Weather Conpensation - heating settings

That is often the challenge with the gas boiler industry looking to shift kit. 

So what this is doing is lowering the water temperature then also lowering the amount of water flowing through the radiators. 

That is tough to get right.

Then you may also have an on/off thermostat with the weather compensation depending on how it works with your setup.

We are not saying it won't work, it just has the potential of multiple control systems not working well together. 

Thanks for the feedback. I’ll continue with some tests as I like to be methodical so I won’t adjust the TRV’s until I’ve finished checking the weather settings. I’m building a series of steps to check so that I can see what affects what. 
Incidentally on heat pumps do you have a setback setting? This normally automatically adjusts the set point overnight or in some cases for winter or summer

Good plan. 

I suspect that as you are running your gas boiler anyway at a relatively low temperature (for gas boilers), so you are already running you setup more efficiently than the majority of homes. 

At the temperatures you are using without weather compensation , your boiler will also be correctly condensing, again improving efficiency. 

Your experiments will be interesting as you could look to mimic how a standard low temperature ashp might work with your pipes, radiators etc. 

I’ve programmed in the timing and temperature schedule for the setback on mine. Daikin Altherma 3

Can I ask what is meant by ‘large enough’ radiators? Most are around 5ft 6 x 2ft and often doubled ended in each room (apart from the smaller rooms). The house was built around 1963 and it looks like it originally had electric heaters. I’m replacing the radiators one by one to update the system but each year the whole system is cleaned, descaled and rebalanced. We had a small annexe built a couple of years ago with an extra bathroom, laundry room and home gym - this was coupled to the existing system with flexible pipes (they had to use the roof space to link the buildings). At around the same time we upgraded the boiler to match. 
 

Update: I’ve just found this fab btu calculator 

https://www.bestheating.com/btu-calculator

Your radiators are likely to have been specified for a higher flow temperature. If the water is hotter the radiator can be smaller and still emit enough heat. If you're running at a low flow temperature you might need bigger radiators.

I say "might" because few installers did heat loss calculations to work out the correct radiator size. They just installed whatever size radiator fitted on the wall so many houses have oversized radiators.

Might be worth sizing them for a heat pump so you don't need to change them in the future?

First test week completed without weather compensation and reviewing the data, including outside temperatures and general people movement from an average of ~60.7kwh previously used, the system now uses ~51.2kwh. I realise there will be some potential inaccuracy but given the data log (I have approx 2 years of data to make comparisons), I think this should be relatively low. 
For this next week I will remove the TRV’s and again review. For the following week, I will switch the weather compensation back on to check for this without TRV’s 

We have a similar setup, but only using a Bosch EasyControl.  It has been set up by ‘trial and error’ and a bit of internet help. There is plenty of room for error and very little help from Bosch.

We use a room influence of 2, found as recommended by Bosch engineer on internet,

living area day temperature 19 C,

and a night threshold of 15 C, we don’t like it too hot, but again Bosch recommend keeping the house ‘fabric’ at a minimum of 15C. Keeping the ‘fabric temperature’ up does seem to make the house more comfortable, presumably the effect of radiated heat.

The curve is still being tweaked, it’s working reasonably well, but have yet to test it at the extremes. 

I would not rely on day to day variation in consumption, there are far too many variables and lag in the system. I often see these effects, no system changes, but a warmer day using more energy than the previous cold day and this applied pre weather compensation. On our system we seem to see a gain when comparing equivalent monthly data, but as the boiler is already ‘smart’ we expect the gains are going to be small.

Good to hear from you @Taj. It’s interesting to compare. If I use similar settings to you, I get the water pump active almost all day and night. 
Our setback is 12deg C and the room with the smart thermostat is set as a high influence (3).

Reading various pieces of info and with the tests I’m doing (comparing similar days; temperature; solar gain; people movement), I’m not convinced that weather compensation works that well in my situation. 
We do have a small annexe which has programmed radiator valves but that part is useful with potential differences compared to the main building. Like I mentioned earlier, our room layout is rather open plan and so it is not easy to figure what’s best. 
Part way into testing without TRV’s (apart from the annexe) and it looks like they don’t help our system at all.