380 replies to this topic

[davemate]

i always thought the flaw way the filtering of the air, the transfer of the air from the heater to the dash and the air lost in the dash its self. although i remember seeing a thread of sealign up the heater to improve losses that way.

[slindborg]

Let's take a step back for a minute.

What is the limiting part of the original heater design [or lack of design]?

Is it airflow?

It is simply surface area of the matrix?

Is it the temperature of the coolant entering the matrix?

Is it the rate of flow of coolant through the matrix?

Is it simply system losses?

There are clearly system losses due to gaps in the matrix surround, the attached piping and gaps under the dash, however i suspect people who have performed the heater mod still feel it doesn't perform well. Therefore not losses. The airflow at maximum appears acceptable, it's not the strongest i've seen, but certainly enough to transmit the heat to the cabin. therefore not airflow.

My gut feeling is that it's either poor heat transfer due to a crap matrix design, or a too low flow rate from the pump? thoughts?

The matrix itself is 150% ovespecced as I found out*, the coolant flow rate and temperature is fine, the fan itself is 'fine'.... Its just been chucked in a box by what can only be described as a retard...


*actual %age may vary

[fezzasus]

The matrix itself is 150% ovespecced as I found out*, the coolant flow rate and temperature is fine, the fan itself is 'fine'.... Its just been chucked in a box by what can only be described as a retard...


*actual %age may vary

Wouldn't that mean that with the heater and dash sealed, the heater works very well? It's my impression that while it's an improvement, it's never as good as a typical shed.

Here's my thinking;

From fan and matrix back the system is under positive pressure, which forces hot air out of all the gaps, however because it's under positive pressure it means that there shouldn't be cold air mixing with the hot air that DOES reach the cabin. The air coming out of the vents at full is never hot, simply warm. this implies that the air isn't heated effectively enough at the source [the heater matrix] rather than the cause being any losses along the way. This points towards a crappy matrix or crap coolant flow. I can't make up my mind about the matrix; the round tubing is poor for conduction, but it's got multiple passes to make up for it, and honestly I don't know about the flow to the matrix.

Edited by fezzasus, 11 May 2011 - 04:23 PM.

[Mangham54]

The matrix itself is 150% ovespecced as I found out*, the coolant flow rate and temperature is fine, the fan itself is 'fine'.... Its just been chucked in a box by what can only be described as a retard...


*actual %age may vary

Wouldn't that mean that with the heater and dash sealed, the heater works very well? It's my impression that while it's an improvement, it's never as good as a typical shed.

Here's my thinking;

From fan and matrix back the system is under positive pressure, which forces hot air out of all the gaps, however because it's under positive pressure it means that there shouldn't be cold air mixing with the hot air that DOES reach the cabin. The air coming out of the vents at full is never hot, simply warm. this implies that the air isn't heated effectively enough at the source [the heater matrix] rather than the cause being any losses along the way. This points towards a crappy matrix or crap coolant flow. I can't make up my mind about the matrix; the round tubing is poor for conduction, but it's got multiple passes to make up for it, and honestly I don't know about the flow to the matrix.

Conversely I would read what Stuart as saying exactly as he said... That the biggest problem with the VX heater is nothing more than a completely unsuitable heater case. Every other part could be fine, but with everything else producing pressure against the air flow, then a lot of the pressure is dumped back on the fan wheel. Now if the casing is not suitable it will just bleed pressure and even possibly draw cold air around the side of the mixer flap and into the hot air flow.

When I looked at it I couldn't believe how childish the design seemed and I am no engineer! Mine is due to be removed in the coming month or so, in an attempt to have another go with it when it is pretty much surplus to requirements.

[slindborg]

Put it this way, (as I've said MANY times) I made a box for the OEM heater matrix to live in with air in and out inline and then when being used it overcooled the engine and made the cabin unbearable OK that was with an inline fan but imho it puts out less pressure/flow than the OEM one.

[Gizmotron]

Put it this way, (as I've said MANY times) I made a box for the OEM heater matrix to live in with air in and out inline and then when being used it overcooled the engine and made the cabin unbearable

OK that was with an inline fan but imho it puts out less pressure/flow than the OEM one.

I also made my own heater box, but used a larger rad from a fiat x19 my heater mod and 100% agree that if the heater box was sealed like any other car heater box and there was no silly letter box flap to direct hot and cold air then the cabin gets extremely hot which i can vouch for. Even with the slightest flow in to my matrix my cabin get hot quickly.

