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

malc_b

orrery wrote: »

Nope, simply trying to make sure that the hall radiator isn't shutting down the heating before the rooms are up to whatever setting the OP has set.

That's the same thing. You balance the radiators (i.e. balance water flow) so that all rooms heat up properly. Just turning off the hall is the same as cranking up the hall thermostat. The boiler will run longer. But if 90% of the water is going to the lounge radiators then the lounge will just get over hot, the rest of the house will still be cold. With thermostatic valves on all radiators then what will happen if you turn off the hall rad or wind up the thermostat is first one room will get warm, then the flow will move on to the next room and so on. Meanwhile the boiler will be cutting in and out or modulating down because it doesn't have enough radiator surface to take the full power.

The correct fix is to balance the radiators.

John_Pierpoint

the_devil_made_me_do_it wrote: »

Just thought I'd ask a few questions:


Last year I moved into a small 2 bedroom bungalow. I rent it off a social landlord. Unfortunately they ain't the best when it comes to modernising their properties. It was bit in the early 90's, but still has the original patio door which has a metal frame and a hard wood front door with a small non double glazed window.


It does have upvc windows throughout which have a controllable vent. The patio door as a vent of sorts, but it may aswell be closed for the good it does.


Every room has a radiator, with control valves (going from 0 to 5) and a thermostat in the hall way.


Now my main concern really is would it be better condensation wise to leave the heating on all day? During the summer there was no condensation at all. However, since it's getting colder, there is condensation on the patio door and on my bedroom window. This doesn't bode well as I suffer with asthma.


I'm also not clued up with thermostat controls either on the radiators or in the hall. The only room which I don't use heating in is the kitchen. The radiator is too close to my fridge so have had to turn that off completely. Although I'm hoping that when they re-fit the kitchen, they will some how move the radiator away from the fridge area.


The property does have decent loft insulation, although I'm not too sure about cavity wall. I have asked the landlord to fit a ventilation system in the property, but they are just trying to ignore my request. I can't afford to fit one myself, but would have to get permission anyway.


If someone can give me a hand sorting my heating out, it would be much appreciated


Oh and I hope I've made this a comprehensible picture of my circumstances.

I have lived in conditions similar to yours until I double glazed all of my 13 windows by replacing the single sheet of glass with a double sealed unit with an infra fed reflector "invisaible" layer on the inside of the units. [All "illegal" because I am not FENSA registered]

The most important thing for you to do is to get rid of the overnight build up of "fuggy" air and mop all the condensation off the glass and window frames and probably the puddles on the cill. Don't let any of this water soak away down cracks into the fabric of your building.

Back in the 1950s it was accepted practice to throw open the windows of a house and strip back the beds while having breakfast, before remaking the beds and drying off any remaining condensation. Infact the beading was often aired out of the windows - but that may well have been as much about avoiding lice, bugs and flees as reducing moisture levels.

Now people, especially those in crampt social housing, fear that this will cost a fortune and leave the dwelling hermetically sealed, with parcel tape if needed, all winter and then complain like mad about the black mould and the peeling wall paper.

There is almost no heat in a house full of air and the water vapour condensinhg on the windows is just a transmission mechanism for moving the heat that was used to evapourate it onto the coldest part of the "envelope" of the building where it can leak away the fastest. So mop it up and tip it down the sink.

The heat is in the structure of the building not the air.

Then we come onto radiant heat. What homeowners are seeking is "comfort" not temperature. If I remember my CGSEs of 50 years ago the radiation from a body is proportional to the fourth power of its absolute temperature (ie That Glasgow scientist Lord Kelvin). We feel comfortable when the heat our bodies are producing is leaking away at the came rate as the surroundings are trying to heat us up again. So if we are sitting next to a dark sheet of glass with a cold garden outside. draw the curtasins and instantly feel warmer.

