Heater specification

[David W.]

I see two heater specs for the Morris. One is 2.8kW, and the other is 3.something kW. What are they measuring to get that kW spec?
2.8kw is about 3.8hp, or around 200 amps at 12 volts.
I think I've attached a picture of the fan I have. It's mounted in the engine compartment, not in the heater itself.

[palacebear]

That looks like a pre-heater, usually only fitted to export cars destined for cold climates. Its only purpose is to accelerate the fresh air supply into the heater itself. IIRC you will also have a fan as part of the standard heater set-up under the dash.

[oliver90owner]

Heater specs? Are we talking about the size of the heater matrix under standard conditions of water and air flow?

If the engine is producing 30kW, there will be around three times that amount of waste enegy being produced - hot exhaust gases, noise, radiated heat from the engine surfaces, latent heat of water vapour in the exhaust, etc plus the main heat loss through the radiator cooling system - about 10kW, probably more. That is the heat source, at approx thermostat temperature, for the heater.

Maybe one heater has an extra row of tubes? Different material of matrix? Better finning of the tubes? Larger area? Higher water flow rate? More air fow?

Your pic only shows the fanand connecting cold air ducting. A moggy with dynamo only produces just enough leccy to run the car with heater, wipers and lights all switched on.

[les]

I'll bear that in mind, if I ever have heater issues!

[David W.]

That's my only fan, and it puts out a lot of air. I had the whole heater disassembled when I got the car, it having been derelict for 14 years. This car is a 64. My other is a 60, with the round heater and integral fan.
I'm curious about how they came to rate the heaters in kW's. That calculation of percent of engine output seems a bit round about.

[firedrake1942]

PB is right see attached topic, I thought, as he does, that it was an addition to the under dash heater.

https://www.mmoc.org.uk/MessageBoard/vi ... 11&t=65627

It looks like it was also used as a simple blower in hot countries albeit without the heating element.

It can be replaced but is rather expensive. (Well it is for an Aston Martin)

http://www.classicastons.com/aston-mart ... ing-parts/

[palacebear]

The OP says this is the only blower in the heating system. Whilst I'm sure he is correct, I can't understand how it can work efficiently. I'm pretty sure that effective windscreen demisting can only be achieved by having a blower located adjacent to the heat source (i.e. the heater matrix) inside the cabin.

Refering to firedrake's post (and adding to my previous), I think the fan in the air trunking was specified for many 'extreme' climates, with the ability to boost fresh air for either heating or for simple enhanced ventilation. I recently saw a Minor van with this installation. The van had started its life in Switzerland, so not a particularly hot climate.

[philthehill]

The type of blower fitted to the OPs Minor is typical of the period and was fitted to several different types of BMC vehicles and other marques and did/does not have to be adjacent to the heater element to be efficient.

https://s-media-cache-ak0.pinimg.com/or ... d96e03.jpg

The blower in the picture above is just behind the radiator N/S.