Weather compensation sensor with Hive on new combi boiler

[fix]

I'm getting a new Vokera Pinnacle 30C installed with a Hive V4 thermostat which has open therm support, and there will be smart TRV's on most radiators.

I mentioned about a weather compensation sensor to my heating engineer who's said they can be a faff and he doesn't like them.

I'm interested to see if people think they are worth it or not? I really want it setup and to leave alone, not to mess about with etc....

The Vokera boiler has a pretty good modulation ratio so it should already reduce flow temperatures pretty well when not used, but not sure how that works when on but not much heating needed etc..

It's in a dormer bungalow, so upstairs isn't well insulated, but the entire downstairs has just has 100mm or kingspan added to the floors, and there is some old wall insulation in there (not spray foam, apparently not beads, but some kind of loose foam).

Any advice is appreciated thanks!

 

[CountryFan]

@vulcancontinental @muggles May know how best to answer this. Afaik, it’s best to have one type of system, eg OT rather than mix an match, but happy to be proven wrong

 

[fix]

@vulcancontinental @muggles May know how best to answer this. Afaik, it’s best to have one type of system, eg OT rather than mix an match, but happy to be proven wrong

Hi thanks, if I'm better sticking with the Hive Opentherm/rad TRV's and along with decent boiler modulation I'm happy to do so, just trying to get best efficiency I can out of the system

 

[muggles]

Not tried one with Hive and not sure how good Hive's OpenTherm is. I tend to use the EPH CP4i and no weather comp

 

[Exedon]

Not tried one with Hive and not sure how good Hive's OpenTherm is. I tend to use the EPH CP4i and no weather comp

Agree with cp4i nice bit of kit with a 5 year warranty.
We have a number fitted to ideal vogue's with weather compensation works really well.

 

[fix]

I actually had an EPH fitted to an old boiler and it wasn't bad, the Ember app wasn't the best though so decided to try something different...

 

[vulcancontinental]

Don't use Hive apparently, their OT doesn't control DHW temp. I haven't first hand knowledge on this but it was passed to me.

EPH are good for OT but I haven't used it with WC, I think the boiler WC takes preference.

I use WC and time it for two settings, comfort and setback.

Use a simple external timer to switch between temperatures. You can use the embedded timer in the Pinnacle but it's not intuitive.

I can post a long video on how to set the WC up if required, once done simply let it run.

 

[ericmark]

Thank you for asking, I will admit I don't know the answer. I started by asking google

How It Works
A sensor installed on a north-facing, exterior wall monitors the outside temperature. This data is fed to the boiler controller, which adjusts the flow temperature (the heat sent to radiators or underfloor pipes). If the weather is mild, the radiator temperature is lower; if it is cold, the system increases the water temperature to maintain a steady, comfortable indoor environment.

That does seem to make sense, until one asks, why does it need to measure outside temperature to lower the radiator temperature.
With my mother's old house, (this house does not have a modulating boiler) I fitted electronic TRV heads, and set the wall thermostat so it would only get warm enough when the weather was warm, to turn off. It was in the hall, which was only set to heat to 18°C on the TRV head, and 19°C wall thermostat, as the wall thermostat was slightly higher, it would turn off, but not very often.

The radiators would typically just stay warm, except when heating first switched on, and maintained the rooms to temperature set very well. So without any TRV heads being linked to the boiler, it worked well. But what I can't say is how efficient the boiler was running, and it seems the weather compensation is not to maintain heat of the house any better, but just to do it cheaper. The gas meter was really hard to get to so was not read that often, and even if we did, not data to compare it to.

So to answer the question, we need two homes as identical as possible set up spot on, one with and one without weather compensation. Can't see that happening.

So with a well set-up system using all analogue controls, will it help? I think unlikely. With a digital (off/on) system, not to turn the boiler on flat out each time turned on, yes that will likely allow more latent heat to be extracted from the flue gases. But will an analogue system it will rarely be turned on flat out anyway, so seems unlikely it will help.

As to OpenTherm with DHW, not sure how that would work? The DHW needs to be over 60°C to prevent legionaries, so circulating water needs to be around 70°C at least, so when heating the DHW the circulating water needs to be hotter. I question the whole idea of using the central heating boiler to heat DHW.

Quantity of DHW used, with move the goal posts. Also, distance of taps to boiler and/or storage cylinder. And if set to instant water heating or stored, I know my mother's boiler had an "Eco" button, so you could select if a store is used or not. Plus the cost of gas/oil, and electric. I pay 8.5p/kWh overnight, and loose 12p/kWh if I don't export, but use electric myself, and 31.94p/kWh if I do not have enough solar that day. Since I set time to heat DHW, I actually pay 8.5p/kWh with the immersion heater, and it also means the pipework boiler to cylinder is not heated. So for me, I am sure an immersion heater is cheaper than using oil. But that does not mean it is the same for everyone.