How much oil does heating boiler consume per hour?

[MM]

My new house is equipped, in the garage, with a wall-mounted oil-fired central heating and hot water boiler. It is an "HRM Wallstar", approx

2' 6" high, 10" deep and 15" wide. There are 9 radiators in total. How much in litres per hour is this boiler likely to consume? This to give a comfortable temperature, but not hot, despite the current rather cold climate (I hate hot houses).

I had 1,000 litres filled on 21st December (the tank was almost empty) and was pleasantly suprised the other day to see that the level has not gone down much at all since then. Obviously, the house is well insulated. The hot water is, if anything, too hot.

MM

[John]

The data you give is meaningless. 9 radiators gives no indication at all of how big, how many panels, what you consider to be a comfortable temperature probably does not agree with someone else, what your hot water usage is, the room sizes, whether you have a detached or a terraced house of bungalow etc etc etc. So in short its impossible to give any form of sensible answer I'm afraid.

You should have a cylinder thermostat which you can turn down but don't turn it down too far or legionella might start to grow in your system:-(

[James Salisbury]

Post some details of your boiler, and what thermostats you can find round the place.

[Dave Liquorice]

The documentation should have that information or it might be on the rating plate. Our big cast iron lump has a spec that around 7l/hour but it is big, 38kW output. Oil has about 10kW/l of energy so that means about 50% effiency which for ordinary cast iron conventionaly flued boiler is about right.

Tiddly tank then. Filled ours up with 2000l on the 23rd Oct more than half of that has gone, estimated reorder date for another 2000l is 2nd Feb, that should last until October. Drafty old stone built house with little insulation at 1400' on the North Pennines, so a little different to the sub-tropical south. B-)

[Alec]

The oil consumption is on page 8 here :

[The Natural Philosopher]

On a 3500 sq ft house, I have got through 2200 liters since August - just about to refill. I reckon a modern well insulated 4-bed family house of half the size probably would take half that or less. Usage seems to be almost zero in 3 summer months, and twice as much in winter a spring and autumn. Which means that 2200 liters is for me autumn and half a winter.

Or anbout 3 months of winter usage. So I am cracking around 700 liters a month in winter. It snot been a month since dec 21st., so I would probably have used 500 liters in that time.

I would guess that you have used less than 250 liters.

[Rob Morley]

Watts aren't energy, they're power. Joules are energy.

[MM]

Thanks, Alec, for the the information I requested!

MM

[Malcolm Reeves]

He meant kWhr (or electricity units if you prefer). 28sec oil, or kerosene, is 10.35kWhr/l. So 85% efficient boiler and 24.68p/l the equivalent unit price is 2.80p.

BTW in case anyone is interested the figures for LPG are about 600 units in 47kg (the large bottle). So at 26.50 per bottle that 4.4p per unit. Add in the boiler efficiency and full rate electricity is cheaper than LPG!

[Tony]

if you want to know how many US Gallons (for some reason its what the measure it in) per hour you use , you will need to know your pum pressure and your nozzle size (in US Gal) I have a chart to work it all out for 35sec oil , but not 28sec oil , dont think it would make to much difference though

-- Tony

[Rob Morley]

But when you're snowed in and the power goes down you'll be glad you use LPG instead of electricity :-)

[Dave Liquorice]

Most boilers still need electrickery to operate the gas valve and then of course there is the circulation pump...

I also suspect that most people using LPG for space heating would be using bulk LPG rather than bottled. How many litres are there in a

47kG cyclinder?

[Malcolm Reeves]

Not necessarily. The installation requirements for an LPG tank are much stricter than bottles. Tanks have to be metres from the house or underground. Bottles can be right next to the house. We have both in my village, tanks in the middle of the lawn (3m from boundaries so you need a big garden) and bottles next to house on a blank wall.

I reckon it is 24150 l, so 0.11p/l for 47kg at 26.50. How does that compare with bulk LPG?

[sylva]

I read that the propane density is 500kg per m^3, lpg is a mixture but principally propane, that gives me 94 litres to the 47kg cylinder and at GBP26.5 for 47kg about 27.5p/ltre, 4.3p/kWhr.

AJH

[Dave Liquorice]

eh that doesn't sound right. Our 2,500l oil tank is 6' x 4' x 4'... Maybe you are thinking of the gas volume? Which isn't how you buy LPG as gas volume is *far* too dependant on temperature and pressure.

1m^3 of propane weighs 583kg at -40C (near as damn it it's boiling point) so 47kg occupies 0.08m^3 or 80l thats more like it.

Or more correctly 33p/l which fits vaugely with autogas prices... I think bulk (no road) LPG is nearer the 20p/l or less mark...

[Mike]

That's far more like it. Bulk was 23p/litre when we had it and when it when up for the fourth time in a year I told them to come collect their tank and put in oil.

Of course oil prices then went into overdrive as well but that's another story :-)

[Malcolm Reeves]

Oops. I seem to have propane as 0.5kg/m3 so I think I have missed a

1000 there somewhere. And I worked the numbers out wrong too! Doh!

Sounds like bottles are not that much more than bulk 23p/l vs 27.5p/l.

And we agree on the kWhr price.