Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!
ASHP Cut-off Temperatures: What's Your Setting and is a Your Heating Still On?
My system has been running 24/7 on weather compensation from last September until today when I fitted a thermostat.
I did think about just changing the weather comp curve to 20@20, but then the pump would still run.
My wife still has the heating on as of this evening, she wanted it at 24 in the lounge. I tweaked the low temperature end of the curve up from 35 to 37.5 to make the rads feel warm when she turns the stat up.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
I imagine that for those of you with “automated” systems, your heat pumps must have kicked in this week with the chill in the air.
For the rest of us with more basic, older controls (like mine), when do you plan on switching your heat pumps on for heating? Or did you give in to the colder temperatures these past few days?
New to heat pumps? Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
Rewritten and updated for 2027
📘 From Zero to Heat Pump Hero
🛠️ Bodge Buster
🎧 Prefer to listen? Heat Pumps Explained
This year it been rubbish weather in Scotland, think we missed out on summer, it was too wet to get warm. Last year it was October before the heat went on, this year beginning of September - global warming doing it's thing - making Scotland colder! But it's let me fiddle with settings and PV pays for any mistakes and any higher electricity consumption.
@editor as my smart thermostat system is "on" all the time I guess you could class it as automated and yes it has kicked in in early mornings and a little at night this week.
In the wilds of Cambridgeshire we have had a couple of 3 - 5 degree nights but the temperatures this year have been frequently under par since the start of La Nina
5 Bedroom House in Cambridgeshire, double glazing, 300mm loft insulation and cavity wall insulation
Design temperature 21C @ OAT -2C = 10.2Kw heat loss, deltaT = 8 degrees
Bivalent system containing:
12Kw Samsung High Temperature Quiet (Gen 6) heat pump
26Kw Grant Blue Flame Oil Boiler
4.1Kw Solar Panel Array
34Kwh GivEnergy Stackable Battery System
If heating shuts off for the summer but is still needed to heat hot water is that economical or expensive due to heating from cold?
@suzy-shadow Hi, Domestic hot water production is generally less efficient in itself. For example my combined heating and hot water efficiency is on average 4.3 COP. Hot water only production over the summer has been a COP of 3.6.
Is it more or less expensive? That is a difficult question to answer as it depends on tariff prices, hot water tank efficencies etc. In my case I find it cheaper to heat my 200 litre tank to 55 Celsius and take a hit on my COP value which all happens during a cheap electricity period in the night. This tank full in most cases lasts all day and costs on average 17p per day. If I made the COP value better by reducing the tank temperature then the hot water would possibly need 2 heating cycles in a day, 1 in the morning and another in the afternoon due to hot water running low, costing approximately 40p to 50p a day if that makes sense
Hopefully that helps answer your question
5 Bedroom House in Cambridgeshire, double glazing, 300mm loft insulation and cavity wall insulation
Design temperature 21C @ OAT -2C = 10.2Kw heat loss, deltaT = 8 degrees
Bivalent system containing:
12Kw Samsung High Temperature Quiet (Gen 6) heat pump
26Kw Grant Blue Flame Oil Boiler
4.1Kw Solar Panel Array
34Kwh GivEnergy Stackable Battery System
- 26 Forums
- 2,724 Topics
- 63.8 K Posts
- 720 Online
- 7,126 Members
Join Us!
Installer Finder
Degrees of Separation
Latest Posts
-
RE: Jokes and fun posts about heat pumps and renewables
@transparent I’ve heard that that is why American cars ...
By Toodles , 50 minutes ago
-
RE: HeatGeek vs Octopus surveys: puzzling disparity - any ideas why?
Have either quote provided room by room heat loss calcu...
By Old_Scientist , 15 hours ago
-
RE: Heat Pump Servicing & Maintenance – Good Value or Rip-Off?
@old_scientist if you are going DIY then you may wan...
By Papahuhu , 2 days ago
-
RE: Indevolt Batteries UK Support & Info Thread
After a short while that was followed by the 'power war...
By JamesPa , 2 days ago
-
RE: Samsung heat pump - data cable issue
That's well done. Cable is the correct type (LIYCY = 2x...
By bobflux , 2 days ago
-
RE: Electricity price predictions
I agree, we will find out at the next budget whether th...
By Old_Scientist , 3 days ago
-
RE: Missing flow temperature in Heat Geek proposal
@editor I went through HG website, so should be ok for ...
By sttpd1917 , 3 days ago
-
Who did the Freedom Heat Pump cloud server and what did...
By Mars , 3 days ago
-
RE: Who's your electricity provider and what's your tariff?
Reading between the lines of what octopus are doing wit...
By JamesPa , 3 days ago
-
RE: Air to air bus grant installer anywhere
The through wall two hole ones have their place (listed...
By EtchedPixels , 3 days ago
-
I hope it goes ok, Hon can be hard to set up IF the sof...
By Graham Hendra , 3 days ago
-
@clockworks Hi, So there is a big difference between st...
By ASHP-BOBBA , 3 days ago
-
@editor wellvery comprehensive answer. I will get all i...
By Keithb , 3 days ago
-
RE: Advice on my Heat Pump Journey: Old Stone Built Detached Cottage
all good advice I will follow this up
By PaulC , 3 days ago
-
Heat of vaporization of water is 2.25 MJ/kg (0.625 kWh/...
By bobflux , 4 days ago





