gas usage trebled since installing Worcester 37CDi combi?

[pooch251081]

I am at my wits end over what is going on with my heating system and could really use some advice.

We moved into this 2 bedroom 1920s cottage (concrete walls with unfilled cavity, 200mm loft insulation, all double glazed) three months ago and had been getting on ok with our old Ravenheat RSF820 non-condensing boiler, up until a week ago (which was still very cold) our daily gas usage was only 5/6 units according to the meter (I believe it is cubic meters) and our bill around £58 a month (we have no other appliances that are gas except the heating).

Now we have fitted a new condensing Greenstar 37CDi boiler from Worcester because we are planning to extend next year into a 4 bed house with 2 bathrooms. Now, I realise this is probably too big for our 2 bed house currently, but what is going on makes no sense. I have turned the CH thermostat down to 4/5 so the water inside the boiler heats to 63 degrees (the same setting as with our ravenheat) yet the room takes nearly 3 hours to reach 20 degrees when our old boiler only took half an hour? Surely this new boiler is more powerful and should heat the rooms much quicker? We also now see that our gas consumption has trebled since fitting although none of our timers have changed their programming and cannot see any obvious leak (have had the fitter round to do more checks) as the meter doesnt change when the system is off.

Does anyone have any ideas why this might be happening and is there anything I can do to lower our gas consumption using this boiler because I don't think using 14 units a day when we were using only 5 last week is even possible yet this is what we are facing?!

 

[stratovarius692]

Hot water, the worcester is using 30 KW to heat it whereas the ravenheat ~24kw... Hence more gas usage. The CH will modulate down as it gets to temperature

 

[simond]

Gas usage is proportional to external weather temperature.

Have you seen the weather recently?

I should stop counting the dials on the meter and find something more useful to do with your time. Reading MoneySavingExpert forums perhaps?

Joking apart, you will only see a realistic comparison after a year or so is averaged out, especially because of the exceptional weather.

 

[KevC1]

Turn your boiler up so the temp is 75. It will be in condensing mode for longer and be more efficient. The heating shouldn't cost any more than before.

Incidentally, why didn't you go for stored water if you're having more than one bathroom?

 

[paulburton]

As I have the Worcester 30 CDI Combi (great boiler) I thought I would add, I noticed mine was using a few units extra, even with the heating off, I then read the manual, and found out to turn off the ECO button (this is pre heating the hot water) - it may keep turning it's self back on because of the timer. If you are out during the day, and don't need this feature, turn it off


Paul

 

[pooch251081]

Lol ok fair point, I'm sure I do sound very finicky but it just annoys me as we have spent all this time and cash investing in a supposedly efficient boiler to find on the same settings its stuffing out three times the gas.

R.e water, yes that may be worth looking at, at the moment we've got it on the "e" setting, thinking this was meant to be the most economical but perhaps while were only using one shower could try turning thermostat down on water maybe, good idea or not?

I know the weather is horrendous but as I explained we only replaced the boiler three days ago and it was just as cold last week in terms of temp but we used far less gas with the old boiler, just v odd how on same setting this energy ridden thing is taking so so long to heat up the room

 

[pooch251081]

Yeah I also realised about that eco button for water pre heat and now have it timed to only come on in the morning and at night but still our usage is way too high? I did notice that the water in the boiler heats to about 63 and then burner cuts out for a bit and then re ignited about 5 min later, but I have it on setting 4 because I thought condensing will only take place if output is low enough to ensure return temp is 55 default or less, no? Just wondering if 75 might be too high in that case?

 

[dumbrill]

Does anyone have any ideas why this might be happening and is there anything I can do to lower our gas consumption using this boiler because I don't think using 14 units a day when we were using only 5 last week is even possible yet this is what we are facing?!

