Adsibob Posted August 17, 2022 Share Posted August 17, 2022 So last couple of months we've averaged 11kWh of Gas per day and 10kWh of electricity per day. Somewhat disappointed that this is that high given that our only gas usage would be for our system boiler to heat our 300L hot water tank to about 56C and every single lightbulb in the house is a low energy LED (bar one actually, in the kids bathroom - which is a halogen). I haven't insulated the tank yet, so will do that this month, but I've at least insulated the pipes. Electricity seems high, though I do work from home and we do a lot of laundry as we have two young kids and we watch a lot of TV. How's your energy usage at the moment? Particularly interested to hear from those who also have a gas heated hot water tank. I've now turned the thermostat on the tank down to about 53C to see what difference this makes. It's difficult to know the exact temp it's set to as the analogue dial shows 45C and 65C and then two equally spaced increments in between which should be equivalent to 51.67 and 58.33. Link to comment Share on other sites More sharing options...
SteamyTea Posted August 17, 2022 Share Posted August 17, 2022 Mine is around 3 kWh/day, but I am all electric, so easy to monitor. Two things though. How much DHW do you actually use, you may find a minute les in the show helps more. Turning down the boiler flow temperature may affect the condensing efficiency of the boiler, that would need more investogation. 1 Link to comment Share on other sites More sharing options...
Adsibob Posted August 17, 2022 Author Share Posted August 17, 2022 4 minutes ago, SteamyTea said: How much DHW do you actually use, you may find a minute les in the show helps more. I think the problem is that the kids have a bath almost everyday, but not everyday. I have a bath maybe once or twice a week. Otherwise it's all shower use. I originally wanted a mixergy tank as that makes understanding how much hot water there is left much easier. At the mo, we're just estimating and probably activating the boiler unnecessarily to produce more hot water than we actually need on the days we have baths, to avoid running out mid bath just in case. 4 minutes ago, SteamyTea said: Turning down the boiler flow temperature may affect the condensing efficiency of the boiler, that would need more investogation. Plumber told me the boiler had to output heat at 65C and that I shouldn't change this. Something to do with the low loss header and overall system working best at this temp. But then he also told me "why don't you just leave the boiler on all the time, and let the thermostat on the tank regulate things for you"! I thought this was crazy, so just have the boiler coming on for 35 minutes in the morning and 45 minutes in the evening. Link to comment Share on other sites More sharing options...
Radian Posted August 17, 2022 Share Posted August 17, 2022 26 minutes ago, Adsibob said: I've now turned the thermostat on the tank down to about 53C to see what difference this makes. That should be OK but be warned that turning down the boiler flow temp might end up with it not being able to meet the demand and staying on unnecessarily. We're a family of three spread over 280m2 using around 15kWh of leccy a day, and the same again for gas. That's a condensing system boiler with flow temp set to 63oC and a vented HW tank set to 55.0oC And I mean 55.0 as I chucked the old analogue thermostat and use a digital sensor connected to the Raspberry Pi that does all the heating control. Like you say, the dial types are just too imprecise. Link to comment Share on other sites More sharing options...
Adsibob Posted August 17, 2022 Author Share Posted August 17, 2022 1 hour ago, Radian said: be warned that turning down the boiler flow temp might end up with it not being able to meet the demand and staying on unnecessarily. Yes, I’m not touching the boiler settings. I’m just toying with the tank thermostat and the timer/programmer. Link to comment Share on other sites More sharing options...
Mr Punter Posted August 17, 2022 Share Posted August 17, 2022 We have been 10kWh/day gas in the summer for dhw and gas hob for 4 of us. Electric tends to be about 15kWh/day year round. Link to comment Share on other sites More sharing options...
joe90 Posted August 17, 2022 Share Posted August 17, 2022 No idea, we are all electric (apart from bottle gas for hob) and last months bill was £102 🤷♂️ Link to comment Share on other sites More sharing options...
JohnMo Posted August 17, 2022 Share Posted August 17, 2022 Gas -June to today, average 2kWh, mostly 2 of us, but had a long weekend with 6 in the house. Combi boiler with preheat cylinder upstream, heated by solar. Electric average 8.4kWh for same period. Have 3.1kW solar with diverter Link to comment Share on other sites More sharing options...
Remington Posted August 17, 2022 Share Posted August 17, 2022 We're at 9.2kWh gas per day for hot water only - no idea if the hot water schedule is just enough or overkill (1 hour per day on a 210 cylinder). (system boiler, no seperate immersion heater) Electric is average of 19.1kWh per day, this seems steady in the time i've been logging the data (5 months) Link to comment Share on other sites More sharing options...
SteamyTea Posted August 17, 2022 Share Posted August 17, 2022 (edited) 17 minutes ago, Remington said: We're at 9.2kWh gas per day for hot water only - no idea if the hot water schedule is just enough or overkill (1 hour per day on a 210 cylinder) 4.2 [kJ/kg.K] x 210 [lt or kg] x (65 - 15) [delta °C] = 44,100 kJ Convert to kWh 44,100 [kJ] x 0.00027778 = 12.25 kWh So assuming your water delta T, difference between mains temperature and final temperature is a bit lower. About 37°C, before system losses. Edited August 17, 2022 by SteamyTea 1 Link to comment Share on other sites More sharing options...
