Weather compensation climatic heat curves
We have a Grant Aerona3 R32 installed 3 years ago by a previous house owner hence we were not involved in the installation and are trying to work things out now. I have checked the install and weather compensation is enabled but I am a bit surprised at the heat curve settings and am looking for advice. The Maximum outgoing water temperature in Heating mode is set to 50C (Tm1), the Minimum outgoing water temperature in Heating mode (Tm2) is set to 45C, the Minimum outdoor air temperature corresponding to maximum outgoing water temperature (Te1) is set to -4C and Maximum outdoor air temperature corresponding to maximum outgoing water temperature (Te2) is set to 20C. To me, that is not much of a curve.... I appreciate this varies between installations. Unfortunately I have not been supplied with the heat loss calculations for the property but am trying to get it. It is an old house but reasonably well insulated. We live in the north of Scotland on the Black Isle, beside the sea, north of Inverness and aim for an indoor temperature of 18.5C
I think you assessment is correct. I would try and reduce the 45C end initially and see how the house feels.
Also 20C OAT is quite a high setting particularly if you prefer 18.5 inside. I would knock that down a couple of degrees too.
It’s a bit trial and error really to get the result that suits you. Just make small changes and see how that feels to get the lowest flow temperature you find comfortable.
House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60
Those settings are crazy and barely do any weather compensation at all. Perhaps they were set up by someone who thought that the radiators had to feel hot to be heating the house.
If your target IAT is 18.5 Id start with the WC curve at something like 30 (FT) (or even less - maybe 27 or even 25) at 15 (OAT). I would then slowly reduce the 'cold' end of the curve until your house just heats up enough. Once the cold end is set up you can tweak the warm end a bit later in the season.
Make sure that any external controls are permanently calling for heat. This means turning up thermostats/TRVs to well above the desired point, and ensuring heating is timed to come on 24*7 except when the system is heating DHW.
That should get you to a near optimum setting. Allow a couple of weeks, you can make bigger changes at first but once you are getting near change by only a degree every 24hrs.
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
Many thanks for that advice. I did think it was a bit crazy. The previous owners would not made these settings as they were in their 80s....
I have implemented and will report back...
There is one other setting in the Grant heat curve group which is the Hysteresis of water set point in heating and the default is 8C. Am I right that this relates to the hysteresis of the hot water tank heating and not the central heating and says that the hot water will come on if the hot water tank heating will come on when programmed if the tank is 37C and switch off at 52C as the tank is set to 45C?
I realise now that this hysterisis setting is controlling when the heating comes on e.g. Heating : Outgoing water temp ≥ Water set point (parameter 2100~2105) – Hysteresis (parameter 2141)
@jamespa thanks for the advice. If I am tweaking the curve for low temps, should I first increase the Maximum outgoing water temperature in Heating mode (currently 45c) (Tm1) or the Minimum outdoor air temperature corresponding to maximum outgoing water temperature (Te1) - currently -4C. Maybe Tm1 to 45C or Te1 to -1C??
To tweak for low temps I would increase or decrease (as appropriate) the target flow temperature at the minimum outdoor temperature end of the curve.
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
- 26 Forums
- 2,149 Topics
- 47 K Posts
- 34 Online
- 5,667 Members
Join Us!
Podcast Picks
Latest Posts
-
RE: Midea ASHP – how to set weather compensation
@pash44pump - the installers heat loss calculations app...
By cathodeRay , 3 minutes ago
-
RE: Electricity price predictions
the post code lottery is only one thing that is very wr...
By Judith , 16 minutes ago
-
RE: How Do I Know When the Hot Water Has Run Out?
@grahamf Personally I would consider bypassing one of t...
By JamesPa , 3 hours ago
-
RE: What crazy nonsense are inverter limits and why are they imposed?
No I'm not mining anything @drei but I am doing R&...
By Transparent , 3 hours ago
-
RE: A Customer's Lessons Learnt from a Heat Pump Installation in a Large House
Yes, the 'global warming potential' GWP of R32 is quote...
By Temperature_Gradient , 4 hours ago
-
RE: Rodents! A word of warning for heat pump owners
Wasps caused frequent tripping of my lighting circuit a...
By JamesPa , 4 hours ago
-
This is one of my biggest bugbears these days, how AI d...
By cathodeRay , 5 hours ago
-
RE: Ecodan & MelCloud scheduling
Yes, the 2 are separate. To add to the complex desig...
By HCas , 2 days ago
-
I should clarify that the FoxESS web interface is not l...
By Old_Scientist , 2 days ago
-
RE: Mitsu Wireless Controller and MelCloud
@robs Hi Rob, At the end of a note to Mitsu UK, thank...
By DavidAlgarve , 3 days ago
-
RE: Why so many sigenergi installer recommendations?
@adamk Tesla is a great option, it’s also one we instal...
By SAEnergy , 3 days ago
-
RE: Flexi-Orb Heat Pump Scheme: A Game-Changer for the UK's Heat Pump Industry
As a potential heat pump customer, it would be good to ...
By Temperature_Gradient , 4 days ago
-
RE: Octopus replacing the fixed 15p/kWh export rate with a market tracking one
@trbob I have just extracted the details for Agile Expo...
By Toodles , 4 days ago
-
RE: Heat Pump Books For Beginners – Bodge Buster & From Zero To Heat Pump Hero
The Ultimate Guide to Heat Pumps is less than a month a...
By Mars , 4 days ago
-
RE: Air source heat pump roll call – what heat pump brand and model do you have?
@editor Hi Mars, We have just installed a Grant Aerona...
By GrahamF , 5 days ago
-
RE: Sanity check please. Battery storage and inverter sizing.
There are MCS guidelines about how close to the edge/ri...
By Old_Scientist , 5 days ago
-
RE: Balancing financial efficiency and comfort using the Octopus Cosy tariff
I estimated our usage on the following basis. The mos...
By Old_Scientist , 5 days ago
-
@editor Something changed in this last 12 months, they ...
By ASHP-BOBBA , 6 days ago
-
RE: Does anyone have experience of a smart water meter?
Just to give a sense of scale, I've used the CCW water ...
By Majordennisbloodnok , 1 week ago
-
RE: Powerwall 3 or Myenergi or something else?
We have a Tesla Powerwall 3, recently installed, so I m...
By Old_Scientist , 1 week ago