I have a zetex with raceline water rail and a cabin heater that only pumps hot air when the fan is on.
When I have the roof on it does get a bit warm in side and even with the roof is off, it would be great to modulate the temps!
So I was thinking can I put a simple valve on the water circuit to the heater matrix and as I do not use the choke, this could be used to adjust the valve.
I saw this on ebay but this seems to divert the water when as far as I can tell I just need to adjust or stock the flow.
https://www.ebay.co.uk/itm/16mm-5-8-Heater-Control-Valve-Pull-to-Bypass-Kit-Car-Classic-Car-Taxi-TX2/192279138616?hash=item2cc4bad138:g:-ggAAOSwBq1ZlC 5v:rk:22:pf:0
Does this make sense and if so what can I use that can be easily adapted to enable the choke cable to operate the valve?

https://www.ebay.co.uk/itm/16mm-5-8-Heater-Control-Valve-Push-to-Close-Kit-Car-Classic-Car-Taxi-TX1/201955250144?hash=item2f05788fe0:g:iLUAAOSwrH5ZlBa X:rk:7:pf:0
May be simpler, depending on your plumbing.
The choke cable will s=need to be the solid, piano-wite type, not the flexi multi-strands.
But simple emough to connect up, you just need to mount the valve somewhere.

OR for a really simple solition, you can just use a plumbing water shut-off valve. Copper pipe with an olive soldered on is a good fit for 5/8 16mm hose.
Or
https://www.ebay.co.uk/itm/15mm-5-8-Heater-Valve/281886927967?hash=item41a1c52c5f:g:HBwAAOSwCGVX2SRV:rk:10:pf:0

Thanks for the ideas.. I like the really simple idea but will first look how easy it is to get a push/pull wire through

I have fitted a few of these cheap and do the job , I do now however put copper pipe inside as I did crush the pipes on one.
Matty