russbost
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| posted on 18/1/12 at 08:36 AM |
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Heat Pumps??? What do we know??
Heat pumps are something I have been a little interested in for some time, was recently browsing wondering whether there were any government schemes
encouraging you to fit these now with all the clean energy/global warming/save energy etc etc (separate subject, please don't get sidetracked)
& I noticed they seem to have massively dropped in price, air/air units seem to start from around £350.
Now I have a lot of difficulty getting my head around heat pumps, after all 1kW in - 4 kW out sounds like perpetual motion (+ a bit!!), but of course
you're actually gaining the extra energy by taking free heat from the surroundings (putting it very simply, & assuming I actually do
understand how they work), but if you can genuinely get 4kW but only pay for 1Kw of electricity then suddenly electric is much cheaper than gas. I
also notice you can actually get some portable units which can do hot or cold, ie they can be an air conditioning unit too, I can't see exactly
how these collect & distribut their air, I assume they must work a bit like a portable air conditioner where you put a hose through a vent or
window? I believe all the fixed units need an outside wall to work from?
My main Q is this - do they work in a real life environment, ie, are they going to be capable of putting out heat when we most want it ie when
it's -5 degrees (or worse) outside & you really need some heat, I'm thinking of a garage heater particularly, tho' using one to
generally warm the house doesn't sound like a daft idea either.
If they are actually anything like as good as they are purported to be why aren't we all being encouraged to fit these instead of condensation
boilers?
I do know that air/ground units are supposed to be much better, but they are also very expensive to fit involving dirty great boreholes in your garden
going halfway to the centre of the earth !
Would really like to hear from anyone who fits them or has one & has real world experience of what they are actually capable of?
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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dhutch
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| posted on 18/1/12 at 08:51 AM |
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I understand the main issue with air-to-air heatpumps is that once it get cold outside they get increasingly less efficient which is where you need it
most. Find for holiday cottages where you need aircon most of the time, and a burst of heat just for damp days, but for whole-house heating you really
need a ground source heatpump.
Dont know any figures, and am only passing on what ive read.
Daniel
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fesycresy
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| posted on 18/1/12 at 09:00 AM |
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I'll u2u you my mobile if you are interested, I'm in industrial not domestic a/c, but it's all the same.
The cheap ac units have a low coefficient of performance (COP), say 3:1 or less, and their performance drops massively when the ambient lowers below
freezing.
Some Mitsubishi Power Inverters or Daikin Supers quote up to 6:1 under ideal conditions, and work down to an ambient of -20 (reduced performance
obviously).
I wrote this a few years ago: how ac works
Have a look for the Renewable Heat Incentive (RHI), but the grants have dropped as the Government have no money, which I feel will cause them to push
back the 'no natural gas into new builds' which was planned for 2016.
I have a/c in the house, but it's cold around here and I need more insulation, so my main heat source is a modern combi boiler.
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The sooner you fall behind, the more time you'll have to catch up.
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keithice
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| posted on 18/1/12 at 09:02 AM |
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They work exactly like an A/C or fridge... in fact most are reversible and if sized correctly will do as they say... an air to air unit at -5 degC
outside will probably run at -10 to -15 degC or possibly more to give the req'd inside temp. air or earth acts as a heat sink so you do get the
rating they suggest... I would expect losses from the fans and the cost of a Kwh of electricity to similar in gas or otherwise would, as you suggest,
make them a better proposition than boilers... I work on the supermarket side of fridge so my knowledge is a little limited.. if they were that cheap
though myself and all my colleagues would have them not just the couple who have put in A/C for the summer. (conservatory/front room)
Smile and wave boys.... Smile and wave....
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keithice
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| posted on 18/1/12 at 09:05 AM |
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Damn, beaten to it...ignore me fesycresy is obviously more knowledgable
Smile and wave boys.... Smile and wave....
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russbost
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| posted on 18/1/12 at 11:02 AM |
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Thanx for the info so far,
So - for instance, something like
MERLIN CHS12RA 3.5kW Through Wall Air Conditioning Heat Pump - BNIB | eBay
or
3.5Kw / 12,000 btu Air Source Heat Pump, ASHP, Heater | eBay
would take the chill out of the garage (normal double garage approx 5 x 6m) even on a day when it's -5 outside?
What happens when the efficiency drops, do you simply not get the temperature you required or does it start to use more energy?
What's involved in fitting these units, they just say "simple to fit", presumably there is some pipework & electrics involved
& presumably the system has to be charged with refigerant - is that something you can do with a DIY kit or do you have to have a proffesional in
to do it?
& what about servicing, topping up refigerant etc. - how often & is that possible to DIY or is it an expensive little man in a van?
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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fesycresy
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| posted on 18/1/12 at 01:31 PM |
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The first is just a Chinese / Korean made portable I assume, with a 4" flexi hose or two smallers ones through the wall. Keep the hose as short
as possible and insulate it if you can. Easy job.
These second, well, I've never sold / maintained a Chigo, so I don't know how reliable they are. It looks like you are just buying the
evap and condenser, no pipe work etc.
