Air Source Heat Pumps

TiredGeek

/QUOTE] As regards the EcoDan you can only buy one if you are a Mitsubishi accredited installer.

In saying that I have seen a couple of shocking installs that in no way even point a nod to the install instructions...

Cheers[/QUOTE]

Have a look on ebay
http://www.ebay.co.uk/itm/Mitsubishi-Ecodan-Air-Source-Heat-Pumps-5Kw-8-5Kw-14Kw-/170818246197?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item6d73e00150#ht_769wt_1396

Shocking installs, yep I concur

TiredGeek

Cardew wrote: »

Another difficulty is the customer proving the performance is unacceptable; how do they measure? All they can do is complain of sky high electric bills.

Seemingly REAL will only take action AFTER you have paid a BRE registered engineer roughly £800 per day to carry out a survey on the system and prepare a report.
If there's evidence that the system is not correct they'll take action, though what that action is was unclear to us.

Unfortunately I can say no more for legal reasons....... non disclosure clause and all that

Sky high bills? ours were in orbit

AH9999

I’ve just read 60 pages on this forum relating to Air SourceHeat Pumps (ASHP) – very interesting albeit far from an exact science.

I’m new to this and would welcome your thoughts on my outline plan below – extremely high level at the moment:

Currently:
· 1940’s built house – 5/6 bedroom (2 x adults, 1 x toddler)
· Cavity wall insulation
· 200mm loft insulation (likely to increase to300m or 400mm)
· Double glazing throughout
· No under floor heating, Steel radiators throughout
· No mains gas
· Oil fired AGA Rayburn Heatranger 499k, ~100,000btu used for CH, HW & Cooking
· Electric mains supply
· Dorset based so a relatively mild climate

Current costs:
· £110 per month for electricity, normally about 2,300 kWh per year
· £180 per month for oil, normally 2,500 to 3,000 litres per year

Solar PV:
· Installation is scheduled to take place on Monday (17th September 2012):
o 16 x Sanyo HIT250 PV Panels (4kW)
o Sunny Boy (SMA) 4,000 Inverter
o Sunny WebBox/Data Logger
o Cost = £10k, payback ~11 years
o ....….so that will reduce my electric bill by way of the Feed In Tariff (FIT) whilst providing some ‘free’ electricity by way of the FIT Export system

My next plan was to reduce my oil costs using solar hotwater…..
· Over the Spring/Summer 2012 I’ve only been using the AGA Rayburn for HW & cooking – the HW & cooker timed to turn on and off which works well for our lifestyles
· Using the AGA Rayburn for HW & cooking only seems to use relatively small amounts of oil, I don’t have an accurate consumption figure but I’m going to guess at ~15% of my oil usage therefore, 375 to 450 litres per year or (£276 to £331 based on 70p per litre + 5% VAT)
· Based on my calculations an installed system(4m2) would cost about £3,500 and save between £100 and £150 per year

..…..so I’ve ‘parked’ the solar hot water idea and diverted my focus to CH which seems to be the costly part in terms of oil.

So here’s my next idea:
· Size and install an ASHP for CH only – upgrading to aluminium/oversized radiators where required
· I would continue to use the AGA Rayburn for HW and cooking
· 99% of the year I would use the ASHP for CH
· 1% of the year if/when things get very cold,switch back to the AGA Rayburn for CH if required
· I’m assuming the ASHP installation process would be relatively simple:
o External unit well away from neighbours so noise won’t be an issue
o Plenty of space to create a dedicated/specific concrete base for the ASHP
o Relatively short external pipe runs for the ASHP
o Simple power access/supply
o I’m assuming the ASHP would just connect into the existing CH output from the back of the AGA Rayburn – is this correct? That way, with the AGA Rayburn CH turned off the ASHP would deliver the heat – if and when I turned the AGA Rayburn CH on the ASHP would switch automatically off because the CH water temperature would exceed whatever setting it had (i.e. 40 degrees limit for the ASHP and the AGA Rayburn would be pushing out ~70 degree CH water)……does this make sense?
· Based on my very rough calculations I believe I could save between £750 and £1,000 per year on oil with an ASHP (maybe more with the ASHP times to use ‘free’ electricity’ from the FIT Export whereverpossible)
· Rough estimate ~£7,000 for a fully installed Mitsubish system (very much a guess, I haven't received any quotes yet)

Any thoughts, comments or feedback would be much appreciated- if my logic/assumptions/rough calculations are wrong please let me know JJ

P.S. anyone had any good or bad experiences with WeatherCompensation technology linked to CH?

zeupater

AH9999 wrote: »

...
I’m new to this and would welcome your thoughts on my outline plan below – extremely high level at the moment: ....

