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Ecodan ASHP low flow rate 6L

 
Air Source Heat Pumps (ASHPs)
Last Post by DavidM 12 months ago
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 DavidM
(@davidm)
Active Member Member
Joined: 12 months ago
Posts: 4
Topic starter 26/10/2024 9:02 am  

Hi I've been trying to setup my ASHP in wc mode recently as been running it just like a gas boiler recently found out that was stupid and was why the cost of electricity was sky high

 

Been on a mission to learn as much as possible  about the ftc5 to get this sorted  I've got the WC setup but pump just kept cycling through reading and learning I've found out the flow rate is 6l my unit  PUZ-WM85 should be around 15l  the pump speed is at 5 dhw is also at 5 but speed is still 6L I drained the tf1 filter nothing much came out and the prrssure in the system is at 1.5bar 

 

Anyhelp would be appreciated 



   
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Toodles
 Toodles
(@toodles)
Illustrious Member Contributor
Joined: 3 years ago
Posts: 2191
26/10/2024 9:25 am  

How old are your radiators? Might they have a build up of sludge? Toodles.


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


   
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 DavidM
(@davidm)
Active Member Member
Joined: 12 months ago
Posts: 4
Topic starter 26/10/2024 9:30 am  

They were installed same time as the heating they are the thicker radiators aswel when trying to bleed through radiators just the clean antifreeze that comes out they do heat up evenly also



   
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Toodles
 Toodles
(@toodles)
Illustrious Member Contributor
Joined: 3 years ago
Posts: 2191
26/10/2024 9:58 am  

@davidm Maybe there is a restriction caused by a partially open/shut valve? It sounds as though, though the pumps are working hard, there is an obstruction to a free flow of water through the system. A partially open or shut valve would cause a restriction, turbulence and probably additional noise.

Other than that might there be some obstruction from ‘gunk’ that was dislodged during the plumbing work that has lodge itself in a pipe (possibly at a joint). A lot to check I know but if pump is working its’ socks off and the water isn’t flowing fast enough - it is almost bound to be an obstruction or restriction - or (shudder) a kinked pipe! Regards, Toodles.


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


   
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 DavidM
(@davidm)
Active Member Member
Joined: 12 months ago
Posts: 4
Topic starter 26/10/2024 10:17 am  

Yeah that's what I seems like to me if you up the pump speed on the actual pump the flow still doesn't change, unfortunately I'm not equipped to take apart any of that

it was a company that fitted the system and my housing association plumbers ain't clued up on the ASHP at all, they sent someone round before when I moved in to help me setup didn't have a clue what to do, taken it upon myself to learn and I enjoy tinkering but at a loss what to do now



   
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Mars
 Mars
(@editor)
Illustrious Member Admin
Joined: 5 years ago
Posts: 3623
26/10/2024 10:30 am  

@davidm welcome to the forums.

It sounds like your Ecodan system could benefit from some adjustments to optimise both flow rates and pump sizing. With pre-plumbed Ecodan cylinders, the internal pumps are often undersized for anything but the best-designed systems, and they may not provide the 12–14 L/min flow rate recommended for an 8 kW unit like yours. This kind of consistent flow is critical for efficient heating and to reduce unnecessary cycling, especially in weather compensation (WC) mode.

If you have system separation, such as a buffer tank, it might be worth considering removing it. By eliminating it, your system can circulate more freely and reach the needed flow rates more consistently. 

Also, controlling valves across all rooms can reduce flow efficiency. Instead, consider limiting smart TRVs to just bedroom zones if a cooler environment is desired overnight. For the best results, aim to keep all other valves open, allowing the system to circulate freely without restriction. This should help the heat pump function more smoothly in WC mode, minimise cycling and improve efficiency – keeping those energy bills in check.


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 DavidM
(@davidm)
Active Member Member
Joined: 12 months ago
Posts: 4
Topic starter 26/10/2024 10:40 am  

All my trv valves are full open around the whole house removing anything wouldn't be a option as it doesn't belong to me (housing association)

You say reaching needed flow rates consistently it doesn't reach them at all it's just 6l on pump speed 5 if I turn it to 3 flow rate goes to 0 

Kind of looking for information to pass onto the h/a to maybe actually get somewhere with it as their own plumbers ain't clued with these as most houses around are gas but the small village I'm in doesn't have gas most are oil heating or electric here



   
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