Posted by: @agentgeorge

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Buffer Tank or Low Loss Header: Yes

I'm surprised by this.  Is it 2 port or 4 port?

Forum Handle: @BruceR

Manufacturer: Vaillant

Model: Arotherm Plus 7kW

Type: ASHP

Arrangement: Mono

Area of Country: Southern England

Home Type: House

Size: Square Metres: 227

Insulation Level: Scale of 1 to 10 possibly ~7

Heat Loss Calculation: 8-11kW @ -2C, depending on who did the calculation

Type of Controller: 1 Zone with TRVs on all rads

Type of Control: Weather Compensation

System Type: Radiators

Total Output of Heat Emitters: 13 kW

Buffer Tank or Low Loss Header: No

Secondary Pumps: No

Solar PV System: 1.5kWp

Power Diverter: Yes

Battery System: small 2kwh 500w peak output

Hitachi Yutaki SCombi Heat Pump
(Indoor Unit ) RWD-3.0RW1E-220S-K
(Outdoor Unit) RAS-3WHVRP1

2024 build bungalow
200m2
High level of insulation
Underfloor heating
All 12 circuits are fully open all the time
1 thermostat in family room
3kw heat pump
50 litre buffer tank

Mitsubishi 8.5 kW Ecodan Standalone (PUZ-WM85VAA)

Forum Handle:@DowallyDrifter

Manufacturer: Samsung

Model: AE160CXYDEK (MCS: EHS R290 16KW)

Type: ASHP

Arrangement: MONO

Area of Country: PERTHSHIRE

Home Type: House

Size: Square Metres: 240

Insulation Level: 7?

Heat Loss Calculation: 13.3kW @ Amb. Temp, of: ?C

Type of Controller: Thermostats (for original UFH on oil))

Type of Control: Weather Compensation

System Type: UFH both floors (under slate/hardwood)

Total Output of Heat Emitters: unknown kW

Buffer Tank or Low Loss Header: BT 40l

Secondary Pumps: one on one UFH manifold (if I understand the question)

Solar PV System: No

Power Diverter: No

Battery System: No

Commissioned mid May, trying to get to grips with it for summer conditions.

Posted by: @dowallydrifter

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Commissioned mid May, trying to get to grips with it for summer conditions

What, if anything, are you finding difficult.  What are the weather comp settings?

@jamespa 

Hi,

No major issues just learning to live with it I guess.  Not sure how to answer the weather comp question

 Hot water temp is fine at 50C though lower at the tap than we had with oil - no problem.

Just been experimenting with turning heat off in hot spell and monitoring energy use to provide HW for two at-home adults (washing up/showers only).  Noticing bathroom floors distinctly cooler with heating off for 4 days, outside temp has dropped the last few days to mid teens.  Room stats not calling for any heat but bathroom floors on (I believe) open circuits that used to be on timer combined with room demand. (26yo UFH system and controls).  Heat turned back on to auto this a.m. so will see how that goes.

We use the away setting if away for 2-3 days at a time as you'll see on the energy use below.  EDF standard rate as no smart capability here due to poor wireless singals.

@dowallydrifter 

OK.  

I would recommend you read this introduction to ASHPs to help you understand a bit more about them and explain the terminology. 

Weather compensation ('WC') (Samsung call it 'water law') is the function of heat pumps that adjusts the flow temperature of the water from the heat pump according to the outside temperature, in order to match closely the energy emitted by the emitters with the loss from the house.  This is an essential feature of heat pumps and important to understand.  It also exists on many boilers, but rather stupidly we rarely use it for boilers in the UK.

As the introduction explains heat pumps should, in most cases, be operated (for greatest efficiency) in almost the polar opposite way to the way we operate boilers.  Typically they are most cost effective when left on 24*7 during the heating season, with TRVs/Thermostats set 2 degrees above target temperature so they act as limiters (eg in the case of solar gain) not controllers and are essentially always calling for heat.  The WC curve is then adjusted down so it just heats the house to the desired temperature.  It may be necessary to 'balance' the zones/loops on the LSVs/zone valves.  Again in most cases (there are always exceptions) departing too far from this will significantly increase running costs.  Obviously you wont notice that so much now, but you will in winter!

DHW is generally best reheated once or max twice per day on a schedule, not continuously reheated.  Heating to 50 or even a bit lower is normal with ASHPs - again for efficiency.  I have mine set at 48 which is still hotter than I ever need, so its always diluted in practice with cold water.  

Feel free to ask any questions or for more detailed information but I do recommend you read the ABC guide.