.... Current costs:
· £110 per month for electricity, normally about 2,300 kWh per year ...

... Any thoughts, comments or feedback would be much appreciated- if my logic/assumptions/rough calculations are wrong please let me know JJ

Hi

Welcome to the forum ....

The most striking immediate issue is the cost of electricity in your calculations.... £1320 for 2300kWh seems a little excessive ....

HTH
Z

AH9999

@zeupater

Thank you and well spotted - monthly £ value is correct, I'm doing some double checking but I think the usage is actually more like 4,137kWh per year

[Deleted User]

AH9999 wrote: »

I’ve just read 60 pages on this forum relating to Air SourceHeat Pumps (ASHP) – very interesting albeit far from an exact science.

I’m new to this and would welcome your thoughts on my outline plan below – extremely high level at the moment:

Currently:
· 1940’s built house – 5/6 bedroom (2 x adults, 1 x toddler)
· Cavity wall insulation
· 200mm loft insulation (likely to increase to300m or 400mm)
· Double glazing throughout
· No under floor heating, Steel radiators throughout
· No mains gas
· Oil fired AGA Rayburn Heatranger 499k, ~100,000btu used for CH, HW & Cooking
· Electric mains supply
· Dorset based so a relatively mild climate

Current costs:
· £110 per month for electricity, normally about 2,300 kWh per year
· £180 per month for oil, normally 2,500 to 3,000 litres per year

Solar PV:
· Installation is scheduled to take place on Monday (17th September 2012):
o 16 x Sanyo HIT250 PV Panels (4kW)
o Sunny Boy (SMA) 4,000 Inverter
o Sunny WebBox/Data Logger
o Cost = £10k, payback ~11 years
o ....….so that will reduce my electric bill by way of the Feed In Tariff (FIT) whilst providing some ‘free’ electricity by way of the FIT Export system

My next plan was to reduce my oil costs using solar hotwater…..
· Over the Spring/Summer 2012 I’ve only been using the AGA Rayburn for HW & cooking – the HW & cooker timed to turn on and off which works well for our lifestyles
· Using the AGA Rayburn for HW & cooking only seems to use relatively small amounts of oil, I don’t have an accurate consumption figure but I’m going to guess at ~15% of my oil usage therefore, 375 to 450 litres per year or (£276 to £331 based on 70p per litre + 5% VAT)
· Based on my calculations an installed system(4m2) would cost about £3,500 and save between £100 and £150 per year

..…..so I’ve ‘parked’ the solar hot water idea and diverted my focus to CH which seems to be the costly part in terms of oil.

So here’s my next idea:
· Size and install an ASHP for CH only – upgrading to aluminium/oversized radiators where required
· I would continue to use the AGA Rayburn for HW and cooking
· 99% of the year I would use the ASHP for CH
· 1% of the year if/when things get very cold,switch back to the AGA Rayburn for CH if required
· I’m assuming the ASHP installation process would be relatively simple:
o External unit well away from neighbours so noise won’t be an issue
o Plenty of space to create a dedicated/specific concrete base for the ASHP
o Relatively short external pipe runs for the ASHP
o Simple power access/supply
o I’m assuming the ASHP would just connect into the existing CH output from the back of the AGA Rayburn – is this correct? That way, with the AGA Rayburn CH turned off the ASHP would deliver the heat – if and when I turned the AGA Rayburn CH on the ASHP would switch automatically off because the CH water temperature would exceed whatever setting it had (i.e. 40 degrees limit for the ASHP and the AGA Rayburn would be pushing out ~70 degree CH water)……does this make sense?
· Based on my very rough calculations I believe I could save between £750 and £1,000 per year on oil with an ASHP (maybe more with the ASHP times to use ‘free’ electricity’ from the FIT Export whereverpossible)
· Rough estimate ~£7,000 for a fully installed Mitsubish system (very much a guess, I haven't received any quotes yet)

Any thoughts, comments or feedback would be much appreciated- if my logic/assumptions/rough calculations are wrong please let me know JJ

P.S. anyone had any good or bad experiences with WeatherCompensation technology linked to CH?

