Dear all,

Many thanks again for helping me getting started with evoHome a few days ago. evoHome has had a few days to learn and so far I'm duly impressed. I've set up temperature logging with evoLogger - many thanks to all of those having put in hard work into getting the evohome module for Python done (and then also sharing them out to everybody)

There is one question I could do with a little bit of help for, please. Recap - I have a Worcester Bosch Greenstar 24RI boiler with an open-vented system for HW and CH. evoHome is talking to the BDR91 as a boiler relay, which will operate the CH valve, which in turn will fire the boiler. I don't have the HW kit (yet). I've set up optimum start / stop. I'm pretty sure I haven't double bound the BDR91 by accident. I deleted the previous binding, before binding it once as a boiler really in evoHome.

I have four HR92s already fitted, with another four arriving next week.

Like many others I have noticed that the boiler is on much more often since evoHome is "in charge", but for much shorter intervals. I'm aware of the explanation in other threads - it's probably TPI (which I've read the white paper on). I like the analogy that was given in another thread - once you've reached 70 mph in your car you then don't floor it to maintain 70, but instead apply "small doses" to keep the speed up.

My question is around the cycles / hour. The evoHome controller help menu says "refer to the boiler manufacturer". I've been up and down the WB installation manual for my boiler, but it doesn't talk about cycles per hour.

It's currently set to the default 6, with a default on time of 1 minutes. I've definitely seen the boiler come on for 1-ish minutes multiple times once rooms were up to temperature, probably just to satisfy a low heat demand through TPI.

However, I also have a three-minute default pump overrun (controller by the boiler). So every 10-ish minutes, the boiler might come on for 1 minute, then the pump runs for another 3 minutes.

I have also found a passage in the WB manual that says the boiler needs 45 seconds to get the flame stabilised.

So now I'm wondering what I should set the cycles / hour and the minimum time to.

As the pump overruns by 3 minutes, I wonder whether 6 / hour is too much. I'm tempted to reduce down to 3 / hour. As the flame needs 45 seconds to stabilise, I'm also wondering whether I should set the minimum on time to 2 minutes.

I'm wondering what the long term effects are of the valves operating, plus the boiler firing potentially every 10 minutes for 1 minute at the default settings.

So I guess my questions really are:

1) does anybody have any recommendations with regards to cycles / hour and on times for this particular boiler?
2) based on what I have described above, does it sound right to change to 3 cycles / hour with a minimum of 2 minutes on time?
3) am I worrying too much about long term effects? Should I just leave the system to do what it is designed to do and stop worrying about it?

Many thanks in advance, please let me know if any clarification needed

Martin