Fan assistance for radiators.

[foxhole]

Airflow, will always cool a radiator, or any other hot/warm surface down quicker, and transfer the heat to the surrounding more effectively. If that source of heat is replenished, as a radiator, supplied by a boiler would, then it will continue to transfer more heat - why would it not?

Output from radiator is fixed , fan has no effect.Once the air is circulating there is nothing to be gained by a fan.

 

[Harry Bloomfield]

Output from radiator is fixed , fan has no effect.

Output is quoted for convection, the output can be increased, by improving the airflow.

 

[RandomGrinch]

Output is quoted for convection, the output can be increased, by improving the airflow.

So for an equivalent case - if we had a 1 kW electric heater and added a fan to it, are you saying it's output power will increase from 1kW?

The fan will definitely enhance the heat distribution within the room.

 

[bsr]

So for an equivalent case - if we had a 1 kW electric heater and added a fan to it, are you saying it's output power will increase from 1kW?

The difference is the delta T. The difference between the heat emitter temperature and the room temperature.

For an electric element the dT is several hundred degrees so regardless of a fan the element will kick out the 1kw.

For a radiator or wet kickboard heater the dT will be 20-40 degrees between flow and room temperature and the quoted heat output of the radiator will make an assumption about that dT. Increasing air flow rate will lower the temperature over the heat exchanger, increasing the amount of heat transferred.

See page 280 for a description from Myson:

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.myson.co.uk/static_files/my/media/downloads/33926%2520Product%2520Range%2520Brochure%2520-%2520Back%2520End%2520P1.pdf&ved=2ahUKEwjrwb7a3O6DAxUN7rsIHS__CogQFnoECBgQAQ&usg=AOvVaw1wxS9E9Nbt0GOrHtbfMYPE

 

[RandomGrinch]

The difference is the delta T. The difference between the heat emitter temperature and the room temperature.

Thanks, I was getting into the delta Ts.
I was reacting to Harry's post about airflow, without noticing he had qualified it in the previous post -

If that source of heat is replenished, as a radiator, supplied by a boiler

 

[Harry Bloomfield]

So for an equivalent case - if we had a 1 kW electric heater and added a fan to it, are you saying it's output power will increase from 1kW?

The fan will definitely enhance the heat distribution within the room.

If the boiler were able to maintain the temperature, then yes, a fan would add more heat into the air.