Performance in the current cold snap…
Posted by: @derek-mPosted by: @hughf@derek-m single heat pump, just run on weather comp, no stats, no setback.
The Carel platform that my heat pump is built on allows full tuning of the PID settings, along with full control of the compressor ramp speeds. It’s close to maintaining setpoint, but I’ve still got some work to do. I’d like to deal with the initial overshoot next, I think I’ve got the oscillation damped quite well.
When it’s around freezing outside, it runs happily for a long period of time, it’s dealing with the overshoot when it’s cycling that’s the next area of tuning that needs my attention.
I suspect that it will not be possible to accurately control the LWT during milder weather conditions, simply due to the fact that the heat pump will be starting to operate outside its control envelope. i.e. it cannot turn-down any further.
As far as controlling IAT is concerned this should not be a major issue, though it could take some time to optimise for maximum efficiency.
Out of interest what are your PID settings?
It is my suspicion too, that in milder weather, we are simply oversized. I didn't take into consideration the possibility that the ACH value used in the heat loss spreadsheet (and by heating engineer) could be considerably higher than we actually achieve.
The fact that it was tracking the requested setpoint to within 0.1 degree during the last 2 weeks of freezing weather leads me to think my PID settings aren't a million miles off.
At the moment they are: P = 5 deg. C, I = 50 secs, D = 0 secs.
The controller also allows me to open up the overshoot window, which gives headroom for compressor rampdown - currently set to 5 degrees. I can't remember the rampdown settings though, it's specified in Hz/sec inside the Power+ inverter settings.
To comment on the original question in the thread title - I was away for a lot of the 2 week freeze, but the residents reported stable internal temperatures (21-22) 24/7 and there were no issues with defrosting, even with our limited system volume.
Whole house electric consumption was running around 50kWh/day - all electric house now.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
- 26 Forums
- 2,122 Topics
- 46.6 K Posts
- 104 Online
- 4,529 Members
Join Us!
Podcast Picks
Latest Posts
-
RE: Solar Power Output – Let’s Compare Generation Figures
We had an excellent four months (11/3 to 15/7) generati...
By JulianC , 5 hours ago
-
You may well be right, @jamespa.
By Majordennisbloodnok , 9 hours ago
-
RE: Is this just haze or something more?
I think the present somewhat cooler hazy days show the ...
By Judith , 10 hours ago
-
RE: My misgivings about installing ASHP and solar panels via the ECO4 scheme...
All noted and accepted and as I say I am sorry that you...
By JamesPa , 12 hours ago
-
I think it is very much me that is sitting outside the ...
By Grantmethestrength , 13 hours ago
-
-
RE: Replacing Refrigerant on Mitsubishi Heat Pump
@davidalgarve It should just be recovered by both servi...
By dgclimatecontrol , 2 days ago
-
RE: Who's your electricity provider and what's your tariff?
Aggregators have been recognised for many years, and it...
By Transparent , 2 days ago
-
RE: Help me keep the faith with my air source heat pump installation
Great news I edited my previous post (probably af...
By JamesPa , 2 days ago
-
RE: Double or Triple Glazed Windows?
@toodles Glad to hear things are progressing well for y...
By TRBob , 2 days ago
-
RE: 300 Liter Tank - Do I have to heat it all?
I agree with @morgan. You can turn down the target t...
By JamesPa , 2 days ago
-
How to waste energy (and time) playing with AI.
A friend of mine who subscribes to an AI service was ex...
By Toodles , 2 days ago
-
RE: Heat Pump Books For Beginners – Bodge Buster & From Zero To Heat Pump Hero
@topher you’re more than welcome to, yes. I’ll send you...
By Mars , 3 days ago
-
RE: Fitting new shower valve ..........
I’ve never taken a chance when fiddling and changing ou...
By Mars , 3 days ago
-
You should contact the council and report the unsatisfa...
By JamesPa , 3 days ago
-
RE: Benefits of an extra horizontal loop for GSHP
I would deffo install an additional slinky run, especia...
By Transparent , 4 days ago
-
RE: Say hello and introduce yourself
@editor fab - thanks Mars, and keep up the great work o...
By normpang , 4 days ago
-
RE: Compressor and Evaporator Stratification
@trebor12345 So I think the 1st zigzag section shows so...
By ASHP-BOBBA , 4 days ago