Heat pumps........yeah right !

[bernardgreen]

Water contains heat (energy) at a fixed rate. 4200 joules / kg regardless of the temp

The specific heat capacity of water is 4,200 Joules per kilogram per degree Celsius (J/kg°C). This means that it takes 4,200 J to raise the temperature of 1 kg of water by 1°C.

 

[jeds]

Huh, you mean per degree?

 

[mitch66]

If your radiators are double the size then you can deliver the same amount of energy with lower flow temperatures.

Water contains heat (energy) at a fixed rate. 4200 joules / kg regardless of the temp.

Either the system was not designed or installed properly or the heat loss from the building was not accurately measured.

It's not magic.

.

 

[Alec_t]

Deleted (duplicate comment).

 

[sxturbo]

That's one of the major drawbacks with heat pumps. Heat response is very slow so they need to be on 24/7. During cold weather they'll be blowing away more or less constantly.

Incidentally, it is nearly November and we have not had our heating on yet. We are decently insulated but not excessively so.

We've had ours on for a little while, but only on the cold days we've had.

Although our house is reasonably insulated you can feel the cold coming through.

 

[Swwils]

The specific heat capacity of water is 4,200 Joules per kilogram per degree Celsius (J/kg°C). This means that it takes 4,200 J to raise the temperature of 1 kg of water by 1°C.

Yes per 1c change as above.

And also it can deliver 4200 J and decreases 1C.

The ability of the rad to transfer that energy to the air is reduced because of the reduced rad to air temp difference when using a low flow temp. Hence the sizing.

So you can very effectively exchange heating speed (which can be accomplished by rad sizing) for overall efficiency. Especially when going against a heat pumps lower CoP during cold temps. Which in the UK isn't really problematic, might dip to 2.3 at worst.

Think of it this way, take a very large emitter like under floor heating. You don't run it at 70C flow do you???

The biggest worry is the hot water demand, which is why everywhere else in the world heat pump grants are combined with solar PV, storage and insulation offerings at the same time.