Discussion on buffer tanks and heat pumps
Now my install has been plumbed correctly I've turned my attention to the buffer, backup heater and external circulation pump as I believe these are put in purely out of laziness/lack of expertise of the designers, whereas in fact they are making the install and run far more complicated and expensive with these items installed. Get the customers to pay for these extras and pay again in wasted energy using them, so no reason for designers to worry about doing it properly.
There are some key mentions in the Daikin manual which are flags, and just as key there is zero mention of adding an external (CH Circ) pump to the CH system.
the only mention of a field supply pump is here:
My install has a 50 litre buffer, a Grundfos circulation pump and a Backup Heater. So, according to the specs, with a backup heater the minimum volume of water is just 20 litres, that's about 3 radiators panels/ large towel rails. I have the equivalent of 11 doubles, which is 144 litres plus the pipework. So in no circumstance would the install need a buffer tank. That 50 litre buffer represents about 33% of the total volume of the install, so that's 33% lost efficiency, 33% more expense in bills.
Now I have never seen a design for the system, it will be interesting what the handover pack will include.
I have also done some experiments on the CH Circ pump speed.
Turning it off or up to full speed doesn't affect the flow rate displayed on the unit, which must mean the internal pump is pushing water faster than the external Grundfos.
Turning the Grundfos off negatively impacts the CH flow, all the Rads went cold even though the F&R temps on the Daikin were at 37/35. Which means the buffer was acting as a bypass to the heating system without that extra Grundfos inertia
Turning the Grundfos to the slowest speed restored warmth to the Rads and the flow in and out of the buffer was <0.2C (delta).
At the moment my only interest is getting it through RHI. I'm not going to start messing with the layout as I need that MCS certificate but its something I will deal with later. A simple bypass of the buffer or ripping it out completely are my thoughts.
Giving this further thought, the buffer tank should only ever be in circuit as part of an automatic bypass system in case of end user error closing all the Rad valves.
......and in my case limited to a 20l buffer tank
some good analysis there. Have you thought of a change in career?
Seriously though, it isn't right that customers/users end up having to know more about their heating systems that the so-called experts. Imagine if you had to tell your electrician how to rewire your house.
Kev
- 26 Forums
- 2,242 Topics
- 49.9 K Posts
- 424 Online
- 5,903 Members
Join Us!
Podcast Picks
Latest Posts
-
RE: Midea ASHP – how to set weather compensation
@cathoderay unfortunately, I don't have modbus or HA. I...
By pash44pump , 17 seconds ago
-
RE: New build installation query
Unfortunately not. Maybe the website interprets any jp...
By JamesPa , 9 minutes ago
-
RE: Mitsubishi Ecodan R290 10kW performance
@jamespa Thank you, just need to get it fixed!
By Ecoste , 9 minutes ago
-
Thanks for the response @batpred Your conversational ...
By Transparent , 12 minutes ago
-
I've got melpump with the wifi adaptor plugged into the...
By davidnolan22 , 27 minutes ago
-
RE: Daikin Octopus installation update - I saw my first defrost. 😍😂
Thats encouraging. As I say normal motion in pipework ...
By JamesPa , 38 minutes ago
-
RE: What should we do with our Aga?
One slightly off-the-wall suggestion is that, if you li...
By Majordennisbloodnok , 1 hour ago
-
RE: Help me keep the faith with my air source heat pump installation
I think there may be some oddities about the COP report...
By JamesPa , 4 hours ago
-
RE: One room is colder than the rest of the house
I would personally be sceptical about reaching any conc...
By JamesPa , 14 hours ago
-
RE: My experience with 3 heat pump surveys: Heat Geek, British Gas & Octopus
If you paid for any of the assessments try asking for t...
By JamesPa , 16 hours ago
-
@drei Thats a nice designer radiator which it would ...
By JamesPa , 16 hours ago
-
I've created a separate post here, wondering about radi...
By DREI , 17 hours ago
-
RE: Air source heat pump roll call – what heat pump brand and model do you have?
@ecoste, @walnut-tree-cottage these are both great piec...
By JamesPa , 18 hours ago
-
RE: Solar inverters - where does the energy go when clipping?
You will, of course, check the dimensions and weight be...
By Transparent , 22 hours ago
-
RE: The Hidden Secret to a Successful Heat Pump: Pipe Size Matters
17l/min is enough for only 6kW at 5C DT, not surprising...
By JamesPa , 1 day ago
-
-
RE: End of Summer Time Reminder to Ecodan owners
As I understand it....ha....Melcoud will over ride any ...
By Abernyte , 1 day ago
-
Finding flow temp data from Samsung 16kw HP
Hello, I have a Samsung MIM-E03 16kwh heat pump, and ...
By martingale , 1 day ago
-
RE: Faulty Clivet heat pump out of the box
We would never win these projects as we spend 1 whole d...
By ASHP-BOBBA , 2 days ago




