Energy myth-busting: Is it cheaper to have heating on all day?

jet104

I think it's better just to control each room with the radiator valves. The problem with having a 'house' thermostat is they're usually in a communal area or hall and unless you have it permanently high some rooms never get warm even if the radiator valve is fully open. I've experienced this with a downstairs toilet that was always baltic.
And if you permanently have the thermostat high you need to control each room with the radiator valves anyway.

System

jet104 wrote: »

I think it's better just to control each room with the radiator valves. The problem with having a 'house' thermostat is they're usually in a communal area or hall and unless you have it permanently high some rooms never get warm even if the radiator valve is fully open. I've experienced this with a downstairs toilet that was always baltic.
And if you permanently have the thermostat high you need to control each room with the radiator valves anyway.

Welcome to the forum. Sadly, no one solution suits all. For example, I have a TPI thermostat which is designed to get a property up to temperature and keep it there. Fiddling with the system uses more gas than just leaving it to do its own thing.

orrery

jet104 wrote: »

I think it's better just to control each room with the radiator valves. The problem with having a 'house' thermostat is they're usually in a communal area or hall and unless you have it permanently high some rooms never get warm even if the radiator valve is fully open. I've experienced this with a downstairs toilet that was always baltic. And if you permanently have the thermostat high you need to control each room with the radiator valves anyway.

This is a very wasteful solution as the system will be running all the time. Most modern thermostats will operate in 'proportional' mode as they get close to the set temperature i.e. they will turn the heating on and off proportionate to the heating required, which helps keep boilers in condensing mode. Not having a main thermostat means that the boiler is likely to be out of condensing mode for the majority of the time and delivering the worst possible efficiency.

The problem you have might be best approached by restricting flow to other radiators so that the downstairs toilet gets more flow and is up to temperature before the system is shut down and/or fitting a double radiator instead of a single, or adding a towel rail in addition to the rad, if there is space..

A thermostat also helps shut the system down if the outside temperature is high and no heating is required or there is ample gain from the sun.

System

Abi_J wrote: »

I think leaving your heating on all the time will drain a lot more energy from inefficient homes, as the heating works a lot harder to replace lost heat. So you actually need to make sure that your home is well insulated and drought proofed in order to minimize heat loss.

In general, I would agree, however, it depends on your property, boiler and heating controls. Modern, modulating, condensing boilers are at their most efficient when operating in what is known as the low temperature condensing mode. My boiler has been ticking over throughout the day with recorded usage averaging 0.3 cubic metres/hour (3.5kWhs/hour). If I turn it down and go out for, say, 3 hours then the gas usage to get the house back up to temperature exceeds the gas saved. I know as my gas usage is recorded every 15 minutes. For most of the day, my boiler has had a flow temperature of 45C. When there is a significant heat demand, my thermostat will demand a flow temperature of 70C which takes the boiler out of its most efficient operating mode.

malc_b

jet104 wrote: »

I think it's better just to control each room with the radiator valves. The problem with having a 'house' thermostat is they're usually in a communal area or hall and unless you have it permanently high some rooms never get warm even if the radiator valve is fully open. I've experienced this with a downstairs toilet that was always baltic.
And if you permanently have the thermostat high you need to control each room with the radiator valves anyway.

Sounds like your system is not balanced. Google balancing radiators to see what this. I reckon most houses have unbalanced radiators as it is just a time consuming PITA to do :-). Some people also have the idea that TRVs will fix an unbalanced system (which they won't) so you don't need to balance a system which has TRVs.

The only true house wide control would be to sense each room temperature and then work out if heat is needed or not and use that to decide boiler on or off. As that is complicated then the cheaper option is to sense a typical location to control the boiler and use TRVs to give finer regulation of each room. The hall is meant to be typical, centre of the house, no activity or people which might heat the location and give the impression no boiler heat is needed.

System

malc_b wrote: »

The only true house wide control would be to sense each room temperature and then work out if heat is needed or not and use that to decide boiler on or off. As that is complicated then the cheaper option is to sense a typical location to control the boiler and use TRVs to give finer regulation of each room. The hall is meant to be typical, centre of the house, no activity or people which might heat the location and give the impression no boiler heat is needed.

That is exactly what a zoned heating system such as Evohome, Tado or Wiser does. The controller adds the various zone demands together and sends a calculated total heating demand to the boiler. Finer granularity can be achieved with Opentherm boiler control which adjusts the gas valve.

Hearty74

Interested in thoughts/opinions on merits of replacing standard gas boiler & hot water tank with combi boiler for central heating / hot water. Hot water tank fitted with thermostat which can be regulated so that when temp of water is reached heating system bypasses coil in tank which has certainly improved efficiency / cost saving but plumber / heating engineer maintains further savings could be made by converting to combi. Not sure if his advice has merits or is he just looking for further work

JDogg

Should I have the gas fire on in the living room, or all the radiators in the house?
When I worked for British Gas, I was a member of one of the few teams trained as energy experts. We were advised by the engineer running the course that it took just as much energy to use the gas fire as it did to heat the whole house with radiators, with the major difference that if one just used the fire, every time you left the room you'd be cold, while the C/H kept the temperature the same throughout the property.

blimeyharri

It's like having the kettle constantly boiling all day just in case you want a cup of tea at some point...

Cardew

Hearty74 wrote: »

Interested in thoughts/opinions on merits of replacing standard gas boiler & hot water tank with combi boiler for central heating / hot water. Hot water tank fitted with thermostat which can be regulated so that when temp of water is reached heating system bypasses coil in tank which has certainly improved efficiency / cost saving but plumber / heating engineer maintains further savings could be made by converting to combi. Not sure if his advice has merits or is he just looking for further work

Welcome to the forum.

If you do a search the combi v standard boiler discussion/argument has appeared many times in this forum.

There is no 'one size fits all' answer! It depends on a host of factors - type of usage, length pipe runs etc etc. One thing is certain, even in the cases where a combi might be marginally cheaper(and how would you prove it anyway) it would never justify the installation costs of a new boiler, removal of tanks etc.

Modern well insulated Hot water tanks lose very little heat - pence per day - and any heat 'lost' warms the fabric of the house. That is why they are often in airing cupboards.

Costs apart, a standard boiler is a far better system for many(most) people. Copious supplies of Hot water from the tank.