Boiler efficiency in the real world - old WB vs new Intergas

Discussion in 'Plumbing and Central Heating' started by StuB, 17 Jan 2019.

  1. StuB

    StuB

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    We currently have a WB 35 CDi RSF ii that is about 13 years old and has given good service but looks like it needs a new diverter valve and possibly heat exchanger which can probably be sorted for somewhere between £200 and £400.

    My other option is to put the repair costs towards a new boiler and I'm looking at the Intergas Xclusive 36 which should be around £2K fitted.

    The WB has an efficiency rating of 78% and the Intergas doesn't seem to be listed on the site but there are references of it being 89% elsewhere.

    My question is in the real world does this actually pan out as the numbers suggest or are the figures just headline grabbing?

    While I appreciate that the cheapest option is to repair the existing and carry on if it's likely to save £70 a year in gas along with the repair costs and leaves me with a boiler with a 10 year warranty and no future aggro then it's worth considering.
     
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  3. StuB

    StuB

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    One more thing is the Intergas Xtreme worth the extra money for a bit more efficiency?

    Looking at the spec sheet it looks like the Xtreme 30 should provide the same amount of hot water as the Xlcusive 36 (13.5l/min) however the warranty looks to be 7 years not 10 and I'm guessing it's going to be more complex inside negating part of the benefits of the boiler in the first place.
     
  4. muggles

    muggles

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    The quality of the installation is as important as the boiler being fitted. If you think you're going to get a decent job done for £2k on an Intergas Xclusive 36, you're going to be sorely disappointed.

    The efficiency of the boiler will be affected by a number of things. Using a decent OpenTherm control such as a Honeywell T6 will help a lot, as will running the boiler as cool as possible (which OpenTherm will help with anyway). Condensing boilers only condense when the return temperature is below 52°C; above that, the efficiency drops off. Space heating efficiency on the Xclusive is 92%, water heating is 89%. The Xtreme is aimed at the new-build housing market; I don't think there's any advantage to the average consumer
     
  5. bernardgreen

    bernardgreen

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    is that a test laboratory result or a real life result. The intergas heat exchanger has a significant amount of aluminium that has to be heated before any heat reaches the water flowing to taps. When the tap is turned off the heat in the aluminium disipates as wasted heat.

    probably not as the Intergas seems to be a landlord friendly boiler.
     
  6. StuB

    StuB

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    Thanks for the quick replies and info. I've got a Drayton Wiser thermostat with remote control radiator valves on almost all rads. This system supports opentherm so hopefully that should all work with the Intergas.

    As it's replacing an existing system where the pipework and waste for condensate are already in place and the flue should be easily replaceable I was hoping it would be a fairy easy install. Radiators will need flushing. How much would you expect a quality install to be?

    If a ballpark figure suggests it'll be lots more then obviously it makes the upgrade less economic and obviously I'll get a proper quote if I decide to go ahead. I'm based near the Intergas factory and they've given me numbers for a couple of local installers they recommend.

    Any idea if the 78% for the old WB is an average for both heating and hot water?

    If the existing system returns water at less than 52C when the heating is on and the house is warm enough on cold days, does this mean that the new boiler should condense?

    And if it does would you expect the efficiency gains to materialise as the numbers suggest?

    Thanks again for the help and advice, it's much appreciated.
     
  7. Razor900

    Razor900

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    Go for the Xclusive you don't need an Xtreme and the extra 3 year warranty clinches it.

    They work well with Wiser and the low load performance when only a couple of rads are on will be light years ahead of your existing boiler

    I'd ignore Bernie, it's uncertain whether he's ever actually seen a working Intergas boiler and he definitely hasn't seen a working Xclusive - unlike me!

    2k would be doable if it's a straight swap but obviously the internet isn't the place to quote for something unseen although a picture might make it easier

    If you can narrow your location down at all, it would help?

    Oh and the Xclusive is an awesome boiler (y)
     
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  8. StuB

    StuB

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    @Razor900

    Thanks for the info.

    The extra simplicity, lower cost and extra warranty draws me to the Xclusive.

    I'm based in Bromsgrove, Worcestershire and have spoken with one of the recommended installers who gave a ballpark of £2K based upon description and I've not heard back from the other yet.

    Interesting you mention about low load performance. It's an old house with no cavity walls in most of it and both myself and my other half work from home quite a lot and often spend a lot of time in one or two rooms so a lot of the time just one or two rads are on.

    In that scenario from an efficiency point of view can you quantify how much better the Intergas would be than the WB? Just trying to see if the man maths works :D
     
  9. Mottie

    Mottie

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    Wont most, if not all, modern boilers modulate down if only a couple of rads are in use? I’m sure my Vaillant does.
     
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  11. bernardgreen

    bernardgreen

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    Does one have to see a working appliance to be able to form an opinion about its operation ?

    It is possible to form a valid opinion about the operation of an appliance from technical drawing and/or images of that appliance.
     
  12. Dan Robinson

    Dan Robinson

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    And what primary sources of data have you used??
     
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  13. Razor900

    Razor900

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    Not in your case Bernard. You made an assumption then searched for facts to support it instead of collecting empirical evidence and basing your conclusions from that. That's why you persist with your test houses and conspiracy nonsense when the reality is the boiler was tested in the same manner as every other boiler.

    So even if the test is somehow flawed the results between different brands are still comparative
     
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  14. Razor900

    Razor900

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    Same sentiment but rather less verbose @Dan Robinson :LOL::LOL::LOL:
     
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  15. Razor900

    Razor900

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    Yes but it depends how far the modulate down, some boilers even on low fire still put out more power than the house needs when up to temp.

    With modern controls there may only be one or two rads in use which makes it even more crucial.

    I've seen the Xclisive running at considerably less than the rated minimum output with some careful setting up
     
  16. Razor900

    Razor900

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    Really hard to quantify as you can probably imagine. How much do you spend on gas a year?
     
  17. StuB

    StuB

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    Not loads at about £550 to £600 a year but if it makes £60 or £70 a year difference then over 10 years and with not having the the repair costs of the WB then it starts to make more financial sense.

    I'd spotted that the Xclusive modulated down to about 4kw instead of the 7kw+ of the Eco RF.
     
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