Oil Boiler - best way to use

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Hi there,

I moved into my end of terrace three bed room house about a year ago and I installed Grant 15/21 oil conventional boiler to run my eleven radiators (all with thermostats but all at maximum). Oil usage has been around 1700 litres with about 200 still in the tank from that. I am working on what I still need to insulate as the house is often far from warm.

In terms of the usage I have left the Grant at the output the plumber suggested, with the dial set to about a third of maximum power output. The thermostat for the house is in the hall but I had to move it closer to the transmitter (its wireless) as the signal kept dropping. Its currently set at 20.5 C although the house never really reaches that temp even if the heating is left on all day. We close the door next to the thermostat as the back of the house (two story extension) is quite cold and with the door closed the rest of the house is warmer.

So, my question, should I up the output of the boiler with the thinking being the house might reach the temperature quicker and it will then keep it there occasionally adding hot water to the system. Or should I leave it as it is although the boiler maybe on more trying to reach the unattainable temperature?

Obviously I am concerned with oil usage so I don't want to burn loads more. Whats the best approach?

Any help is greatly appreciated.
 
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Install bigger radiators that is your problem. If your current radiators
are hot and the rooms aren't getting to temperature the radiators
aren't up to it.
Double convectors.

You can zone the house switching off upstairs during the day.

The boiler is up to it. It will be outputing about 18kw which is about right.
 
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Most of the radiators are doubles but not all have convector fins. I am planning to add an upright radiator to the kitchen anyway.

When we originally had the boiler installed the plumber sized the radiators and I think he said they were about right, but evidently not.

Is there an easy way to calculate, basically, how big should I go?
 
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Most of the radiators are doubles but not all have convector fins. I am planning to add an upright radiator to the kitchen anyway.

When we originally had the boiler installed the plumber sized the radiators and I think he said they were about right, but evidently not.

Is there an easy way to calculate, basically, how big should I go?

You find a fairly good one online from wickes.
It allows for insulation, outside walls etc.
 
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In terms of the usage I have left the Grant at the output the plumber suggested, with the dial set to about a third of maximum power output.
Are you talking about the boiler thermostat, that's the round knob marked 65, 75, 85 and °C?

If so, it should be on about 75 in the winter and 65 in the summer. If it's very cold and the house does not get up to the required temperature you may have to turn it up a bit.

Setting the TRVs to Max does not heat the room up any quicker and will not compensate for undersized radiators.
 
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Thanks for the replies.

dcawkwell - funnily enough I was just going onto their website I will check it out.

D_Hailsham - I am not sure, if I take the front off the boiler there is a knob marked "Heating Temperature" - there are no values around the outside although it is marked, similar to this .

So its not easy to tell where to set it. I have actually put a pencil mark on it so I know where I have had it set. I assume by going upwards you burn more oil??
 
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if I take the front off the boiler there is a knob marked "Heating Temperature" - there are no values around the outside.
OK I got the wrong model.

If you turn the dial clockwise until it stops, where is the pencil mark (e.g at 4 o'clock)?

I assume by going upwards you burn more oil??
Not necessarily. If the boiler is set too low it can run continuously because the house never gets up to temperature, so the room thermostat never turns the boiler off. Setting a higher temperature means that the house will heat up faster and reach the required room temperature, which then turns the boiler off. The boiler will only come on again when the temperature has dropped about 1 degree.
 
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Well I just did a test and I am a bit surprised. As I say, I have never adjusted the output on the boiler. So I twisted the knob clockwise, so I could answer the question, and there is not much play at all. It will turn perhaps a 1/4 of the way around, so when it is fully clockwise (the output then seems to be at its maximum) my pencil line is at about 2 pm. The pencil line (when aligned at 12pm) also seems to be at the very minimum of the boiler output, ie I can't turn it any more anti-clockwise.

So my pencil line, which is drawn at 12 o'clock, seems to indicate the boiler is at its minimum 'heating temperature'. If twist the know to maximum output it sits at 2pm-ish. So not much movement at all.
 
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Turn the knob clockwise so that the thicker marking is at your reference point. To get your house to an acceptable temperature will consume an amount of oil to acheive that level. With more heat, you will reach it quicker. This can mean hotter radiators, controlled by this knob on the boiler, or if that fails, then you need to install bigger radiators.
 
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Well I definitely need more radiators in the kitchen, its a big room that did have a oil range thrumming away which now has an electric over instead, I do need more heat down one end.

Anyway, I have pushed the boiler output up to half way from the minimum it was on. We will see what happens now.
 
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I have just been in the kitchen and timed what the boiler was doing. It seems to run in 3 minutes cycles with 1.45mins on and 1.15 mins off. Temperature has gone up to 17c at the thermostat since turning boiler up with radiators definitely hotter to the touch.
 
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If your boiler is cycling that frequently, then it suggests it is way too big for the system, or there are circulation problems. It is cutting itself off on its own thermostat as it is not clearing sufficient of the heat it is creating.
What speed is the pump on?
Are the pump valves fully open?
Do you have a 'Y' plan or 'S' plan?
Are you running both heating and hot water together?
Does it still short cycle if you select heating only?
 
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