New boiler uses more gas than 16 yrs old boiler.

HTC

We had an A rated Worcester combi boiler installed in September, replacing 16 yr old combi boiler. The first gas bill shows we used 88% more gas compared to last year. The Boiler now has been checked by engineer twice by different person and appears to be working OK. So they say maybe the meter is wrong. The Scottish power says the meter looks OK looking at our usage but costs over ￡１００if we insists to check the meter. The plumber asked to run the hottest water for two min. and read the usage, which was 0.1 cubic meter, he says it's normal. Since then we started checking gas usage every day.
Last year we used ave.7.71 c.meter/day during Dec-March. So far we use 8.56c.meter/day from end Nov.to today. Also it took 5 or 6 hours to raise room temperature from15C to 20C when outside was around zero. We live in the same house, same people, same life style. But we changed two radiators in the lounge and dining. We don't know whom we can turn to. Please help.

HappyMJ

HTC wrote: »

We had an A rated Worcester combi boiler installed in September, replacing 16 yr old combi boiler. The first gas bill shows we used 88% more gas compared to last year. The Boiler now has been checked by engineer twice by different person and appears to be working OK. So they say maybe the meter is wrong. The Scottish power says the meter looks OK looking at our usage but costs over ￡１００if we insists to check the meter. The plumber asked to run the hottest water for two min. and read the usage, which was 0.1 cubic meter, he says it's normal. Since then we started checking gas usage every day.
Last year we used ave.7.71 c.meter/day during Dec-March. So far we use 8.56c.meter/day from end Nov.to today. Also it took 5 or 6 hours to raise room temperature from15C to 20C when outside was around zero. We live in the same house, same people, same life style. But we changed two radiators in the lounge and dining. We don't know whom we can turn to. Please help.

Turn the temperature up on the boiler if it's taking too long to heat. May not condense as much and therefore be a little less efficient but you'll be warmer quicker. Last winter ended up quite mild in the end. You need to compare to the weather and your usage seems reasonable.

HTC

We turned up to 4 while the book recommends between 1 and 2. Just can't understand why we use gas more than last year. Last week had been cold but apart from that period isn't it normal?

HappyMJ

HTC wrote: »

We turned up to 4 while the book recommends between 1 and 2. Just can't understand why we use gas more than last year. Last week had been cold but apart from that period isn't it normal?

Colder weather, bigger boiler, radiators cleaned out allowing more heat transfer to the rooms therefore using more gas. Could be any reason....oh...I don't trust the efficiency figures. The don't save as much as they say they do. What efficiency was your old boiler and what is the efficiency of the new boiler? Only replacing G rated boilers seems to save much money. Replacing a boiler that was 16 years old won't save too much in running costs.

jalexa

HTC wrote: »

Also it took 5 or 6 hours to raise room temperature from15C to 20C when outside was around zero.

That is almost certainly key to what is happening (the increased consumption).

The system balance has been changed probably by the radiator replacement. During the longer time it is taking to heat the room you are monitoring, all the other less controlled radiators are outputting more heat than previously.

If I'm right this is an installer problem (assuming the boiler installer also changed the radiators). In the circumstances of an unbalanced system with inadequate output in an area controlled by thermostat, turning up the boiler to 4 further increases consumption.

MillicentBystander

HappyMJ wrote: »

Colder weather, bigger boiler, radiators cleaned out allowing more heat transfer to the rooms therefore using more gas. Could be any reason....oh...I don't trust the efficiency figures. The don't save as much as they say they do. What efficiency was your old boiler and what is the efficiency of the new boiler? Only replacing G rated boilers seems to save much money. Replacing a boiler that was 16 years old won't save too much in running costs.

And if the old boiler was working and 'safe' (no matter how inefficient it was supposed to be) the move will effectively cost you money when you take into account the expenditure.

HTC

HappyMJ wrote: »

Colder weather, bigger boiler, radiators cleaned out allowing more heat transfer to the rooms therefore using more gas. Could be any reason....oh...I don't trust the efficiency figures. The don't save as much as they say they do. What efficiency was your old boiler and what is the efficiency of the new boiler? Only replacing G rated boilers seems to save much money. Replacing a boiler that was 16 years old won't save too much in running costs.

The old boiler is Halstead Quattro Gold combi fan flue boiler. We tried to find the rating of this but couldn't. The new one is Worcester Greenstar 30si and its efficiency is 90.1%

Suppose the boiler's efficiency is 90% but it uses more gas. We understand this theory but then it is a con!

HTC

jalexa wrote: »

That is almost certainly key to what is happening (the increased consumption).


If I'm right this is an installer problem (assuming the boiler installer also changed the radiators). In the circumstances of an unbalanced system with inadequate output in an area controlled by thermostat, turning up the boiler to 4 further increases consumption.

Yes,the installer changed the two radiators. If the turning up the ooiler to 4 increases consumption, the only way to make the room warmer is increase the TRV but it is already 4 which aims at 24C.

closed

7.71 - 8.56 /day is 11% not 88%, which could easily be explained by a slight variation in average temperatures outside or a variety of factors inside.

radiators bled?

if the trv is still letting hot water through, there is no point increasing the setting

Are the 2 radiators the same size, why the change?

Perry525

This year has been cold and miserable, compared to last year.
I have a weather station with transmitters outside and in temperatures, I get a printout which records the current temperatures every five minutes.
Merely looking and going outside, tells me all I need to know, its been colder.

You have a new boiler, what is its output in kilowatts.
How does it compare with your old one?
Is it the same size, smaller?

The new radiators. Are they in the same places? How does their output compare with those you had before?

Using the laws of nature, if you are burning more gas, then more heat is entering your home, so it will be warmer in general, except that the heat may be more widely spread, or in a different place.

Do you have one controlling thermostat?
Is it in the same place?
Do you have temperature gauges in each room? Are they in the same places, are they showing roughly he same temperatures as last year and earlier?

Have you had any other work done to your home, even a small 9mm hole can make the difference between a home being warm and being cold.

When you have holes in your home, perhaps a window slightly open? You have uncontrolled ventilation, the position of the hole, perhaps a trap door to the loft not correctly replaced, can mean a very large increase in the "stack effect" - this is where rising warm air escapes to the loft pulling in cold air from outside.

The relative location of the holes changes the effect when the wind blows, one high and one low hole will strip the warm air much quicker than two holes at the same height.

jalexa

HTC wrote: »

Yes,the installer changed the two radiators. If the turning up the ooiler to 4 increases consumption, the only way to make the room warmer is increase the TRV but it is already 4 which aims at 24C.

You need to state if you have a roomstat, if so in which room and its setting.

The symptoms you describe suggest either an inadequately sized radiator and/or the lockshield valve needs opening up. How "hot" is the radiator getting compared with others?

The aim of "balancing" is (approximately) to equalise the temperature drop across every radiator. That should have been performed by the installer after changing the rads. If you do not have a roomstat, one should have been provided to comply with regulations.

IMO this is an installer created system issue not a boiler issue.