A window is the worst example but a wall that has been allowed to get really cold while the heating has been off, will cause a similar feeling of lack of comfort, that is one of the reasons why the barrons lined their castles with tapestries. At least the tapestry warmed up a bit in the glow from the filre the massive walls would take weeks to do the same.

It is the same effect as a cloud going over the sun - it feels chilly until the sun comes out again. Has the temperature changed? - no.

orrery

malc_b wrote: »

That's the same thing. You balance the radiators (i.e. balance water flow) so that all rooms heat up properly. ...
The correct fix is to balance the radiators.

I'm sorry - I didn't suggest balancing the radiators, you did. I simply wanted to make sure that the system was staying on long enough so that the TRVs could regulate to the temperature that the OP has set. I was suggesting a fix to a (potential) problem where the system shuts down even though the rooms haven't got to the temperature set on the TRVs.

In reality, there is less need to 'balance' a system that has TRVs as they restrict the flow somewhat, even when fully open (although I too would recommend it, if you are confident you know what you are doing). And, as you suggest, the flow will re-distribute as the first rooms come up to temperature.

Please - if you have a suggestion to help the OP then address your suggestion to the OP and don't try to tell me how to do something I'm perfectly capable of doing, but wasn't trying to do here.

hesperus_2

I have my heating on during the day because I am there most of the time being retired. In summer, it is off, autumn and spring it is on morning and evening, winter I try for just a mid day boost but in very cold weather all the time - so, as I said it all depends.

Drying clothes I switched to an airer years ago, having worked out how much the drier was using!

orrery

hesperus wrote: »

Drying clothes I switched to an airer years ago, having worked out how much the drier was using!

We try to hang the clothes outside, where possible. Otherwise a clothes rack with a dehumidifier and desk fan does the job well at about the same cost as a tumble drier, but is more solar friendly.

Jools19_2

From personal experience, I have found it cheaper to turn the BOILER thermostat down but have it on for longer rather than the boiler setting up high but only have it on while I'm in or timed for a bit before I'd be due to get home. The room stat can be set a bit lower while you're out and then turned up when you get in. This gives a much more comfortable house and will reduce the likelihood of condensation problems, which can be made worse by the house going cold during the day when you're out. By leaving the boiler on low and longer allows the structure to warm up and hence reduce condensation. The BOILER stat controls the temperature of the water circulating in the radiators. One comment said by turning the rad valves down the radiators wouldn't get so hot. The temperature of the radiators themselves is controlled by the boiler setting and hence the temperature of the water circulating the system, not by the rad valve. What the setting of the rad valve does is to turn the radiator off when the room gets up to the temperature set.
Regarding using a tumble drier. I never do. I hang washing outside whenever possible. In the winter when the heating is on, I hang the washing in the bathroom with the radiator on, use a small dehumidifier and close the door. This keeps the room warm and prevents condensation in the rest of the house. My dehumidifier is 200W and my tumble drier is 2200W so I could run it for 11 hours for the same cost. However it doesn't need anything like that long to dry the clothes.

captainhindsight_2

Jools19 wrote: »

From personal experience, I have found it cheaper to turn the BOILER thermostat down but have it on for longer rather than the boiler setting up high but only have it on while I'm in or timed for a bit before I'd be due to get home. The room stat can be set a bit lower while you're out and then turned up when you get in. This gives a much more comfortable house and will reduce the likelihood of condensation problems, which can be made worse by the house going cold during the day when you're out. By leaving the boiler on low and longer allows the structure to warm up and hence reduce condensation. The BOILER stat controls the temperature of the water circulating in the radiators. One comment said by turning the rad valves down the radiators wouldn't get so hot. The temperature of the radiators themselves is controlled by the boiler setting and hence the temperature of the water circulating the system, not by the rad valve. What the setting of the rad valve does is to turn the radiator off when the room gets up to the temperature set.
Regarding using a tumble drier. I never do. I hang washing outside whenever possible. In the winter when the heating is on, I hang the washing in the bathroom with the radiator on, use a small dehumidifier and close the door. This keeps the room warm and prevents condensation in the rest of the house. My dehumidifier is 200W and my tumble drier is 2200W so I could run it for 11 hours for the same cost. However it doesn't need anything like that long to dry the clothes.

