The Day Arrives

Dean from ICE Energy arrived this morning for the commissioning of the heat pump system. The sequence was:

Check all the plumbing and electrics and then add glycol to both the ground loops.

plumping in the heat pump

plumping in the heat pump

The mix has to be exactly right to avoid freezing without making the flow sluggish. Dean checks this constantly with his refractometer until he is happy with the level (-1.2)

plumping in the heat pump

Then a certain amount of programming of settings and – at last – time to switch on. And the sensors show heat being produced within a couple of minutes

plumping in the heat pump

And if you really want to, you can check out the switch-on event here on video (coming soon) – well, it seemed momentous to us after such a lot of time, work, money and general scepticism that it would actually work.

plumping in the heat pump

Then as the evening wore on, the house warmed up and we had hot baths, we were both overcome with the strangeness of it all. Not only no more oil being burnt, but no primary fuel at all – just some extra electricity to run the pumps and compressor when they are needed. A very good feeling – which will be even better if we can generate this electricity as well by wind power early next year.

And the second strange thing was the absense of any timers we have to set: the system uses three sensors (will be four when the pool heating side is wired in) and decides itself when to produce heat for either the hot water or the radiators.

So this phase of the greening of Hedgerley is done and we could not be more delighted.

on Tuesday, October 11th, 2005 at 12:29 pm and is filed under All things Solar, Heating.
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3 Responses to “The Day Arrives”

  1. John Brooks Says:
    As a heating engineer, I’m always interested in practical experience of leading-edge energy systems.
    If you could respond to some of these questions, I’d be most grateful.
    – net effecting ground-source heat pumps: have you calculated yet the net effect (in financial and energy terms) of your system? Eg. likely costs over planned life of kit, taking account of increased electricity use for pumps, compressor, etc.- actual increased cost in maintenance, replacement parts, servicing, emergency call-outs, over conventional system.

    – actual performance of system now it’s bedded-down. Eg. Does it meet performance spec? your expectations? your minimum requirements?

    – practical drawbacks (if any)


  2. Administrator Says:
    Hi – thanks for your questions. I’m looking forward to being able to answer them in detail once the system has been going for longer – two and a half months only so far.My first reactions are:
    – the output is good: it gives us all the hot water we need and heats a 5-bedroom house to 19 degrees C even in these very cold days when the temperature of the ground loop is -1.
    – the running cost is currently much too high. In discussions with ICE energy they believe that this shouldn’t be the case and we are experimenting with different settings. Obviously the degree of insulation in an (old) house is a major factor. I will be monitoring costs closely for the rest of the winter. At the moment it is more expensive than the previous oil system, whereas they claim in should be about a third of the cost, so something has to be done.
    – no practical drawbacks so far. it is extremely easy to run because of the high degree of automation.

    Do you experience of similar systems and what their typical net effectiveness is? Also do you have your own blog?

    More details in this blog when I have them.

    Cheers, Peter.

  3. John Brooks Says:
    Thanks for the info. I’m a ‘bit startled’ (ie. gobsmacked!) that the
    headline running costs of your system are HIGHER than the oil cost. I
    guess the annual maintenance budget also needs to be higher, due to
    increased complexity of the core system. All downside!I’ve not yet got involved with heat-pump systems myself – I’m a CORGI
    engineer working mainly on gas condensing boilers. My current focus is
    the costs of these, taking into account the unfortunate fact that in
    several situations condensers fail to condense to any useful extent.
    Essentially, if you take a conventional oil- or gas-fired wet system and
    try to upgrade it with a ‘high efficiency’ boiler, it may be a serious
    disappointment. The key issue is down to thermodynamics: if the
    radiators are too small and / or based on too high Delta-T then the
    house will not get warm enough in a reasonable time and / or the Return
    temperature to the boiler will not allow the heat exchanger temperature
    to fall below dew point. OK – the boiler will probably be more
    efficient than the one it replaced but it will still not attain its
    quoted maximum SEDBUK efficiency – which is only a statistics-based
    calculation in itself. I’m rapidly coming to the view that SEDBUK is
    actually very misleading: a) because it is not a real efficiency figure
    and b) because in the real world few boilers work optimally.

    Maybe your high running costs are down to a similar problem: if the
    heatpump is being asked to deliver a higher output temperature than that
    for its ‘optimum’ performance, then it will obviously (?) use more

    When you made your decisions about which technology to adopt? Did you
    factor-in the cost of replacing the core of your system when it wears
    out / becomes unrepairable / is overtaken by even-newer technology?
    what about wholesale replacement of radiators, etc. to raise the
    efficiency of the whole system, increase heat-transfer to the rooms,
    etc.? A major factor that seems to have been missed out of the
    calculations which illustrate that condensers are a ‘good thing’ is the
    probable ‘churn rate’. Old-style cast-iron boilers may be inefficient
    but they can last a very long time (I service one installed in 1972 –
    still has its ORIGINAL pump and works as well – or inefficiently! – as
    ever). Newer boilers, with fans, internal pumps, corrodible aluminium
    parts, dodgy electronics, etc., are going to get scrapped MUCH more
    quickly than 30 years!

    BTW, I’m surprised the heat collector goes below freezing so quickly
    when buried 1 metre or so underground. Where is the temperature
    measured – on the output? Surely not!

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