oil fired central heating

[Dc]

With the high price of fioul I would like to make sure my central heating is performing efficiently. Can anyone specify how many times an oil boiler should fire up in an hour and for how long. If there is an optimum performance, what is it and how do I achieve it ? Any comments greatly appreciated.

 

dc

[maude]

sorry but far too many questions to be even considered here-what is the ambient temperature.how old is the boiler and when last serviced.what system controls are there..What temperature do you want the house to be.How well insulated is the property.Does it also heat the domestic water.,Just a few questions.Personally we dont use those systems-too expensive to fit,and lots of people we know cant afford to run them.We stick to oil filled electric radiators as back up, but the main source is a wood fired "insert" which heats kitchenvia an air outlet,dining room where it is sited,and sitting room.The two bedrooms above do not need any form of heat whatsoever-us being ruffy tuffy ex northerners.Hoever wood aint cheep!      Maude

[Dc]

Yes I think you are absolutely right!  Unfortunately I have oil fired central heating and need to know what the optimum performance of the boiler should be to try and get the costs down. Just for the heating how many times should the boiler fire up in say an hour? Next time round it's a woodburner and loads & loads of insulation.

 

dc

[pimpernel]

I think maude covered it by stating there are too many variables to say how many times it should fire up in an hour. It all depends.

[Dc]

so how do you know if your system is efficient?

[Gluestick]

By measuring the overall heat loss; factoring in the boiler output: and calculating the consumption in terms of the fuel's latent heat potential.

Boiler efficiency varies according to manufacturer: this is then impacted by the condition of the burner array: and the state of the water jacket. If the water jacket is corroded, then its Heat Exchange Capacity is impaired and an increasing value of heat output simply vanishes into the flue!

A boiler (of any type) can needlessly "Cycle" owing to what is called the hysteresis of the controlling thermostat. A modern digital solid state 'stat, reduces this unwanted and wasteful effect.

Most boilers have at least on 'stat on the jacket (the boiler thermostat - and one on a selected wall). Modern multi-circuit systems will have one 'stat for each area system.

The best you can do, in practical terms, is to have a service carried out by a fully qualified Chaufaugiste  who will clean the burner array and injector and adjust the inlet pressures for optimum performance: as well as issuing the essential certificate

Thereafter, the condition of your pipework and rads also predicates how efficient your system is. Again, corroded rads can handle less heat exchange. ( Any piped hot water CH system is really two heat exchange systems: the first is the fuel burn to water: the second is the water heat to air, by convection and radiation).

One final comment: one often hears "Last Winter I used x Litres of  oil etc."

Meaningless comment!

As has already been pointed out, your consumption will depend on so many different variables it is really impossible to quantify House By House comparitive efficiency.

The best you can do for an approximation, is get hold of either a heating engineer's circular sliderule or download one of the many heating calculators from the Web and thereafter input your room sizes, construction materials and window sizes etc and compute what heat input each room needs to maintain an approx desired temperature.

Then look at your boiler's output.

Bear in mind that ambient external temperature and wind and wind direction all impact on and exacerbate heat loss (Wid Chill etc).

Alternatively, Damart probably have started their Winter sale by now![I]

[Dc]

Thanks Gluestick you are a star thats exactly what I wanted to know. My problem is that the boiler restarts on a 2 degree drop of temperature on the boiler stat after achieving the required 60 degree this takes about 2 minuters to restart. So it runs for 6 mins then stops for 2minutes until it drops to 58 degrees , restarts and run for 6minutes then stops for 2 and so on until it reaches the required room temperature. I assume that the initial start up of the burner uses the most fuel so if I slow down this 2 minute restart to say 4 minutes I'll use a lot less fuel. Is my hysteresis of 2 degrees the problem or have I misunderstood? All help greatly appreciated.

dc

[Gluestick]

The boiler ' stat simply measures the water temp. in the water jacket, as you know.

Older boilers can needlessly recycle, as the jacket water temp drops.

Once the circulating pump kicks in, the normal water flow moves the static jacket water round the system: unless, of course, a control valve (motorised valve, solenoid one-way valve) is off, when there can be no effective flow, of the TRVs have shot off and the water is circulating straight back with little temp differential.

Now the pump used to be enabled-dis-enabled by the room stat in older systems: so if room temp is within desired and pre-set tolerance, the boiler stat could cycle the boiler, needlessly!

A correctly set-up system should run from fire up, continuously, until the desired room temp is reached and then once the flow stops ( room stat dis-enables the circulating pump) and thus jacket temp rises and boiler cuts out.

Unless, the boiler stat is wired in a fail-safe to guard against excessive jacket temps.

OK so far?

Does your boiler "Kettle"? i.e. make crackling sounds when it's heating up?

It seems as if your system is cycling, needlessly, to me.

Could be the boiler stat has drifted out of tolerance: could be the pump; could be an erratic control valve.

Tell me what installation you have, in detail, please. (e.g. room stat/s; control valves; programmer; silly French diverter flow vale (the four way jobby!), etc.

 

[Dc]

have sent e-mail.

 

dc