Heater control valve

[kiloran]

Originally Posted by Michaeleff

Very worth while downloading the full catalogue from Car Builders Solutions:

Here:

They list a number of simple heater valves, as well as loads of other very useful bits and pieces!

Very helpful people.

To save everyone else time in crawling this massive document the valves of interest are listed on page 295.

Search for #BCOHV & #COHTV (the latter looks veery adaptable to the HCV setup in the 940 RHD non a/c as an alternative to the mythical part 9447892)

[bob12]

Originally Posted by Rumbo

Someone from "Brookhouse Volvo" got back to me and said that "Volvo" are looking into reproducing this part later on this year because of demand...Sounds like a good idea!

If it hasn't been mentioned the easiest fix is the Mk 1 Golf VAG etc valve off ebay for about £6/8 plus a few small bits of pipework. I put up a post some years ago with the details.

Bob

[Laird Scooby]

Originally Posted by Michaeleff

A simple 12 Volt DC solenoid operated water valve should do the trick.

See Here:

Only problem would be it has just two states: fully open or fully closed.

Boil your feet or freeze!

When clearly, what is required is an adjustable valve: which would mean a "Stepper" motor as against a solenoid.

Another small thought.....

Since the Solenoid valve is NC (Normally Closed) and requires 12 volts DC to enable it, quite simple to create a small 12 V DC circuit using a Thermistor, which could turn the Valve On and Off (via a small relay) when desired temperature is reached. could measure the outgoing matrix feed pipe temperature; or the heater housing box etc.

One could also use a simple dash-mounted Potentiometer to adjust the desired temperature.

See Here:

The rotary heat control should be retained only to operate the heater air inlet flap (extreme clockwise setting) as this provides re-circulating air in the car, rather than constant fresh air taken from the scuttle duct.

Wrong in almost every assumption there Michael! The OE valve has two states, open or shut, it is closed when minimum temperature is selected by the slide/rotary temperature selector on the heater controls. As the control is moved away from minimum it opens rapidly and the temperature is controlled by the air mix flap. Overcomplicating it with stepper motors would not just be a PITA to design and make but total overkill on the needs of the heater system

A simple valve such as the Mk1 Golf valve (abailable for about £5 on fleabay) is much easier to implement and almost a direct replacement - some minor mods will be needed obviously but nothing like the control system for a stepper motor!

Originally Posted by kiloran

Thinking further on this - and bearing in mind I know nothing about circuits, but do know a fair bit about smart home and bluetooth/wifi would these options solve the issue?

1. Smart radiator valve - bluetooth controlled? I'm guessing that they must give variable heat settings rather than the on/off of a solenoid? There are also battery-powered solenoid valves used for irrigation systems which cuts down on wiring requirements. Bluetooth control appeals to me - after all, it was invented by Swedes and has very low power requirements and high resilience.

2. Raspberry Pi-controlled system? There are solenoids available that work on a 12v supply

e.g. https://thepihut.com/products/adafru...2v-1-2-nominal
(has a minimum pressure requirement of 3psi and only flows one way though - not sure if that's an issue - only draws 1 amp)

Or

https://thepihut.com/products/adafru...ve-12v-1-2-nps

Which is 12v/3A

There's plenty of space behind the dash to locate the control box and a Pi is perfectly happy running on 12v DC - and is quick to boot. If you use the car regularly you could leave the Pi permanently powered.

I'm probably massively over-complicating things!

Originally Posted by kiloran

To save everyone else time in crawling this massive document the valves of interest are listed on page 295.

Search for #BCOHV & #COHTV (the latter looks veery adaptable to the HCV setup in the 940 RHD non a/c as an alternative to the mythical part 9447892)

As i've said above, massive over-complications! A simple 12V solenoid valve with a 15mm bore (you'd even get away with 12mm) and a microswitch to close the solenoid when in the cold position fitted to the back of the heater control panel would work and above all, is simple so there is less to go wrong.

Some facts to bear in mind :

The heater valve is only closed when the temperature selector is set to minimum

The coolant temperature is in the region of 90C so that needs to be taken into consideration

Most solenoid valves are either open or shut, very few (if any) are also one-way restrictors as well as being simple open/shut devices.

There are loads of cost-effective, simple solutions to this problem, you just need to look and think outside the box

Also remember when considering any fruit-based devices that are designed for 12V, they are designed for 12V - not 14V as the output from the alternator is. Chances are, they will fail in short order if used in a car unless a 12V voltage regulator is used.
Net result - empty wallet, fruit flambe and fried chips followed by tears.

[kiloran]

Originally Posted by bob12

If it hasn't been mentioned the easiest fix is the Mk 1 Golf VAG etc valve off ebay for about £6/8 plus a few small bits of pipework. I put up a post some years ago with the details.

Bob

Thanks, that's useful. What I'm slightly struggling with is how the pipework works behind the valve. Does it just push through the firewall and connect directly to the lower of the heater circuit pipes in the engine bay?

[Laird Scooby]

Originally Posted by kiloran

Thanks, that's useful. What I'm slightly struggling with is how the pipework works behind the valve. Does it just push through the firewall and connect directly to the lower of the heater circuit pipes in the engine bay?

Short link hose between the valve and heater matrix then an elbow into the bulkhead and out into the engine bay.

Using the Mk1 Golf valve (as i also suggested in my long post above) is more or less a straight swap in terms of hose connections at least.

[bob12]

If this link works you will see the post I put up re the Golf Mk 1 heater valve work around. Bob

https://www.volvoforums.org.uk/showt...=144937&page=2

[Laird Scooby]

Originally Posted by bob12

If this link works you will see the post I put up re the Golf Mk 1 heater valve work around. Bob

https://www.volvoforums.org.uk/showt...=144937&page=2

Took me a while to find it from the link Bob, here's a link to the actual post :

https://www.volvoforums.org.uk/showp...5&postcount=16

Probably doesn't help my posts per page is set to 25 so it went to page 2 which started 9 posts ahead of your relevant post!

[bob12]

Bit like your monster pics I have to deal with scrolling across the page!! Only too happy to make you work for it Sorry, about the small size of print. Bob