update for r2d2,water sys and jimbo

Discussion in 'Plumbers' Talk' started by jonob, Feb 8, 2007.

  1. jonob

    jonob Member

    re excessive gas use

    had bg round and they have done all the tests on boiler

    its burning correctly , its modulating correctly

    he says its impossible for the boiler to burn so much gas on the load its working at

    you couldnt leak that much , he says :)

    so getting a meter test - its the only other option so bg says

    but when i rung my energy supplier to ask for a meter test they were extreamly snotty - even though i have to pay its £75
     
  2. Jimbo

    Jimbo Screwfix Select

    How old is the meter? Has to be changed by supplier every ten years iirc.

    I'd write them a letter about it, stating that you're happy to pay the £75 charge but if gas use returns to normal you will expect full refund and will reduce the amount owed over the suspect period by the same %age.

    It's such an enormous amount of gas for a domestic property, I can't see you'll have much problem?
     
  3. jonob

    jonob Member

    meter is only 6 months old

    paid £144 bg call out and told them if meter is proved to be faulty then i expect £144 + £75 back

    good thing is as soon as they put a new meter in i will know straight away if old one was faulty , as per readings on the new one !
     
  4. Water Systems

    Water Systems New Member

    meter is only 6 months old

    paid £144 bg call out and told them if meter is
    proved to be faulty then i expect £144 + £75 back

    good thing is as soon as they put a new meter in i
    will know straight away if old one was faulty , as
    per readings on the new one !

    <u>If they are wrong they pay.</u> That has always been the case even when the superior Gas Board was running things.
     
  5. doitall

    doitall New Member

    And if you had bothered to do the simply 2min test I ask for at the very start of your 1st thread, it would have answered the question.
     
  6. r2d2

    r2d2 New Member

    its burning correctly , its modulating correctly

    So can you drop the flow temperature by using the boiler controls alone ???
    What was the corgi guys view on this ??.
     
  7. r2d2

    r2d2 New Member

    Potterton confirmed that their is NO CH flow temperature control on this boiler.
    So it has to be fitted separately.
     
  8. jonob

    jonob Member

    apparently this type of boiler modulates it self and adjusts the flow temp its self

    corgi guy says its doing this correctly

    from potterton book " to suit conventional rad systems the boiler will output a flow temp of 80 deg ,the boiler control will automatically repsond to lower central heating needs by reducing output - thus saving wasteful on-off cycling "

    its here on page 7

    http://www.potterton.co.uk/products/literature/PowermaxHE_InstallationService.pdf

    thanks so far

    doitall - whats your verdict then ?
     
  9. jonob

    jonob Member

    if i turn off ufh and run rads only (all on trvs)

    or run ufh only

    or run both together the consumption fo gas is the same ?
     
  10. r2d2

    r2d2 New Member

    apparently this type of boiler modulates it self and adjusts the flow temp its self


    By modulating the burner down to maintain 80c flow or slightly lower to prevent the overheat stat locking out the boiler as the return temperature rises.
    Their is NO <u>basic</u> flow control fitted on the control panel to prevent the flow temperaure reaching 80c and the tech guy I spoke to at Potterton confirmed this.
     
  11. jonob

    jonob Member

    what would you reccomend that i need then ?

    surely if i run the rads only the trvs will control the temp

    the boiler has a sensor to check the temp of the flow and return temp of the ch

    these are working correctly - the corgi guy checked

    do i just need a room stat connected to the boiler

    how will this control the ch flow temp

    i thought these boilers were the best type available at present ?

    ie ones that modulate
     
  12. Jimbo

    Jimbo Screwfix Select

    The modulation allows the boiler to control the flame size to ensure the flow temp is maintained at the set point.

    Traditionally, boilers thermostats had a large hysteresis which means the boiler heats the water to (say) 75*C, switches off the burne, then switches it back on again when the temp is (say) 65*C. Modulation allows a steadier flow temp.

    What is the model of the boiler?
     
