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Comparing heating power

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akis:
Hi guys, I have not explained well what information I was after.

There is no doubt that electric devices (eg hairdryer, electric heater, kettle etc) are exactly what's on the label and really generate 2000W of heat if the label says so. I have also verified with power meter.

From past experience, and recent tests into a 20m2 room, with 5 thermometers around the room and fan assisted heating, I can say that 2000W is not enough to warm this room from say 13C up to 20C in reasonable time (2 hours). Actually it never reaches 20C (outside temps anything from 0C to 12C) - I switch it off at about 17C-18C.

Central heating, water filled radiators, report their power (in watts) based on the strict condition that [ radiator temp - room temp =  50C, known as "Dt50" ]. To explain this metric, when your radiator is at 70C (average) and your room is at 20C, the difference being 50C, at that precise point the radiator is said to emit 2000W of heat.

Intuitively I know that those radiators produce 2-3 times the heat of the hair dryer or the electric heater, but they are all rated at the same wattage, 2000W.

It follows that the Dt50 power rating for water filled, central heating radiators, cannot be readily compared to our tried and tested electrical power ratings.

Is there a rule of thumb equivalence or conversion, between Dt50 and electrical power ratings?

wraper:

--- Quote from: akis on December 22, 2023, 06:26:23 am ---There is no doubt that electric devices (eg hairdryer, electric heater, kettle etc) are exactly what's on the label and really generate 2000W of heat if the label says so. I have also verified with power meter.

--- End quote ---
Far from that. As I said about oil radiators, they technically don't lie about power rating but are an utter scam because they consume rated power only while heating up with some rare exceptions, which are, surprise, much larger than the rest. Even My $170 1500W oil radiator does this, albeit to lower extent than cheap ones, becoming about 900W IIRC. It has 3 power level settings, highest one being utterly useless.

akis:

--- Quote from: wraper on December 22, 2023, 08:21:58 am ---don't lie about power rating but are an utter scam because they consume rated power only while heating up

--- End quote ---

The electrical heater does not have enough surface area to generate adequate air flow by convection only. It gets really hot and switches off even though the room is cold.

I have put an upright fan behind my electrical heater, like a fan assisted heat sink, and the glow light never goes off, so I know it is consuming full power.

I have placed 5 thermometers in the room and they record different temperatures, about 2C-3C difference from side to side, and maybe up to 5C difference from floor to ceiling. This is with fan active in the room. It would be much worse with fan off.

wraper:

--- Quote from: akis on December 22, 2023, 08:48:37 am ---The electrical heater does not have enough surface area to generate adequate air flow by convection only. It gets really hot and switches off even though the room is cold.

--- End quote ---
So you just confirmed its specs are an utter deception, external fan is not part of the radiator, and not how it's intended to be used. Original question implies why some radiators with same power rating are larger than others? Yes there are radiators with true power rating and no deceptive practices, Delonghi Dragon for example.

NiHaoMike:

--- Quote from: EPAIII on December 22, 2023, 03:24:16 am ---But heat pumps are not portable, they are installed in the building with pipes/tubes carrying gas and liquids back and forth between inside and outside.

--- End quote ---
Portable heat pumps exist.
https://www.midea.com/us/air-conditioners/portable-air-conditioners/midea-duo-12-000-btu-sacc-smart-inverter-portable-air-conditioner

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