Your browser isn't supported
It looks like you're using an old web browser. To get the most out of the site and to ensure guides display correctly, we suggest upgrading your browser now. Download the latest:

Welcome to the MSE Forums

We're home to a fantastic community of MoneySavers but anyone can post. Please exercise caution & report spam, illegal, offensive or libellous posts/messages: click "report" or email forumteam@. Skimlinks & other affiliated links are turned on

    • Un0riginal
    • By Un0riginal 18th Oct 16, 12:44 PM
    • 29Posts
    • 33Thanks
    Boiler Quotes and understanding flow rate implications
    • #1
    • 18th Oct 16, 12:44 PM
    Boiler Quotes and understanding flow rate implications 18th Oct 16 at 12:44 PM
    Wow, that was a long title

    OK, so, my Worcester 28si is on the blink again, and rather than spend a couple hundred getting if fixed I thought now would be an opportune time to look at replacing it (I think it is about 16 years old). I have had a number of quotes with quite a variance in price, but first I was trying to figure out what the deal with DHW flow rate is. My current boiler is 13.5 @ 30 degrees rise, the new ones are all listed as @ 35 degree rise, how this equates I don't know how to calculate, but it provides a nice shower through mixer taps. Mains cold water at is 16 l/min.

    I have had differing responses from engineers, some saying that I should opt for the a (Ideal Vogue 40Kw) 16.4 l/min boiler as this will enable someone to be in the shower, and someone to be running taps/flushing toilet without massively affecting shower temperature/flow. I have also had the direct opposite saying that ones at (Worcester Bosh 30i) 12.3 or (ideal Vogue 32Kw) 13.1 would be sufficient as that still leaves 3(ish) excess that would enable other usage without massively affecting the shower.

    Both of these cannot possibly be accurate, and I cannot seem to find any reliable data to back up one premise or the other. So I turn to you oh wise and not at all opinionated internet...
Page 1
    • bridgedino
    • By bridgedino 19th Oct 16, 11:04 PM
    • 326 Posts
    • 153 Thanks
    • #2
    • 19th Oct 16, 11:04 PM
    • #2
    • 19th Oct 16, 11:04 PM
    How does your current 28kw boiler perform when showering & flushing / running other taps?

    The general rule is the greater the kW, the better it will be at providing hot water and flow rates

    Apparently the Worcester Bosch 42CDI can provide enough hot water to run two showers at once but I've yet to meet anyone that has used it for such
    • southcoastrgi
    • By southcoastrgi 19th Oct 16, 11:30 PM
    • 5,334 Posts
    • 3,086 Thanks
    • #3
    • 19th Oct 16, 11:30 PM
    • #3
    • 19th Oct 16, 11:30 PM
    Your existing boiler would give around 11.7 ltrs @35 rise when new
    you might put 16 in but you won't get 16 out, don't forget if you put a boiler in of those sizes your gas pipework will almost certainly need increasing in size which will add to the cost
    I'm only here while I wait for Corrie to start.

    You get no BS from me & if I think you are wrong I WILL tell you.
Welcome to our new Forum!

Our aim is to save you money quickly and easily. We hope you like it!

Forum Team Contact us

Live Stats

1,602Posts Today

5,573Users online

Martin's Twitter
  • It's the start of mini MSE's half term. In order to be the best daddy possible, Im stopping work and going off line?

  • RT @shellsince1982: @MartinSLewis thanx to your email I have just saved myself £222 by taking a SIM only deal for £7.50 a month and keeping?

  • Today's Friday twitter poll: An important question, building on yesterday's important discussions: Which is the best bit of the pizza...

  • Follow Martin