendly tariffs? Link to comment Share on other sites More sharing options...
Conor Posted October 16, 2023 Share Posted October 16, 2023 (edited) Are you able to just run the ashp on the low rate only? We're on economy 7 and do exactly that, 90% of the time. During a real cold snap we'll run it 24x7 on the days required. If your heat losses are high (sounds like a a big house) then you would be better off running 24x7 on weather comp, low flow temp and a the cheapest standard tariff that doesn't penalise you for daytime use. Edited October 16, 2023 by Conor 1 Link to comment Share on other sites More sharing options...
dpmiller Posted October 16, 2023 Share Posted October 16, 2023 can you program a slightly higher flow and room temp during the E7 period, to charge the house up? Whilst there's a small efficiency loss running during the lowest ambient temps of the early morning you're still going to gain over running at the day rate. That's what we're doing, and solar gain reduces daytime losses so there's actually very little heating needed during the day and evening 2 Link to comment Share on other sites More sharing options...
Conor Posted October 16, 2023 Share Posted October 16, 2023 (edited) Actually, looking at the cosy, if you just set your ashp to avoid the evening peak, looks like a winner, esp as it sounds like, you run your ashp near continuously. Set your timers, weather comp and stats accordingly. Edited October 16, 2023 by Conor 1 Link to comment Share on other sites More sharing options...
Pocster Posted October 16, 2023 Share Posted October 16, 2023 Just swapped to cosy . Do have ASHP but also batteries - so no need to modulate my ASHP with off peak times 1 Link to comment Share on other sites More sharing options...
Paene Finitur Posted October 16, 2023 Author Share Posted October 16, 2023 Thanks for the responses guys. Yes, I was going to enquire with Nu-Heat, who deigned/supplied the system, whether it would be possible to centrally adjust the system to go to low power during the peak period or something like that. I have Heat Miser controls in each of the rooms, but was advised to switch off the timer part and just set to a constant temperature. 24x7 steady running was the message that was drilled home to me when it was installed. Easy to advise when you don't have to pay the bills! 🙂 I'll take a look at setting the timers - would like to do that centrally of course, but can't figure out how to link them to WiFi. A project for another time I think - bills down first! More broadly, I've got to admit that having installed a big (and quite expensive) ASHP/UFH system, I'm afraid I still feel quite naive when it comes to getting the best out of it. Are there any guides out there for novices to all ASHP concepts (i.e. COP, flow, weather comp) that might help me get more au-fait and manage it better myself? Link to comment Share on other sites More sharing options...
Paene Finitur Posted October 16, 2023 Author Share Posted October 16, 2023 12 minutes ago, Pocster said: Just swapped to cosy . Do have ASHP but also batteries - so no need to modulate my ASHP with off peak times I wish I had gone with batteries. Co-incidentally, I have basement sump pumps that are backed up with a decent but sump-pump specific, battery back up system. I was so focused on ensuring the basement didn't flood and focusing on the design of the water management for the basement that I didn't see the bigger picture of using a similar battery bank centrally to cover the sump pumps but also even out the peak periods. What a chump!! Well, you live and learn. Did you go with a specific battery system? At some point, when the sump batteries wear out, I'm considering changing to a central system, but that's further down the line. Link to comment Share on other sites More sharing options...
JohnMo Posted October 16, 2023 Share Posted October 16, 2023 (edited) First thing to do, is check to see if the different thermostats are switching the heating zone on/off during the day or night. Systematically go around each area and note down if none, some or all are switching on/off. Do this when it's different temperatures outside, this will also tell you if your WC curve is correct. Write it all down so you make sense of it later. Installers will set everything too high and let your thermostats sort it it out, great for a gas boiler, but rubbish for a heat pump. The switching on/off would indicate the flow temp is too high, lowering flow temp has a big impact on running cost. Second, you need to have a small setback overnight, about 2 degrees. This will again save you money. The timing for the radiators will be easy enough, about an hour before you go to bed and a hour before you get up. The underfloor heating, will have an offset, due to the storage heater effect, so that maybe turned down and started up 4 to 6 hours offset from your radiators. Analysis first - adjust second Edited October 16, 2023 by JohnMo 1 Link to comment Share on other sites More sharing options...
joth Posted October 16, 2023 Share Posted October 16, 2023 2 hours ago, Paene Finitur said: The usage was coming in at around 650KWh per week over last Christmas/new year period. Just for context, I live in a 160m2 4 bed 1960s house that used 850kWh on heating over the entire last year. (20°C internal temperature, deep renovation to PH standard). About 45kWh per week in December & January ISTM swapping to a cheaper rate or using batteries really is just pissing in the wind, your issue is the house is wildly underperforming at keeping heat in. 1 Link to comment Share on other sites More sharing options...
