Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Renewable Heating
Thermostats, Volumi...
Finding a Thermosta...
 
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!

Finding a Thermostatic Shower Valve That Works with Heat Pump Systems

 
Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls
Last Post by Toodles 1 year ago
10 Posts
3 Users
4 Reactions
1,772 Views
RSS
 ChrisJD
(@chrisjd)
New Member Member
Joined: 1 year ago
Posts: 2
Topic starter 06/11/2025 8:22 pm   [#2576]

I currently have a concealed thermostatic shower valve, installed 21 years ago, along with a 3-output diverter.

I am currently on the point of ordering a Heat Pump boiler replacement, but am concerned about the lower water temperature this would provide.

I conducted some tests by adjusting my existing boiler. I found that with our current shower (a Bristan PM TSHCVO C with the diverter PM 5WDIV C) which uses a pumped water supply, our chosen temperature is approximately 39°C. This is comfortably achieved with a temperature at the bathroom sink of 66°C.

However, with the sink temperature lowered to 55°C, the shower could only achieve 35°C, which felt too cold. The anticipated 50°C from the heat pump system would certainly not be acceptable.

The original supplier tells me that "All of our showers will require a minimum water feed at 60°C for the showers to perform correctly."

I have emailed several manufacturers and suppliers. Their common response, so far, is very much along the line of "We must inform you that we do not produce thermostatic mixers that are suitable for systems where the hot water supply is only 50°C".

I guess that, in the fullness of time, things may change. Right now, does anybody have knowledge of any thermostatic shower valve which claims to have the necessary lower differential to give, around 40°C output with 50°C input?

The actual experience may differ from my expectations, but it looks as if I may have to take the unwelcome step of running the water tank inefficiently warm.

 

 



   
🤔
1
Quote
Morgan
 Morgan
(@morgan)
Noble Member Member
Joined: 6 years ago
Posts: 704
07/11/2025 7:37 am  

I have a Grohe shower with a 3-way diverter fitted to an Ecodan ASHP. DHW at max 50 °C.  No problems at all.


Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.


   
👍
1
ReplyQuote
 ChrisJD
(@chrisjd)
New Member Member
Joined: 1 year ago
Posts: 2
Topic starter 07/11/2025 8:43 am  

Posted by: @morgan
↑

I have a Grohe shower with a 3-way diverter fitted to an Ecodan ASHP. DHW at max 50 °C.  No problems at all.

Thanks, that's interesting. Grohe responded to me "we do not produce thermostatic mixers that are suitable for systems where the the hot water supply is only 50 degrees celsius"

Out of curiosity, at the setting you desire, what temperature do you actually get at the shower?

 



   
ReplyQuote
Morgan
 Morgan
(@morgan)
Noble Member Member
Joined: 6 years ago
Posts: 704
07/11/2025 10:30 am  

@chrisjd 

 I don't know, but it's too hot to go full heat and quite hot enough just below the safety stop button.


Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.


   
ReplyQuote
Toodles
 Toodles
(@toodles)
Famed Member Contributor
Joined: 4 years ago
Posts: 3069
07/11/2025 11:37 am  

@morgan Our Mira thermostatic shower system is fed from a Sunamp Thermino ePV210 heat battery via their standard Tempering Valve. This valve is set to maximum and we have no problems at all; we never need to go above 6.5 on the Mira shower setting. I’m sorry, I don’t know what temperature we use but there seems to be plenty in reserve for anyone needing higher temperatures! Regards, Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
ReplyQuote
Toodles
 Toodles
(@toodles)
Famed Member Contributor
Joined: 4 years ago
Posts: 3069
07/11/2025 11:45 am  

And as best I can tell from the Sunamp details, the maximum water output temperature is 55 deg. C Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
ReplyQuote
Morgan
 Morgan
(@morgan)
Noble Member Member
Joined: 6 years ago
Posts: 704
07/11/2025 2:26 pm  

Posted by: @morgan
↑

@chrisjd 

 I don't know, but it's too hot to go full heat and quite hot enough just below the safety stop button.

@toodles your reply should be addressed to @chrisjd 

 


Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.


   
ReplyQuote
Toodles
 Toodles
(@toodles)
Famed Member Contributor
Joined: 4 years ago
Posts: 3069
07/11/2025 2:46 pm  

@morgan I’m sorry, the system doesn’t lend itself to replying after someone else has already done so as the only space given to reply contains the replyee’s reference. I was rushing and had less time than I needed to go back and take things from the ‘quote’ box which is all that was offered. I use extreme magnification to read the text and sometimes unfortunately miss link or text box entry point. Again sorry, will try to do better. Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
😂
1
ReplyQuote
Morgan
 Morgan
(@morgan)
Noble Member Member
Joined: 6 years ago
Posts: 704
07/11/2025 2:52 pm  

Posted by: @toodles
↑

@morgan I’m sorry, the system doesn’t lend itself to replying after someone else has already done so as the only space given to reply contains the replyee’s reference. I was rushing and had less time than I needed to go back and take things from the ‘quote’ box which is all that was offered. I use extreme magnification to read the text and sometimes unfortunately miss link or text box entry point. Again sorry, will try to do better. Toodles.

@toodles LOL. By my reply, I was only trying to ensure that @chrisjd was notified of your response. You are hereby forgiven LOL.

 


Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.


   
ReplyQuote
Toodles
 Toodles
(@toodles)
Famed Member Contributor
Joined: 4 years ago
Posts: 3069
07/11/2025 3:48 pm  

@morgan I should just have written ‘Mea Culpa’ shouldn’t I? 😉 Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
😂
1
ReplyQuote
Forum Jump:
  Previous Topic
Next Topic  

Currently viewing this topic 5 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