Discuss Just fitted K3 radaitor and the centre front panel won’t heat up in the UK Plumbers Forums area at PlumbersForums.net
There's also a fairly high pressure drop through even the clean boiler Hx, if you wanted say 20kw output at a dT of 15C, (1146LPH) (to achieve reasonably high radiator outputs then the Hx pressure drop alone is almost 3M so doesn't leave much remaining head available to circulate the system if a LLH isn't installed.
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I thought the 20C dT was a sort of standard to compare different boilers but didn't know that the boiler would try and maintain this but difficult on a heat only boiler since it doesnt contol the circ pump. Some Vaillants have return temperature control but I rarely see it mentioned.
Hello John,This shows perhaps why a K3's front panel doesn't heat up as much as the others and should also be filled very slowly?.
I have quite a few old double panel type 22s, these have only two little manifolds on the bottom connecting the two panels, nothing on the top except two bracing strips of welded on steel plate but both panels have separate air vents which makes them very easy to refill and get rid of the air.
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Hello JohnGlad to hear, Ben, that you are back in form again,
Regarding that pesky K3, Renewing the cast iron rads should help but I feel that installing a UPS3 pump would improve the flow considerably as you have established that the rad does, more or less, emit its rated output when running on its own since the boiler doesn't cycle on/off.
The UPS3 is a giant of a pump even though a "6M"(6.4) pump like the UPS2, (6.2M) see below.
The other alternative is to install a low loss header, LLH, where one pump deals with the boiler heat exchanger pressure loss and the other pump deals with the rads/system losses.
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Hello John,Glad to hear, Ben, that you are back in form again,
Regarding that pesky K3, Renewing the cast iron rads should help but I feel that installing a UPS3 pump would improve the flow considerably as you have established that the rad does, more or less, emit its rated output when running on its own since the boiler doesn't cycle on/off.
The UPS3 is a giant of a pump even though a "6M"(6.4) pump like the UPS2, (6.2M) see below.
The other alternative is to install a low loss header, LLH, where one pump deals with the boiler heat exchanger pressure loss and the other pump deals with the rads/system losses.
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Hello JohnExcellent news, what mode and setting are you running the UPS3 at?
Hello JohnIs it a sealed system with expansion vessel?
Hello JohnThe UPS3 is now probably pumping at it full 6.4M head (speed 3) so next time its running have a look, or get someone to have a look in the attic, and hold a "glass" of water under the vent pipe with the end of the pipe immersed in the glass and see does the level remain the same, you don't want any air ingress through the vent, also, if possible watch the vent when someone stops/starts the pump and see if any spurt of water.
Reply to Just fitted K3 radaitor and the centre front panel won’t heat up in the UK Plumbers Forums area at PlumbersForums.net
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