380 replies to this topic

[moneyhunster]

Does anyone know what amps the original heater draws?

[slindborg]

errrr less than 10 amps (but will have a switch on surge) as for sub £100, I think some of you are a touch deluded... I'd "just" about be able to knock out my shitty looking one for £100 taking fcuk all for the labour, so a company doing it with a £20 valve, £30-£40 fan, atleast £20 in high power speed control resistors and then the rad/airbox assembly you are knocking on the door of £100 without labour and profit (no profit isnt a dirty word)

[Lou_m]

errrr less than 10 amps (but will have a switch on surge)

as for sub £100, I think some of you are a touch deluded... I'd "just" about be able to knock out my shitty looking one for £100 taking fcuk all for the labour, so a company doing it with a £20 valve, £30-£40 fan, atleast £20 in high power speed control resistors and then the rad/airbox assembly you are knocking on the door of £100 without labour and profit (no profit isnt a dirty word)

[T7Design]

Hi Guys, As Slindborg has said the replacement is definitely not going to be £100 or less. Just off the top of my head I think the parts list on top of just the heater box will include: Heater box inc fan & rad Bypass valve Fan control module (if resistor pack is not compatible)* Length of correct size ducting to feed cabin SS Clips for ducting SS clips for heater hose Bolt pack for above * I am currently working on a microprocessor controlled module to give 3 fan speeds for up to 3 fans (totalling a whopping 570cfm or 991m3/hr) and up to 3 pairs of servo's (for controlling air direction). I will have to see what the outputs are on the original VX220 switch to see if this is compatible otherwise I will have to supply a correct spec resistor pack. The Microprocessor system controls the fans by PWM (pulse width modulation) and as there is nothing that gets hot there is nothing to wear out. Regards, Adam

[ChrisS1]

Fair play sounds like you know your stuff Adam! Looking forward to seeing what you can come up with. Good luck :up

[Paulus H]

Adam, keep going with the heater project. We NEED a solution for the heater problem. Paul

[T7Design]

Here is a custom solution I designed for my Dad's MGB, it is based on an original but was extended outwards to incorporate a thicker fan and twin radial fans that I imported from the states, these fans are more powerful, flow 250cfm each and are very loud so definitely needed a fan controller. The pictures you see are of the stainless steel version before polishing, I think in the end it got powder coated black as it looked better within the engine bay. I doubt anything as complex will be required as the MGB unit but at least you guys can see some idea of the quality of construction I aim to achieve with this project.

Attached Files

•  MGB Heater 1.jpg   260.37KB   6 downloads
•  MGB Heater 2.jpg   189.67KB   3 downloads

[techieboy]

Not sure what the stats are for the OE fan in the VX but, it's already plenty powerful and feels like it flows a decent amount of air. It might well be more cost effective to try and reuse this fan module (it does come off the heater box) and concentrate more on the heater box and matrix. It's the leakage from the standard kit (all the way through the different parts of the system) which really affects what gets into the cabin.

[Paulus H]

I agree with Techieboy. Keeping the cost sensible so you can sell these to a lots of VX220 owners has to be better than selling a few to owners with big pockets who are looking for a furnace! Paul

[moneyhunster]

So the electrical things in the original box are just resistors to control the flow from the fan? Why are they in the heater box, and why not use a variable type resistor on the dial in the car? Testing mine tomorrow.

[techieboy]

Why? Who knows? Probably a parts bin special from some defunct manufacturer that Lotus got a special deal on. But, yes, two resistors to knock back the current to the fan, to give the three speeds.

[moneyhunster]

What's the worst that could happen adding the resistors to the modular heater from T7?

[T7Design]

The resistor prevents a percentage of power in the line passing by removing it in the form of heat and so they need to be cooled, this is why the resistor pack has been placed within the airflow. You will find a lot of older cars lose fan speed one (slowest) as this resistor has to remove the most amount of electrical energy as heat, you may find that this resistor is larger however it may also be the most used fan speed setting. @MoneyHunster. I am not 100% sure on the exact details but the resistors have to be matched to the voltage, the total current draw and then you have to know how much you want to reduce the current to the fan by to give you your desired fan speed. I am sure somebody on here with an electrical engineering background can explain it far better than I can!

Edited by T7Design, 08 January 2011 - 11:43 PM.

[techieboy]

Adam can probably answer that better. I guess the worst case is that there is too much current with the new fan and it burns out the resistor wire leaving you stuck with full speed only.

[techieboy]

Bugger. Beaten to it.

[moneyhunster]

On the heater which wire is positive and negative? Black and green?

[slindborg]

Adam, if you need any electronics/software help give me a shout Automotive electronics/software is the day job. The resistor wires are in the airbox as its got a flow of air, even if you got the air to 30Deg C its still going to cool the resistors to stop them having a fit. OR use some high quality ali cased resistors that you can bond to the ali chassis to dump the heat better/more reliably

[moneyhunster]

The resistors seem to work fine once installed in the T7 modular box. Still got 3 speeds.

[Paulus H]

Moneyhunster, sounds like you have a T7 prototype. Apart from the fan speeds, how is it shaping up??? Paul

[moneyhunster]

Moneyhunster, sounds like you have a T7 prototype. Apart from the fan speeds, how is it shaping up???


Paul

Naah not yet bud, I bought the T7 modular box and retro fitted it today, I couldn't wait for the replacement, use the car every day and having a gaping hole in my heater box I had to do something. Already seems hotter, Had a glass of wine with tea so can't road test it until tomorrow but I'll post the results after work, should give us an idea. The air flow should be even better on the road. Looking forward to a cosy drive to work!