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View Full Version : does any 1 know HOW much cheaper it is to heat with AC heatpump compared to a boiler?



kaspastarr
28-11-2007, 05:42 PM
Ive been told its 4-5 times cheaper than heating with a boiler, but does any 1 know exactly how much and weather it varies with different units????

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frank
28-11-2007, 06:04 PM
Ive been told its 4-5 times cheaper than heating with a boiler, but does any 1 know exactly how much and weather it varies with different units????

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Hi kaspastarr, and welcome to the forum.

You can calculate the cost of running the equipment by looking at the efficiencies of the equipment, i.e. how much energy is produced for a given energy input.
With condensing boilers, the manufacturers are quoting efficiencies around 90% - 95% these days, so, for every 1kw of energy input you will get 0.9 - 0.95kw output, the rest being energy losses.

With heat pumps,in heating mode, the efficiencies can vary by manufacturer and type, (non inverter, old gas to inverter driven, R410A).
Efficiences, can be anywhere between, say 200% to 350%, and upwards. This is normally called Co-efficient of Performance (COP). So, for every 1kw of energy input you can get upwards of 3.5kw of energy output.

Obviously, there is also a difference in the energy costs to consider and lifetime maintenance costs but when you look closely at specific equipment and do the maths then heat pumps appear to be more economical.

kaspastarr
28-11-2007, 06:17 PM
thanx mate thats well helpfull, im just learning about COP in the 3rd year of collage, thanx for the explanation :)
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old gas bottle
28-11-2007, 06:53 PM
untill you get your electric bill ! i,am just monitering it now with mine at home, hoping it balances the gas /electric out.

us guys normaly only fit it or have one in the consevatory, i am using one in our main living area so its in my best interest to know.:D

at present the gas is down but the electric is well up:eek:

wkd
28-11-2007, 07:24 PM
You need to be careful with the application of a heat pump in terms of the temperature leaving the unit.Most standard packaged units will suffer low pressure problems at water leaving temperatures below about 30C. So it may be more realistic to use a pre-heat boiler to maintain the system temperature in order to get the best from the HP.Unfortunately thats another maths excersise but no pain no gain as they say.

The Viking
28-11-2007, 08:19 PM
As you have London entered as your location, I assume that you are enquiring about UK conditions?

If so, the answer is ZERO, Zilch, Null and Nill.
Sorry, but the gas is sold so much cheaper than electricity over here.

Have a look at THIS (http://www.refrigeration-engineer.com/forums/showthread.php?t=10084) recent thread on the same matter, there are some calculations on running costs there (based on real UK condition/prices)

kaspastarr
12-12-2007, 12:38 AM
have u insulated your conservatory well?? i live in a converted attic and it FCUKING freezing in the winter and BAKING in the summer. if i had a job ide buy an A/C unit and install it my self but he ho.
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