Observations...

It is unlikely your existing CH pipework and rads will be suitable for the flow rates required by the Ecodan/most ASHPs. CH Pipework also needs to be insulated.

To heat your house using conventional rads with a 40c limit is unlikely to be successfull. ASHPs run most efficiently with UFH or fancoils which make best use of lower flow temps. Expensive though. For that size of house you could spend nearly £7k just on nice fancoils.

£7k is unlikely to only cover the of the cost kit never mind the labour.

Likely to be difficult to find an installer who will link up two systems. From experience we could not find anyone to link a new system to an old system they did not install. To much risk.

You don't mention what size of Ecodan you were thinking off which makes me think you need to calculate your heat requirement for the property first.

The PV quote seems high. We paid £10k for a high end system a year ago for the much higher FIT. Also the typical power produced by PV will only reduce the ASHPs annual running cost by 10% ish. So if the ASHP is costing loads to run in such a big house don't expect the PV to make much difference.

Suggest getting site visits from as many heating installers as possible, not just renewables, to talk through your options. Also try to visit reference sites so you can speak to owners.

Cheers

AH9999

@jeepjunkie

Thank you.

I've got no problem changing the existing radiators, I'm actually expecting that I'll need to do this and done correctly shouldn't impact internal decor too much - probably aluminimum rather than Steel.

Insulating CH pipework is a different matter - I assume you are referring to the pipework which is under the floorboards in which case this is a lot more invasive.........all of CH pipework runs under the 1st floor and down to through the walls to feed to ground floor radiators, so 99% of it is in a 'warm' environment anyway - it's 15mm do you think I'll still need to do this?

My £7k was a rough guess, I'm hoping to get real estimates in the next couple of weeks

Very much a first principals stage so no sizing has been done yet, absolutely this is where the experts will be engaged

Cardew

I’m assuming the ASHP would just connect into the existing CH output from the back of the AGA Rayburn – is this correct? That way, with the AGA Rayburn CH turned off the ASHP would deliver the heat – if and when I turned the AGA Rayburn CH on the ASHP would switch automatically off because the CH water temperature would exceed whatever setting it had (i.e. 40 degrees limit for the ASHP and the AGA Rayburn would be pushing out ~70 degree CH water)……does this make sense?

I will just comment on the above.

It is not easy to combine two heating systems - and in fact can be downright dangerous. How will you stop the Heat pump water flowing back through the AGA, and vice versa. You should not fit a stop valve on the output side of a boiler, and I doubt if a plumber will do so.


You need something like a Dunsley Neutraliser

http://www.dunsleyheat.co.uk/neutralizer%20layouts.html

I am not a fan of Heat pumps, but if you get one, then I would use straight electric heaters for the days when you feel the ASHP won't cope.(you state 1%)

Just take advice on the combining of two systems.

Cardew

Just a further note on 'money saving'.

You have a working CH system.

I suspect an ASHP system for a 1940's 5/6 bed will cost nearer to double the £7k you estimate.

However let us take £10,000 as a cost. That invested in a long term Account will earn 4% - taxable unless in ISA. So 3.2% after 20% tax.

That is £320 a year in lost interest you need to save on heating bills before you start paying of the £10,000.

If you have to borrow £10,000 the position is a lot worse.

zeupater

Hi AH9999

I don't follow the need to insulate any heat delivery pipework as long as it's inside the living area of the property .... inside a loft or garage would be different, but anywhere within the building envelope is just increasing the performance by delivering heat ....

As for aluminium vs steel ... I don't really see the need for this. Aluminium is faster at conducting heat but as soon as the metal has reached temperature, the additional thermal gradient would provide very little advantage at the temperatures involved in heating systems ... if the water is 40C inside the radiator it can't be over 40C on the surface and both metals would have painted surfaces which would transfer heat to the surroundings at the same rate/unit surface area ....

HTH
Z