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Products: Water saving aerators, litres per min flow not enough for WB combi

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    • CommentAuthorDarylP
    • CommentTimeJan 5th 2010
     
    I am not sure if this is the correct place for this , but I will try anyway....

    Having fitted water saving aerators on to the taps, the flow rate is so low now that the flow switch in the WB combi boiler does not 'sense' water flow, and so does not fire....
    Has anyone fitted/used this type of aerator, with a flow rate of around 3 litres per min @ 3 Bar.

    Thanks in advance.......:smile:
    • CommentAuthorCWatters
    • CommentTimeJan 6th 2010
     
    Looks like you may need to find a better flow sensor for the boiler. However even if that does allow it to fire up the water may get too hot. Depends if the boiler can modulate down far enough. If not it might cycle on/off with possible consequences for the water temperature.
    • CommentAuthorDarylP
    • CommentTimeJan 6th 2010
     
    Yes I understand the implications... The boiler is a WB Greenstar 35 condensing combi. It can modulate , but the problem is telling it that DHW is flowing..... I think that this is going to become a bigger issue when 'CfSH - style' low water usage taps become more common.......?

    Cheers....
    • CommentAuthorbrig001
    • CommentTimeJan 6th 2010
     
    Read this http://www.elementalsolutions.co.uk/downloads/combis%20and%20low%20flows.pdf yesterday. Seems you are not alone. I have also read about combis having flow restriction built in which had to be adjusted/removed when water pressure was reduced or the boiler was fitted on high rise buildings. Could this be an option for yours? If you are borderline now, removing a restriction upstream might increase the flow enough to allow the boiler to operate.
    • CommentAuthorCWatters
    • CommentTimeJan 6th 2010 edited
     
    Deleted as you beat me to it.
    • CommentAuthorDarylP
    • CommentTimeJan 6th 2010
     
    Brig & CW.....
    Many thanks for the link. That summaries the problems, although how you found the document I don't know, I spent most of last night on Google looking for something just like that......?

    Anyway, does anyone have an answer?.... :-)

    The way I see it (from a CfSH point of view) is ...

    1. 2 'sizes' of aerator, 2.79 lpm in cold taps, 3.5 lpm in hot taps (or enough to fire the DHW in the combi anyway)
    2. Storage/combis that rely on stored water temp to fire DHW , rather than flow switches
    3. .... not worked this one out yet :shamed:

    Any suggestions welcome, and thanks again to the above. :smile:
    • CommentAuthorCWatters
    • CommentTimeJan 6th 2010 edited
     
    Google can find flow switches around that work down to 1L/min but finding someone to fit an unauthorised part to your gas boiler will be hard..

    2L/min http://www.heatweb.com/products/fs22t.html
    1L/min http://www.mamut.net/controls/shop/shops/12/8/productdet.asp?gid=163&subgid=168&wwwalias=vflowsolutions&pid=5290

    Another option might be to convert it to partially stored hot water system. eg install a small DHW tank for supplying the low flow rate outlets. This would be connected to the heating side of the boiler via a motorised valve and tank stat. The DHW outlet of the boiler could be retained and used for higher flow rate outlets like the bath or shower.
    • CommentAuthorbrig001
    • CommentTimeJan 6th 2010
     
    http://www.google.co.uk/search?hl=en&source=hp&q=combi+boiler+minimum+flow+rate&btnG=Google+Search&meta=&cts=1262794345935&aq=f&oq= Annoying isn't it? Sometimes I search for hours and someone else puts the words in a different order and gets it straight away... Grrr.

    Contact WB and see if they have any recommendations.

    http://www.worcester-bosch.co.uk/installer/our-company/news/pressure-to-perform-under-new-water-restrictions- doesn't immediately look relevant, but "a combi boilerĂ¢â‚¬â„¢s flow regulator and silencer could be removed to allow higher flow rates" was what I was alluding to above. This might give you a slightly higher flow rate allowing the boiler to operate. Is there anything else upstream that could be changed to give a slightly higher flow?
    • CommentAuthorDarylP
    • CommentTimeJan 6th 2010
     
    Brig,

    Yes, I was looking with a slightly different search string.... I am not sure about pulling the guts out of brand new WB combis just to get some 'greenie' points for the CfSH assessment.. I tried to talk to WB tech today, but they are swamped, iced up external condensate runs have 'melted' their call centres..... :smile::smile:

    Anyway, I think we will experiment with some aerator inserts to get the minimum flow that just fires the DHW , and then see where we go from there...In the meantime I will pursue WB tech, and see what their opinion is.

    Thanks again......:wink:
    • CommentAuthorCWatters
    • CommentTimeJan 7th 2010
     
    Posted By: brig001 http://www.worcester-bosch.co.uk/installer/our-company/news/pressure-to-perform-under-new-water-restrictions-" rel="nofollow" >http://www.worcester-bosch.co.uk/installer/our-company/news/pressure-to-perform-under-new-water-restrictions-doesn't immediately look relevant, but "a combi boilerĂ¢â‚¬â„¢s flow regulator and silencer could be removed to allow higher flow rates" was what I was alluding to above. This might give you a slightly higher flow rate allowing the boiler to operate. Is there anything else upstream that could be changed to give a slightly higher flow?


    err Isn't the problem that he wants a low flow rate to save water? Otherwise he could just remove the aerators on the taps.
    • CommentAuthorDarylP
    • CommentTimeJan 7th 2010
     
    I just got through to WB Tech, useless as usual.....:shocked:
    The flow switches are sealed, non adjustable and they don't even know the flow rates, so I have nothing to aim at.... :sad:

    However Vaillant do just the thing; a 937 Storage Combi. It has a 'mini' thermal store combined in the unit with a temp sensor, so even with very low flow rates, DHW is available. The DHW is taken from the store, which is replenished when it reaches a minimum temp. Looks like Vaillant will be a popular choice for CfSH jobs this year.....:smile:

    Thanks again to the above
    • CommentAuthorCWatters
    • CommentTimeJan 7th 2010 edited
     
    Deleted.
    • CommentAuthorbrig001
    • CommentTimeJan 7th 2010 edited
     
    Posted By: CWatterserr Isn't the problem that he wants a low flow rate to save water? Otherwise he could just remove the aerators on the taps.


    Good point :shamed: but I did say slightly...
    • CommentAuthorDarylP
    • CommentTimeJan 10th 2010
     
    .... just for info, I did some tests over the weekend (how sad am I?:shamed:)

    WB Greenstar HE switches DHW at 3.00 lpm. The aerators we have are running at 2.55 lpm....

    I have some others on order to test, when they make it through the snowy wasteland...?

    Cheers...:smile:

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