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Is it crucial to get flow temperatures with heat pumps right?

Alfapat · 2025-01-05T14:04:50Z

I read a lot about Flow temperatures on various threads on the forums. Are they crucial to get it right?How do I know what the flow temperature should be and is it adjustable,I have virtually no one locally that is able to help me run this system (Samsung 16 kW) as the installers went into liquidation and it been a nightmare getting the system running efficiently as far as I am able.

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Toodles

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10/01/2025 3:20 pm

@bontwoody I am attaching three screen shots which I hope will show most of what the Dashboard information screen provides. I tend to select a few salient features at a time from the ‘menu’ and look at them on their own to avoid the clutter. Regards, Toodles.

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

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Toodles

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10/01/2025 3:27 pm

@bontwoody I would further point out that the art of balancing your radiators requires some time and dedication (frequently with the addition of your partner’s understanding of your endeavours!) and is a job that demonstrates patience and dedication -but it is worth it in the long run!) I think I hint at this in my article on the subject. Rough adjustments in the first ‘round’ are followed by more delicate tweaks in subsequent rounds. Regards, Toodles.

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

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bontwoody

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10/01/2025 3:38 pm

@toodles Thanks, thats actually more than I expected so quite useful.

House-3 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
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JohnnyB

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10/01/2025 3:56 pm

Posted by: @bontwoody

↑

Im not sure how much information it provides,

Very little in the home owner app.

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bontwoody

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10/01/2025 4:04 pm

@johnnyb Is that different to what Toodles has shown in the response above?

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Toodles

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10/01/2025 4:15 pm

@johnnyb The Homely app is just for setting temps. DHW routines and programming the heating schedule(s) plus the preferences and tariff or TOU settings really. The Dashboard is supposedly for the installer (and I have lobbied Homely to amend their feelings on this) and not for the user! They feel that such access might well overburden the installer with unnecessary call-outs due to user ignorance I think! The dashboard really is useful to the initiated user and I think @editor mentioned that Homely may be re-thinking this (due I suspect to RHH member’s pressure!) I think it really would be in their interest to include the dashboard facilities in the app though. Regards, Toodles.

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

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Alfapat

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Topic starter 11/01/2025 8:27 pm

@bontwoody Ok , on the case I have two rads on adjustment just now I have gone from 20c to 18 c (they are bedroom)so trying to match both at 20 c . My question is just with this, as the evening is getting colder I can adjust against OAT , but what happens tomorrow when is to get warmer the flow temp is it, or does it ,stay the same ? Does the heat pump flow take control or do I then get say 22c! tomorrow night

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bontwoody

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11/01/2025 9:03 pm

@alfapat that is what water law is for Pat. It automatically adjusts the flow temperature to take into account the OAT. Once you have the rad valves right you won’t need to change them again.

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Alfapat

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Topic starter 11/01/2025 9:21 pm

Posted by: @bontwoody

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@alfapat that is what water law is for Pat. It automatically adjusts the flow temperature to take into account the OAT. Once you have the rad valves right you won’t need to change them again.

Flow temp at 46c , so adjusts itself or something like Homely .

As I get to know from the knowledge I have read, if the temp manages at less thn 46c for costs/kwh then all good.

Onward and up ward then , Ill need to get a move on , I am getting complaints about cold at night as Ive not done that room Yet!

Will let you know . 😐 Incedently it does look like the further I get away from the first rad It looksn like I need to compensate by opening the next rad open more to get room temps the same .

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bontwoody

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11/01/2025 9:58 pm

@alfapat yes if you can get the maximum flow temp to 46C from 50C that will be a result.

you will find that each adjustment will affect every other radiator but as you get closer it will have less and less effect.

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Alfapat

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Topic starter 12/01/2025 2:18 pm

This is crazy , I m still only at two rads trying to get 20-20.5 c , I thought I had it right last night -5c , but its warmer outside today 3c and the HP is not under the same strain, and they are small rooms OH well!

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JamesPa

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12/01/2025 3:48 pm

Posted by: @alfapat

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This is crazy , I m still only at two rads trying to get 20-20.5 c , I thought I had it right last night -5c , but its warmer outside today 3c and the HP is not under the same strain, and they are small rooms OH well!

Apologies if you already know this but dont try to get the temperatures right by adjusting the rads, aim to get them approximately the same. That should be pretty much independent of flow temp.

LSVs can be tricky and often actually have any effect only when they are within a turn or even half a turn of being closed. If you want to know more look at 'valve authority' on Heat Geek.

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.

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