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We fit a few Vaillant Ecofit Pure system boilers, usually the case when an old Heat Only boiler goes and we replace with a system rather leaving OV, better all round solution. Ecofits are great as they're rear flues and fit in cupboards.
So when replacing we usually replace like for like in terms of heat input, usually as they're correctly sized and you're tied to what the current gas main is. Many are 15/18kws which are on 22mm runs then the last bits 15mm - fine if boiler is 18kw.
So the Ecofit Pure range if you buy a 18kw boiler it'll actually output 25kw on P.01 mode. This is the only time it'll ever do this or if you use Vaillants own controls to do HW priority. It'll only ever output 18kw on heating or when in Chimney sweep mode.
So my question really is, how would you size your gas pipe? If you're fitting what's advertised to do 18kw, it'll only do 18kw in heating mode (And for instance if you're replacing an 18kw boiler) but it'll do 25kw in p.01 test mode then what should you be sizing your gas pipe for? My argument is really that you would size it to 18kw but i'd be interested to hear what everyone else thinks?
Luckily on all the ones i've fitted it's been just within the inlet allowable range. It did puzzle me on my first one why it was 25kw and not 18kw when I gas rated! Should add that this only applies the to EcoFit range and not any of the EcoTec Plus system ones.
So when replacing we usually replace like for like in terms of heat input, usually as they're correctly sized and you're tied to what the current gas main is. Many are 15/18kws which are on 22mm runs then the last bits 15mm - fine if boiler is 18kw.
So the Ecofit Pure range if you buy a 18kw boiler it'll actually output 25kw on P.01 mode. This is the only time it'll ever do this or if you use Vaillants own controls to do HW priority. It'll only ever output 18kw on heating or when in Chimney sweep mode.
So my question really is, how would you size your gas pipe? If you're fitting what's advertised to do 18kw, it'll only do 18kw in heating mode (And for instance if you're replacing an 18kw boiler) but it'll do 25kw in p.01 test mode then what should you be sizing your gas pipe for? My argument is really that you would size it to 18kw but i'd be interested to hear what everyone else thinks?
Luckily on all the ones i've fitted it's been just within the inlet allowable range. It did puzzle me on my first one why it was 25kw and not 18kw when I gas rated! Should add that this only applies the to EcoFit range and not any of the EcoTec Plus system ones.