30m2 @ 150w/m2 = 4.5kw, so the Chigo would be too small. You'd have to check the spec but -5 is low for one of these budget systems.
The pipe sizes are probably 1/4" and 3/8" (possible 1/2), you will need refrigerant grade copper (15m coils or 3m drawn lengths) and
insulation. You'll need to flare each end, although you can sometimes cut the indoor flares and braize them. The outdoor will need flaring, we
use a concentric flare tool for R410a.
You should pressure test with oxygen free nitrogen and then vacuum the system to zero torr. You shouldn't really purge the refrigerant through
although many do, if you have a leak it's gone. The unit should come pre-charged with refrigerant for up to 10m (trim charge required after
that). They should never need topping up because they should be fully sealed from day 1. If they ever require more gas it's either because you
have a leak or an insufficient trim charge was added when commissioned.
Every couple of weeks I get calls from people who have had a go themselves and now they want us to come along and repair their pipe work, vacuum and
charge the system. I won't commission / repair any ones elses work, they can get lost.
If I were you I'd pop along to a local refrigeration parts supplier and ask for the name of a recommended engineer who would want to help you on
a Saturday for some beer money. Explain you are going to buy a unit, you'll mount it and put the power on, they can sort the rest, half a day
tops and they'll supply the pipe work, I bet 
Try FSW: FSW Essex
[Edited on 18/1/12 by fesycresy]
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The sooner you fall behind, the more time you'll have to catch up.
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tegwin
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| posted on 18/1/12 at 01:37 PM |
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I installed a 12Kw air>water heatpump 3 years ago. It actually replaced a 25 yearold machine of a similar capacity. The house requirements are
closer to 20Kw but the owner of the house(my grandmother) decided this shcheme was the one she wanted
It is setup for a max return temp of arund 48 degreesC which it can manage admirably during the warmer partsof the year. During the winter it has to
be "helped" by a couple of electric direct heaters in series with it. It can manage a max of 11 degreesC between inlet and outlet.
The ASHP (air source heatpump) feeds into the system as if it were a normal boiler. Flows through 17 rads...
In an ideal world you would run it with a thermal store to collect the heat energy during the day (plus top up with solar) and then run lower temp
underfloor heating.
Its deffinately a clever technology and not really that complicated when you look at it.
For small properties with a heat requirement of say 10kw, a 12Kw machine would, I suspect provide adequate heating all year.
Even down to 0 degrees C the machine is still rated at 8Kw.... black magic and voodo if you ask me!
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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Ninehigh
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| posted on 18/1/12 at 04:14 PM |
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Hold on, there's a unit that give out heat based on the air outside, even if the air outside is below freezing?
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tegwin
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| posted on 18/1/12 at 04:32 PM |
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quote:
Originally posted by Ninehigh
Hold on, there's a unit that give out heat based on the air outside, even if the air outside is below freezing?
Dont forget that 0 degrees C is NOT actually freezing, its just an impirical number. Absolute zero or -273.15 degrees C is the point at which the
atoms can no longer move.
At 0 degrees C there is still plenty of energy in the air mollecules that can be recovered :-)
[Edited on 18/1/12 by tegwin]
[Edited on 18/1/12 by tegwin]
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Would the last person who leaves the country please switch off the lights and close the door!
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Ninehigh
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| posted on 18/1/12 at 04:53 PM |
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Yeah what I mean is how can you get an output of 25 degrees from an input of 5 degrees or below?
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tegwin
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| posted on 18/1/12 at 05:37 PM |
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Dont think of it as "temperature".... its just energy... if you collect the energy packages at an ambient of say 5 degrees and squish them
together you get the sum total of their energy which you can then pass into the water.
Worth reading fridge theory, its all to do with the expansion and compression of gasses.....which I know little about!
Weirdly, you can do this passivley..
If you have a sealed insulated box with a heatsink inside and another heatsink on the outside of the box connected to the one inside via a thermally
conductive metal..... If you blow air over the external heatsink you can drop the temerature inside the box lower than the temperature outside the
box.. Weird.. but it works well enough to get ice inside the box
[Edited on 18/1/12 by tegwin]
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Would the last person who leaves the country please switch off the lights and close the door!
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russbost
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| posted on 18/1/12 at 05:47 PM |
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quote:
Originally posted by Ninehigh
Yeah what I mean is how can you get an output of 25 degrees from an input of 5 degrees or below?
As I understand it, & my knowledge is fairly limited, & in extremely simplistic terms, you take the chunk of air/water/ground outside your
garage/house or whatever & you cool it down from -5 deg to, say, -20 deg, in cooling it down the heat generated has to go somewhere & you can
then take that chunk of heat & put it inside your garage/house whatever. It would seem to me to be highly underused technology & if it was
persued correctly I think we'd probably all have heat pumps rather than boilers, unfortunately that would then make us all the more reliant on
electricity, which now we've pretty much given up on nuclear, we can't generate anywhere near enough of without burning fossil fuels!
Thanx for all the info guys - fesycresy I may pester you for that mobile no.!
I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator
headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names
furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours.
http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
|
NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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