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
- 2,113 Topics
- 46.4 K Posts
- 94 Online
- 3,410 Members
Latest Posts
-
RE: Say hello and introduce yourself
Hi @seatonian - Yes, I know Seaton, and I have the Nat...
By Transparent , 8 hours ago
-
RE: Buffers, hot water and cooling
The principal reason that heat pumps have minimum flow ...
By JamesPa , 9 hours ago
-
@seatonian got your email. Will connect you with a reco...
By Mars , 21 hours ago
-
RE: Wood burner with ASHP - direct air?
I love the new fully Viking look... best personal avata...
By Mars , 1 day ago
-
RE: No-code, plug-and-play monitoring for your heat pump
I think I have found “The One!” Waveshare ESP32-S3-POE-...
By Grantmethestrength , 2 days ago
-
@downfield and @toddles, this isn’t in the settings cur...
By Mars , 3 days ago
-
RE: Homely launched for Grant Aerona ASHP control
I haven't bought the Aerona Smart Controller (£700!) bu...
By Prunus , 3 days ago
-
RE: Antifreeze top up for my heat pump - is this a rip off?
For the record, Grant supply ethylene glycol for their ...
By Prunus , 3 days ago
-
RE: Compressor attempts start but fails - Nibe Fighter 2005 8kW
@skyefarmer amazing. Well done!
By Mars , 3 days ago
-
RE: Air source heat pump roll call – what heat pump brand and model do you have?
Ebac 5kw - Monobloc R32. Developed and made in UK - Mit...
By marcinwloch69@gmail.com , 5 days ago
-
RE: Is a Valliant Inline 6kW heater a BUS buster?
Just another thought - it might be worth thinking about...
By JamesPa , 5 days ago
-
RE: BUS Grant: removal of all other fossil fuel heat sources
@rikiarn - just have a think as to how much it will cos...
By Transparent , 6 days ago
-
Don't do much digging around.That's best left to the pr...
By Transparent , 6 days ago
-
Hi all, I was wondering if anyone had an idea of how th...
By Wh0am3ye , 6 days ago
-
RE: EBAC re-entering the ASHP market in 2023
@toodles confirm i have Ebac 5kw ASAP + homely and it w...
By marcinwloch69@gmail.com , 6 days ago
-
RE: Compute heat loss from energy used
@jamespa Ebac must be similar to Mitsubishi as they buy...
By marcinwloch69@gmail.com , 6 days ago
-
@pie_eater I have been thinking of adding cooling to my...
By TechnoGeek , 1 week ago
-
RE: Victorian Semi Retrofit / Extension ASHP and UFH Advice
Agree, but you may have a hard time convincing them, as...
By JamesPa , 1 week ago
-
RE: Seal the Deal: Don't Let Your Heat Pump Leak Energy
Hi - fyi - there's a dead image link in the 'Optimal In...
By seatonian , 1 week ago
-
RE: Ripped Off: How UK Homeowners Are Paying Gas Prices for Wind Energy
@chandykris Horses and beggars…. 😉 Toodles.
By Toodles , 1 week ago