Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Renewable Heating
Air Source Heat Pum...
Towns water feed to...
 
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!

Towns water feed to air source heat pump system

 
Air Source Heat Pumps (ASHPs)
Last Post by JamesPa 3 months ago
4 Posts
2 Users
0 Reactions
332 Views
RSS
 DavidAlgarve
(@davidalgarve)
Reputable Member Member
Joined: 3 years ago
Posts: 248
Topic starter 04/05/2026 4:25 pm   [#2979]

As installed, my system had a buffer tank which I had converted to a return-line CH volumiser.

It was badly done and I now plan to improve the pipework by putting the volumiser in the CH flow and reducing the number of multiplex elbows, all with the objective of improving flow.

The towns water feed to pressurise the system is still as original, i.e. to the middle of the buffer/ volumiser tank, (as diagram below) but I am uncertain if this is still the best point for the towns water pressurisation.

The DHW flow is from the 3 way valve and its return taps into the main return to the Ecodan.

Comments would be appreciated.

Screenshot 2026 05 04 at 16.23.38

 

 


This topic was modified 3 months ago by Mars

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW


   
Quote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 5200
05/05/2026 8:32 am  

Posted by: @davidalgarve
↑

The towns water feed to pressurise the system is still as original, i.e. to the middle of the buffer/ volumiser tank, (as diagram below) but I am uncertain if this is still the best point for the towns water pressurisation.

Ultimately I doubt it matters much because pressures will inevitably equalise.  I would probably choose to put it upstream of valves just so there is no possibility of forcing a valve open, although even this isn't absolutely certain because there are of course two paths from any one place in the system to any other place.

Maybe someone else can come up with a reason why it would make a material difference, but I cant!


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.


   
ReplyQuote
 DavidAlgarve
(@davidalgarve)
Reputable Member Member
Joined: 3 years ago
Posts: 248
Topic starter 05/05/2026 3:09 pm  

@jamespa Thanks James. As you say, the pressures should equalise.

I was contemplating teeing it into the return line to the Ecodan. 

There does not seem to be the same need to pressurise the much simpler and shorter DHW circuit, but I suppose it can't be separated.

I do now see that I have no air bleed on the DHW heating coil circuit and this may need to be added.


342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW


   
ReplyQuote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 5200
05/05/2026 4:17 pm  

Posted by: @davidalgarve
↑

DHW circuit, but I suppose it can't be separated.

I do now see that I have no air bleed on the DHW heating coil circuit and this may need to be added.

The DHW circuit cant be separated (well it could, you could use a plate heat exchanger, but why bother).

There needs to be an air bleed at every locally highest point.  I guess it might well be possible to plumb a DHW cylinder so it (or some part of its pipework) isnt a locally highest point, but its tricky!


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.


   
ReplyQuote
Forum Jump:
  Previous Topic
Next Topic  
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