Flow temperature- At what point?
Hi, I’m sure this would of been asked before but a question for the more knowledgeable on these matters.
At what point does it start becoming a false economy by lowering the flow temperature as to attempt to increase the COP.
I ask as I presume there’s a point at when the flow temperature is lowered to a certain point the Heat pump will simply be forced to work to hard to reach the room target temperature.
Thanks in advance.
Barry
If you are running on weather compensation then room target temp doesn't factor into it, the heat pump will be running 24/7 and your house won't reach target temperature as it will be losing heat faster than its being put into the house as the flow temp will be set too low.
IMO, COP isn't a good measure of anything other than instantaneous efficiency, depending on TOU tariffs etc the best COP may not even be the most financially economical. I run at a higher temp at a COP of 3 overnight to defer the need to run at a COP of 4 during the day as electricity is 1/4 of the price overnight, worse efficiency but 1/3 the cost.
The primary function of my heating is to keep me warm, secondary factor is how much it costs to run, appreciate that may not be the same for everybody.
Thanks for the reply Gary.
Just to note I’m running on auto adaptation.
I had read on here somewhere that running on A/A the set flow is immaterial as the system finds itself the best flow temperature but from what I can see with my ecodan that seems not the case.
@westkent Ah your question makes more sense now, auto adapt does use the room temp and uses the weather comp curve set as a starting point but then will adjust the flow temp from that base curve as it learns how the room heats up at various outside temps.
Is there a specific issue you have?
I have been running my curve at 45c to -2 but last night moved it down to 38c to see if it helps efficiency wise.
I guess my original question was how low would I be able to lower the curve before it either wouldn’t be able reach the desired (20c) or the H/P ends up running continuously hence affecting efficiency??
Im still on somewhat of a learning curve myself on these situations.
@westkent I'm not that familiar with autoadapt as it for use with radiators and I have UFH. I think there may be limitations within the service menu on how far auto adapt can move the curve, if that's the case if you move to too low then it won't be able to maintain the temperature, but this is purely speculation on my part. It may be that autoadapt just ignores any changes you make and will do its own thing.
I think you will just have to experiment, once it gets to 2C or lower mine runs continuously anyway as it has to have down time for defrosts and needs to run continually to keep the house temp at the desired level
Posted by: @westkentI have been running my curve at 45c to -2 but last night moved it down to 38c to see if it helps efficiency wise.
I guess my original question was how low would I be able to lower the curve before it either wouldn’t be able reach the desired (20c) or the H/P ends up running continuously hence affecting efficiency??
Im still on somewhat of a learning curve myself on these situations.
You have to experiment, reducing it a degree at a time until it fails to heat the house up sufficiently. TRVs (if you have them) all fully open and and external (or internal) thermostat set at least a couple of degrees above desired temperature while you do this (which most should be anyway), and don't change it more than once per day
Heat pump running continuously at lowest possible flow temperature is exactly what you want, certainly when it cold (say 10C or less). Thats the most efficient operating point. For every degree you can notch down the WC curve you should save 2-3%. That soon builds up!
As you have discovered Mitsubishi features an auto adaption mode, its not entirely clear how this works but the basic concept is that you dont have to get the WC spot on, so it may be that turning it down further manually doesn't in fact help because the machine will do it for you. I don't know, maybe those more familiar with Mitsubishi 'in practice' do.
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.
- 26 Forums
- 2,238 Topics
- 49.8 K Posts
- 395 Online
- 5,900 Members
Join Us!
Podcast Picks
Latest Posts
-
RE: DESNZ doing a survey which asks the right questions!
@jamespa but is MCS capable of knowing the difference b...
By Judith , 27 minutes ago
-
RE: Solar inverters - where does the energy go when clipping?
Since the combination of fitting plus scaffolding makes...
By Judith , 42 minutes ago
-
RE: Designing my house system with a mix of air to air and air to water
@jamespa Cheers James, it's great reading. In quite a f...
By pipebaron , 1 hour ago
-
RE: PV Panels on roof in Conservation Area
If there is any way you can determine daily oil consump...
By JamesPa , 1 hour ago
-
RE: Octopus Cosy Heat Pump Owners & Discussion Thread
@editor The Good: How efficient have you fou...
By wreckguru , 2 hours ago
-
RE: My experience with 3 heat pump surveys: Heat Geek, British Gas & Octopus
Good plan and pretty much what I did in the end (there ...
By JamesPa , 3 hours ago
-
RE: Grant 13kW Aerona3 - issues getting zones to temp
attached is prelagged in case indicates anything. &nb...
By Crimson , 5 hours ago
-
RE: The Hidden Secret to a Successful Heat Pump: Pipe Size Matters
The more we learn about about an ASHP potentially repla...
By colinc , 5 hours ago
-
RE: Solis S6-EH1P8K-L-PLUS – Why I Chose It and What I’ve Learned So Far
Via the cloud and via the online, similar data is shown...
By Batpred , 8 hours ago
-
@old_scientist yes. No E911 error. Very odd. Thanks for...
By bontwoody , 10 hours ago
-
RE: Incorrect Billing of Customers with a Smart Meter
How odd @korwraith - that functionality being offered ...
By Transparent , 11 hours ago
-
This is what I do, but I have a very simple economy 7 l...
By JamesPa , 14 hours ago
-
RE: Master & Slave Zones/Setback
Re outdoor probes can be added from the ones attached t...
By bretix , 15 hours ago
-
RE: Octopus Cosy & Octopus EV + bidirectional smart tariff, together. What, eh?
Thanks for sharing this, it is clearly disappointing, B...
By Batpred , 22 hours ago
-
I'm seriously considering an air to air A2A multi-split...
By springswood , 1 day ago
-
RE: Effect of Mitsu PAR WT60 Wireless Controller
@sunandair We were not present to do a tidy changeover ...
By DavidAlgarve , 1 day ago
-
I’m frankly amazed you think anything I have posted on ...
By Majordennisbloodnok , 1 day ago
-
RE: Replacing knackered oil boiler with Samsung ASHP - Perthshire
Thanks for your full reply @mike-h. It certainly cleare...
By DowallyDrifter , 1 day ago
-
RE: Daikin Octopus installation update - I saw my first defrost. 😍😂
I don't seem to have a mixer valve. Just pressure regul...
By Jancold , 2 days ago