If the original matrix was used in a sealed box using the existing fan then i reckon enough heat would fill the cabin. The only draw back is the loss from the ducting under the clam that enters the cabin. i have even sealed up my dash to prevent a lot of the losses, but its not enough for a fast rate of air flow

Edited by Gizmotron, 12 May 2011 - 09:15 AM.

[chrisgold]

My added problem is I have a pro alloy rad and my engine only reaches 73c when being thrashed, idling etc..... so never gets hot enough to produce heat... here is my solution- http://cgi.ebay.co.u...#ht_3097wt_1139 Its the best one for they money 200w and its ceramic and only £17 ish

[Paulus H]

Chris, does that really heat up the car in winter??? Best regards, Paul

[NickCG]

73c is still pretty damn hot, if you had an efficient heater system I'm sure it would be sufficient. I thought about one of those heaters but when I saw my mate's I realised they give out very little - 200W is not much at all, and you lose a lot through the hood, it's a big heat sink with all the metal in there - it is a small space it's got to heat though so might be worth a try? How do you find it Chris?

[slindborg]

Chris, does that really heat up the car in winter???

Best regards, Paul

Doubt it very much... I've been working with some electric car heaters recently and to get nay form of whole cabin warmth you need ATELAST 2Kw output but preferably 4KW for winter....
And thats with a super efficient PTC heater element




Oh and 73Deg is dangerously low imho.... 80-85deg MIN would be ideal but hey.

[T7Design]

Hi guys, I have passed over the prototype heater to MoneyHunster, and his results reflected what I felt comparing the unit to the original on the bench in that the flow was comparable, however moneyhunster did say that the heat output was greater. I have since ordered 4 sizes of squirrel cage fans, and 4 sizes of radiator core to see what will work best. Prototype no.2 is on the way!

[T7Design]

I cant work out how to edit my previous post to include some other points I forgot to add!

Anyway, even the most powerful squirrel cage fan that I have purchased is cheaper than both the 2 fans currently in prototype 1, however the cores are approximately the same cost but as they come with 5/8" fittings already there is no need to use the following hose adapters which saves on cost further. I believe I may be able to come up with something cheaper than I originally anticipated but definitely not sub £200.

http://www.t7design....products_id=274

The fans also have a 3 speed system built in, so I believe we can throw away the existing resistors and hook them up directly to the switch that is already installed. Stay tuned for more updates!

[Paulus H]

Adam please offer us something that is a direct replacement for OEM. Works like OEM but much warmer. The details are interesting but results are very important. Paul

[moneyhunster]

thats exactly whats being designed.

[Crazyfrog (Fab)]

My gut feeling is that it's either poor heat transfer due to a crap matrix design, or a too low flow rate from the pump? thoughts?

mine is to hot......do i blame the itb's ?

[T7Design]

Adam please offer us something that is a direct replacement for OEM. Works like OEM but much warmer.

The details are interesting but results are very important.

Paul

Hi Paul,

That is exactly what I am aiming to do. Initially the prototypes are to test out the fans and cores & so will look very basic and a bit heath robinson, if they are a success and the people testing the prototypes are happy with the results then I will concentrate on finalising the system to meet the following specification:

• Install using existing mounting holes.
• 3 Speed fan operation using original fan control switch.
• Use existing air inlet to heater box.
• Incorporate a removable dust filter.
• Fully sealed box - constructed out of laser cut aluminium panels & powder coated for a quality finish.
• Include a 2 way water valve to replace flap within original heater box, this is cable operated so will work with original heater panel in interior.
• Include all hose, fittings, wiring and full instructions to offer an easy to install solution.

Please add to the list if you feel there is anything else I have missed out.

Edited by T7Design, 21 May 2011 - 12:31 AM.

[stigg10]

• Compatible with both RHD & LHD (for our Opel Speedster driving friends)

[KurtVerbose]

• Compatible with both RHD & LHD (for our Opel Speedster driving friends)

...and to expand your market!

[Paulus H]

If you can hit all those targets, it will be a no brainer to buy your heater. For my sake, I hope it all works out - I use my my car all year round. Paul

[moneyhunster]

If you can hit all those targets, it will be a no brainer to buy your heater. For my sake, I hope it all works out - I use my my car all year round.

Paul

same here bud, it will improve winter driving no end!