Pocster Posted October 16, 2023 Share Posted October 16, 2023 22 minutes ago, Paene Finitur said: I wish I had gone with batteries. Co-incidentally, I have basement sump pumps that are backed up with a decent but sump-pump specific, battery back up system. I was so focused on ensuring the basement didn't flood and focusing on the design of the water management for the basement that I didn't see the bigger picture of using a similar battery bank centrally to cover the sump pumps but also even out the peak periods. What a chump!! Well, you live and learn. Did you go with a specific battery system? At some point, when the sump batteries wear out, I'm considering changing to a central system, but that's further down the line. I’m basement also lol i have PowerWall and SolarEdge . yep effectively act as a ups to the sump 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted October 16, 2023 Share Posted October 16, 2023 9 hours ago, Paene Finitur said: We have a 16KW Nibe ASHP with UFH in the basements and ground and rads on the 1st/2nd floors Generally, you have two different flow temperatures, one for UFH and the other for radiators. Chances are your UFH is running too warm, and with probably only building reg minimum insulation under it, you are keeping the worms cosy. Then you have the flow temperature for the DHW, usually at the higher end of a heat pumps delivery, around 55⁰C. Do you know any of these flow tempers? Link to comment Share on other sites More sharing options...
ReedRichards Posted October 16, 2023 Share Posted October 16, 2023 More context, I live in a timber frame bungalow built in 1980, about 195 m2, (based on the external dimensions). My heat pump used about 6500 kWh last year for heating and hot water. It's never turned off so the heating will come on on a cold day in summer, but I use Weather Compensation so it does not have to work very hard then. Link to comment Share on other sites More sharing options...
Paene Finitur Posted October 16, 2023 Author Share Posted October 16, 2023 12 hours ago, joth said: Just for context, I live in a 160m2 4 bed 1960s house that used 850kWh on heating over the entire last year. (20°C internal temperature, deep renovation to PH standard). About 45kWh per week in December & January ISTM swapping to a cheaper rate or using batteries really is just pissing in the wind, your issue is the house is wildly underperforming at keeping heat in. Hmm, I kind of agree with you there. There's still too many places where we don't yet have curtains up to keep some of the heat in. But that can't be the full story. During the period over the summer this year, our consumption according to Octopus has never really gone below 150kWh per week. That's at a time when all the stats were switched to freeze protection i.e. the heating was effectively off. It seems that the ASHP is the culprit but I'm at a loss to know how it's taking up so much power for effectively just heating the hot water. Link to comment Share on other sites More sharing options...
SteamyTea Posted October 17, 2023 Share Posted October 17, 2023 6 hours ago, Paene Finitur said: I'm at a loss to know how it's taking up so much power for effectively just heating the hot water. How much hot water do you use? Have you measured it? Link to comment Share on other sites More sharing options...
JohnMo Posted October 17, 2023 Share Posted October 17, 2023 8 hours ago, Paene Finitur said: Hmm, I kind of agree with you there. There's still too many places where we don't yet have curtains up to keep some of the heat in. But that can't be the full story. During the period over the summer this year, our consumption according to Octopus has never really gone below 150kWh per week. That's at a time when all the stats were switched to freeze protection i.e. the heating was effectively off. It seems that the ASHP is the culprit but I'm at a loss to know how it's taking up so much power for effectively just heating the hot water. @joth was quoting for heating only, you need to compare apples with apples. I take it you're is total electric usage. Your 151kWh in summer is your house usage and DHW which is 21kWh per day, which is high. But is high normal(ish) house. Our average electric last your without a heat pump was 13kWh. Have since been around the house understood where the energy was going and fix it, that what you need to do also. Link to comment Share on other sites More sharing options...
Conor Posted October 17, 2023 Share Posted October 17, 2023 What other electrical appliances do you have that could maybe be faulty and consuming large amounts of electric? Tho with that consumption there would be a lot of waste heat generated and fairly noticeable in the summer. You could completely isolate your ashp and DHWC for 24hrs and monitor the house consumption. Link to comment Share on other sites More sharing options...
ReedRichards Posted October 17, 2023 Share Posted October 17, 2023 Do you have any of: Swimming pool? Hot tub? Electric Aga? I would have thought that just using an immersion heater you would be hard-pressed to use 150 kWh per week heating your hot water. If you were heating water from 10 C to 60 C using an immersion heater you would be using over 2500 l of hot water per week to consume 150 kWh. That's possible but your household would need to be taking several baths per day, in which case you would have had a big fuel bill in your previous property however it was heated. Link to comment Share on other sites More sharing options...
joth Posted October 17, 2023 Share Posted October 17, 2023 If you have the indoor display unit, you can look at the live power draw on it, and slowly turn all the circuits off in the consumer unit one by one noting how much the power draw drops by when each is isolated. Probably you'll find some background power hog on a ring main so repeat the process turning off each device on that ring one by one. If it's a lively house with lots of people and change expected, investing in a multi circuit monitor maybe we'll worth it. E.g. https://www.amazon.co.uk/3-Phase-Emporia-Electricity-Metering-Conserve/dp/B08CJ3VC79/ Even so, we're talking about the 150kWh summer base load, that 500kWh heating load in winter far outweighs it. Link to comment Share on other sites More sharing options...
