Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Sustainable Sidetra...
Electricity, Tariff...
Who's your electric...
 
Notifications
Clear all

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!

Who's your electricity provider and what's your tariff?

 
Page 72 / 72
Electricity, Tariffs, Monitoring, Electrics & Providers
Last Post by Papahuhu 2 minutes ago
855 Posts
64 Users
422 Reactions
264.4 K Views
RSS
 Papahuhu
(@papahuhu)
Honorable Member Member
Joined: 1 year ago
Posts: 427
02/10/2026 10:10 am  

@andris 

So you have an import rate of 5.71p, but surely that’s only an overnight rate for 5 or 6 hours. Isn’t your heat pump running fir 24 hours a day?



   
ReplyQuote
 Andris
(@andris)
Estimable Member Member
Joined: 6 years ago
Posts: 131
02/10/2026 10:31 am  

I’ve tried running it 24/7, but it doesn’t work for me. I have a 16 kW heat pump (which I think is slightly oversized, as my house is about 250 m², but it’s a new build that I insulated myself).

 

The lowest setting is still too much to run 24/7. My heat pump doesn’t actually stop when it reaches the target temperature; it just keeps running at the lowest output it can, which is around 900 W of input power, plus the circulation pumps. If I let it run 24/7, it overheats the house.

 

So what I’ve been doing is running it only during the 6-hour cheap-rate window, but setting the flow temperature higher than I would normally need if it were running all day.

O

I heat my hot water with the immersion heater, so the heat pump can focus entirely on heating the house during those 6 cheap hours.

 

I used to have the electric backup heater turned off on the heat pump because I didn’t need it. However, now that I need a higher flow temperature, I’ve allowed it to kick in when necessary at around 0°C outside. It’s a two-stage 2 kW + 4 kW immersion backup. I only use it to help during defrost cycles and get the temperature back up, and it’s quite rare that it’s needed because I’m in Edinburgh, right next to the sea.

 

We built the house ourselves and put 15 cm of Celotex insulation board under the underfloor heating. We also installed 20 mm pipe instead of the usual 16 mm.

 

This seems to work really well for heating the house overnight. We set the downstairs temperature to go up to 22.5°C, and it’s able to hold a very steady temperature until midnight. I’ve never seen it dip below 21°C.

 

Only upstairs, where we have radiators, does the heating kick in during the afternoon, usually for about 3 hours.

 

I hope that makes sense! 😊

 


16kw Samsung TDM ASHP. 8.4kw PV, power optimizers 20×420watt panels 6kw SolarEdge inverter.


   
ReplyQuote
 Papahuhu
(@papahuhu)
Honorable Member Member
Joined: 1 year ago
Posts: 427
02/10/2026 10:46 am  

@andris That sounds a very unusual way to run your system, it’s the opposite of most people. Doesn’t make much sense to me, but if that’s how’s you want to run it then fine.

I too used to live in Edinburgh and my son has just moved away from St Andrews, it gets very cold, blowy and damp in the winter. I can’t believe how only heating overnight can keep the house warm for the remaining 18hrs, seems impossible to me. I guess you do know that there are special corrosion requirements regarding warranties for running a heat pump near the coast.

 



   
ReplyQuote
Page 72 / 72
Forum Jump:
Next Topic  
Related Topics
Topic Tags:  electricity (5) , tariff (9) ,

Currently viewing this topic 5 users ( Old_Scientist, JamesPa, Papahuhu, Toodles, Andris ) and 55 guests.

Share:

SPONSORS

Join Us!

Installer Finder

Degrees of Separation

Latest Posts

SPONSORS

Click to access the login or register cheese
Protected By
Shield Security PRO