Harry Bloomfield wrote:
ARW used his keyboard to write :
"rick" wrote in message
...
On 14/01/2016 12:34, Harry Bloomfield wrote:
Has anyone got any thoughts on the correct setting for the temperature
dial on a condensing boiler please?

Its only marked MAX and MIN and has always been left on MAX since it
was
installed a few years ago. Our HW stat is on 80C, because that is
what I
want. Set the boiler output temperature too low and it will constantly
cycle on and off unable to achieve the demand.

Suggestions and your reasoning please?

I run mine of max at all times .... control handed over to tank stat,
which cuts boiler off when it reached 65 degrees


TBH I have never seen a tank stat that goes over 65 deg.

Drayton HTS-3 It has markings every 10C up to 80 then just a mark for 90C.

Thanks for the replies. It is just a simple basic condensing boiler, no
separate sensing for HW and heating, so I am stuck with the MAX boiler
setting.

With your electronic skills, you should be able to modify the boiler for
dual temp setting.

The sensor is usually a thermistor. I bought one as a spare part on ebay
for a few quid and measured it at various temperatures and found that it
closely complied with one of the standard curves for thermistor sensors.

With a relay you can switch in an extra resistor (or variable resistor)
in series or parallel the flow temp sensor and drive the relay coil from
the DHW demand signal to give one setting for CH and a boost for DHW.