Tweaking gas central heating settings when heating one room.

I've rented a house with gas central heating and I'm trying to figure out how best to heat only one room. I've thought about getting an electric portable heater, but I gather gas central heating works out cheaper. However, it's a three floor fairly thin house, with the kitchen on the floor, bedroom and bathroom on the middle and the lounge on the top. The thermostat is in the kitchen. Could anyone help me with the answers to these questions

1) Do I have to have the radiator in the lounge set to max? I could lower it but the wiki says the thermostat goes by the room it's in, so cranking it down to 1 or lower would just mean the gas central heating stayed on regardless. I really don't need the kitchen heating, plus the heat generated by the radiator presumably gets spread throughout the upstairs landings as there's no door on the kitchen.

2) Is there any harm in turning radiators off, rather than having them stuck at one? I've heard say that you need to have some water flowing through them and turning them to 0 stops this happening.

3)Does turning a radiator down actually use less gas? So if I have the lounge one at 5, then crank it down to 2, will it be using less gas to heat it?

Advice would be appreciated. I can't actually fit any extra bits and bats as I'm renting.

I'm no heating expert but have I have a fair knowledge and I've played about with different settings on our systems over the years. I'll try to explain the whole thing in simple terms, apologies if it comes across like I'm telling my granny how to suck eggs...it's not meant to.

The system is either on or off. This is controlled by a master switch - in your case it's the kitchen thermostat (there will be another actual master switch but I'm trying to keep it simple). If the thermostat is set hotter than the actual kitchen room temperature then your system will be on. When the system is on it will pump hot water to any radiator that "calls for heat". When it's off it won't pump to any radiator, irrespective of whether you have your lounge set to 5 or not.

Thermostatic Radiator Valves (TRV's) like you have fitted to your radiators (with the frost, 1,2,3,4,5 settings) are clever valves which determine how hot the room is, and they "call for heat" or not as per their setting. Normally there's a couple of degrees difference between the number settings, so setting 1 is maybe 12 degrees, 4 is maybe 22 degrees, but 5 will mean the rad calls for heat all the time. Therefore if your kitchen stat is set such that the system is on...then it would pump hot water constantly to your lounge if it's set at 5, but would only pump water to it until the lounge got to 22 degrees if set at 4.

With old style radiators (ie without TRV's) you would feel the rad and adjust the flow rate so that it would be cold, tepid or hot as required. This is not the case with TRV's - the radiator will be hot when it's on and cold when off, and the TRV does the work for you. So don't be fooled by the radiator being really hot when you've only set it at 2...this is because the TRV has decided that the rad needs full heat until the room gets to 14 degrees, then it'll turn cold, and this will happen repeatedly as required. Leaving a rad set at 1 will stop all flow to it unless that room is colder than 12 degrees. Obviously different TRV's have differrent temperature settings so you'll need to play about with yours a bit.

I've found over the years that having the house "not freezing cold" uses less gas, since it doesn't take so much gas to heat it back to normal temp every morning/night. We never turn ours off, but reduce the thermostat to 18 when out/sleeping, which keeps the house tepid and "easy to heat back up". In your shoes I'd try this...

Set a timer if you require it, ie if you don't want heat during the night etc. Set the kitchen wall thermostat to about 21 degrees, and the kitchen TRV about 2 or 3. This will mean the system will be pretty much on constantly (according to your timer), and your kitchen won't be freezing. Then set each room to the temp you want it to be, using the TRV's. Set the rooms you want to be cool at about 1.5 or 2, and set the lounge at about 4. The hot water will flow to all rads while the rooms are heating up, then each rad will cut off when its room gets to temp. On our system when all the rads have cut off there's a bypass which returns the (still hot) water to the boiler, so although the boiler is still on and the pump is running, it hardly uses any gas to re-heat the (still quite hot) water. I believe other systems will shut down altogether until heat is required.

Thanks for the info - that makes more sense. I actually gave this ago, putting the heating to 15 degrees c and putting all radatiors to the frost setting. The gas light only kicked in when turned the lounge radiator up to 5. Hurrah! Should I periodically put the other radiator valves on 1 just to make sure water is flowing through the pipes?

Putting them on at 1 won't allow water flow through them unless the room is colder than about 10 or 12 degrees. If you're worried about them seizing up you'd probably be better turning them on full for half an hour once every month or so.

I've been tweaking the heating settings for a bit, but I've hit a snag. I'd ideally like to now heat the upstairs, 2nd floor bedroom and third floor lounge, and landing again without heating the kitchen too much. However, I don't have a radiator on the landing. I have a very large radiator in the kitchen, the same room where the thermostat is. I have a medium sized one in the lounge, a slightly smaller one in the bedroom and a really small radiator in the bedroom.

It seems like I have two options - unless anyone can suggest others..

1) Leave all the radiators on, since the heat in the kitchen will presumably drift upwards - it's got a very open staircase with no door.

2) Use the upstairs radiators, but open the door so that the heat from the bathroom and lounge radiator heats the landing.

Does anyone have any other suggestions as how to keep the upstairs warm without heating the kitchen unnecessarily? It's a weird arrangement as my house was originally two houses. I rent so I can't add anything to the system. All the radiators have TRVs.

Honeywell Evohome

You dont bother to tell us your boiler model.

However, whatever size it is likely to be extremely inefficient using it to just heat one radiator.

Far better to use a thermostatically controlled fan heater. They are always 100% efficient.

Tony