UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

robwoolls

Hi, I have just purchased a 12,000 btu ashp. I am hoping to heat most of my bungalow with it.

I have to choose between the following two locations for the internal unit

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|.................. |............ option B........... |................ |................... |
| ..................| ...................................| BATHROOM |................... |
|. BEDROOM... |............ LOUNGE........... |..................|.. KITCHEN.... |
|.................. |................................... |................ |................... |
|.................. |................................... |....

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|.................. |
| ...................................option.A................................................|

---

...

---

Aplogies for the diagram!

Option A looks ok, I can set the louvres to swing left and right... But im not sure how acute/obtuse the angle will be. The doorways are in a staight line along the bottom wall. But they are all very close (6inches) to the wall)

If I have the swing setting on Option B will it travel to any other rooms?

The outside unit has an ideal location near option B

If there is not much between the two options B is easier for that reason.

(P.S.I cannot place the unit above any of the doorways. not enough space left above unit)

opinions appreciated

Many thanks

clc5

Have just received a Home Report on Renewables and Energy Efficiency from the Energy Saving Trust. I currently have a G rated gas combi boiler. According to the report an ASHP would cut my 3 bed semi's heating bill by only £20 per year "Based on an ASHP with co- efficient of performance (COP) of 1.75 for space heating delivered through radiators, and 1.52 for hot water."

The EST advisor told me during her visit that they always give the worst case scenario and installers always give the best case figures.

The report makes some general points about ASHP's:

"The internal heat pump unit has a compressor which generates some hum. Generally this is a hum similar to that produced by an extractor fan or air conditioning unit. As the compressor clicks on and off during the day it can be audible depending on where the unit is located inside your home. There are ways of reducing noise where necessary,
such as placing the unit on a rubber mat or using articulated pipe."

I had previously thought the only noise issue was noise from the external unit but it seems internal noise is also an issue.

"It is important not to choose a heat pump that is too large for your needs. Too large a system will provide more heat than your home may need during milder winter days. This will mean the pump may be prevented from operating continuously which will result in more energy

intensive ‘stop-start’ heating, which will in turn increase running costs."

Does this mean the pump has to run 24/7?

richardc1983

clc5 wrote: »

Have just received a Home Report on Renewables and Energy Efficiency from the Energy Saving Trust. I currently have a G rated gas combi boiler. According to the report an ASHP would cut my 3 bed semi's heating bill by only £20 per year "Based on an ASHP with co- efficient of performance (COP) of 1.75 for space heating delivered through radiators, and 1.52 for hot water."

The EST advisor told me during her visit that they always give the worst case scenario and installers always give the best case figures.

The report makes some general points about ASHP's:

"The internal heat pump unit has a compressor which generates some hum. Generally this is a hum similar to that produced by an extractor fan or air conditioning unit. As the compressor clicks on and off during the day it can be audible depending on where the unit is located inside your home. There are ways of reducing noise where necessary,
such as placing the unit on a rubber mat or using articulated pipe."

I had previously thought the only noise issue was noise from the external unit but it seems internal noise is also an issue.

"It is important not to choose a heat pump that is too large for your needs. Too large a system will provide more heat than your home may need during milder winter days. This will mean the pump may be prevented from operating continuously which will result in more energy

intensive ‘stop-start’ heating, which will in turn increase running costs."

Does this mean the pump has to run 24/7?

That article you have pasted is a load of rubbish basically. The internal unit if you are using air to air systems just sound like a fan.

Inverter units do not make a clicking sound, they come on very softly and start up very slowly. A proper sized inverter heat pump will operate 24/7 in the winter period as it will reduce its output based on the internal conditions and how much heat is required.

clc5

richardc1983 wrote: »

That article you have pasted is a load of rubbish basically. The internal unit if you are using air to air systems just sound like a fan.

Inverter units do not make a clicking sound, they come on very softly and start up very slowly. A proper sized inverter heat pump will operate 24/7 in the winter period as it will reduce its output based on the internal conditions and how much heat is required.

Thanks. It wasn't an article as such, it was general info provided by the Energy Savings trust, in effect, the government.

richardc1983

clc5 wrote: »

Thanks. It wasn't an article as such, it was general info provided by the Energy Savings trust, in effect, the government.

Old fashioned fixed speed units would come on with a jolt a bit like a fridge can do as the compressor is kick started. However inverters turn on slowly like when you turn on a light with a dimmer switch.

Cardew

clc5 wrote: »

Have just received a Home Report on Renewables and Energy Efficiency from the Energy Saving Trust. I currently have a G rated gas combi boiler. According to the report an ASHP would cut my 3 bed semi's heating bill by only £20 per year "Based on an ASHP with co- efficient of performance (COP) of 1.75 for space heating delivered through radiators, and 1.52 for hot water."

The EST advisor told me during her visit that they always give the worst case scenario and installers always give the best case figures.

The report makes some general points about ASHP's:

Whilst I believe some of the overall system COPs quoted by manufacurers are wildly optimistic, for the EST to quote COPs of 1.75 & 1.52 without specifying the outside ambient temperature is meaningless.

I can readily believe the performance might have dropped that low on a few of the very cold nights we had last year, but you cannot use those figures as the basis calculating annual heating costs.

Unless an ASHP system had an overall COP of around 3.0 averaged over the year, it wouldn't compete with a modern gas boiler.

clc5

Cardew wrote: »

Whilst I believe some of the overall system COPs quoted by manufacurers are wildly optimistic, for the EST to quote COPs of 1.75 & 1.52 without specifying the outside ambient temperature is meaningless.

I can readily believe the performance might have dropped that low on a few of the very cold nights we had last year, but you cannot use those figures as the basis calculating annual heating costs.

Unless an ASHP system had an overall COP of around 3.0 averaged over the year, it wouldn't compete with a modern gas boiler.

I rang the EST for clarification. Their COP figures are the overall COP averaged over the year taking account of fluctuations in the outside ambient temperature. However, the advisor said their figures were based on out of date data and did not reflect what could be achieved with modern systems, "less than worst case" was how he described their COP estimates. He said to qualify for RHI payments the average COP would need to be at least 2.9

theheatison_2

Hey Cardew

Looking for some advice if you can spare a moment.
I live in a 1200 ft2 duplex apartment currently "heated" by storage heaters. There is no gas supply available.
I was considering having them updated with the more recent Dimplex Duoheat range when someone mentioned Airsource Heatpumps, something which you seem to have quite a bit of knowledge about.
I own the roof space above the duplex (currently a roof garden) which would offer ample space for the unit.
I was just wondering how effective they are? I live in Dublin city centre. Do you know if a retro fit is a realistic?

Anyway if you could offer some advice it would be much appreciated

Best

Warren

richardc1983

theheatison wrote: »

Hey Cardew

Looking for some advice if you can spare a moment.
I live in a 1200 ft2 duplex apartment currently "heated" by storage heaters. There is no gas supply available.
I was considering having them updated with the more recent Dimplex Duoheat range when someone mentioned Airsource Heatpumps, something which you seem to have quite a bit of knowledge about.
I own the roof space above the duplex (currently a roof garden) which would offer ample space for the unit.
I was just wondering how effective they are? I live in Dublin city centre. Do you know if a retro fit is a realistic?

Anyway if you could offer some advice it would be much appreciated

Best

Warren

Warren

I have responded to your PM.

clc5

When I get round to buying my ASHP I will also need a hot water cylinder. Cylinders from the likes of Mitsubishi and Daikin seem expensive and I'm wondering whether it is advisable to buy a cheaper cylinder separately? Or are there advantages in buying the ASHP manufacturer's own make? Any advice would be appreciated.