Mitsubishi Ecodan ASHP or NIBE F2040

[Hansodeon]

We are getting an Air Source Heat Pump installed into our large (2000sq ft) 1970s house which currently has very inefficient electric ceiling heating (!). We are in a village with no gas supply and this will be our only source of heat and hot water. I am dithering between 2 different firms' quotes. The cheaper one (by £2000) is planning to fit a Mitsubishi PUHZHW112 VAA Ecodan, the other firm is proposing a NIBE ASHP F2040 - 16KW. The cheaper quote will not sort out electricity cables or drainage whilst the other firm will. My main question is which of these units is most recommended and likely to give less problems/better performance. Are there any particular questions I should be asking of these firms? Would you imagine that these work by being on most of the time during the winter? Thanks so much for any advice

 

[Brambles]

Hansodean,

I am biased as my main business is the design and installation of renewable energy heating and power systems. So I accept that my views are are marginally polarised.

The effectiveness (and indeed long long life expectancy) of an air source or ground source heat pump is the design of the overall installation and the control system. They are very difficult to re-engineer if the hydraulic side is not properly designed correctly.

With airsource, if it is not working properly, you do not have the flexibility ( as you do with gas) to increase the flow temperature. Retrofitting into an existing property is even harder to achieve a good result.

With respect to the pump. Panasonic are ( in my view the best) - they can be completely configured to customise the installation. MHI ( Mitsubishi) are good, but you are tied to the Mitsubishi control systems - they are very difficult to interface with standard control systems such as Honeywell. They appeal to installers who do not know too much about Air Source - they are “plug and play” installation.

NIBE are slightly niche - very good quality, a good choice if you are regularly expecting winter temperatures below -5 degrees C, but that comes at a price. I have only fitted two, very good results - but spares are not stocked in the UK - they are on a 5 day courier from Sweeden.

If I was a customer, I would want the installer to undertake (or take responsibility ) for everything and offer guarantees on noise ( can be a big issue for neighbours) and internal temperatures achieved against ambient outside temperatures.

Performance guarantees generally sort the sheep from the goats.

 

[Hansodeon]

Hansodean,

I am biased as my main business is the design and installation of renewable energy heating and power systems. So I accept that my views are are marginally polarised.

The effectiveness (and indeed long long life expectancy) of an air source or ground source heat pump is the design of the overall installation and the control system. They are very difficult to re-engineer if the hydraulic side is not properly designed correctly.

With airsource, if it is not working properly, you do not have the flexibility ( as you do with gas) to increase the flow temperature. Retrofitting into an existing property is even harder to achieve a good result.

With respect to the pump. Panasonic are ( in my view the best) - they can be completely configured to customise the installation. MHI ( Mitsubishi) are good, but you are tied to the Mitsubishi control systems - they are very difficult to interface with standard control systems such as Honeywell. They appeal to installers who do not know too much about Air Source - they are “plug and play” installation.

NIBE are slightly niche - very good quality, a good choice if you are regularly expecting winter temperatures below -5 degrees C, but that comes at a price. I have only fitted two, very good results - but spares are not stocked in the UK - they are on a 5 day courier from Sweeden.

If I was a customer, I would want the installer to undertake (or take responsibility ) for everything and offer guarantees on noise ( can be a big issue for neighbours) and internal temperatures achieved against ambient outside temperatures.

Performance guarantees generally sort the sheep from the goats.

This is so helpful. Thank you so much! Our house is older and so I guess this would be a retrofit. Other than asking for guarantees on temperatures achieved are there any other ways of assessing how good the design of the system they are proposing (for an amateur). Many thanks again for your insight!

 

[Brambles]

Hansodean,

Air and Ground Source heat pump systems are best suited to wet underfloor heating systems. Generally these are not straightforward to retrofit into existing properties.

The norm is to try and get a wet underfloor system on the ground floor and a system of large SINGLE panel radiators on the upper floors - wet underfloor systems on the upper levels can be utilised using aluminium floor panels.

If either of your installers are proposing just using radiators, they need to be designed as large single panel rads. If not, this should ring alarm bells.

Improved home insulation is key, both for the effectiveness of the installation and if you are claiming a subsidy through the RHI scheme.

With respect to performance guarantees, only you can do that. Write down what is important to you for your heating system at home. In my wife’s case, it is being able to touch a hot radiator - it took a long tome to convince her that a home can be warm without radiators!!

 

[Renewable Heat]

I have fitted loads of Mitsi Ecodans over the last 5 years. Superb bits of kit with very little call backs. Very user friendly as well. I have recently done Nibe training and have fitted 3 Nibe Ashp and 2 Nibe ground source. Also very reliable and performs very well.

I would be very happy with either. They will both perform well. The main factor to consider ia making sure the installer carry’s out a proper heat loss and design. This is crucial and will play a major factor in performance and running costs. Also make sure a ASHP is the best solution for your property. The low flow temps really suit well insulated homes and UFH were possible. It will work well with radiators as long as they are sized correctly and the home is insulated properly.

if the property does suffer from poor insulation, drafts etc Biomass may be a better option?
Hope this helps

 

[SJB060685]

Brambles

My knowledge lies with oil fired appliances but always looking to learn new information. I've been reading this post and have found what you said good information. You say when installing air source or ground source then only single panel rads are used, why is that? The reason I ask is my flat has a Daikin ASHP with double panel rads. I know larger rads are used due to lower flow temperatures but didn't know they should ideally be single panel.

 

[Renewable Heat]

Brambles

My knowledge lies with oil fired appliances but always looking to learn new information. I've been reading this post and have found what you said good information. You say when installing air source or ground source then only single panel rads are used, why is that? The reason I ask is my flat has a Daikin ASHP with double panel rads. I know larger rads are used due to lower flow temperatures but didn't know they should ideally be single panel.

Most of our ASHP install designs have double and even triple panel radiators.

 

[Brambles]

Generally low temperature heating systems are optimised with correctly designed UFH systems. If you opt for the radiator route, the physics would dictate the optimum ratio to target would be the highest ratio of surface area / volume. ie. a large surface area and low water content.

Obviously convector fin radiators (K2 /K3 et al) are not effective at low flow temperatures.

If you have Ecoglosie type radiators (Swedish) multiple panel, but low volume, they work well. Multiple panel with fins are ineffective (in my opinion).

Be aware that retrofitting an air source heat pump to an existing panel radiator system without modification will probably work, but the COP is likely to be very low.

Without being pedantic, also check how often your ASP is defrosting - if it is working against an ineffective installation, it will defrost frequently. Defrosting dramatically reduces system efficiency.