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we read it the 1st time. 
gas usage trebled since installing Worcester 37CDi combi?
- Thread starter pooch251081
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we read it the 1st time.
Think the forum is screwed mate there are double triple and quadruple posts all over the place not the posters fault
Sorry, appears to be some fault with the site as keeps repeating my posts, sorry!!
It's happening on all of the forums not your fault mate
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Is it short cycling at all in CH mode? I.e. firing repeatedly every few minutes
It sounds like your boiler is oversized for your currently installed system. Whilst it will modulate to match the load, its highest efficiency is at higher output. It's worth getting a reading of your return temperature to check its dissipating enough heat through the rads to work in condensing mode.
A condensing boiler not working in condensing mode is just a boiler. That efficiency improvement comes almost completely from recovering waste heat from the flue gases. If the temperature difference between the flue gases and the return is too small, there will be no condensing and no extra efficiency.
It sounds like your boiler is oversized for your currently installed system. Whilst it will modulate to match the load, its highest efficiency is at higher output. It's worth getting a reading of your return temperature to check its dissipating enough heat through the rads to work in condensing mode.
A condensing boiler not working in condensing mode is just a boiler. That efficiency improvement comes almost completely from recovering waste heat from the flue gases. If the temperature difference between the flue gases and the return is too small, there will be no condensing and no extra efficiency.
we had some hulking great boiler with a preheated reservoir in an house - i was watching the gas usage weekly at that time and it used £14 quids worth of gas while we were away on a two week holiday.
it was summer, so the heat demand was off, that brute was costing me around £365 a year before i even turned on a tap. and this was 7 years ago.
it's worth reading the manual very carefully with some of these machines,
some designers idea of a great feature might be your idea of a hare brained idea....
it was summer, so the heat demand was off, that brute was costing me around £365 a year before i even turned on a tap. and this was 7 years ago.
it's worth reading the manual very carefully with some of these machines,
some designers idea of a great feature might be your idea of a hare brained idea....
You are most likely correct, i know it's know its too big for the current system but as I said before we plan to extend and that will add on almost twice the size of room space so twice the rads, underfloor heating and a second bathroom hence the 37CDi choice (we dont want a large water tank). So what Im sort of asking I guess is how to mamximise its efficiency for now so i can just keep my gas bills as low as poss until we extend.
For example, can I turn the water thermostat down and only turn it on when I want to have a shower perhaps?
Yes, at setting 4 it was cycling every 5 minutes as it wasnt holding room temperature well, now i have turned it up to setting 5 (70 degrees water temp in boiler) it is holding much better and not cycling so much, but is this a double-edged sword? i.e. ive had to turn the energy output up so even if its not cycling so much its still using more energy to cycle?
For example, can I turn the water thermostat down and only turn it on when I want to have a shower perhaps?
Yes, at setting 4 it was cycling every 5 minutes as it wasnt holding room temperature well, now i have turned it up to setting 5 (70 degrees water temp in boiler) it is holding much better and not cycling so much, but is this a double-edged sword? i.e. ive had to turn the energy output up so even if its not cycling so much its still using more energy to cycle?
If you assume it's heating the house for 10 hours then the 20kW calculated heat loss becomes 14W. Your 26500 BTU equates to 8kW. So the difference has narrowed to 6kW. Things that might help bridge the gap are hot water usage, is it -1°C outside or actually a lot colder, is the 14 units day a true reading for one 24 hr heating cycle? Also there's no account of the extra energy used to raise the house temperature once in the morning and once in the afternoon, rather than maintaining a steady temperature. Given that this is a very rough and ready calculation I don't think your gas usage sounds drastically wrong.
Its between -1 and -3 outside here at the moment, so I'm guessing its working pretty hard, but still, what I dont understand is how the old boiler can have been using so much less, I guess this must just be because it was a lot smaller and hence more closely matched to our current system.
What does everyone think about me turning the water stat down and only switching the water on when I need to use it? Not sure what setting to put the water on though as thought the "e" mode was meant to be the most efficient?
What does everyone think about me turning the water stat down and only switching the water on when I need to use it? Not sure what setting to put the water on though as thought the "e" mode was meant to be the most efficient?
It may be possible to alter the settings on the boiler to lower the max output in C/H mode, thereby creating a lower power boiler that is more suited to your current house (I work with Vaillants, which have this feature, I'm sure a WB would too). This may improve things. A properly commissioned condensing boiler will be more efficient than your old Ravenheat. There should be a 20ºC difference in the flow and return temperatures. It may be that your central heating system needs balancing also.
On the hot water side, if you think a combi boiler of any description is going to be able to cope with providing hot water to two bathrooms simultaneously I'm afraid you're very much mistaken, you really need a hot water cylinder for that.
On the hot water side, if you think a combi boiler of any description is going to be able to cope with providing hot water to two bathrooms simultaneously I'm afraid you're very much mistaken, you really need a hot water cylinder for that.
Oh no, I wasn't expecting to be able to power both bathrooms at once, but there'll be more water based areas and i'd like to think it will be possible to use hot taps and have a shower at least and if the house is going to be 4 bed, then I don't want to be operating a boiler that's struggling.
So, I thought exactly what you were thinking about lowering the CH output on the thermostat, thats why I tried setting it to 3 but it wouldnt even reach room temp?? This is what is weird, how can this be a bigger boiler yet not even reach 20 degrees on setting 3? I now have it on 5 and its heating quickly yet not cycling so much Im not sure if this is good or bad
So, I thought exactly what you were thinking about lowering the CH output on the thermostat, thats why I tried setting it to 3 but it wouldnt even reach room temp?? This is what is weird, how can this be a bigger boiler yet not even reach 20 degrees on setting 3? I now have it on 5 and its heating quickly yet not cycling so much Im not sure if this is good or bad
Oh yes and the system was definitely balanced so I think that can be ruled out. Still wondering about this "e" mode on the DHW? Any ideas anyone?
Agreed. If any of the rads are receiving too much flow and not dissipating that excess heat then the return temp is going to be unnecessarily high. This will reduce efficiency, not only through being less able to condense but also due to the inevitable additional cycling if it cannot modulate low enough.
Mathew
How was it done? What were the temps and drops?
Did you mention fitting new rads? If so, has it subsequently been rebalanced?
Really; do not underestimate the benefits of a properly balanced system - not only for efficiency but efficacy too.
Mathew
Yeah the boiler was fitted just after the new rads were put in and the system was then balanced, I had the installer check this again tonight though and he said it is fine, he couldnt find any fault with the boiler or the pressure/pipes/gas consumption at the meter
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