Air Source Heat Pumps

TiredGeek

Cardew wrote: »

I wouldn't have done so if 'TiredGeek Mk1' (who spent £14,000 on a system that just didn't work) had posted as above.

'TiredGeek Mk2' is more forgiving;)

That £14000 is so last year
The final figure is a little north of £20000 now it's had so many mods and fixes specified by the previous company and when we finally had the guts to pull all the bills out and throw a calculator at them.

I can't praise the new company highly enough though, they fixed everything without any fuss and at a lower figure than we originally paid. Superb company who I'll recommend to anyone :beer:
Jeepjunkie,
I'm in the enviable position now of being able to check the operation of the system and look back over records of the input and output figures.
Bearing in mind that since the middle of December it's been on frost stat at 10'c, so sometimes not actually doing any heating (which drags the COP down) the system as a whole has averaged a COP of 4.35! (one has done 4.98 the other 3.72)
Compared to systems one to four that's amazing
(one to three never made it through a winter, system four used £430 in 33 days - on frost stat)

We've no chance of mains gas, the only realistic options for us was oil or LPG. Yes, they'd have been (much) cheaper after all that's happened but now the system is working well we have no regrets

Harryo

shortperson wrote: »

Thanks Harryo - when you say UFH will be more expensive than radiators, do you mean in the cost of buying and getting it installed, rather than to run the system? I think we will need to take the floors up anyway to insulate underneath them so laying the UFH system underneath wouldn't be a problem.

The supply and installation cost will be higher (unless you would be having some of the expensive designer rads which can cost an arm and a leg).

The running costs should theoretically be a bit cheaper as the air temperature can be controlled at a slightly lower level than with rads, to provide the same comfort level. However, typically users tend to keep UFH operating for longer periods than rads, due to the time lag and therefore the quantity of saving is very difficult to judge. There is a possibility that UFH will cost more than rads depending on how it is controlled and the occupancy pattern.

As your system will be below a timber floor the time lag will not be as great as with a system buried within the screed but it will still not be as reponsive as a radiator system.

I would suggest you get advice from one of the specialist installation companies and probably get them to design and either install or provide the materials to the heating contractor. Consideration needs to be given to the potential detrimental effect of heat on the timber and the effect on heat output from any floor coverings you have. I would suggest you do not just rely on the advice of a plumbing contractor, who may not have adequate knowledge of such matters.

Theoretically the UFH should physically last longer than a rad system (say perhaps 50 years rather than 30 years - yet to be proven as no modern UFH system is that age yet). The boiler, pumps, valves, controls and other mechanical components would require replacing though probably once or twice within the 50 year period.

Also UFH will probably not date where rads are likely to, which can influence the decision to replace the system.

richardc1983

TiredGeek wrote: »

Probably.

If you have access to mains gas then it's most likely the cheapest to run.
It's also a far cheaper system to install.

Also, as you have mains gas you won't qualify for the RHI should it ever actually come in, so the ASHP won't be subsidised in any way, therefore if it is actually a bit cheaper to run an ASHP system it'll take years and years to break even with a good gas boiler, and if gas turned out cheaper you'd never see a return.....

I can't believe I'm saying this, but put the money you save by not buying an ASHP in the building society and the interest will more than cover any higher running costs a gas boiler may have (though it may be cheaper to run gas anyway).

(Cardew has just fallen off his chair )

Hi TiredGeek

You are required to report your findings with your system lol over at http://www.refrigeration-engineer.com/forums/showthread.php?38540-Calling-Tired-Geek if you have got time could you drop a few lines?

Cheers
Richard.

[Deleted User]

TiredGeek wrote: »

Jeepjunkie,
I'm in the enviable position now of being able to check the operation of the system and look back over records of the input and output figures.
Bearing in mind that since the middle of December it's been on frost stat at 10'c, so sometimes not actually doing any heating (which drags the COP down) the system as a whole has averaged a COP of 4.35! (one has done 4.98 the other 3.72)
Compared to systems one to four that's amazing
(one to three never made it through a winter, system four used £430 in 33 days - on frost stat)

We've no chance of mains gas, the only realistic options for us was oil or LPG. Yes, they'd have been (much) cheaper after all that's happened but now the system is working well we have no regrets

Great stuff, sounds like all is going well.

We are still in winter wonderland here but nice and cosy inside. If we were still on LPG here or oil in a previous property we'd be well and truly bankcrupt by now not to mention cold

ASHPs that work in winter, jeez who would have thought eh! The work of the devil and all that :rotfl:

TiredGeek

richardc1983 wrote: »

Hi TiredGeek

You are required to report your findings with your system lol over at http://www.refrigeration-engineer.com/forums/showthread.php?38540-Calling-Tired-Geek if you have got time could you drop a few lines?

