High oil usage

[Geek]

Hi,

We've just had an extension built and a new oil boiler installed (Greenstar 25/32 CF /RS). The original oil boiler was a worcester bosch that was at least 15- 20 years old. It used about 1500 litres oil per year.

The new boiler used 1000 litres in its first 3 months and it looks like its continuing that trend. The extension added 2 new rads and under floor heating as well as replacing the copper tank for a new sealed cylinder.

The UFH is set to 21 degrees for 3 hours in a morning and about 5 hours at night. The rest of the time it is set to 16 degrees. The rads come on for the same amount of time as the UFH is at 21 degrees and hot water about the same. Any thoughts anyone. Does that seem right.

 

[jtsplumbing]

I know little about oil, but that increase in usage is stupid new boiler and consumption as more than doubled have you checked for leek in supply line or someone is steeling it.

 

[SimonG]

How big was the old boiler?
Who installed the new one?
Who commissioned the new one?
Whats the square metreage of underfloor?
Whats the boiler stat set too?
Whats your installer say about it?

 

[Gray0689]

Well heating on say 8 hours a day boiler running flat out possibly poor insulation
Jet size say .65 gallon an hour
Over 90 days roughly 1000litrs

And all simon asked above too

 

[Roger Welton]

How much extra have you added to the house?

With UFH you are better keeping a more steady temperature constantly than letting it constantly heat up and then cool off.

 

[Geek]

Thanks for the quick replies.

A few answers...

Oil isn't being stolen as it is well away from any public access and is in a new locked tank. The installer came back and checked the supply pipe doing a pressure test to make sure there were no leaks.

The floor size for the UFH is about 10m x 4m

Not sure what size the old boiler was.
Stat on the front of the boiler is set half way and on the burner is set to 4.

It was installed by an oftec certified plumber who reckons it is fine.

The new extension is stuffed full of insulation which is where the UFH is.

 

[Gray0689]

What is Total size of house now
What insulation is in extension
What is the floor sand and cement screen ? What depth what size underfloor pipes?

 

[Geek]

House is now 4 beds (was 3)

Insulation is kingpin not sure what type

Floor is Concrete slab, then kingspan foam type insulation about 3 inches or more deep, then screed poured over the pipes

 

[lame plumber]

frost stat coming on, no pipe stat, just been to one of these, now set up properly

 

[PhoenixServices]

What was the boiler before and now?

 

[Geek]

frost stat coming on, no pipe stat, just been to one of these, now set up properly

Thanks. Where would the frost stat normally be located?

 

[magicno1]

Well heating on say 8 hours a day boiler running flat out possibly poor insulation
Jet size say .65 gallon an hour
Over 90 days roughly 1000litrs

And all simon asked above too

How did you get to 1000ltrs???? Not being funny just how you don't the math?

 

[Chalked]

I would work it out like this.

.65 nozzle boiler timed to be on 8 hours a day, but will probably fire for 3/4 of the time.= 6hours.

.65 x 6=. 3.9 gallon per day ( us gallon)

x 90 days = 351

x 3.78 ( us gallon - litres) =1326 litres in 90 days.

 

[magicno1]

I would work it out like this.

.65 nozzle boiler timed to be on 8 hours a day, but will probably fire for 2/3 of the time.= 6hours.

.65 x 6=. 3.9 gallon per day ( us gallon)

x 90 days = 351

x 3.78 ( us gallon - litres) =1326 litres in 90 days.

I see
thanks very much

 

[Gray0689]

I would work it out like this.

.65 nozzle boiler timed to be on 8 hours a day, but will probably fire for 3/4 of the time.= 6hours.

.65 x 6=. 3.9 gallon per day ( us gallon)

x 90 days = 351

x 3.78 ( us gallon - litres) =1326 litres in 90 days.

Exactly how I did it
Just was being on the low side that's why I said 1000litres

 

[SimonG]

25/32 uses a .75

 

[Gray0689]

There you go even more conservative estimate

 

[Geek]

Thanks for all of the replies. I guess the figures are correct then. just hope spring comes soon!

 

[Chalked]

25/32 uses a .75

So could have used 1500 litres.

the op was concerned abut using 1000 litres, looks like it's working correctly.

 

[SimonG]

Its always the same with a new boiler. I go to price up a new boiler and somebodys been in before saying they will save over 20% on fuel. Oh no you wont.

 

[Best]

The underfloor heating I believe tends to have the boiler running on & off for a very long time as it builds the heat up. It is never cheap.
The boiler heating rads shouldn't be firing 6 out of 8 hours on, unless it is very undersized. First hour is the long burn time, but that would normally be maybe half an hour overall in average weather & the next hour much less, until only a few minutes each hour if heating kept on.

 

[Millsy 82]

Its always the same with a new boiler. I go to price up a new boiler and somebodys been in before saying they will save over 20% on fuel. Oh no you wont.

That's especially true with oil as even the old ones are fairly efficient.

 

[Nostrum]

That's a big boiler for a 3 bed with a well insulated extension

 

[Geek]

Its a 4 bed house now since the extension.

 

[Nostrum]

Even so, it's quite large. Do
uou know the floor area?