Weather Conpensation - heating settings

Hello @BPLightlog,

as I understand it it the pump is designed to be permanently running. This went against the grain for me, but it eventually sank in that for my modulating boiler the pump was already ‘permanently’ running. The only time it shut off was during the night when the set temperature was 14.5C and the room temperature was above 15C.

Is your room influence a tad high? Zero is no influence, and it increases from there.  I would guess that at 3 you’ve got maximum influence so minimum effective weather compensation. I do wonder about the effectiveness of room thermostats, setting up weather compensation is problematic enough without the room stats getting involved.

You are right, every house is different and what serves me will not work for others. You’ll have to discover what works for you, but don’t throw out weather compensation if you can help it. Treat it as a learning curve for heat pumps, unless you are my age you will almost certainly have one eventually and it will involve some form of low temperature heat exchange for rooms.

Good discussion this, good to hear from you, @Taj - you’ve had 3 green tech badges added to your forum profile. Now we know what you have and that you might be able to share your learnings for someone following in your footsteps...

So I’m at the end of another test week and it has all been very interesting. 
Caveat: I appreciate that my findings won’t necessarily work in another situation. 
 

The system now runs effectively without TRV’s in play. Weather compensation is also off although the gas boiler works by adjusting flow temperature presumably by load feedback. 
I have compared similar days, temperatures, people movement as best as I can and this appears to be the clearest indication 

The green line is the latest set up with no TRV and weather compensation disabled. 
The pink line is a similar day but with weather compensation enabled. 
While there are similarities, it’s the area under the curve which gives the energy used (lhs scale is kWh) and as such there is a significant reduction in energy consumption without wc but achieving the same heat level through the house. 
Perhaps the boiler on its own is a good controller along with the smart stat which provides the programmed temperature required. 
I calculate that I save around 12% of fuel without weather compensation enabled. The one thing wc does help with is on very cold mornings, the house gets up to temperature more quickly. Perhaps I can look into a modified control to switch on wc just overnight if the outside temperature is below -2 deg? I’ve started looking at an IFTTT app for that

Thanks for posting.

I wonder if without WC, the boiler is simply operating at a fixed flow temperature, what you are seeing is the boiler switching on and off?

With WC on a cold morning, the WC would kick in with a high flow temperature before falling back as the outside temperature increased? 

How did the house feel, was the temperature stable? 

I don't know what control you have of the weather compensation "curve" but perhaps try adjusting it given what you see in the graph? 

If I look at the boiler during the day, I can see that it ranges the temperature, presumably depending on the load. So it does vary up to the max that I’ve set.

Yes - that’s my point about having WC on below certain outside temperatures for a start but then switching it out after the first hour or so.

It was .. I was a little dubious about my own interpretation given my hand on the controls as such but I asked other family and they commented that the house felt more comfortable.

I can only adjust the start and end point of the curve so am not sure how much control I can actually adjust.

It was just an interesting experiment in that most of the advice I’ve been given was weather compensation gives more cost savings but it is obviously dependant on the specific situation.

Thanks for posting this @BPLightlog . It's very interesting.

A number of people on heat pump forums have made efficiency gains by using the functionality built into the controllers rather than using weather compensation. The Mitsubishi controller, in particular, can often get better efficiency by using both internal and external temperatures to manage the flow temperature. You simply set the internal target temperature and it works out the most efficient way to achieve it.

Maybe the boiler and heat pump manufacturers are actually building systems designed to get maximum efficiency without needing lots of adjustment by the user.

I have come to that conclusion from gathering this info. The boiler is fairly new (2 years old) and I understood it to be built with energy saving in mind. It’s a combi, condensing version and does adjust flow temperature as mentioned earlier. But like other areas of newer technology, there seems little in the way of useful information from manufacturers about how to maximise the built in capabilities. 
I appreciate that my room layout being mostly open plan might be quite different to others but a few suggestions on a few variations would have been useful. 

I also have the Bosch easy control and with so many different circumstances it’s unique to the property where installed. I have a Worcester 30cdi and was struggling with the boiler operation (short cycling) after endlessly looking for an answer I found the sweet spot.

What worked with my set up was to range rate the boiler to match the heat demand or just above, yes I know you shouldn’t have to as it’s a modulating boiler but hear me out. I had also noticed that in my area the internet based outdoor temperature was out sometimes by 4/5 degrees, so I fitted an outdoor sensor to a north facing wall. My room influence setting was on two (medium influence) but the system was still not quite right, the below settings made all the difference.

Range rate boiler ( 30kw to 11kw with my demand)

Outdoor sensor (made a big difference)

Hot water off — (combi only)

Easy control temp — 18.5 degrees

Room influence— None (0) Off  (Given time stopped boiler cycling with the aid of range rating)

Heat curve      —  20 / 82

max flow temperature 75 degrees (although it rarely gets above 65)

Optimisation — on (although this will operate the boiler an hour or two before set start time)

Clock Times —  6am through to 10pm @ 18.5 degrees  (bedrooms @16,5 degrees, zoned)

Night time set back — 12 degrees 

Summer set Back — 16 degrees 

I have the Bosch smart Trv’s that are set to automatic hydraulic balancing, manual Trv’s I would assume be left wide open until the system settles down enabling you to adjust to your needs (bedrooms)

Since making the adjustments the heating has taken on a very noticeable difference with comfort and economy, keep in mind that any adjustment will take time to adjust (allow a day or two).

My system will now return a comfortable indoor temperature, plus being on for approximately 16 hours a day (and when I say on the boiler will only top up when needed).

Although this goes against all recommendations for saving gas, in fact with my circumstance it works out cheaper to leave it on for longer spells as recommended by the manufacturer.

Great results, @Simon.p 

You might find this similar topic posted by the like minded @BeePee worth a look and consider sharing this there: