Air source heat pumps (ASHP)...

[renault12ts]

...does anyone have any direct experience of ASHP in conjunction with under floor heating and existing oil central heating?

 

[Piff]

No experience yet, but will be installing on current project in about 6 to 9 months time.
ASHP has effiency rating of 3.3 according to Mitsubishi Ecodan, converting 1kw of electric to 3.3kw of heat output. My electric is around 11p/kwh so ashp will convert this to 3.33p/kwh
My gas currently costs 3.6p/kwk.
How much does oil cost/kwh?
In the new project I would have to install a condensing boiler - life expectancy 8 to 10 years & possible breakdowns on the way to life expectancy.
ASHP basically fridge technology - life expecantancy 20+ years
Currently govt grant available of about £850 to assist with installation costs and future RHI payments promised - see here and here
Current suggestions are that you will be paid 7.5p/kwh for 18 years when the RHI goes live.
Talking to building inspector last week, he advised for best results to install "whole" system (ashp, cylinder, controls) from one manufacturer and Mitsubishi Ecodan seems to be the one recommended around here.
I'm putting in my own UFH & local heating engineer will link up to ASHP & cylinder. Just had this from him a couple of days ago:
Ball park figure for an 8.5kw ecodan stand alone which you would then need to
supply a cylinder for is £4300+ vat to supply and fit. If you wanted a complete
mitsubishi system with cylinder the figure for a 210lt cylinder with 8.5kw
ecodan would be £6360+ vat.
If starting from scratch, I can remember him saying that ASHP system is similar in cost to oil boiler/oil tank.
Where in the country are you - this engineer may be able to help advise.

 

[renault12ts]

Thanks Piff.

I live in NI. Our electricity is 14.711p per unit. But off peak is 6.224p per unit. So I was going to run the UFH during the night with the ASHP. I already do this at the moment and the system maintains 20oC throughout the 24 hour period. Currently oil is about 65p per litre, which I believe is about 6.6p per unit (KwH).

So with a COP of even 2 that would be a significant saving, and with higher cops it would be even better. I have looked at the Ecodans and the Sanyo systems. The Sanyo is interesting because it uses CO2 as the refrigerant and so is able to heat the water to about 90oC!!

 

[AANDYY]

There might be something here vegetableoildiesel.co.uk - Powered by XMB you might have to do a bit of searching.

 

[renault12ts]

There might be something here vegetableoildiesel.co.uk - Powered by XMB you might have to do a bit of searching.

Not allowed to view apparently.

 

[Ade B]

Seem to recall we put an Unico system into a house in Chelsea. It worked with a conventional boiler and ASHP running both underfloor heating and a mini duct aircon installation and all going through a heat recovery system.

It was relatively complex and expensive for a small building and I think the client was more into the idea of having a whizzy system than any economic benefits that may come through in the long term.

We worked with an Aircon specialist so details are a bit hazy.

Ade

 

[StevenN]

We sell Daykin units.

what would you like to know?

Steve

 

[renault12ts]

We sell Daykin units.

what would you like to know?

Steve

Steve,

We have 50m2 of ufh in the kitchen. The current oil boiler is probably too small to run this and the rads in the rest of the house as effectively as we would like. I therefore thought that rather than get a bigger oil boiler it might be better to run the ufh (and maybe hot water) off an ASHP.

I believe 50m2 would be approx 5KwH, therefore we would need an ASHP capable of running this even on the coldest days (say down to -10 Deg C).

Would it be possible to connect an ASHP directly to the UFH (Rehau manifold)? This would seem to be the simplest option? We could run this on E7 electricity.