[OpenTRV-dev] Basic V0p2 operation

Mon Oct 21 15:25:26 BST 2013

Very helpful. So it is a jazzed-up FHT8R? with some local control?

The missing link for me is connecting FHT8R/FHT8V to boiler control and 
weather compensation. My current project is weather compensation and 
condensing boiler temp control (to ensure full condensing) with a web 
interface.  It is very simple, and uses temperature sensors and controls 
the boiler via the heating thermostat (prototype hardware 90% done, 
mainly the html to do).

OpenTRV would add the individual room demand to that thus allowing the 
boiler go and return circuit to go completely cold if no room demand, 
rather than be kept at temperature with boiler cycling, controlled only 
by one thermostat in the hall. So a better match between boiler output 
and demand, with savings coming from the use of precise individual zone 
time and temp controls rather than (crude) TRVs.

The purpose of my web interface is so that instead of setting schedules 
on devices in fiddly little plastic boxes, you can sit in front of the 
telly with an ipad and set things up at leisure with a nice interface. 
Even with the web server the prototype is cheaper than a Worcester Bosch 
weather compensator controller.

Ultimately I plan to include DHW but that is complicated by the solar 
pv/immersion and solar water inputs that I have.

A small point about the FHT8V, it has a 30mm fitting and replaces recent 
TRVs but not older ones (e.g. Drayton TRV3) with different threads. 
Their adapters are not comprehensive (I'm having to modify an adapter 
for my TRV3s), though mostly I have TRV4s, fortunately.


Stuart Gillies

On 21/10/13 12:20, Damon Hart-Davis wrote:
> Basic outline of V0.2 design operation at Stuart (G) suggestion:
> http://www.earth.org.uk/open-source-programmable-thermostatic-radiator-valve.html#V0p2Basics
> Rgds
> Damon

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