  13. jonob

    jonob Member

    thanks jimbo

    the user guide for the boiler is on this page its a pdf file see post further up to r2d2

    should the boiler modulate and control the ch temp acording to the load

    the corgi guy says so

    he says its impossible to use that amount of gas

    see page 7 on user guide

    im off out now till late tonight will be in touch later

    thanks so far

    you seem knowledgable on boilers ;):)

    if i turn of ufh and run rads only there are all on trvs the use is the same (gas wise )
     
  14. jonob

    jonob Member

    im happy for flow temp to be at 80 deg for rads

    but once at 80deg it should use hardly any gas at all

    according to corgi boy

    but once at 80 deg its still doing 1 cu mtr/hour
     
  15. Water Systems

    Water Systems New Member

    what would you reccomend that i need then ?

    surely if i run the rads only the trvs will control
    the temp

    the boiler has a sensor to check the temp of the flow
    and return temp of the ch

    these are working correctly - the corgi guy checked

    do i just need a room stat connected to the boiler

    how will this control the ch flow temp

    i thought these boilers were the best type available
    at present ?

    ie ones that modulate

    There is no "control interlock" between the zones and the boiler. It needs one, the regs say.

    You have a primary loop from the boiler. The two UFH zones and a rad zone are taken off. If all TRVs modulate down and UFH on those zones are not calling for heat the boiler is pumping on nothing. You need as a bare minimum an auto by-pass valve between the flow and return pipe at the boiler (is one integral to the boiler?)

    Fitting a flow switch on the primary loop can switch out the burner/pump. When no flow the boiler is off. When a UFH manifold calls for heat the valve opens and there will be flow in the primary loop. This will activate the flow switch and bring in the boiler/pump circulating around the primary loop.

    On the rad CH loop have Grundfos Alpha auto speed pump. When the TRVs are down there will be no flow and pump winds down. When the TRVs open there is flow, and the flow switch is switched on and the boiler burner/pump is switched in.

    Then you can have a timeclock for each zone (two UFH and one rads) No need to switch the boiler as the flow switch does that. The boiler automatically is brought in and out if a zone calls for heat. No call it say out.

    The boiler modulates the burner to suit the demands on the primary loop. The UFH zones should not get over hot as they have their own controls. However I would have a high limit stat on each UFH zone to cut out the boiler or UFH pump if water over 50 to 55C enters the loop - this protects the plastic pipe.

    Even so I doubt this is the real reason for the excessive fuel usage.

    The floor needs to have foam insulation under (enough of it too) and to the sides up the wall to screed level - like a tray. Most don't do the sides of the slab and this is a major cause of flanking heat loss. You may be heating the ground.
     
  16. jonob

    jonob Member

    thanks water systems

    yes the boiler has an auto bypass built in

    the corgi guy said these boilers are most efficent if they are permantly on

    they will cycle and modulate themselves

    is that correct, as he was corgi i took it that he was correct

    this is what i have under floor insulation its 75mm

    http://www.knaufinsulation.co.uk/output/products/page272.html

    can anyone explain why if i turn off ufh and run rads only the consumption is still approx 1 cu mtr /hr a;; rads have trvs
     
  17. jonob

    jonob Member

    sorry forgot to mention dont have that insulation up walls to screed level, have a thinner 10mm that was supplied with the ufh kit
     
  18. jonob

    jonob Member

    have just turned off the ch and run dhw for 1 hour on its own

    the water was cold to start with and in 1 hour its used 2cu mtr gas - its a 150l tank

    does this still sound excessive

    the input to hw/ch is 7.8w - 25.8 kw
     
  19. jonob

    jonob Member

    r2d2 my user guide from nu-heat

    says set boiler to max output and cylinder stat to 55 deg

    boiler pump on speed 3 and ch pump on speed 3

    ive done all this its what i cant understand
     
  20. doitall

    doitall New Member

    21Kw to heat a cylinder is excessive, what temperature did you start and finish with.

    Repeat again.

    How much gas in 2mins on full load :(
     

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