Switching off radiators…or not?

Reed_Richards

@Mstty

Energy Used Electricity only 7100kWh a year 4 bedroom detached house EPC high B ASHP Mitsubishi Ecodan, under floor heating ground floor, radiators 1st floor. Multi-fuel burner in lounge.

So how much of that 7100 kWh is powering the heat pump?  Presumably most of the rest will be background heating the house.  And if your house loses heat overnight but gains heat during the day (despite it being colder out than in), to what do you attribute that gain?

Mstty

Reed_Richards said:

@Mstty

Energy Used Electricity only 7100kWh a year 4 bedroom detached house EPC high B ASHP Mitsubishi Ecodan, under floor heating ground floor, radiators 1st floor. Multi-fuel burner in lounge.

So how much of that 7100 kWh is powering the heat pump?  Presumably most of the rest will be background heating the house.  And if your house loses heat overnight but gains heat during the day (despite it being colder out than in), to what do you attribute that gain?

Bit of sun generally this time of year. You can tell the difference from East and North sides of the house to West and South as the Sun makes its way through the sky. At the moment we have some morning sun and with just the fridge freezer (integrated) running in the kitchen we have gone from 17.9oC to 18.5oC in about an hour and a half.outside temp is currently 12oC

So my theory was the  fridge freezer certainly doesn't heat the kitchen from 1oC to 17.8oC overnight so I presumed it's a very efficient house and keeps the heat in with little escaping. Hence my original reply to your point that your internal.house temp matches the outside with no heating

We have led bulbs everywhere that for their 2-5w use don't account for creating large quantities of heat. Use of the projector is forbidden due to energy costs until movie night and large TV watching largely replaced by the 10w iPad. Only heat source overnight would be 30 mins heating the hot water tank via ASHP (once a week going to 60oC for bacteria killing) we haven't felt the need to light the fire in the lounge as that is West facing so from 1pm becomes the warmest room in the house. Appreciate the oven on for cooking adds 1-1.5oC to the kitchen and the washing machine may add some to the utility room and into the hallway. Of course all things add heat including people but without all of this the house would not match the outside temp internally.

We are 10 months into ownership of this house so still working out the breakdown but doing on others than run Mitsubishi Ecodan ls with similar size house and age (so rough about 3750-3950kWh) but we are on an energy saving drive and suspect our overall usage for the year to be 6500kWh for the first year and trying for 6000kWh for the second year with hopefully around 3400-3600 ASHP use.

So what is your property, Age, insulation EPC rating and size etc. Maybe that can explain what is happening to yours?

Ultrasonic

Kim1965 said:

Some boilers have pump overuns some dont,. Have one rad with two manual valves is a catch all. 
Any well designed house will have the roomstat located in a room with no trv. Think about. You shut the trv off, room goes cold  room stat calls for heat. Why have two stats in conflict. 

What would you say is common practice for homes with mobile rather than fixed thermostats?

QrizB

Reed_Richards said:

QrizB said:

Also, it's almost May. Unless your toddler is particularly vulnerable, can you turn the CH off completely and leave it off until at least October?

N. Hampshire must be a lot warmer than here in the north of England.  My smart thermostat maintains a weather report (presumably taking data from a nearby weather station).  In the last 30 days the maximum reported temperature was 16 C and the minimum was about 1 C.  It is 10 C outside at the moment and would be much the same inside if I turned the heating off.

Apologies for the late reply, I spent yesterday on public transport and (between flaky signal and my low-end phone) couldn't reply effectively until now.

Mssty has made the point I was going to make regarding the temperature stability of a house. I don't have any fancy data loggers but I've not seen my living room thermometer below 14C since switching the heating off, and we've had overnight frosts during that time. The house only cools slowly and gets decent passive solar gain so by 9am or so it's usually warm enough for shirt sleeves.

And if you have thermostatic control there should be no need or reason to turn the heating off.   

The counter argument is why wouldn't you turn it off if you don't need it?
I do have a wall thermostat and TRVs but they don't know the weather forecast and can only react to current conditions (and hysteresis means they're really reacting to *past* conditions). So there's a real chance that, if I leave it switched on, it will heat my house in the early morning without realising that passive sunshine would have achieved the same result a couple of hours later.

I guess there must be weather-predictive or internet-linked control systems that will know in advance how warm tommorrow will be, and are able to adjust your heating profile to suit, but I don't have one of those.

k_man

QrizB said:

Reed_Richards said:

QrizB said:

Also, it's almost May. Unless your toddler is particularly vulnerable, can you turn the CH off completely and leave it off until at least October?

