Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Renewable Heating
Thermostats, Volumi...
Low temperature rad...
 
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!

Low temperature radiators

 
Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls
Last Post by Prunus 5 years ago
3 Posts
2 Users
2 Reactions
3,216 Views
RSS
 Prunus
(@prunus)
Estimable Member Member
Joined: 5 years ago
Posts: 75
Topic starter 24/04/2021 2:41 pm   [#57]

I've put the room heat loss numbers I generated from the MCS Heat Pump spreadsheet into the 'Domestic RHI SPF Calculator' spreadsheet which has a radiator sizing tab... and all our radiators are too small. This is not a surprise as they're all single-panel from 1970s.

When upgrading the radiators, I can obviously go for type 22 (double panel) or 33 (triple panel), but there's a fairly brutal derating factor. The radiator sizing spreadsheet gives a number for derating the advertised heat output of a Stelrad radiator of 0.3 - in other words, you get 30% of the rated output. Given we're taking radiators designed to run at deltaT of 50C (average water temp 70C) and running them at deltaT of 20C (water temp 40C) this isn't very surprising.

So I wondered, are there any radiator designs which are better at emitting heat at low temperature? There are fan assisted radiators (which I might start another post about) but let's consider passive radiators for now. I could imagine you could do different things with the fins, channels etc to design for a lower temperature.

Any models that are worth looking at?



   
👍
2
Quote
Topic Tags
radiators
 Kev M
(@kev-m)
Noble Member Member
Joined: 5 years ago
Posts: 1276
24/04/2021 7:58 pm  

We have standard Stelrad K2s and they work well at a maximum input temp of 50.  The fins make them emit heat/air out the top instead of the front.  They are a bit bigger than boiler hesting systems but not excessively so.  The K3s emit more heat per unit area but are thicker and also quite a bit more expensive. Have you tried running your existing rads at 50 degrees?



   
ReplyQuote
 Prunus
(@prunus)
Estimable Member Member
Joined: 5 years ago
Posts: 75
Topic starter 24/04/2021 9:40 pm  

@kev-m I haven't tried running rads at 50C as the old oil boiler is very unhappy if the output temp is set below 70C. I'm just curious whether there are rads that are better designed for low temps than simply oversizing conventional rads. If I'm doing a replacement anyway I would like to see if I can budget for a flow of more like 40-45C to improve the COP.



   
ReplyQuote
Forum Jump:
  Previous Topic
Next Topic  
Related Topics
Topic Tags:  radiators (8) ,
Share:

SPONSORS

Join Us!

Installer Finder

Degrees of Separation

Latest Posts

SPONSORS

Members Online

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