Extra Uses For Off-Peak Electricity

[SteveJol]

Crikey, an immersion without a thermostat would be a terrifying device! (Yes, they all have them.)

I adjusted mine down today, to 60⁰ (which I believe is the minimum due to legionnaires risk). Had it set at 65⁰ overnight and was too this morning.

Annoyingly my smart meter has stopped sending readings so am not sure how much energy was consumed overnight.

 

[HenryT]

Crikey, an immersion without a thermostat would be a terrifying device! (Yes, they all have them.)

I once had a fish tank with a separate heater and thermostat. Thermostat failed overnight, needless to say the fish didn't fare too well.

It was nice and warm in the kitchen that morning mind.

 

[Adopado]

I once had a fish tank with a separate heater and thermostat. Thermostat failed overnight, needless to say the fish didn't fare too well.

It was nice and warm in the kitchen that morning mind.

...and breakfast ready cooked

 

[Casss]

Can someone check (and correct as needed) my thinking on underfloor heating settings? (Air Source Heat Pump incase that factors much - we are entirely underfloor heating apart from towel rails).

- Rooms where temperature is critical or most commonly occupied throughout the day are 'on' always, so as to tick on and off as needed to maintain temperature, and thus removing need to do a big heat-ramp

- Rooms that are not as frequently occupied just set to come on in our off-peak period

Although I see two camps when it comes to this. Some say only have the underfloor system on for times when the room is colder, and some say have key rooms on tickover always because the efficiency impact of heating those up from stone cold A) takes around 30mins at 100% and B) probably negates the benefit of only having it on in a set window.

The difficulty is I see no way of easily getting a factual answer on this for our circumstances... so what does everyone go for?

 

[Fursty Ferret]

Some say only have the underfloor system on for times when the room is colder, and some say have key rooms on tickover always because the efficiency impact of heating those up from stone cold A) takes around 30mins at 100% and B) probably negates the benefit of only having it on in a set window.

It is not, and never has been, more efficient to keep any form of heating on 24/7 at a low level as opposed to running it as and when it's needed.

 

[ACarneiro]

I think it depends on whether your goal is maximum savings or maximum efficiency.
If the former then probably reasonable to turn your heating up at the start of “cheap o’clock” as the electricity is so much cheaper that it’ll offset the somewhat reduced efficiency of the heat pump in the middle of the night (when temperatures are lowest), and then let the thermostat go down to your desired temperature during the day. Your house would then be a sort of “thermal battery”.
If efficiency and emissions-reduction are your greatest objective, then I would imagine keeping rooms cooler until you use them (heat loss is an exponential process so the warmer the room is, the greater the heat loss will be). Also, the heat pump will work at its best when the temperature delta is the highest (so better efficiency when warming a colder room).
This is all assuming your insulation is the best it can be. If not, maybe start there?

 

[Casss]

It is not, and never has been, more efficient to keep any form of heating on 24/7 at a low level as opposed to running it as and when it's needed.

Is it that simple? Is that true in all cases with underfloor heating and a much cheaper night rate for example?

Edit: should have clarified efficiency as in using less electric during the day at high rates of the difference in perceived comfort is minimal

 

[Casss]

I think it depends on whether your goal is maximum savings or maximum efficiency.
If the former then probably reasonable to turn your heating up at the start of “cheap o’clock” as the electricity is so much cheaper that it’ll offset the somewhat reduced efficiency of the heat pump in the middle of the night (when temperatures are lowest), and then let the thermostat go down to your desired temperature during the day. Your house would then be a sort of “thermal battery”.
If efficiency and emissions-reduction are your greatest objective, then I would imagine keeping rooms cooler until you use them (heat loss is an exponential process so the warmer the room is, the greater the heat loss will be). Also, the heat pump will work at its best when the temperature delta is the highest (so better efficiency when warming a colder room).
This is all assuming your insulation is the best it can be. If not, maybe start there?

Thanks - useful food for thought! Insulation is ~3 yrs old and as good as it can be within reason.

Just wondering if I’m missing a trick with the way it’s set up.

Might look into a smart thermostat for a few rooms and see if that sheds any light over a couple of weeks of use.

 

[chemirocha]

Thanks - useful food for thought! Insulation is ~3 yrs old and as good as it can be within reason.

Just wondering if I’m missing a trick with the way it’s set up.

Might look into a smart thermostat for a few rooms and see if that sheds any light over a couple of weeks of use.

I'd be interested to know how you get on with a smart thermostat. We have underfloor heating in the kitchen (using a gas boiler) and a dumb room thermostat so it often kicks in overnight as the temperature drops. I'm thinking of changing the thermostat so that I can programme a lower temperature overnight and then higher at certain times of the day when we're more likely to be using the room. However, it does take a while to heat the room from 10C to 18C, so I'm not sure it would work any better than just having the fixed temperature.

