Toshiba estia air source heat pump

[Aircon467]

Wowzers!!

Ive installed this estia system.

Totally amazed / concerned its costing around £7.50 per day to run

Wtf .... This is just for the central heating.

Anyone else with experience on this... Just glad i have fitted in my house and not a customers.... How can this be justified when my gas boiler cost £2 per day to use.

[Brian_UK]

One has to ask.... is it sized correctly?

[Aircon467]

Im presuming the rads need upgrading... Which is gunna get done as they are old rads.

House is very well insulated. 1950's 3 bed semi, max total floor space 100sq m.

Its a 14kw system only running the rads @ the minute.

It just amazes me how a gas boiler with same rads etc can heat the house for £2 p/d

Just in process of buying new rads.., not very optimistic tho. But will see.

Im new to ashp so will be a learning curve for me, with any sound advice welcome.

Trying to size new rads is a grey area for me... As i dont know how poorly the current ones are.

Going to replace 2 at a time with some trial & more than likely error.

[yinmorrison]

Air and Ground source heat pumps are much better suited to underfloor systems which only require 35C flow temp due to larger heat dissipation area. The maximum flow you will be getting is around 50-55C to radiators that were probably designed for 82/71C flow/return. You will only be getting about 50% of the original radiator capacity so the system is either not even bringing house up to temp or taking twice as long to do so and hence higher running cost.Attached wee chart from Stelrad details percent falls on a radiator considering average return water and room temp difference.10126
Hope this helps.However me thinks you will still be more expensive than gas even when you do upgrade rads.

[Aircon467]

Yeah im in the same line of thought. Gunna try change 3 down stairs to brand new rads (as they are very old) see what i get. I'll measure any diff... Then move them upstairs. Prob gunna add 1 more rad down stairs and possibly change a couple to triple panel rads.

Its bit of a learning curve... Dont wanna go ott but more surface area is critical & better positions of a couple will help.

I knew itd be a more costly, but not quite what it is now. Lol.

[Aircon467]

I will update as i do the mods.... Currently waiting for the correct 3 port valve to arrive.

[The Viking]

There is also another thing that the people flogging heatpumps here in UK seldom mention...

Here in UK there is a huge difference in the energy prices if you look at kW versus kW, so you might find yourself in a situation where you save energy but waste money :(


Today's price offering (from Sainsburys online) is 11.861 p/kW for electricity versus 4.057 p/kW for the gas. If you do the maths you will see that your heatpump will have to be 3 times as effective as the boiler before you make any monetary profit what so ever. (Unless you are on oil, that is a completely different kettle of tar)

And on an old radiator circuit heatpumps rarely, if ever, perform to their (top) theoretical efficiencies. :mad:

:cool:

.

[Aircon467]

Well luckily im doing every room up in my house so changing pipe work / electrics as i hit each room.

Its mad living in a house with a family whilst trying to modernise it.... Seem to do everything twice or just arse about face.

[Aircon467]

Oh & yes they advertise the fact they are deffo cheaper than oil burners.