Are your unit figures in m3 or ft3 and are you reading the red or black figures on the meter. Also on a typical day in which you are using 14 units how long is the heating switched on for, eg. 5am on until 10pm would be 17 hours. With these figures and based on the fact the its currently very cold it's possible to do some ball park calcs on energy used which will test some of the numbers your giving.

 

[PEDANTICVINDICTIVEMAN]

Because we have all been sold down the river with all this energy saving bollokks, I was told it would be no harder to fit a condenser than an ordinary boiler, yea right, so why do flue analizers all of a sudden become compulsory, and condensate pumps and condensate nuetralizers and soakaways and filters and plume kits ad nauseum, welcome to the world of "efficient" boilers

 

[pooch251081]

Ok so more specifics... I've got the DT10RF timer and its got 4 on times, from midnight to 530am its set to 15 degrees so the house doesn't get like an icicle overnight (but presumably doesn't need to fire excessively at this temp?) Then at 530 it comes up to 20 until 745 then it drops down to 8 so its not on all day until I get in at 530pm where it stays at 20 most of the evening. I've got the CH output on 4 to 5 at the moment and water on "e" whatever that is, and yes, its in cubic meters not feet

 

[Tibbot]

Because we have all been sold down the river with all this energy saving bollokks, I was told it would be no harder to fit a condenser than an ordinary boiler, yea right, so why do flue analizers all of a sudden become compulsory, and condensate pumps and condensate nuetralizers and soakaways and filters and plume kits ad nauseum, welcome to the world of "efficient" boilers

Good points. Add to that spiralling spares prices, 'once only' use door seals and rotting heat exchangers, so clad with plastic they'll end up in landfill rather than be re-cycled........ CON-densing indeed.

 

[dumbrill]

Ok so more specifics... I've got the DT10RF timer and its got 4 on times, from midnight to 530am its set to 15 degrees so the house doesn't get like an icicle overnight (but presumably doesn't need to fire excessively at this temp?) Then at 530 it comes up to 20 until 745 then it drops down to 8 so its not on all day until I get in at 530pm where it stays at 20 most of the evening. I've got the CH output on 4 to 5 at the moment and water on "e" whatever that is, and yes, its in cubic meters not feet

It sounds as if you have your heating on around 7 hours a day and in that time you're saying you use 14m3 of gas. That equates to 558361kJ of energy. You use that energy over 7 hours, ie. 79766kJ/hr or 22kW of heat loss. If the boiler is 90% efficient then your using approx 20kW to heat your house. It sounds a lot for a small house. I guess at the moment most systems would be working at their rated capacity and 20kW is a lot of radiators.

How hot do have the thermostat set to and is it really only on for seven hours?

If you assume that for every 1m of single panel radiator the heat loss is 1kW than how many kW in total have you got?

 

[pooch251081]

No I think its on for 9 hours but I've also got it set to 15/16 overnight so it's less heat but its another 5 hours on occasional firing? Plus we obviously both shower once a day on top of this and my hot water is timed on for two hours in the morning and from 5pm all evening. I really don't have many rads, the overall BTU is 26500 not sure what the conversion to kW is but its not a lot! I realise its an old house and its got two layer unfilled cavity walls (but does have 200mm loft insulation) but this seems far too high still. Not sure what to do??

 

[SpecialK]

Any ideas why it might be taking 3 hours to heat your house? Do the radiators not get as hot as on the old system?

 

[pooch251081]

R.e. three hours to heat to room temp... I have no idea, I would have thought that since its a more powerful boiler it surely should have taken less time?? Ive actually replaced two of the rads for double convectors and twice the length, not sure if this has affected it but i know that between 530 and 630 it only heats up from 15/16 degrees to 19 on setting 4/5 i.e. digital display says water is at 63 degrees in boiler. The old system seemed to heat it up quicker at a lower setting but perhaps boilers are directly comparable on their individual settings and i know if i turn up the CH thermostat the rads do get much hotter but is this just going to waste even more gas? Doesnt seem very "efficient"!