Adsibob Posted August 17, 2022 Author Share Posted August 17, 2022 On the overkill point, it's very difficult to know without a mixergy cylinder or additional thermostats on the cylinder to work out whether or not it's overkill. I say that because obviously the thermostat will stop calling for heat from the boiler once it's reached temp, but that still doesn't stop one heating a cylinder full of water when one doesn't use it. In that sense a storage combi would have been more efficient I think, but I was advised that even Viessman's rather massive storage combi might not be enough for our needs, so we didn't go for it. Is there a way of adding additional thermostats in different locations on a Telford Tempest 300L vertical UVC to simulate the extra data that a mixergy cylinder has? Link to comment Share on other sites More sharing options...
Johnnyt Posted August 17, 2022 Share Posted August 17, 2022 July gas usage DHW average 9.2Kwh a day 500l UVC at 53c. Occasional top up with solar when I could remember to manually switch and not draw from grid. Divert now in place a week and battery, Happy Camper. Link to comment Share on other sites More sharing options...
Radian Posted August 17, 2022 Share Posted August 17, 2022 21 minutes ago, Adsibob said: Is there a way of adding additional thermostats in different locations on a Telford Tempest 300L vertical UVC to simulate the extra data that a mixergy cylinder has What's the extra monitoring on the mixergy then? All I could see is the rather easy to replicate, but ultimately pointless, cloud control. Link to comment Share on other sites More sharing options...
Gone West Posted August 17, 2022 Share Posted August 17, 2022 3 hours ago, joe90 said: No idea, we are all electric (apart from bottle gas for hob) and last months bill was £102 🤷♂️ What you need is a PV array 😃. Our last quarterly electric bill was £160 which I guess is due to the PVs and ST. 1 1 Link to comment Share on other sites More sharing options...
JohnMo Posted August 17, 2022 Share Posted August 17, 2022 27 minutes ago, Adsibob said: but I was advised that even Viessman's rather massive storage combi might not be enough for our needs Does that make sense? A storage combi should give you an endless supply of hot water, at better flow rates than a normal combi. Our Atag combi was doing two high flow showers at a time this weekend without complaint from the boiler or the users. Link to comment Share on other sites More sharing options...
joe90 Posted August 17, 2022 Share Posted August 17, 2022 1 minute ago, Gone West said: What you need is a PV array 😃. Our last quarterly electric bill was £160 which I guess is due to the PVs and ST. On my to do list 🤯 Link to comment Share on other sites More sharing options...
Radian Posted August 17, 2022 Share Posted August 17, 2022 Got the Mixergy manual downloaded. Digesting it now. Link to comment Share on other sites More sharing options...
Gone West Posted August 17, 2022 Share Posted August 17, 2022 1 minute ago, joe90 said: On my to do list 🤯 Yeah I know, just teasing. 1 Link to comment Share on other sites More sharing options...
Adsibob Posted August 17, 2022 Author Share Posted August 17, 2022 (edited) 5 minutes ago, JohnMo said: Does that make sense? A storage combi should give you an endless supply of hot water, at better flow rates than a normal combi. Our Atag combi was doing two high flow showers at a time this weekend without complaint from the boiler or the users. Endless supply yes, but not at an endless rate. Not that a system boiler and UWC gives an endless rate, but apparently it is slightly better than a storage combi. Maybe I got bad advice, but the advice I got was consistent with Viessman's own website where I entered my requirements and they steered me towards their Vitodens system boiler, over their storage combi. Edited August 17, 2022 by Adsibob Link to comment Share on other sites More sharing options...
Adsibob Posted August 17, 2022 Author Share Posted August 17, 2022 2 minutes ago, Radian said: Got the Mixergy manual downloaded. Digesting it now. my understanding is that by taking temperature readings at different locations within the cylinder (at two or three different heights) it can work out how much hot water is in the cylinder). This is one of its features (and probably the most useful). Link to comment Share on other sites More sharing options...
LA3222 Posted August 17, 2022 Share Posted August 17, 2022 This thread makes me feel.a.bit better about my own consumption. All Electric house, 280m2 and using around 12kWh a day. I've got a 2.5kWp system on the roof. Link to comment Share on other sites More sharing options...
Radian Posted August 17, 2022 Share Posted August 17, 2022 5 minutes ago, Adsibob said: my understanding is that by taking temperature readings at different locations within the cylinder (at two or three different heights) it can work out how much hot water is in the cylinder). This is one of its features (and probably the most useful). So, something close to a linear interpolation between the 'official' lower thermostat pocket and the hot takeoff at the top should do the trick. Easy to clamp a probe to the pipe union up there. Natural stratification would keep the hottest water at the top regardless of the location of the indirect heat source. I'm not sure if there's an active circulating system to de-strat the tank or not. The brand name hints at something like that but it could be nothing. In addition to all the marketing BS, a 75W standing heat loss would put me off that product. If all you want to do is have a graphical display of temperature and heat 'charge' and additionally get voice control of setpoint/boost etc. all that needs is a couple of 1-wire sensors, Raspberry Pi or similar and a bit of software. Link to comment Share on other sites More sharing options...
Radian Posted August 17, 2022 Share Posted August 17, 2022 20 minutes ago, LA3222 said: This thread makes me feel.a.bit better about my own consumption. All Electric house, 280m2 and using around 12kWh a day. I've got a 2.5kWp system on the roof. 12kWh includes your self generated energy or just your import? Link to comment Share on other sites More sharing options...
jayc89 Posted August 17, 2022 Share Posted August 17, 2022 For July we used, on average, 14kw a day of electric and 12kw a day of gas. 3 bed house, 2 adults working from home and 2x kids who don't know how to turn anything off. Link to comment Share on other sites More sharing options...
Adsibob Posted August 17, 2022 Author Share Posted August 17, 2022 7 minutes ago, jayc89 said: 2 adults working from home and 2x kids who don't know how to turn anything off. I empathise! My kids also know how to switch stuff on, but not off! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now