replacing heater valve with dc solenoid valve?
04-15-2003, 04:58 PM
#1
Bumbling Neophyte
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replacing heater valve with dc solenoid valve?
Has anyone ever thought about replacing the heater control valve with a 12v solenoid? I think I will pull the wires off the vaccum solenoid and attach them to the coil of a automotive style DC relay and wire the contacts to a 12V brass body 1/2 inch solenoid valve. This way the climate control signal is not changed and I remove the ever leaky vaccum from the system.
Any questions?
KK
Any questions?
KK
04-15-2003, 05:05 PM
#2
Three Wheelin'
A $10ish heater valve and 50 cents worth of vac line will solve the problem for years to come.
If I was to mod the heater valve, it would be just that. To improve on the plastic valve itself. The weak link, as I see it, is not the vac, it's the plastic material the valve is made of.
BTW, as I finish up my intake r/R, I'm relocating the vac lines and splitters to areas which will not require intake removel to check and sercice most of them.
If I was to mod the heater valve, it would be just that. To improve on the plastic valve itself. The weak link, as I see it, is not the vac, it's the plastic material the valve is made of.
BTW, as I finish up my intake r/R, I'm relocating the vac lines and splitters to areas which will not require intake removel to check and sercice most of them.
04-15-2003, 08:19 PM
#5
Nordschleife Master
What kind of current draw are you going to get on the system?
The problem, as I see it, is that the HVAC spends lought of time in both the of and off possion, but reletivly rarely switched between the two.
When the vacume is held to the valve, as long as there is not a leak, there is no drain on the engine. When the vacume is not supplyed to the valve, again, no drain on the engine. The only time that there is ever a drain on the engine is when you switch it from no vacume to vacume. Not much to worry about, energy wise.
The problem that you might run into with the solenoid is that you'd probably wire it up so that the valve was open, when the solenoid was off. That means when your driveing down the road, with the heat off, the solenoid is drawing current. When you've got the heat off, usualy, you have the a/c on. The compresser's electric clutch sucks up some serious amperage.
I know my 928's altnater is under sized as it is. If I throw the 928's high power ignition system, the head lights, runnding lights, the radio, and a/c it staggers. This is expecaly true in stop and go traffic. I'd hate to add the current draw from the solenoid on top of it.
The reason I said you'd probaly wire it up so that the solienoid was powered when the heater was off is because that the way Porsche did the vacume valve. The reason that they seem to have doen this is because when you stop the car for more than just a little bit, the vacume powers down, and the heater valve open up, and the convection currents carry heat away from the engine, into the heater core. Suppositly hopeing for a more even cool down for the back side of the engine. You could potentialy wire it up the other way around, but it would not act the same way that Porsche designed it to. I wouldn't see it as a problem.
However, you'd still have the draw of the solienoid when the heater is on, but thats better than haveing the power draw when the a/c clutch is on!
The problem, as I see it, is that the HVAC spends lought of time in both the of and off possion, but reletivly rarely switched between the two.
When the vacume is held to the valve, as long as there is not a leak, there is no drain on the engine. When the vacume is not supplyed to the valve, again, no drain on the engine. The only time that there is ever a drain on the engine is when you switch it from no vacume to vacume. Not much to worry about, energy wise.
The problem that you might run into with the solenoid is that you'd probably wire it up so that the valve was open, when the solenoid was off. That means when your driveing down the road, with the heat off, the solenoid is drawing current. When you've got the heat off, usualy, you have the a/c on. The compresser's electric clutch sucks up some serious amperage.
I know my 928's altnater is under sized as it is. If I throw the 928's high power ignition system, the head lights, runnding lights, the radio, and a/c it staggers. This is expecaly true in stop and go traffic. I'd hate to add the current draw from the solenoid on top of it.
The reason I said you'd probaly wire it up so that the solienoid was powered when the heater was off is because that the way Porsche did the vacume valve. The reason that they seem to have doen this is because when you stop the car for more than just a little bit, the vacume powers down, and the heater valve open up, and the convection currents carry heat away from the engine, into the heater core. Suppositly hopeing for a more even cool down for the back side of the engine. You could potentialy wire it up the other way around, but it would not act the same way that Porsche designed it to. I wouldn't see it as a problem.
However, you'd still have the draw of the solienoid when the heater is on, but thats better than haveing the power draw when the a/c clutch is on!
04-16-2003, 07:26 AM
#6
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Thanks for all of the input. In the first case, with Greg's concept, my 18 year old car has multiple vaccum leaks, probably all of the HVAC stuff and even the cruise control, so I am trying to simplify the system by removing all vaccum on my side of the firewall. Remember the golden rule of KK engineeering: KISSES.
Viribus also makes a very good point, so I am going to try for a latching solenoid, ie one that can be held in either position without drawing any current.
I'll keep y'all posted!
KK
Viribus also makes a very good point, so I am going to try for a latching solenoid, ie one that can be held in either position without drawing any current.
I'll keep y'all posted!
KK
