Air to air ASHP (HVAC)

Air Source Heat Pumps (ASHPs)

Last Post by Derek M 4 years ago

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Phil3822

(@phil3822)

Estimable Member Member

Joined: 4 years ago

Posts: 38

Topic starter 12/06/2021 5:12 pm

Hello all, a topic spoken about a bit in the forum which I am seeking to learn more about is air to air heat source pumps. Essentially air conditioning which heats too and called HVAC and commonly used in America and other countries. I am about to have an air to air heat pump for two rooms and was talking to an American colleague last week who is new to the U.K. for work on a temporary basis. He was shocked to hear of the air to water methods but did fully understand our properties generally do not have ducting. He also understood for hot water supply and fitting with existing radiators these were all reasons but when looking at cost a whole new air to air system seems more cost effective, (I did not say better) but also cools as well as heats. Of course still water to heat.
I then realised one of my elderly family members has a bungalow with a gas powered boiler and underfloor ducting to air vents for heat. The boiler also heats a tank of water. I bet this set up will be nice to modernise to renewable level! The comfort of this bungalow is so nice and quick to heat.
Thanks for indulging my ramblings but I am interested in any thoughts, discussion and articles anyone can bring. I love the thought of having a versatile market with multiple good options and also want to enrich the forum and my mind with learning and discussion. Again, having wrote this I make no real point to really just some words on a page I hope someone can make sense of.

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Derek M

(@derek-m)

Illustrious Member Member

Joined: 5 years ago

Posts: 4427

13/06/2021 3:07 pm

Hi Phil,

I think it would be quite feasible to convert your family member's system from a gas boiler to an ASHP, though probably not cost effective to do so.

HVAC systems are used extensively on larger buildings in the UK, where the ducting can be incorporated within the initial design, but the technique has not been used widely for domestic properties. I suspect that the reason was that most designers, and builders, were not willing to take the risk of changing tried and tested methods, to produce systems that may be more expensive and less acceptable to the general public.

Having said that, the research I have been carrying out recently would lead me to believe that the most efficient heating and hot water system could be developed using the following techniques.

A highly insulated and airtight property to passivhaus standard or better.

A Mechanical Ventilation Heat Recovery (MVHR) system with an ASHP incorporated, to provide ducted air for heating and cooling.

A solar PV system to produce hot water and also help power the ASHP.

A small Air to Water ASHP to provide hot water in the Winter. (Not for central heating).

The above systems could be more readily incorporated into new builds, rather than retrofit in older properties. Probably one of the primary reasons why these techniques have not been adopted is the fact that MVHR plus ASHP does not qualify for RHI.

Maybe the BEIS and government should re-think some of their policies?

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Phil3822

(@phil3822)

Estimable Member Member

Joined: 4 years ago

Posts: 38

Topic starter 13/06/2021 4:04 pm

@derek-m

Thanks for that explanation, nice to get some innovative conversation. I agree ref family members home and will back away from those thoughts. Reading American websites for retrofit HVAC they seem to suggest basically don’t do it and opt for a air con split system set up. Some great retrofit diagrams out there from Baltimore and other historic areas not to dissimilar to your explanation. PV is something I want to learn more about as I have mentioned before and will also look into heat recovery when I am next wanting to learn.

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