Cheers
Richard.

LOL, I found it before I saw this, but thanks for pointing it out

We're very happy with the system, just got to draft proof the house a bit more this year

Cardew

TiredGeek wrote: »

I'm in the enviable position now of being able to check the operation of the system and look back over records of the input and output figures.
Bearing in mind that since the middle of December it's been on frost stat at 10'c, so sometimes not actually doing any heating (which drags the COP down) the system as a whole has averaged a COP of 4.35! (one has done 4.98 the other 3.72)
Compared to systems one to four that's amazing
(one to three never made it through a winter, system four used £430 in 33 days - on frost stat)

How can you measure the COP?

Obviously you can measure the input consumption, but the output??

Surely you would need to constantly measure both the input and output temperature of the water and calculate heat produced from those measurements??

Both input and output water temperatures would be constantly fluctuating.

zeupater

Cardew wrote: »

How can you measure the COP?

Obviously you can measure the input consumption, but the output??

Surely you would need to constantly measure both the input and output temperature of the water and calculate heat produced from those measurements??

Both input and output water temperatures would be constantly fluctuating.

Hi

A good friend has a GSHP installation which does exactly this by measuring load and flow rate along with both input & output temperatures thus providing the ability to display a current COP and historical metrics by day/week/month/year. I suppose that some ASHPs have the same ability.

Incidentally, our solar thermal does exactly the same, except for measuring the load on the pump ...

HTH
Z

matelodave

We are in our third winter of having an 11kw Daikin LT split heatpump system coupled to a polypipe overlay underfloor heating system laid on top of the existing floor and this has been the coldest winter of the three.

It's installed in a 1986 140sq/m detached bungalow, out in Fenland, so its cold, exposed and windy. The loft is insulated with 300mm rockwool, the walls are insulated (but I'm not sure how well), it's double glazed and the flooring is ventilated suspended timber, which is not insulated (ran out of money and inclination to take up the whole floor)

I am quite happy with the performance and cost of the system although this prolonged cold winter is probably going to use about 500-600kw more than last winter.

I read the electric meter weeky but cant seperate heating from everything else (lighting, water, washing, cooking, drying etc) but our total consumption last year was about 8000kw which I dont think was bad. The highest useage we've had is 1500kw for the 31 days of January 2013 = £160 but in the last couple of summers its averaged only about 250- 300 units in July (we presently pay 10.6p/kw). The unit actually uses just under 3kw a day just keeping itself warm which is a cost that isn't obvious.

We heat the whole place to about 17 degrees all the time with an uplift to 19-20 in the bedroom, bathroom and kitchen in the mornings & evenings and all day in the lounge and study.

We find that with the u'f heating we can keep the temperature a bit lower as it's even all over rather than having hot & cold spots.

We only run the system temperature at 35-40 degrees (except when the temp drops below 0 when it goes up to about 45). We do find that it's a bit slow to respond mainly because its running at a low temperature so it's best not to let the house get cold

I have half seriously considered PV but we wouldn't get any real benefit as the unit uses most energy when the sun isn't shining and we haven't had all that much sun in the past 12 months.

If we'd had the option of mains gas then I would have gone for it with a condensing combi boiler but the alternatives of LPG, Oil or wood pellets were not attractive due to their cost and storage requirements. Everyone where I live have has had to have 2-3 deliveries of their chosen fuel since just before Xmas so I dread to think how much it's costing them.

TiredGeek

Cardew wrote: »

How can you measure the COP?

Obviously you can measure the input consumption, but the output??

Surely you would need to constantly measure both the input and output temperature of the water and calculate heat produced from those measurements??

Both input and output water temperatures would be constantly fluctuating.

Yep, exactly what happens.
Water flow litre per min, outdoor temp, indoor temp, output temp, return temp, electric used by ASHP, electric used by controls, electric used by immersion heater, time run, time idle, and lots and lots of other things measured
All accessible from the interweb in real time, and full records since commissioning.
Currently 9.3' inside, 1.8' outside, neither unit doing anything but one using 0.06kw to keep itself warm
I'm 500 miles away at work.
Utterly superb

Cardew

TiredGeek wrote: »

Yep, exactly what happens.
Water flow litre per min, outdoor temp, indoor temp, output temp, return temp, electric used by ASHP, electric used by controls, electric used by immersion heater, time run, time idle, and lots and lots of other things measured
All accessible from the interweb in real time, and full records since commissioning.
Currently 8.3' inside, 1.8' outside, neither unit doing anything but one using 0.06kw to keep itself warm
I'm 500 miles away at work.
Utterly superb

How about passive solar gain?

Zeupater's house I believe has a high solar gain.

I have a detached annex that I don't heat unless occupied(or in danger of frost damage) and inside it gets well above the outside ambient temperature.