Heat pump / inverter DIY

anthonykeates

Johnhowell wrote: »

My post at: http://forums.moneysavingexpert.com/showthread.html?t=1328643&highlight=Heat+pump+%2F+inverter has run for a couple of weeks now.

What I would like to know is how to determine which Wattage/BTU unit is required for a conservatory south facing - area approx 25sq m and volume approx 65 cu m.

I initial looked at: LG Air Conditioning S09AW-N40 Wall Mounted Heat Pump 2.6 Kw / 9000 Btu Inverter:

[FONT=Verdana, Arial, sans-serif]http://www.orionairsales.co.uk/lg-ai...rter-585-p.asp [/FONT]

but possibly need a larger 18000BTU unit?

What is the calculation?

Also, has anyone else got the 5% VAT rather than the 15% VAT?

Many thanks,
John

http://www.heatandplumb.com/acatalog/radCalcs.html is a calculator for working out BTUs - may be some help in sizing the heat requirement for your room?

stevehead

Johnhowell wrote: »

My post at: http://forums.moneysavingexpert.com/showthread.html?t=1328643&highlight=Heat+pump+%2F+inverter has run for a couple of weeks now.

What I would like to know is how to determine which Wattage/BTU unit is required for a conservatory south facing - area approx 25sq m and volume approx 65 cu m.

I initial looked at: LG Air Conditioning S09AW-N40 Wall Mounted Heat Pump 2.6 Kw / 9000 Btu Inverter:

[FONT=Verdana, Arial, sans-serif]http://www.orionairsales.co.uk/lg-ai...rter-585-p.asp [/FONT]

but possibly need a larger 18000BTU unit?

What is the calculation?

Also, has anyone else got the 5% VAT rather than the 15% VAT?

Many thanks,
John

Hi John, Why don't you just get a 1-2-3Kw Fan heater and find out which setting actually keeps you comfortable? Nothing beats a real test, and then you'll get the heat pump capacity right.

Johnhowell

Thanks for the links - it says I need 21000BTU !!!

Shall have to think about the testing idea.

Regards,
John

richardc1983

210000btu is a lot!

That website will be working out the cooling side of things though.

For heating work out with an electric heater see what the lowest setting is u can have it on!

Johnhowell

The conservatory is not built yet. Hoping for the builder to install it at the same time as the conservatory.

I think that link was for standard boiler/radiator heating systems - the result was 21 thousand BTU. Another website (http://www.airconditioner.me.uk/BTU-Calculator.html)- did give a BTU of 18000 for a heat pump system over and about the floor area we intend to have. "Pro-rata"ing their little table gave a BTU of 13750 cooling capacity.

I would like to select a unit that will not be too small and stuggle, but not get too big a unit and have my partner complain for ever and a day about it!!!

Thanks,
John

thechippy

Johnhowell wrote: »

The conservatory is not built yet. Hoping for the builder to install it at the same time as the conservatory.

I think that link was for standard boiler/radiator heating systems - the result was 21 thousand BTU. Another website (http://www.airconditioner.me.uk/BTU-Calculator.html)- did give a BTU of 18000 for a heat pump system over and about the floor area we intend to have. "Pro-rata"ing their little table gave a BTU of 13750 cooling capacity.

I would like to select a unit that will not be too small and stuggle, but not get too big a unit and have my partner complain for ever and a day about it!!!

Thanks,
John

John,

This is my job. I will make the correct calculations for you tomorrow. I use a £750 programme which is rarely wrong.

G.

thechippy

paceinternet wrote: »

Please acknowledge my post #65, or show me some evidence that a COP of 3 is available in all conditions. It isn't. The "Aircon" industry seems to use a value which has some "seasonal" calculation built in so that all equipment can be compared.
There is much more data available from the air to water heat pump brigade who seem prepared to tell more of the story, but they do not have to comply with the "Aircon regs" whatever they are.
In both cases, it is still a good story, but if you are checking your electrical consumption during a week of -5 degC outside, it is unlikely to be the same as when it is +10 degC outside.

For some definitions:
http://www.comfort.uk.com/faq.htm#cop

For a graph that might typically apply, see the eficiency section:
http://www.fosterair.com/heatpumps_and_air.html

Hi Pace,

As a rule of thumb. Most modern ashp's will consistently give a c.o.p of around 3 to 3.5 @ 5-7c. They will often bottom out at around -15 / 20c depending on the make and model. Above 7c they can go anywhere up to a c.o.p of 5.9 at this time and this is set to improve!
This is the future of heating, make no mistake.

Johnhowell

thechippy wrote: »

John,

This is my job. I will make the correct calculations for you tomorrow. I use a £750 programme which is rarely wrong.

G.

G.

Many thanks for this. If you require any other information please do not hesitate in asking - I shall monitor throughout the day.

John

ABN

Been following this thread with interested for some time.

Next year will be looking to move. Hope to get a larger property in need of repair so we can modernise it to out taste. Part of that modernisation will for course be aimed at reducing heating costs, hence the interest in this thread. The size/layout of the property could be influenced by the reply to the following question.

I have no doubt that my understanding of how these systems work is incorrect and hence the question may well be rather stupid.

As I see it the efficiency gain by these systems is directly related to the air temperature, the higher the ambient temp the more efficiency gain you get. Now assuming you have the space for a small sound proof(ish) boiler room within the house can units that are normally mounted outside be moved inside and hence use the higher internal air temp of the house. This would mean that eventually they would be working at 20C+ and be super efficient. Ideally the rest of the house would be heated via ductwork rather than separate small units placed around the house.

As said probably a stupid suggestion but would be interested as to why.

richardc1983

No they wouldnt work at all in fact it would probably break down. An air conditioning unit in heat mode works in reverse, so rather than the heat being rejected outside from inside the indoor unit rejects heat indoors and the outdoor unit unit has the cold air blowing out of it. IF you install in a room or boiler room or even a garage the unit would just remove heat out of the air and it would get colder and colder in there. The unit would initially remove heat from the warmer room but then it will just get colder and colder and colder. Outdoor units have to have outside air to work, this air has to be constantly be replaced otherwise your going to have problems. THe same would happen in reverse in summer, you would have the indoor unit removing heat from the room and it would be dumped in this boiler room (enclosed space) and then the room would heat up getting hotter and hotter each time the outdoor unit working harder and harder to remove heat from the space. You would actually reduce efficiency and raise operating costs.