JohnMo Posted October 17, 2023 Share Posted October 17, 2023 You will be amazed at standby losses add up. Our TV, set top box when in standby mode are using 17W, so multiply by 24hrs and 7 days, gets you to 3kWh. If you have the same in a 3 bedrooms and the lounge, that 12kWh just on that. If your DHW isn't set correctly your immersion could be kicking on for an hour a day, that another 21kWh for the week etc..1 Link to comment Share on other sites More sharing options...
Ferdinand Posted October 17, 2023 Share Posted October 17, 2023 19 hours ago, Paene Finitur said: Hmm, I kind of agree with you there. There's still too many places where we don't yet have curtains up to keep some of the heat in. But that can't be the full story. During the period over the summer this year, our consumption according to Octopus has never really gone below 150kWh per week. That's at a time when all the stats were switched to freeze protection i.e. the heating was effectively off. It seems that the ASHP is the culprit but I'm at a loss to know how it's taking up so much power for effectively just heating the hot water. We could have some fun with these. This is mine for the same period. Single occupancy in a 205sqm house. My heating is gas, but I hardly used any in the period, and I use a heat pump for cooling. Solar generating about 5MWh per annum, exporting about 3MWh. What do you think happened 5-11th June? And the air fryer arrived 4 weeks ago... Link to comment Share on other sites More sharing options...
Paene Finitur Posted October 21, 2023 Author Share Posted October 21, 2023 Thanks for all the amazing feedback. To answer some of the points: @SteamyTea I'm not sure that I can separate out the heating from the hot water in terms of energy use. There's a separate meter for the ASHP and one from the immersion for the header tank. We had a big spike last Christmas because the thermostat for the header tank got slightly dislodged resulting in the ASHP having to work much harder and the immersion kicking in to make up. Thankfully, that got solved. @JohnMo Yeah fair point, and you're absolutely right; when I was checking last winter, the non-heating/HW electric usage was around 22KWh/day so probably mainly not the ASHP over summer. @Conor I suspect that was mostly washing machine, and also the tumble drier, which Mrs Paene Finitur insists on using. There are 6/7 of us living here though, with two of us working from home regularly so I suspect it's probably not that unreasonable, though I will look at the stand-by issue. Thinking of getting this or something like it round the back of the TV. @ReedRichards I don't have a swimming pool, hot tub or electric Aga. We have a dual rangemaster and the oven will take a chunk but is infrequently used. I guess it's the washing and drying that will take up most of it. @joth I wish I'd known about this last year when they were setting the electrics up. I have 25 MCBs on my board so slightly too many and now the trunking is in, it might make it a bit difficult but what a great device! @Ferdinand I'm guessing you had visitors in June? 😁 Link to comment Share on other sites More sharing options...
ReedRichards Posted October 22, 2023 Share Posted October 22, 2023 This device lets you monitor the energy used by any appliance and can also be used as an on/off timer https://www.amazon.co.uk/dp/B0B831STBX?ref=ppx_yo2ov_dt_b_product_details&th=1 (the pack of 2 is currently priced as only £1 more than the single). 1 Link to comment Share on other sites More sharing options...
Ferdinand Posted October 22, 2023 Share Posted October 22, 2023 16 hours ago, Paene Finitur said: Thanks for all the amazing feedback. To answer some of the points: @Ferdinand I'm guessing you had visitors in June? 😁 Actually no - I had 3 weeks in hospital which started very suddenly around 19 May - straight from the GP so no time to turn anything off. For some reason my Smart Dehumidifier went beserk at the start of week 3 and stayed on until I got home. Why? I know nothing. Link to comment Share on other sites More sharing options...
Paene Finitur Posted October 22, 2023 Author Share Posted October 22, 2023 15 minutes ago, Ferdinand said: Actually no - I had 3 weeks in hospital which started very suddenly around 19 May - straight from the GP so no time to turn anything off. For some reason my Smart Dehumidifier went beserk at the start of week 3 and stayed on until I got home. Ouch!! Hope you're better now. Certainly not what you want to come home to. I suppose at least you weren't bothered by humidity on you return. My de-humidifier has recently taken to tripping the MCB, which saves me quite a bit! 😁 Link to comment Share on other sites More sharing options...
Square Feet Posted October 22, 2023 Share Posted October 22, 2023 Maybe your neighbour has tapped into your leccy for their weed farm..... 😉 1 1 Link to comment Share on other sites More sharing options...
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