28-12-2011, 10:28 PM
Hello Alan,
It's connected the right way (I think!!) top to top bottom to bottom The HW tank is fitted with a gravity flow copper coil (28 mm) and not a pumped 22 mm coil as in oil fired honeywell "Y" plan. all the plumbing pipe stats I have seen on the net are the cheapo type I might have to knock up an electronic one and solder a sleave to take an electronic temp sensing element directly on the the HW flow pipe where the present thermostat is fitted.
As it stands now nothing really adverse happens, I tried to push the whole system to its limits by flash firing up the stove from cold with very dry wood and a good combustion air intake ie: worst case scenario, as was expected the top of the boiler started "singing" almost boiling before the stat previously described kicked in, there was a three minuit delay even though the pipe it was attatched to was well above the 85 degree C temp that the stat was set to, most of the gassing bubbled off by virtue of the physical upward gradient of the pipes and then up the expansion pipe to its overflow into the header tank.
The main reason for wanting to sort the stat issue out is that internal gassing of the boiler and external condensation on the boiler is the main reason for the eventuall demize of wood/solid fuel boilers. The external boiler condensation effect is not at issue by virtue of of the set low temp stat on the CH return pipe where it enters the boiler, that set up works fine as I have offset the temp setting by a few degrees to compensate for the reasonably large hysterysis effect in that type of stat.
The set high temp stat needs to snap in (real time, little delay) when the actuial pipe it is referenced to reaches the actual temp that the stat is supposed to operate at, to that extent I could offsett the temp setting on that stat to a lower setting to compensate for the thermal transfer delay that exists, but that tends to lead to it cutting in more frequently thus in effect it is self defeating to a certain extent in increasing the gravity flow beween the flow and return pipes differential temperatures if that makes sense.
I have seen in the past temperature sensors of the electronic type (thermocouple maybe ?) where the probe is placed on a say a power transistor heat sink and the reading is almost instantainious and direct. I think this is the kind of thing/system I will eventually need by whatever means.
Lawrence.
It's connected the right way (I think!!) top to top bottom to bottom The HW tank is fitted with a gravity flow copper coil (28 mm) and not a pumped 22 mm coil as in oil fired honeywell "Y" plan. all the plumbing pipe stats I have seen on the net are the cheapo type I might have to knock up an electronic one and solder a sleave to take an electronic temp sensing element directly on the the HW flow pipe where the present thermostat is fitted.
As it stands now nothing really adverse happens, I tried to push the whole system to its limits by flash firing up the stove from cold with very dry wood and a good combustion air intake ie: worst case scenario, as was expected the top of the boiler started "singing" almost boiling before the stat previously described kicked in, there was a three minuit delay even though the pipe it was attatched to was well above the 85 degree C temp that the stat was set to, most of the gassing bubbled off by virtue of the physical upward gradient of the pipes and then up the expansion pipe to its overflow into the header tank.
The main reason for wanting to sort the stat issue out is that internal gassing of the boiler and external condensation on the boiler is the main reason for the eventuall demize of wood/solid fuel boilers. The external boiler condensation effect is not at issue by virtue of of the set low temp stat on the CH return pipe where it enters the boiler, that set up works fine as I have offset the temp setting by a few degrees to compensate for the reasonably large hysterysis effect in that type of stat.
The set high temp stat needs to snap in (real time, little delay) when the actuial pipe it is referenced to reaches the actual temp that the stat is supposed to operate at, to that extent I could offsett the temp setting on that stat to a lower setting to compensate for the thermal transfer delay that exists, but that tends to lead to it cutting in more frequently thus in effect it is self defeating to a certain extent in increasing the gravity flow beween the flow and return pipes differential temperatures if that makes sense.
I have seen in the past temperature sensors of the electronic type (thermocouple maybe ?) where the probe is placed on a say a power transistor heat sink and the reading is almost instantainious and direct. I think this is the kind of thing/system I will eventually need by whatever means.
Lawrence.
