Why Isn't My New Worcester As Efficient As My Old Boiler?

[pototea]

I have a house which was two flats when I bought it, but not converted properly. So I made it back into a house and was left with a combi Potterton boiler that controlled the heating and hot water downstairs and a combi Potterton that controlled the heating and hot water upstairs.

My quarterly bill for this time last year read (2 Pottertons & 2 bills):

Date------------------------------Units--------------Cost
07 Mar 08 - 27 May 08----------5234.53----------£180.57
28 May 08 - 25 Aug 08----------1448.24----------£90.01

That was for a 2 bathroom house with 3 adults.

In February, I got an loft conversion. I decided to get the boiler issue fixed as two bills was more expensive plus the 2nd boiler was in a bedroom which meant I couldn't rent it out at a good rate etc so I got a Worcester 440Cdi combi installed.

Now I have a 3 bathroom house with 4 adults and one extra storey with a small radiator.

I am quite surprised at the increase of the number of units:

Date------------------------------Units--------------Cost
02 Mar 09 - 25 May 09----------5866.32----------£210.96
26 May 09 - 26 Aug 09----------2665.76----------£109.67

Ignoring the cost as prices have fluctuated a lot over the past one year, does anyone have a logical explanation of why the usage is significantly higher? I really can't see how there is an 84% increase just by having 1 extra person in the house compared to this time last year. The heating has not been used in the past 3 months.

Is there a way for me to measure the gas usage of the boiler? The only other gas appliance is the cooker.

Is it possible to reduce the temperature of the water in the internal water tank of the boiler so I can stop it maintaining the water at that temperature? When I look at the boiler, quite often I see it "on" even though no-one is demanding any hot water. I am assuming it is heating the internal hot water tank.

 

[DP]

Is a room thermostat fitted to the new boiler?

A combi is a thirsty beast. 40kwatts as opposed to say 16kwatts- even seconds on a 40kwatts boiler will consume fair amount of gas during cycling when boiler fires needlessly or heats water every time a hot tap is run.

 

[pototea]

Is a room thermostat fitted to the new boiler?

A combi is a thirsty beast. 40kwatts as opposed to say 16kwatts- even seconds on a 40kwatts boiler will consume fair amount of gas during cycling when boiler fires needlessly or heats water every time a hot tap is run.

I have a digital thermostat in the hallway and TRV's on all the radiators. But since the heating hasn't been on in the last quarter then I am struggling to see the high cost of the bill.

How can I measure how much the cooker uses?

 

[namsag]

Its not the cooker its the boiler heating its stored water

 

[pototea]

Is there a way to stop it?

 

[gas4you]

Is not the wb 440 the same as the 400 except an HE version? If so this is only a 23Kw boiler with a small hw cylinder fitted.

I cannot see how your gas consumption can go up so much!

the boiler will be using some extra gas to keep the small hw cylinder hot and ready for use, but not this much.

 

[bengasman]

Your total bill has gone from £270 to £320 if my maths are correct, that is hardly a 84% increase, in fact less than 20%. The price of fuel has gone up enormously during that period, that alone could be the difference. It could also be based on estimated readings in stead of actual meter readings.
You will gain some (up to about 10%) by turning down the boiler stats to such a temperature that the return is below 55C.
It could well be that your system is not set up correctly, and the balancing is off.
Having the roomstat in the hall is not the most economic either.
Turning the roomstat down by 1 degree and the trv's by 1 click will also safe you 5 - 10 percent.
There is a more extensive bit about thermostats and how to set them to minimise the gasbill in FAQ.

 

[pototea]

Hi, my bill is always based on actuals, never estimates. I always ensure of this as I hate paying over or under.

The thermostat has nothing to do with the bill as I haven't used the heating in the last three months.

I was ignoring the cost and only looking at unit usage as I know the cost has fluctuated a lot.

 

[D_Hailsham]

When water is stored in a cylinder, i.e non-combi system, it needs to be at a temperature above 60°C to prevent the growth of Legionella. This is not necessary with a combi boiler.

What number is the Hot Water temperature control set to (Min = 45°C, Max = 65°C)? As typical bath and shower temperatures are between 35°C and 40°C, there is no need to heat the water to above 45°C.

Have you tried using the Economy button? This turns off the hot water storage, so you don't get hot water instantanously. But if you put the plug in as soon as you turn the tap on, you won't waste any water - you just don't have to run the cold tap for so long to obtain the desired temperature in the bath/basin.

 

[doitall]

Now I have a 3 bathroom house with 4 adults and one extra storey with a small radiator

Makes I laugh, at the thought of some sales shark flogging a combi to some poor old dear that don't know better.

I would say occupancy habits would play a large part in the usage, and I can't see how you can compare one against the other.

 

[pototea]

Why should it make a difference if I have one person or ten people in the house? All the plumbers recommended a storage tank and standard boiler but I wanted a combi for my own reasons and I am happy with my choice.

It is on a rare occassion that more than one person is using a shower and the 440Cdi is built for 2 bathrooms. I don't live in a mansion, I have a standard mid terrace with 13 radiators, all of which are appropriately sized for the room.

All I am looking for here is some advice on what could cause such a significant increase in the number of units used comapred to this time last year.

And yes I can compare to the Worcester to the Potterton because the only change in the bills I am comparing is extra use of the shower and cooker.

 

[bengasman]

Why should it make a difference if I have one person or ten people in the house?...

Provided the extra 9 people do not bathe, shower or cook, it makes no difference at all how many people are in the house.

Do you have any idea why the difference between the 2 march bills is 10% in units, and about the same in price, whilst the may bills show nearly double the units, and only 20% increase in price?
Do you often change suppliers to take advantage of the best price?

 

[pototea]

Do you have any idea why the difference between the 2 march bills is 10% in units, and about the same in price, whilst the may bills show nearly double the units, and only 20% increase in price?

I have no idea why. The people in the house did not change during end February to end of August. Both bills were definitely based on actuals and not estimates and it confirms this on the bills "we read your meter"..

Do you often change suppliers to take advantage of the best price?

I do keep a regular look out. I am on BG Click 4 and I haven't changed tariff for about one and a half years. But as I said earlier, the cost is irelevant as this time last year I had two boilers and two gas bills with the unit tiered pricing. Which is why I am comparing the unit usage only.

 

[doitall]

Are they the same adults now as before.

Of course it can make a very big difference, to the water usage.

Compare 4 adults having a shower once a day 5 mins each, to 4 adults having baths, Females tend to use twice as much water as males.

Are the runs from the hot water source twice as long now you don't have a cylinder, meaning you waste more water.

I can think of a dozen reasons why 1 adult would use twice as much water as another.

As I said you cannot compare the two boilers, because the occupancy has changed.

 

[pototea]

Hi, there is one new female adult in the house compared to this time last year, the rest are the same. She has showers, not baths.

I am really trying to pin point where the extra usage is coming from, whether it is the cooker or the boiler.

Is there a way to clip a device onto the meter, like with the electric, to see how much gas each appliance uses? I have an old cu ft meter so looking everytime after someone has a shower or cooks doesn't really change it.

I am just trying to work out what has caused a significant jump in the last quarter May - August compared to this time last year when the previous quarter March - May seemed an as expected "normal" increase compared to the same period last year.