N. Hampshire must be a lot warmer than here in the north of England.  My smart thermostat maintains a weather report (presumably taking data from a nearby weather station).  In the last 30 days the maximum reported temperature was 16 C and the minimum was about 1 C.  It is 10 C outside at the moment and would be much the same inside if I turned the heating off.

Apologies for the late reply, I spent yesterday on public transport and (between flaky signal and my low-end phone) couldn't reply effectively until now.

Mssty has made the point I was going to make regarding the temperature stability of a house. I don't have any fancy data loggers but I've not seen my living room thermometer below 14C since switching the heating off, and we've had overnight frosts during that time. The house only cools slowly and gets decent passive solar gain so by 9am or so it's usually warm enough for shirt sleeves.

And if you have thermostatic control there should be no need or reason to turn the heating off.   

The counter argument is why wouldn't you turn it off if you don't need it?
I do have a wall thermostat and TRVs but they don't know the weather forecast and can only react to current conditions (and hysteresis means they're really reacting to *past* conditions). So there's a real chance that, if I leave it switched on, it will heat my house in the early morning without realising that passive sunshine would have achieved the same result a couple of hours later.

I guess there must be weather-predictive or internet-linked control systems that will know in advance how warm tommorrow will be, and are able to adjust your heating profile to suit, but I don't have one of those.

We have had a few overcast mornings recently, so lack of passive solar means we would have stayed closer to the overnight low for much longer (with a short CH burst).

House aspect and window locations mean if we miss morning sun, it takes until late afternoon to get any more benefit from passive solar.
Just need a heat exchanger on the south facing wall!

Reed_Richards

I think there is a very interesting debate to be had about about how houses "magically" heat themselves.   Solar gain, waste heat from appliances, heat lost from a hot water cylinder and people are the factors I can think of but perhaps there are others.

Then there is another debate on whether people are happy to be cooler inside when it is warmer outside.  That's certainly the case in North America where homes with air conditioning tend to be colder in summer than in winter, in my experience.

But both debates seem off-topic for what is supposed to be a discussion on turning off radiators in cold rooms.  

Mstty

@k_man

Those are definitely factors into how well the home heats up without any heating for sure.

Haven't looked into heat exchange is this a good option to consider?

Yesterday as an example it was overcast for the morning which meant the front of house (East facing) didn't get its normal amount of free solar energy that gets trapped inside due to good insulation on colder days.

Luckily the afternoon the sun came out and heated up the South and West facing rooms which in turn heated the whole house nicely for free.

So it seems the ability to leave the heating off at this time of year depends on. Personal tolerance to temperature changes, free solar gain and position of property, energy produced by other internal heat sources and insulation to keep the heat where it is and not lose it through walls, floors and roofs.

Nothing magical about it @Reed_Richards just free solar gain in the main and insulation keeping the gain in.

Unlike our house in Spain where it's designed to be 5oC-10oC cooler than outside and painted white to reflect heat rather than dark brick to absorb and use the heat here in the UK. 

Kim1965

Ultrasonic said:

Kim1965 said:

Some boilers have pump overuns some dont,. Have one rad with two manual valves is a catch all. 
Any well designed house will have the roomstat located in a room with no trv. Think about. You shut the trv off, room goes cold  room stat calls for heat. Why have two stats in conflict. 

What would you say is common practice for homes with mobile rather than fixed thermostats?

They are a gimmic, fix it to the hall wall, remove the trv

Zandoni

Ultrasonic said:

Kim1965 said:

Some boilers have pump overuns some dont,. Have one rad with two manual valves is a catch all. 
Any well designed house will have the roomstat located in a room with no trv. Think about. You shut the trv off, room goes cold  room stat calls for heat. Why have two stats in conflict. 

What would you say is common practice for homes with mobile rather than fixed thermostats?

I have mine in the lounge and I have removed the top of the TRV, although Kim1965 strangely thinks they are gimmicks I think they are an amazing way of saving money and so much easier to fit.

Ultrasonic

Kim1965 said:

Ultrasonic said:

Kim1965 said:

Some boilers have pump overuns some dont,. Have one rad with two manual valves is a catch all. 
Any well designed house will have the roomstat located in a room with no trv. Think about. You shut the trv off, room goes cold  room stat calls for heat. Why have two stats in conflict. 

What would you say is common practice for homes with mobile rather than fixed thermostats?

They are a gimmic, fix it to the hall wall, remove the trv

I think they're vastly superior to ending up with a thermostat in an area that I don't want heated, as often seems to happen with fixed thermostats.

Please note I don't have any apparent problems with my heating system. I simply don't have TRVs ever set low enough to be an issue in rooms where I've had my thermostat. I appreciate it's possible for someone to end up with a TRV too low in a room so it was off when the thermostat was still sending a demand to heat that room but in practice someone would having to be paying little attention to not realise if that happened IMHO.