25 replies to this topic

[ddpunter]

this is all based on an assumption, so it may get shot down early but here goes. the assumption is that the heater matrix draws its air from the two rectangular holes you can see below the rad as you look through the front grill. if you make a duct/hose from the holes to the underside of the rad would it... i) make the air to the car hotter as it is already pre warmed because it is passing over/through the rad and ii) stop all the dust and crap coming up through the vents and onto the dash because it is no longer taking its air feed direct from the road and keep the air flow at a reasonable level as it is not trying to force it through a 'sock/tights' filter help, any comments cheers d

[goofballs]

I'll help you along with this thread if you don't mind. Keep it right up there when you View New Posts.

[GerryM]

Sounds good, please someone answer this quickly, I am fcuking freezing !!

[caleebra]

I cannot comment on the assumption about where the heater draws it's air from, but I would agree with the thermodynamics part.

[GerryM]

Up to the top !!

[garyk220]

Driving down to Bicester on Sunday evening, I noticed that above 70mph there was very little heat being output. Slowing down to 50-60 in roadworks, busy sections produced a reasonable amount of heat. It was absolutely freezing in Oxfordshire on Sunday & Monday, so I wonder if the airflow through the engine bay at high speeds on very cold days is enough to keep the water temperatures sufficiently cool, and keep the water thermostat closed. If this is the case, no hot water will pass through the radiator, or the heater matrix. Slowing down would reduce the airflow cooling and raise the water temperature enough to open the thermostat, thereby allowing the hot water to flow to the front of the car and pass through the radiator and heater matrix. This effect would be most noticeable on very cold days, which is when you need the heater most unfortunately. If this is the case, then one way to solve the heating isssue would be to replace the engine mounted thermostat for one at the radiator input pipe. This way, the hot water would be able to flow through the heater matrix all the time, only the radiator would be locked out of the system. The downside is the engine would take longer to heat up, but the hot/cold oscillations would be much less severe. I seem to remember a similar mod for Elises - sold by Eliseparts I think - to help protect the K series head gasket from heat cycle damage.

[Steve Crisp]

I have often wondered why they didn't just duct the air going though the radiator into the cab. Ducting has got to be lighter than the heater module. The air flows upward through the rad and out the top, so I guess the main problem is how you can duct away from the top of the rad without lowering the effectiveness of the cooling when you don't want any more heat. They've presumably taken the safe approach of sorting out the cooling issues for the engine before worrying about warming up the cab. Whatever you decide, it'll take major surgery to change the way it is! Steve

[Pipo]

Doesn't bother me. I'm always driving without top, even below 0 °C. As long as its dry out there, of course

[cheeky_chops]

check this puppy out

Attached Files

•  28._20Heating_20__20Ventilation.pdf   188.68KB   810 downloads

[Ricky2772]

do not forget to check the hose exiting the engine....if it is choked by the tie-wrap like mine was, your heater will be crap, guaranteed.

[cheeky_chops]

Goto page 5 (below) and you will see a pic of the engine bay and the heater matrix. My heat USED to be shite until when the heat was on full a begain to fiddle with the "Temperature Flap Lever" on the matrix. I found that even though the heat was set to maximum in the cabin, i could manually turn the "Temperature Flap Lever" another 30degrees. This seemed to do the trick I havent touched the cabin control since October!

Attached Files

•  temp_flap.jpg   92.71KB   10 downloads

[Bengie]

Thanks Cheeky! I knew I'd seem a picture of the layout of the heater flow & return hoses - searched through TIS last night and couldn't find it. Forgot about the Lotus service book thingie.

[iandhd]

There must be some gems in here for the FAQ surely cheers

[dkennedyVXT]

Without sounding too stupid...does that temperature flap lever reside in the front ot back of the car and is it easily visible?

[Bengie]

At the front, and yes, it's easily visible - looks just like the line drawing above ...

[JimH]

I have often wondered why they didn't just duct the air going though the radiator into the cab. Ducting has got to be lighter than the heater module.

Three words.

Air Cooled Volkswagens.

[Bengie]

*shudder* or, rather *shiver*

[JimH]

*shudder*

or, rather *shiver*

That was the first stage. Temperatures soon climbed to the point where milk would boil and cassettes which fell in front of the heater outlet would shrink to 50% their original size. All this while the windscreen was still misted up.

Beetles, eh?

[Lambo]

Is it possible to access the "alloy tubes" that run the length of the car. These will lose a lot of the heat during the run from engine to heater matrix. Lagging these would help. Has anyone measured the temperature of the water in to the heater matrix? Why not feed directly from the hose feeding the main radiator at the front of the car? This will get a much higher flow rate and is likely to be hotter fluid. I don't know what effects this might have on the radiator "balancing". If you could plumb directly in to the radiator you could save the weight of the tubes and fluid to the heater matrix. Any comments? What about fitting a larger heater matrix from another vehicle? A