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.
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)
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
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.
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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December 26th, 2005 at 5:35 pm 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)
December 29th, 2005 at 1:56 pm 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.
December 30th, 2005 at 10:51 am 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!