27-02-2012, 08:08 PM
(29-12-2011, 10:00 PM)pwdrive Wrote: No Mike you are spot on, that is exactly the effect I am getting. Once full gravity circulation is underway the HW tank is well on the way to reaching it's set stat temp. and the metal interface to the pipe on the cheapo stat is well up near the cheapo stats setting (85 C) and thus that stat will then cut in if 85 C is reached as it's body has already been preheated as it were, this then dumps excsesive boiler temperature water into the CH system and by that very nature the flow return is cooler than the boilers exit temperature thus lowering the temp. of the water in the boiler to below 85 C. All the water contained in the boiler is common to both the primary HW flow and the central heating flow, the cross flow arrangement is designed to effect a more even temperature gradient thoughout the boiler thus reducing possible large temperature stresses within the boilers metal plate construction.....I think!!
Lawrence.
I now seemed to have soughted the problem out, I have spent the last couple of days knocking a hole further up the chimmney flue in the living room and re routing the stove flue pipe from rear outlet to top outlet, we now have 6ft of 7" flue pipe exposed in the living room, this new arrangement has evened the wood gas/flame flow over the top of the boiler to a more satisfactory pattern.
As a result of this the boiler no longer kettles when lighting a very quick hot fire from cold before the high temp thermostat kicks in and dumps excess heat into the C/H flow. As a bonus there is also understandably more heat given into the room due to the exposed flue pipe. It is a lot milder hear now but even so the room temp as I write is 82 degrees F with the stove just ticking over so I am well pleased with that.
Lawrence.
I think I messed todays previous post up on this subject due to my editing skills.....
