Discussion ... ASHP(Air/Air) with Solar pv ....
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Good things these high efficiency ASHPs ... if you can keep the small amount of heat they produce in it's surprising how much they actually help-out ....
HTH
Z
Mine's been running pretty much every day from about 9am to 3pm, apart from one day when I generated almost zero, but no heating was needed (grey and warm).
Dawned on me yesterday that at a COP of 4, just the GCH pump wattage run through the ASHP comes out close to my oil filled rad at 400W, which was good for keeping the chill off. Though I'm going to be below a COP of 4 these days I suspect.
Tonight I'll see how this months leccy import compares to previous years.Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Martyn1981 wrote: »Tonight I'll see how this months leccy import compares to previous years.
Leccy import was 189kWh, bit higher due to heat pump, with previous years 160-180, and total household consumption was 269kWh.
I don't have monthly gas figures, and hard to compare due to annual weather differences, but I suspect this quarter could be 500kWh to 1,000kWh lower, but will have to see in a month.Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Hi
Minus silly temperatures here last night, 10.5" of snow on the log store, bright sunshine all day yesterday and similar so far this morning although the sky's quite hazy ... heating went on for a couple of hours again yesterday to increase the background temperature, apart from that the heat-pump is performing really well, despite the fins currently being heavily encrusted with frost! ....
Keep warm ...
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
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Hi Zeupater,
My house has central heating with an oil-fired boiler, and an air-source heat pump. How do you decide when to use one heating system instead of the other? Do you use the heat pump whenever possible, and only turn on the central heating when the heat pump isn't enough?
I have a monitoring system that shows me how much electricity my house is using vs solar generation, so I can see how much the heat pump is costing me when there's not enough solar power. I'm sure the boiler is more expensive to use, but it looks cheaper because I can't see how much oil it's using.0 -
HiSalsaDanca wrote: »Hi Zeupater,
My house has central heating with an oil-fired boiler, and an air-source heat pump. How do you decide when to use one heating system instead of the other? Do you use the heat pump whenever possible, and only turn on the central heating when the heat pump isn't enough?
I have a monitoring system that shows me how much electricity my house is using vs solar generation, so I can see how much the heat pump is costing me when there's not enough solar power. I'm sure the boiler is more expensive to use, but it looks cheaper because I can't see how much oil it's using.
Sounds like you have a true bivalent system where the heat-pump and the oil boiler both feed the radiators, maybe with auto-selection of heat-source depending on outside temperature?
The small air-to-air heat-pump we use is fully independent of other heat sources - it has multi set point/day 7 day thermostatic timer, but it's mainly used on 'manual' as you would an electric or gas fire in the main living area, before opening internal doors to allow heat to balance around the house overnight, and of course, we look to utilise the unit when the solar pv is generating
When the ambient temperature causes the house to cool we progressively use the log-burner then the GCH to top the heat up, however, the combination of masses of insulation & high internal thermal mass means that as long as we don't allow the structure to cool the temperature tends to stay reasonably constant .... it's very rare that we need to use all three heat-sources, but through setting the thermostats at different points everything works well, the log burner normally having the last say! ...
Similar to you, we constantly monitor (real-time) electricity generation and have the advantage if having metered gas consumption although oil heating systems can easily have in-line flow-meters installed to provide similar consumption information .... having calculated the relative heating costs, the comfort & cost priority for us is heat-pump, log-burner then GCH ...
HTH
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle0 -
Hi,
Thanks for the detailed reply. My system isn't bivalent, the radiators are only heated by the boiler. The heat pump runs two air conditioning units in the lounge, and one on the upstairs landing. There's also a wood burning stove in the lounge, so I have quite a few options for heating. An Immersun diverter provides hot water from surplus solar power for most of the year.
The air con units have simple on/off timers, but so far I've been using them in manual mode. I've experimented with a Tado controller for one of the units, which should control the air conditioning using a mobile phone app, but it doesn't work as well as I'd hoped.0 -
Heat Pump has been a real bonus over the last few days.
There was a fault on next doors mains power cable that ended up with us being on a generator for a couple of days, set up by Western Power.
For some strange reason it stopped our GCH from working, but the Solar PV & heat pump carried on working a treat.
Back on normal mains now & GCH working OK again; but still more efficient to use the heat pump as main source of warmth in the lounge.0 -
ASHP's rock!
Been a star in Dec and Jan, but Feb is staggering - most days it's been going like a train, so no need for daytime GCH.
Small benefit of having it in the conservatory is that I can set the heat higher. With the living room ajar (for cats) it's about one degree less than the conservatory, but with the door wide open it's around 4/5 degrees less, so conservatory at 25C, with heat leaking through open window to kitchen, and living room at almost 20C with hallway warm too.
So low gen days, just warm living room, high gen days I pump it up!
Leccy use hard to say, but comparing Jan 18 to lowest previous Jan is +30kWh's, so 200kWh's for a year (6 months) seems a fair to high guess.Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
New plan, perhaps 2020-22.
Add 4 panels in the garden (1.2 to 1.5kWp) south facing 60d pitch.
Add a big batt such as the PWII.
Get an EV.
Get E7.
Should be able to cover house and EV use from Apr to Sept with zero or negligible import.
Mch & Oct, all leccy including ASHP covered by PV and batt, with EV on E7.
Nov - Feb, EV on E7 and batt topped up by E7 to supplement PV.
So, possibly, zero daytime import all year, even with EV use and ASHP supplementing heating.
I think?Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Martyn1981 wrote: »New plan, perhaps 2020-22.
Add 4 panels in the garden (1.2 to 1.5kWp) south facing 60d pitch.
Add a big batt such as the PWII.
If you add some more panels & a battery how will that affect your FIT & Export payments?
It is something I would like to do, maybe add some panels to our east facing roof with a battery to benefit from the 5% VAT rate, but even though we would generate more, if we added 100% more panels would the amount we generate be halved when working out the FIT payments?0
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