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    • zeupater
    • By zeupater 21st Jul 13, 5:35 PM
    • 3,818Posts
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    zeupater
    Discussion ... ASHP(Air/Air) with Solar pv ....
    • #1
    • 21st Jul 13, 5:35 PM
    Discussion ... ASHP(Air/Air) with Solar pv .... 21st Jul 13 at 5:35 PM
    Hi All

    The combination of a small ASHP(Air/Air) with Solar pv seems to be a valid pairing of complementary technologies which has been raised a number of times on this forum.

    The idea of this thread is to encourage discussion of this combination in order to validate what an appropriate equipment specification would look like in order to maximise performance benefits in a typical domestic environment.

    Obviously, it is well understood that a typical domestic-scale solar pv system will not generate sufficient energy to provide winter heating, but should be considered as being a 'shoulder' months supplementary heat source for well insulated properties ... it is therefore best to concentrate on Spring & Autumn as being the target periods for heat provision, with an additional benefit of provision of cooling in heat-wave conditions such as we've been experiencing recently.

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
Page 10
    • zeupater
    • By zeupater 29th Nov 17, 10:52 PM
    • 3,818 Posts
    • 4,731 Thanks
    zeupater
    Notice that GCH has come on a few times this month, either in the morning or evening to warm the bedroom up when the wireless programmable thermostat has called for heat.

    However, with the heat pump running in the lounge and the internal door opens to circulate the warm air, our gas use is down to a less than a third of what it was last October, at a predicted less than 200kWh for the month and electric use only up by about 20kWh, despite the recent poor PV generation.

    From checking stats for October last year, it has been a bit milder so far this year, but by only a couple of degrees, but there has not been much sun
    Originally posted by ASavvyBuyer
    Hi

    Bad News ... It's been dull again today so very little solar gain (again)
    ...
    Better News ... It's just about 3weeks until the shortest day
    ...
    Even Better News ... The log-burner was fired-up for a while today, not bad for the first burn ... almost December & only fed for a handful of hours thanks to the ASHP's contribution .. might need to use the GCH if the promised cold spell is actually cold .. & long!
    ...
    Outstanding News ... solar thermal has only needed the occasional GCH top-up and according to the weatherman it's going to be sunny tomorrow ..
    ...
    And back to the Bad News ... the DHW storage is pretty much depleted so even a really sunny day wouldn't make much difference, so another top-up is due either tomorrow or Friday ... couple this with the recent accuracy of the weather forecast & I'll not be getting too excited either way! ... ...

    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
    Last edited by zeupater; 29-11-2017 at 10:55 PM.
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • Martyn1981
    • By Martyn1981 30th Nov 17, 8:02 AM
    • 6,144 Posts
    • 10,280 Thanks
    Martyn1981
    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
    Originally posted by zeupater
    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)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • Martyn1981
    • By Martyn1981 1st Dec 17, 7:54 AM
    • 6,144 Posts
    • 10,280 Thanks
    Martyn1981
    Tonight I'll see how this months leccy import compares to previous years.
    Originally posted by Martyn1981
    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)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
    • zeupater
    • By zeupater 12th Dec 17, 10:44 AM
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    • 4,731 Thanks
    zeupater
    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
    • SalsaDanca
    • By SalsaDanca 17th Dec 17, 12:07 PM
    • 397 Posts
    • 601 Thanks
    SalsaDanca
    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.
    • zeupater
    • By zeupater 17th Dec 17, 4:34 PM
    • 3,818 Posts
    • 4,731 Thanks
    zeupater
    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.
    Originally posted by SalsaDanca
    Hi

    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
    Last edited by zeupater; Yesterday at 4:41 PM. Reason: +the
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
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