In regards to the boiler thermostat, you need to look up what temperature your boiler runs at its most efficient and set it at that.

Then set your room thermostat to a temperature you like and then this will turn the boiler on and off as and when required.

This means your house stays at a constant temperature but you are using less fuel, because when the boiler is running it is running at its most efficient and for shorter periods of time.

If you have a programmable thermostat, you can set different temperatures for different times of day but I would avoid consistently adjusting a mechanical thermostat regularly because they will break.

Then the point of the thread about leaving the heating on all day, depends on the occupant and the individual house.

There is no one rule which applies to all circumstances, I have solid wall, loft and floor insulation in a 200year old house and a GSHP and leave it running 24/7 and is controlled by a programmable thermostat which maintains a constant temperature because there is almost no heat loss or solar gain the heating requirements are almost the same all year round.

orrery

Jools19 wrote: »

One comment said by turning the rad valves down the radiators wouldn't get so hot. The temperature of the radiators themselves is controlled by the boiler setting and hence the temperature of the water circulating the system, not by the rad valve. What the setting of the rad valve does is to turn the radiator off when the room gets up to the temperature set.

True, but also bear in mind that the Thermostatic Radiator Valve (TRV) is not an on/off device - if gradually restricts the flow at the temperature nears the set-point. So, as the temperature approaches the set-point, the TRV starts to close down and the flow is restricted, so the radiator temperature will fall. Typically, as the flow is restricted you get the inlet pipe being hot and the outlet pipe being cold.

Also, you can't assume that the TRV is on the inlet end - it could be either.

TRVs are commonly abused (by my Mum for one) where people turn the TRV up because they're cold, even though the reason for it being cold isn't to do with the TRV setting. My Mum ends up with all the TRVs in her house set to maximum, which then makes them useless.

Smiley_Dan

orrery wrote: »

True, but also bear in mind that the Thermostatic Radiator Valve (TRV) is not an on/off device - if gradually restricts the flow at the temperature nears the set-point. So, as the temperature approaches the set-point, the TRV starts to close down and the flow is restricted, so the radiator temperature will fall.

...

TRVs are commonly abused (by my Mum for one) where people turn the TRV up because they're cold, even though the reason for it being cold isn't to do with the TRV setting. My Mum ends up with all the TRVs in her house set to maximum, which then makes them useless.

I think there is an interesting nuance to that though which I think you touched on in your first para (tell me if I'm wrong).

If the TRV closes as it reaches the desired temperature (lets call this T1), than means that setting the temperature higher (T2) will achieve T1 quicker because you don't get the closing effect as T1 is approached. Yeah?

But it's a bit pointless because it would then require knowing this point and setting the setting back down to T1. Furthermore, it's probably not desirable to achieve it quickly because you will overshoot the temperature, wasting energy.

matelodave

Most people don't know how thermostats work and crank them up and down and wonder why they don't get the desired effect and their bills are still high.

The one in the boiler controls the water temperature in the system and should be hot enough to ensure that there's enough heat from the radiators to actually heat the room - if it's too low then the room stat or TRVs can be at their maximum and you still wont be warm.

The room stat or TRVs should control the room temperature. By turning them up they won't get the room warm any faster but assuming that the boiler stat is set correctly then the room should get to the required temperature. To get the room warm faster you need hotter water in the radiators which is controlled by the boiler stat however hotter water costs more to produce and will cause the boiler to cycle on & off more frequently.

It's therefore a balancing act to get the optimum water temperature to run the system efficiently - too low and the boiler will run virtually continuously, you still wont be warm and it won't save you money either. Too hot and the boiler & pump will cycle on & off, the room temperature will overshoot and it will cost more than it needs to as there will be a lot of wasted heat in the boiler & pipework.