 

[rotor2k]

I'd be interested to know how you get on with a smart thermostat. We have underfloor heating in the kitchen (using a gas boiler) and a dumb room thermostat so it often kicks in overnight as the temperature drops. I'm thinking of changing the thermostat so that I can programme a lower temperature overnight and then higher at certain times of the day when we're more likely to be using the room. However, it does take a while to heat the room from 10C to 18C, so I'm not sure it would work any better than just having the fixed temperature.

Goodness, a programmable thermostat would pay for itself in literal weeks.

 

[ME_UK]

For those interested - having now run the storage heater in our conservatory for 30 days - at a toasty 19 degrees during the week, and 21 at the weekend - the results are in. More than happy with an average of 58p pence per day on our Intelligent Octopus tariff.

We'll see how we go in the colder months, but we've had a few nights at 2-3 degrees and nothing seems to phase it

 

[WannabeOwner]

Re: underfloor heating and thermostat and using adjustable timer / temperature etc.

My house is Passive House, and as I understand it definitely would be best to run UFH 24/7 and just adjust the flow temperature to a few degrees above ambient, but I don't do that. The response time of any heat input (given huge heatsink in the floor) is so slow that it is very difficult to adjust anything in a fashion that is "useful". What I've found works for me is to set overnight to, say, 1C below target (if temperature actually falls that low then it would come on), set Day to target temperature - if the sun comes out no heating will be will be needed, if not, and temperature actually falls to that level then heating is needed; and set the "Getting up" and "Evening" to 1C over target. Thus they will, invariably come on (although Evening won't if day was sunny as room will already be 1C, maybe 2C, high). That charges the floor (and the rest of the thermal mass in the room).

My plan has always been that if we get a spell of really cold weather I will either increase flow temperature, or the duration of the "overheat" periods, but the last time we had a solid week of artic winter temperatures I never got around to it (typical, for me!) and actually the house daily minimums only fell 0.5C lower than regular winter nights.

If we go away for the weekend in mid-winter and turn everything off the house will lose 0.5C ~ 1C - haven't used any heating yet this Autumn (we have had some frosty nights ... albeit mild recently), and I don't normally expect to until at least mid November. Can't understand why Building Regs don't require Passive Haus for new builds - less than 7% on the build cost, and virtually no heating costs for the lifetime of the building, and can choose to have no boiler at all (use an electric fire on the few cold days each winter) and then have no maintenance / replacement either ... unfortunately retro-fit passive House / EnerPHit is eye wateringly expensive.

So maybe setting a conventional thermostat to over-heat for a few hours in good time before getting up, and before the evening period, and "normal" for the day (if at home) and a bit low overnight would work on UFH systems that have huge-lag / slow response?

But undoubtedly the main benefit I have is the insulation level for Passive Haus. My advice for anyone contemplating a new-build is to go Passive.

 

[yessuz]

Re: underfloor heating and thermostat and using adjustable timer / temperature etc.

My house is Passive House, and as I understand it definitely would be best to run UFH 24/7 and just adjust the flow temperature to a few degrees above ambient, but I don't do that. The response time of any heat input (given huge heatsink in the floor) is so slow that it is very difficult to adjust anything in a fashion that is "useful". What I've found works for me is to set overnight to, say, 1C below target (if temperature actually falls that low then it would come on), set Day to target temperature - if the sun comes out no heating will be will be needed, if not, and temperature actually falls to that level then heating is needed; and set the "Getting up" and "Evening" to 1C over target. Thus they will, invariably come on (although Evening won't if day was sunny as room will already be 1C, maybe 2C, high). That charges the floor (and the rest of the thermal mass in the room).

My plan has always been that if we get a spell of really cold weather I will either increase flow temperature, or the duration of the "overheat" periods, but the last time we had a solid week of artic winter temperatures I never got around to it (typical, for me!) and actually the house daily minimums only fell 0.5C lower than regular winter nights.

If we go away for the weekend in mid-winter and turn everything off the house will lose 0.5C ~ 1C - haven't used any heating yet this Autumn (we have had some frosty nights ... albeit mild recently), and I don't normally expect to until at least mid November. Can't understand why Building Regs don't require Passive Haus for new builds - less than 7% on the build cost, and virtually no heating costs for the lifetime of the building, and can choose to have no boiler at all (use an electric fire on the few cold days each winter) and then have no maintenance / replacement either ... unfortunately retro-fit passive House / EnerPHit is eye wateringly expensive.

So maybe setting a conventional thermostat to over-heat for a few hours in good time before getting up, and before the evening period, and "normal" for the day (if at home) and a bit low overnight would work on UFH systems that have huge-lag / slow response?

But undoubtedly the main benefit I have is the insulation level for Passive Haus. My advice for anyone contemplating a new-build is to go Passive.

As I am coming from the country which has, let's say, slightly colder winters, I look at british houses with the horror If the houses here had same insulation levels as in Lithuania (or Scandinavia), then you would probably never ever have to heat the house with such winter temperatures ))